Showing 1–47 of 47 results for author: Thornton, R T

Testing Meson Portal Dark Sector Solutions to the MiniBooNE Anomaly at CCM

Authors: A. A. Aguilar-Arevalo, S. Biedron, J. Boissevain, M. Borrego, L. Bugel, M. Chavez-Estrada, J. M. Conrad, R. L. Cooper, A. Diaz, J. R. Distel, J. C. D'Olivo, E. Dunton, B. Dutta, D. Fields, J. R. Gochanour, M. Gold, E. Guardincerri, E. C. Huang, N. Kamp, D. Kim, K. Knickerbocker, W. C. Louis, J. T. M. Lyles, R. Mahapatra, S. Maludze , et al. (20 additional authors not shown)

Abstract: A solution to the MiniBooNE excess invoking rare three-body decays of the charged pions and kaons to new states in the MeV mass scale was recently proposed as a dark-sector explanation. This class of solution illuminates the fact that, while the charged pions were focused in the target-mode run, their decay products were isotropically suppressed in the beam-dump-mode run in which no excess was obs… ▽ More A solution to the MiniBooNE excess invoking rare three-body decays of the charged pions and kaons to new states in the MeV mass scale was recently proposed as a dark-sector explanation. This class of solution illuminates the fact that, while the charged pions were focused in the target-mode run, their decay products were isotropically suppressed in the beam-dump-mode run in which no excess was observed. This suggests a new physics solution correlated to the mesonic sector. We investigate an extended set of phenomenological models that can explain the MiniBooNE excess as a dark sector solution, utilizing long-lived particles that might be produced in the three-body decays of the charged mesons and the two-body anomalous decays of the neutral mesons. Over a broad set of interactions with the long-lived particles, we show that these scenarios can be compatible with constraints from LSND, KARMEN, and MicroBooNE, and evaluate the sensitivity of the ongoing and future data taken by the Coherent CAPTAIN Mills experiment (CCM) to a potential discovery in this parameter space. △ Less

Submitted 22 March, 2024; v1 submitted 5 September, 2023; originally announced September 2023.

Comments: Corrected calculation mistake in Eq. 11. Revised sections for submission to PRD

Report number: LA-UR-23-29529

The COHERENT Experimental Program

Authors: D. Akimov, S. Alawabdeh, P. An, A. Arteaga, C. Awe, P. S. Barbeau, C. Barry, B. Becker, V. Belov, I. Bernardi, M. A. Blackston, L. Blokland, C. Bock, B. Bodur, A. Bolozdynya, R. Bouabid, A. Bracho, J. Browning, B. Cabrera-Palmer, N. Chen, D. Chernyak, E. Conley, J. Daughhetee, J. Daughtry, E. Day , et al. (106 additional authors not shown)

Abstract: The COHERENT experiment located in Neutrino Alley at the Spallation Neutron Source (SNS), Oak Ridge National Laboratory (ORNL), has made the world's first two measurements of coherent elastic neutrino-nucleus scattering (CEvNS), on CsI and argon, using neutrinos produced at the SNS. The COHERENT collaboration continues to pursue CEvNS measurements on various targets as well as additional studies o… ▽ More The COHERENT experiment located in Neutrino Alley at the Spallation Neutron Source (SNS), Oak Ridge National Laboratory (ORNL), has made the world's first two measurements of coherent elastic neutrino-nucleus scattering (CEvNS), on CsI and argon, using neutrinos produced at the SNS. The COHERENT collaboration continues to pursue CEvNS measurements on various targets as well as additional studies of inelastic neutrino-nucleus interactions, searches for accelerator-produced dark matter (DM) and physics beyond the Standard Model, using the uniquely high-quality and high-intensity neutrino source available at the SNS. This white paper describes primarily COHERENT's ongoing and near-future program at the SNS First Target Station (FTS). Opportunities enabled by the SNS Second Target Station (STS) for the study of neutrino physics and development of novel detector technologies are elaborated in a separate white paper. △ Less

Submitted 9 April, 2022; originally announced April 2022.

Comments: 38 papers, 24 figures; Snowmass contribution

LANSCE-PSR Short-Pulse Upgrade for Improved Dark Sector Particle Searches with the Coherent Captain Mills Experiment

Authors: R. G. Van de Water, S. G. Biedron, E. -C. Huang, A. J. Hurd, W. C. Louis, S. V. Milton, N. A. Moody, P. deNiverville, C. E. Taylor, R. T. Thornton, M. Fazio, S. I. Sosa, T. J. Schaub, J. W. Lewellen

Abstract: Proton beam dumps are prolific sources of charged and neutral pions, enabling a powerful technique to search for dark matter, axions, sterile neutrinos, tests of short baseline anomalies, and precision measurements of coherent nucleus scattering neutrinos (CEvNS). The Lujan neutron elastic scattering center at the Los Alamos Neutron Science Center (LANSCE) consists of an 800-MeV, short-pulse, 100-… ▽ More Proton beam dumps are prolific sources of charged and neutral pions, enabling a powerful technique to search for dark matter, axions, sterile neutrinos, tests of short baseline anomalies, and precision measurements of coherent nucleus scattering neutrinos (CEvNS). The Lujan neutron elastic scattering center at the Los Alamos Neutron Science Center (LANSCE) consists of an 800-MeV, short-pulse, 100-kW proton and spallation neutron source where such searches are ongoing with the Coherent CAPTAIN Mills (CCM) 10-ton, liquid argon detector. The employment of fast timing coincidence of the beam with the detector is used to identify signals and reject background. The current beam time width is 300 ns with an intensity of $3.1 \times 10^{13}$ protons per pulse at 20 Hz. With upgrades to the Proton Storage Ring (PSR), the beam time width may be compressed to 30 ns with minimal intensity loss, allowing an increase in the signal to background (S/B) of more than 100 and an increase in the sensitivity for dark matter and sterile neutrino searches of an order of magnitude. This can be achieved with PSR accelerator upgrades on a time scale of a few years and at a modest cost. △ Less

Submitted 4 April, 2022; originally announced April 2022.

Comments: 6 pages, 3 figures, contribution to Snowmass 2021

Report number: LA-UR-22-22687

SBN-BD: $\mathcal{O}$(10 GeV) Proton Beam Dump at Fermilab's PIP-II Linac

Authors: Matt Toups, R. G. Van de Water, Brian Batell, S. J. Brice, Patrick deNiverville, Jeff Eldred, A. Fava, Kevin J. Kelly, Tom Kobilarcik, W. C. Louis, Pedro A. N. Machado, Bill Pellico, Josh Spitz, Rex Tayloe, R. T. Thornton, Z. Pavlovic, Jaehoon Yu, J. Zettlemoyer

Abstract: Proton beam dumps are prolific sources of mesons enabling a powerful technique to search for vector mediator coupling of dark matter to neutral pion and higher mass meson decays. By the end of the decade the PIP-II linac will be delivering up to 1 MW of proton power to the FNAL campus. This includes a significant increase of power to the Booster Neutrino Beamline (BNB) which delivers 8 GeV protons… ▽ More Proton beam dumps are prolific sources of mesons enabling a powerful technique to search for vector mediator coupling of dark matter to neutral pion and higher mass meson decays. By the end of the decade the PIP-II linac will be delivering up to 1 MW of proton power to the FNAL campus. This includes a significant increase of power to the Booster Neutrino Beamline (BNB) which delivers 8 GeV protons to the Short Baseline Neutrino (SBN) detectors. By building a new dedicated beam dump target station, and using the SBN detectors, a greater than an order of magnitude increase in search sensitivity for dark matter relative to the recent MiniBooNE beam dump search can be achieved. This modest cost upgrade to the BNB would begin testing models of the highly motivated relic density limit predictions and provide novel ways to test explanations of the anomalous excess of low energy events seen by MiniBooNE. △ Less

Submitted 23 September, 2022; v1 submitted 15 March, 2022; originally announced March 2022.

Comments: Contribution to Snowmass 2021

Report number: FERMILAB-FN-1157, LA-UR-22-22524

PIP2-BD: GeV Proton Beam Dump at Fermilab's PIP-II Linac

Authors: M. Toups, R. G. Van de Water, Brian Batell, S. J. Brice, Patrick deNiverville, Bhaskar Dutta, Jeff Eldred, Timothy Hapitas, Roni Harnik, Aparajitha Karthikeyan, Kevin J. Kelly, Doojin Kim, Tom Kobilarcik, Gordan Krnjaic, B. R. Littlejohn, Bill Louis, Pedro A. N. Machado, Nityasa Mishra, V. Pandey, Z. Pavlovic, William Pellico, Michael Shaevitz, P. Snopok, Rex Tayloe, Adrian Thompson , et al. (5 additional authors not shown)

Abstract: The PIP-II superconducting RF linac is currently under construction at Fermilab and is expected to be completed by the end of 2028. PIP-II is capable of operating in a continuous-wave mode and can concurrently supply 800 MeV protons to a mega-watt, GeV-scale beam dump facility and to LBNF/DUNE. Designs for proton accumulator rings are being studied to bunch the PIP-II protons into the short pulses… ▽ More The PIP-II superconducting RF linac is currently under construction at Fermilab and is expected to be completed by the end of 2028. PIP-II is capable of operating in a continuous-wave mode and can concurrently supply 800 MeV protons to a mega-watt, GeV-scale beam dump facility and to LBNF/DUNE. Designs for proton accumulator rings are being studied to bunch the PIP-II protons into the short pulses needed for neutrino and low-mass dark matter experiments. PIP2-BD is a proposed 100-ton LAr scintillation-only experiment, whose detector design is inspired by CENNS-10 and CCM, that would have world-leading sensitivities to BSM physics, including low-mass dark matter produced in the PIP-II proton beam dump. △ Less

Submitted 23 September, 2022; v1 submitted 15 March, 2022; originally announced March 2022.

Comments: Contribution to Snowmass 2021

Report number: FERMILAB-FN-1152-AD-ND, LA-UR-22-21987

Physics Opportunities for the Fermilab Booster Replacement

Authors: John Arrington, Joshua Barrow, Brian Batell, Robert Bernstein, Nikita Blinov, S. J. Brice, Ray Culbertson, Patrick deNiverville, Vito Di Benedetto, Jeff Eldred, Angela Fava, Laura Fields, Alex Friedland, Andrei Gaponenko, Corrado Gatto, Stefania Gori, Roni Harnik, Richard J. Hill, Daniel M. Kaplan, Kevin J. Kelly, Mandy Kiburg, Tom Kobilarcik, Gordan Krnjaic, Gabriel Lee, B. R. Littlejohn , et al. (27 additional authors not shown)

Abstract: This white paper presents opportunities afforded by the Fermilab Booster Replacement and its various options. Its goal is to inform the design process of the Booster Replacement about the accelerator needs of the various options, allowing the design to be versatile and enable, or leave the door open to, as many options as possible. The physics themes covered by the paper include searches for dark… ▽ More This white paper presents opportunities afforded by the Fermilab Booster Replacement and its various options. Its goal is to inform the design process of the Booster Replacement about the accelerator needs of the various options, allowing the design to be versatile and enable, or leave the door open to, as many options as possible. The physics themes covered by the paper include searches for dark sectors and new opportunities with muons. △ Less

Submitted 8 March, 2022; originally announced March 2022.

Comments: Snowmass white paper

Report number: FERMILAB-FN-1145, LA-UR-22-21987

MiniBooNE and MicroBooNE Combined Fit to a 3+1 Sterile Neutrino Scenario

Authors: A. A. Aguilar-Arevalo, B. C. Brown, J. M. Conrad, R. Dharmapalan, A. Diaz, Z. Djurcic, D. A. Finley, R. Ford, G. T. Garvey, S. Gollapinni, A. Hourlier, E. -C. Huang, N. W. Kamp, G. Karagiorgi, T. Katori, T. Kobilarcik, K. Lin, W. C. Louis, C. Mariani, W. Marsh, G. B. Mills, J. Mirabal-Martinez, C. D. Moore, R. H. Nelson, J. Nowak , et al. (14 additional authors not shown)

Abstract: This letter presents the results from the MiniBooNE experiment within a full "3+1" scenario where one sterile neutrino is introduced to the three-active-neutrino picture. In addition to electron-neutrino appearance at short-baselines, this scenario also allows for disappearance of the muon-neutrino and electron-neutrino fluxes in the Booster Neutrino Beam, which is shared by the MicroBooNE experim… ▽ More This letter presents the results from the MiniBooNE experiment within a full "3+1" scenario where one sterile neutrino is introduced to the three-active-neutrino picture. In addition to electron-neutrino appearance at short-baselines, this scenario also allows for disappearance of the muon-neutrino and electron-neutrino fluxes in the Booster Neutrino Beam, which is shared by the MicroBooNE experiment. We present the 3+1 fit to the MiniBooNE electron-(anti)neutrino and muon-(anti)neutrino data alone, and in combination with MicroBooNE electron-neutrino data. The best-fit parameters of the combined fit with the exclusive CCQE analysis (inclusive analysis) are $Δm^2 = 0.29 eV^2 (0.33 eV^2)$, $|U_{e4}|^2 = 0.016 (0.500)$, $|U_{μ4}|^2 = 0.500 (0.500)$, and $\sin^2(2θ_{μe})=0.0316 (1.0)$. Comparing the no-oscillation scenario to the 3+1 model, the data prefer the 3+1 model with a $Δχ^2/\text{dof} = 24.7 / 3 (17.3 / 3)$, a $4.3σ(3.4σ)$ preference assuming the asymptotic approximation given by Wilks' theorem. △ Less

Submitted 9 September, 2022; v1 submitted 5 January, 2022; originally announced January 2022.

Comments: 10 pages, 4 figures, 2 table

Prospects for detecting axionlike particles at the Coherent CAPTAIN-Mills experiment

Authors: A. A. Aguilar-Arevalo, D. S. M. Alves, S. Biedron, J. Boissevain, M. Borrego, L. Bugel, M. Chavez-Estrada, J. M. Conrad, R. L. Cooper, A. Diaz, J. R. Distel, J. C. D'Olivo, E. Dunton, B. Dutta, D. Fields, J. R. Gochanour, M. Gold, E. Guardincerri, E. C. Huang, N. Kamp, D. Kim, K. Knickerbocker, W. C. Louis, J. T. M. Lyles, R. Mahapatra , et al. (23 additional authors not shown)

Abstract: We show results from the Coherent CAPTAIN Mills (CCM) 2019 engineering run which begin to constrain regions of parameter space for axion-like particles (ALPs) produced in electromagnetic particle showers in an 800 MeV proton beam dump, and further investigate the sensitivity of ongoing data-taking campaigns for the CCM200 upgraded detector. Based on beam-on background estimates from the engineerin… ▽ More We show results from the Coherent CAPTAIN Mills (CCM) 2019 engineering run which begin to constrain regions of parameter space for axion-like particles (ALPs) produced in electromagnetic particle showers in an 800 MeV proton beam dump, and further investigate the sensitivity of ongoing data-taking campaigns for the CCM200 upgraded detector. Based on beam-on background estimates from the engineering run, we make realistic extrapolations for background reduction based on expected shielding improvements, reduced beam width, and analysis-based techniques for background rejection. We obtain reach projections for two classes of signatures; ALPs coupled primarily to photons can be produced in the tungsten target via the Primakoff process, and then produce a gamma-ray signal in the Liquid Argon (LAr) CCM detector either via inverse Primakoff scattering or decay to a photon pair. ALPs with significant electron couplings have several additional production mechanisms (Compton scattering, $e^+e^-$ annihilation, ALP-bremsstrahlung) and detection modes (inverse Compton scattering, external $e^+e^-$ pair conversion, and decay to $e^+e^-$). In some regions, the constraint is marginally better than both astrophysical and terrestrial constraints. With the beginning of a three year run, CCM will be more sensitive to this parameter space by up to an order of magnitude for both ALP-photon and ALP-electron couplings. The CCM experiment will also have sensitivity to well-motivated parameter space of QCD axion models. It is only a recent realization that accelerator-based large volume liquid argon detectors designed for low energy coherent neutrino and dark matter scattering searches are also ideal for probing ALPs in the unexplored $\sim$MeV mass scale. △ Less

Submitted 26 May, 2023; v1 submitted 18 December, 2021; originally announced December 2021.

Comments: Accepted for publication in Physical Review D, in production

Report number: LA-UR-21-28474

Journal ref: Phys.Rev.D 107 (2023) 9, 095036

MiniBooNE Data Releases

Authors: A. A. Aguilar-Arevalo, B. C. Brown, J. M. Conrad, R. Dharmapalan, A. Diaz, Z. Djurcic, D. A. Finley, R. Ford, G. T. Garvey, S. Gollapinni, A. Hourlier, E. -C. Huang, N. W. Kamp, G. Karagiorgi, T. Katori, T. Kobilarcik, K. Lin, W. C. Louis, C. Mariani, W. Marsh, G. B. Mills, J. Mirabal-Martinez, C. D. Moore, R. H. Nelson, J. Nowak , et al. (16 additional authors not shown)

Abstract: The MiniBooNE experiment has provided data releases for most publications. Occasionally it is necessary to move data release pages. This document provides a single point of reference that will be updated by the collaboration to point to the present location of the MiniBooNE data releases. The MiniBooNE experiment has provided data releases for most publications. Occasionally it is necessary to move data release pages. This document provides a single point of reference that will be updated by the collaboration to point to the present location of the MiniBooNE data releases. △ Less

Submitted 25 October, 2021; originally announced October 2021.

Comments: 2 pages, 0 figures

Solutions to the MiniBooNE Anomaly from New Physics in Charged Meson Decays

Authors: Bhaskar Dutta, Doojin Kim, Adrian Thompson, Remington T. Thornton, Richard G. Van de Water

Abstract: We point out that production of new bosons by charged meson decays can greatly enhance the sensitivity of beam-focused accelerator-based experiments to new physics signals. This enhancement arises since the charged mesons are focused and their three-body decays do not suffer from helicity suppression in the same way as their usual two-body decays. As a realistic application, we attempt to explain… ▽ More We point out that production of new bosons by charged meson decays can greatly enhance the sensitivity of beam-focused accelerator-based experiments to new physics signals. This enhancement arises since the charged mesons are focused and their three-body decays do not suffer from helicity suppression in the same way as their usual two-body decays. As a realistic application, we attempt to explain the MiniBooNE low energy excess utilizing this overlooked mechanism, uniquely realizing dark-sector interpretations as plausible solutions to the excess. As proof of the principle, we consider two well-motivated classes of dark-sector models, models of vector-portal dark matter and models of long-lived (pseudo)scalar. We argue that the model parameter values to accommodate the excess are consistent with existing limits and that they can be tested at current and future accelerator-based neutrino experiments. △ Less

Submitted 13 August, 2022; v1 submitted 22 October, 2021; originally announced October 2021.

Comments: 10 pages, 4 figures, 2 tables, Journal submission version

Report number: MI-HET-766, LA-UR-21-30532

First Leptophobic Dark Matter Search from Coherent CAPTAIN-Mills

Authors: A. A. Aguilar-Arevalo, D. S. M. Alves, S. Biedron, J. Boissevain, M. Borrego, M. Chavez-Estrada, A. Chavez, J. M. Conrad, R. L. Cooper, A. Diaz, J. R. Distel, J. C. D'Olivo, E. Dunton, B. Dutta, A. Elliott, D. Evans, D. Fields, J. Greenwood, M. Gold, J. Gordon, E. Guarincerri, E. C. Huang, N. Kamp, C. Kelsey, K. Knickerbocker , et al. (26 additional authors not shown)

Abstract: We report the first results of a search for leptophobic dark matter (DM) from the Coherent CAPTAIN-Mills (CCM) liquid argon (LAr) detector. An engineering run with 120 photomultiplier tubes (PMTs) and $17.9 \times 10^{20}$ protons-on-target (POT) was performed in Fall 2019 to study the characteristics of the CCM detector. The operation of this 10-ton detector was strictly light-based with a thresh… ▽ More We report the first results of a search for leptophobic dark matter (DM) from the Coherent CAPTAIN-Mills (CCM) liquid argon (LAr) detector. An engineering run with 120 photomultiplier tubes (PMTs) and $17.9 \times 10^{20}$ protons-on-target (POT) was performed in Fall 2019 to study the characteristics of the CCM detector. The operation of this 10-ton detector was strictly light-based with a threshold of 50 keV and used coherent elastic scattering off argon nuclei to detect DM. Despite only 1.5 months of accumulated luminosity, contaminated LAr, and non-optimized shielding, CCM's first engineering run already achieved sensitivity to previously unexplored parameter space of light dark matter (LDM) models with a baryonic vector portal. With an expected background of 115,005 events, we observe 115,005+16.5 events which is compatible with background expectations. For a benchmark mediator-to-dark matter mass ratio of $m_{_{V_B}}/m_χ=2.1$, DM masses within the range $9\,\text{MeV} \lesssim m_χ\lesssim 50\,\text{MeV}$ have been excluded at 90% C.L. in the leptophobic model after applying the Feldman-Cousins test statistic. CCM's upgraded run with 200 PMTs, filtered LAr, improved shielding, and ten times more POT will be able to exclude the remaining thermal relic density parameter space of this model, as well as probe new parameter space of other leptophobic DM models. △ Less

Submitted 19 May, 2022; v1 submitted 28 September, 2021; originally announced September 2021.

Report number: Report-no: LA-UR-21-28552

Journal ref: Physical Review Letters Vol. 129, No. 2 (2022)

First Dark Matter Search Results From Coherent CAPTAIN-Mills

Authors: A. A. Aguilar-Arevalo, S. Biedron, J. Boissevain, M. Borrego, M. Chavez-Estrada, A. Chavez, J. M. Conrad, R. L. Cooper, A. Diaz, J. R. Distel, J. D'Olivo, E. Dunton, B. Dutta, A. Elliott, D. Evans, D. Fields, J. Greenwood, M. Gold, J. Gordon, E. D. Guarincerri, E. C. Huang, N. Kamp, C. Kelsey, K. Knickerbocker, R. Lake , et al. (25 additional authors not shown)

Abstract: This paper describes the operation of the Coherent CAPTAIN-Mills (CCM) detector located at the Lujan Neutron Science Center (LANSCE) at Los Alamos National Laboratory (LANL). CCM is a 10-ton liquid argon (LAr) detector located 20 meters from a high flux neutron/neutrino source and is designed to search for sterile neutrinos ($ν_s$) and light dark matter (LDM). An engineering run was performed in F… ▽ More This paper describes the operation of the Coherent CAPTAIN-Mills (CCM) detector located at the Lujan Neutron Science Center (LANSCE) at Los Alamos National Laboratory (LANL). CCM is a 10-ton liquid argon (LAr) detector located 20 meters from a high flux neutron/neutrino source and is designed to search for sterile neutrinos ($ν_s$) and light dark matter (LDM). An engineering run was performed in Fall 2019 to study the characteristics of the CCM120 detector by searching for coherent scattering signals consistent with $ν_s$'s and LDM resulting from $π^+$ and $π^0$ decays in the tungsten target. New parameter space in a leptophobic dark matter model was excluded for DM masses between $\sim2.0$ and 30 MeV. The lessons learned from this run have guided the development and construction of the new CCM200 detector that will begin operations in 2021 and significantly improve on these searches. △ Less

Submitted 19 May, 2022; v1 submitted 28 May, 2021; originally announced May 2021.

Report number: LA-UR-21-24983

Journal ref: Physical Review D Vol. 106, No. 1 (2022)

Measurement of the Atmospheric Muon Rate with the MicroBooNE Liquid Argon TPC

Authors: MicroBooNE collaboration, C. Adams, M. Alrashed, R. An, J. Anthony, J. Asaadi, A. Ashkenazi, S. Balasubramanian, B. Baller, C. Barnes, G. Barr, V. Basque, M. Bass, F. Bay, S. Berkman, A. Bhanderi, A. Bhat, M. Bishai, A. Blake, T. Bolton, L. Camilleri, D. Caratelli, I. Caro Terrazas, R. Carr, R. Castillo Fernandez , et al. (165 additional authors not shown)

Abstract: MicroBooNE is a near-surface liquid argon (LAr) time projection chamber (TPC) located at Fermilab. We measure the characterisation of muons originating from cosmic interactions in the atmosphere using both the charge collection and light readout detectors. The data is compared with the CORSIKA cosmic-ray simulation. Good agreement is found between the observation, simulation and previous results.… ▽ More MicroBooNE is a near-surface liquid argon (LAr) time projection chamber (TPC) located at Fermilab. We measure the characterisation of muons originating from cosmic interactions in the atmosphere using both the charge collection and light readout detectors. The data is compared with the CORSIKA cosmic-ray simulation. Good agreement is found between the observation, simulation and previous results. Furthermore, the angular resolution of the reconstructed muons inside the TPC is studied in simulation. △ Less

Submitted 13 April, 2021; v1 submitted 22 December, 2020; originally announced December 2020.

Comments: 20 pages, 14 figures

Report number: FERMILAB-PUB-20-626-ND

Journal ref: MicroBooNE et al 2021 JINST 16 P04004

Development of a $^{83\mathrm{m}}$Kr source for the calibration of the CENNS-10 Liquid Argon Detector

Authors: COHERENT Collaboration, D. Akimov, P. An, C. Awe, P. S. Barbeau, B. Becker, V. Belov, I. Bernardi, M. A. Blackston, L. Blokland, A. Bolozdynya, B. Cabrera-Palmer, N. Chen, D. Chernyak, E. Conley, J. Daughhetee, M. del Valle Coello, J. A. Detwiler, M. R. Durand, Y. Efremenko, S. R. Elliott, L. Fabris, M. Febbraro, W. Fox, A. Galindo-Uribarri , et al. (55 additional authors not shown)

Abstract: We report on the preparation of and calibration measurements with a $^{83\mathrm{m}}$Kr source for the CENNS-10 liquid argon detector. $^{83\mathrm{m}}$Kr atoms generated in the decay of a $^{83}$Rb source were introduced into the detector via injection into the Ar circulation loop. Scintillation light arising from the 9.4 keV and 32.1 keV conversion electrons in the decay of $^{83\mathrm{m}}$Kr i… ▽ More We report on the preparation of and calibration measurements with a $^{83\mathrm{m}}$Kr source for the CENNS-10 liquid argon detector. $^{83\mathrm{m}}$Kr atoms generated in the decay of a $^{83}$Rb source were introduced into the detector via injection into the Ar circulation loop. Scintillation light arising from the 9.4 keV and 32.1 keV conversion electrons in the decay of $^{83\mathrm{m}}$Kr in the detector volume were then observed. This calibration source allows the characterization of the low-energy response of the CENNS-10 detector and is applicable to other low-energy-threshold detectors. The energy resolution of the detector was measured to be 9$\%$ at the total $^{83\mathrm{m}}$Kr decay energy of 41.5 keV. We performed an analysis to separately calibrate the detector using the two conversion electrons at 9.4 keV and 32.1 keV △ Less

Submitted 27 January, 2021; v1 submitted 21 October, 2020; originally announced October 2020.

Comments: v2: As accepted to JINST

Journal ref: JINST 16 P04002 (2021)

The Continuous Readout Stream of the MicroBooNE Liquid Argon Time Projection Chamber for Detection of Supernova Burst Neutrinos

Authors: MicroBooNE collaboration, P. Abratenko, M. Alrashed, R. An, J. Anthony, J. Asaadi, A. Ashkenazi, S. Balasubramanian, B. Baller, C. Barnes, G. Barr, V. Basque, L. Bathe-Peters, O. Benevides Rodrigues, S. Berkman, A. Bhanderi, A. Bhat, M. Bishai, A. Blake, T. Bolton, L. Camilleri, D. Caratelli, I. Caro Terrazas, R. Castillo Fernandez, F. Cavanna , et al. (163 additional authors not shown)

Abstract: The MicroBooNE continuous readout stream is a parallel readout of the MicroBooNE liquid argon time projection chamber (LArTPC) which enables detection of non-beam events such as those from a supernova neutrino burst. The low energies of the supernova neutrinos and the intense cosmic-ray background flux due to the near-surface detector location makes triggering on these events very challenging. Ins… ▽ More The MicroBooNE continuous readout stream is a parallel readout of the MicroBooNE liquid argon time projection chamber (LArTPC) which enables detection of non-beam events such as those from a supernova neutrino burst. The low energies of the supernova neutrinos and the intense cosmic-ray background flux due to the near-surface detector location makes triggering on these events very challenging. Instead, MicroBooNE relies on a delayed trigger generated by SNEWS (the Supernova Early Warning System) for detecting supernova neutrinos. The continuous readout of the LArTPC generates large data volumes, and requires the use of real-time compression algorithms (zero suppression and Huffman compression) implemented in an FPGA (field-programmable gate array) in the readout electronics. We present the results of the optimization of the data reduction algorithms, and their operational performance. To demonstrate the capability of the continuous stream to detect low-energy electrons, a sample of Michel electrons from stopping cosmic-ray muons is reconstructed and compared to a similar sample from the lossless triggered readout stream. △ Less

Submitted 3 February, 2021; v1 submitted 31 August, 2020; originally announced August 2020.

Comments: 30 pages, 21 figures

Report number: FERMILAB-PUB-20-446-ND

Journal ref: JINST 16 P02008 (2021)

Measurement of Space Charge Effects in the MicroBooNE LArTPC Using Cosmic Muons

Authors: MicroBooNE collaboration, P. Abratenko, M. Alrashed, R. An, J. Anthony, J. Asaadi, A. Ashkenazi, S. Balasubramanian, B. Baller, C. Barnes, G. Barr, V. Basque, L. Bathe-Peters, O. Benevides Rodrigues, S. Berkman, A. Bhanderi, A. Bhat, M. Bishai, A. Blake, T. Bolton, L. Camilleri, D. Caratelli, I. Caro Terrazas, R. Castillo Fernandez, F. Cavanna , et al. (162 additional authors not shown)

Abstract: Large liquid argon time projection chambers (LArTPCs), especially those operating near the surface, are susceptible to space charge effects. In the context of LArTPCs, the space charge effect is the build-up of slow-moving positive ions in the detector primarily due to ionization from cosmic rays, leading to a distortion of the electric field within the detector. This effect leads to a displacemen… ▽ More Large liquid argon time projection chambers (LArTPCs), especially those operating near the surface, are susceptible to space charge effects. In the context of LArTPCs, the space charge effect is the build-up of slow-moving positive ions in the detector primarily due to ionization from cosmic rays, leading to a distortion of the electric field within the detector. This effect leads to a displacement in the reconstructed position of signal ionization electrons in LArTPC detectors ("spatial distortions"), as well as to variations in the amount of electron-ion recombination experienced by ionization throughout the volume of the TPC. We present techniques that can be used to measure and correct for space charge effects in large LArTPCs by making use of cosmic muons, including the use of track pairs to unambiguously pin down spatial distortions in three dimensions. The performance of these calibration techniques are studied using both Monte Carlo simulation and MicroBooNE data, utilizing a UV laser system as a means to estimate the systematic bias associated with the calibration methodology. △ Less

Submitted 9 November, 2020; v1 submitted 22 August, 2020; originally announced August 2020.

Comments: 38 pages, 25 figures

Updated MiniBooNE Neutrino Oscillation Results with Increased Data and New Background Studies

Authors: MiniBooNE Collaboration, A. A. Aguilar-Arevalo, B. C. Brown, J. M. Conrad, R. Dharmapalan, A. Diaz, Z. Djurcic, D. A. Finley, R. Ford, G. T. Garvey, S. Gollapinni, A. Hourlier, E. C. Huang, N. W. Kamp, G. Karagiorgi, T. Katori, T. Kobilarcik, K. Lin, W. C. Louis, C. Mariani, W. Marsh, G. B. Mills, J. Mirabal-Martinez, C. D. Moore, R. H. Nelson , et al. (17 additional authors not shown)

Abstract: The MiniBooNE experiment at Fermilab reports a total excess of $638.0 \pm 132.8$ electron-like events ($4.8 σ$) from a data sample corresponding to $18.75 \times 10^{20}$ protons-on-target in neutrino mode, which is a 46\% increase in the data sample with respect to previously published results, and $11.27 \times 10^{20}$ protons-on-target in antineutrino mode. The additional statistics allow seve… ▽ More The MiniBooNE experiment at Fermilab reports a total excess of $638.0 \pm 132.8$ electron-like events ($4.8 σ$) from a data sample corresponding to $18.75 \times 10^{20}$ protons-on-target in neutrino mode, which is a 46\% increase in the data sample with respect to previously published results, and $11.27 \times 10^{20}$ protons-on-target in antineutrino mode. The additional statistics allow several studies to address questions on the source of the excess. First, we provide two-dimensional plots in visible energy and cosine of the angle of the outgoing lepton, which can provide valuable input to models for the event excess. Second, we test whether the excess may arise from photons that enter the detector from external events or photons exiting the detector from $π^0$ decays in two model independent ways. Beam timing information shows that almost all of the excess is in time with neutrinos that interact in the detector. The radius distribution shows that the excess is distributed throughout the volume, while tighter cuts on the fiducal volume increase the significance of the excess. We conclude that models of the event excess based on entering and exiting photons are disfavored. △ Less

Submitted 8 March, 2021; v1 submitted 30 June, 2020; originally announced June 2020.

Comments: 28 pages, 26 figures

Report number: LA-UR-20-29235

Journal ref: Phys. Rev. D 103, 052002 (2021)

COHERENT Collaboration data release from the first detection of coherent elastic neutrino-nucleus scattering on argon

Authors: COHERENT Collaboration, D. Akimov, J. B. Albert, P. An, C. Awe, P. S. Barbeau, B. Becker, V. Belov, M. A. Blackston, L. Blokland, A. Bolozdynya, B. Cabrera-Palmer, N. Chen, D. Chernyak, E. Conley, R. L. Cooper, J. Daughhetee, M. del Valle Coello, J. A. Detwiler, M. R. Durand, Y. Efremenko, S. R. Elliott, L. Fabris, M. Febbraro, W. Fox , et al. (58 additional authors not shown)

Abstract: Release of COHERENT collaboration data from the first detection of coherent elastic neutrino-nucleus scattering (CEvNS) on argon. This release corresponds with the results of "Analysis A" published in Akimov et al., arXiv:2003.10630 [nucl-ex]. Data is shared in a binned, text-based format representing both "signal" and "backgrounds" along with associated uncertainties such that the included data c… ▽ More Release of COHERENT collaboration data from the first detection of coherent elastic neutrino-nucleus scattering (CEvNS) on argon. This release corresponds with the results of "Analysis A" published in Akimov et al., arXiv:2003.10630 [nucl-ex]. Data is shared in a binned, text-based format representing both "signal" and "backgrounds" along with associated uncertainties such that the included data can be used to perform independent analyses. This document describes the contents of the data release as well as guidance on the use of the data. Included example code in C++ (ROOT) and Python show one possible use of the included data. △ Less

Submitted 29 July, 2020; v1 submitted 22 June, 2020; originally announced June 2020.

Comments: Update document with arXiv ID number in requested citation

First Measurement of Differential Charged Current Quasielastic-like $ν_μ$-Argon Scattering Cross Sections with the MicroBooNE Detector

Authors: P. Abratenko, M. Alrashed, R. An, J. Anthony, J. Asaadi, A. Ashkenazi, S. Balasubramanian, B. Baller, C. Barnes, G. Barr, V. Basque, L. Bathe-Peters, O. Benevides Rodrigues, S. Berkman, A. Bhanderi, A. Bhat, M. Bishai, A. Blake, T. Bolton, L. Camilleri, D. Caratelli, I. Caro Terrazas, R. Castillo Fernandez, F. Cavanna, G. Cerati , et al. (159 additional authors not shown)

Abstract: We report on the first measurement of flux-integrated single differential cross sections for charged-current (CC) muon neutrino ($ν_μ$) scattering on argon with a muon and a proton in the final state, $^{40}$Ar($ν_μ$,$μ$p)X. The measurement was carried out using the Booster Neutrino Beam at Fermi National Accelerator Laboratory and the MicroBooNE liquid argon time projection chamber detector with… ▽ More We report on the first measurement of flux-integrated single differential cross sections for charged-current (CC) muon neutrino ($ν_μ$) scattering on argon with a muon and a proton in the final state, $^{40}$Ar($ν_μ$,$μ$p)X. The measurement was carried out using the Booster Neutrino Beam at Fermi National Accelerator Laboratory and the MicroBooNE liquid argon time projection chamber detector with an exposure of 4.59 $\times$ 10$^{19}$ protons on target. Events are selected to enhance the contribution of CC quasielastic (CCQE) interactions. The data are reported in terms of a total cross section as well as single differential cross sections in final state muon and proton kinematics. We measure the integrated per-nucleus CCQE-like cross section (i.e. for interactions leading to a muon, one proton and no pions above detection threshold) of (4.93 $\pm$ 0.76stat $\pm$ 1.29sys) $\times$ 10$^{-38}$cm$^2$, in good agreement with theoretical calculations. The single differential cross sections are also in overall good agreement with theoretical predictions, except at very forward muon scattering angles that correspond to low momentum-transfer events. △ Less

Submitted 5 October, 2020; v1 submitted 29 May, 2020; originally announced June 2020.

Comments: Accepted for publication in PRL. 8 pages, 3 figures, 1 table and online supplementary materials

Report number: FNAL PUB-20-226-ND

Journal ref: Phys. Rev. Lett. 125, 201803 (2020)

First Measurement of Coherent Elastic Neutrino-Nucleus Scattering on Argon

Authors: COHERENT Collaboration, D. Akimov, J. B. Albert, P. An, C. Awe, P. S. Barbeau, B. Becker, V. Belov, M. A. Blackston, L. Blokland, A. Bolozdynya, B. Cabrera-Palmer, N. Chen, D. Chernyak, E. Conley, R. L. Cooper, J. Daughhetee, M. del Valle Coello, J. A. Detwiler, M. R. Durand, Y. Efremenko, S. R. Elliott, L. Fabris, M. Febbraro, W. Fox , et al. (58 additional authors not shown)

Abstract: We report the first measurement of coherent elastic neutrino-nucleus scattering (\cevns) on argon using a liquid argon detector at the Oak Ridge National Laboratory Spallation Neutron Source. Two independent analyses prefer \cevns over the background-only null hypothesis with greater than $3σ$ significance. The measured cross section, averaged over the incident neutrino flux, is (2.2 $\pm$ 0.7)… ▽ More We report the first measurement of coherent elastic neutrino-nucleus scattering (\cevns) on argon using a liquid argon detector at the Oak Ridge National Laboratory Spallation Neutron Source. Two independent analyses prefer \cevns over the background-only null hypothesis with greater than $3σ$ significance. The measured cross section, averaged over the incident neutrino flux, is (2.2 $\pm$ 0.7) $\times$10$^{-39}$ cm$^2$ -- consistent with the standard model prediction. The neutron-number dependence of this result, together with that from our previous measurement on CsI, confirms the existence of the \cevns process and provides improved constraints on non-standard neutrino interactions. △ Less

Submitted 15 February, 2021; v1 submitted 23 March, 2020; originally announced March 2020.

Comments: 8 pages, 5 figures with 2 pages, 6 figures supplementary material V3: fixes to figs 3,4 V4: fix typo in table 1, V5: replaced missing appendix, V6: fix Eq 1, new fig 3, V7 final version, updated with final revisions

Journal ref: Phys. Rev. Lett. 126, 012002 (2021)

Vertex-Finding and Reconstruction of Contained Two-track Neutrino Events in the MicroBooNE Detector

Authors: MicroBooNE collaboration, P. Abratenko, M. Alrashed, R. An, J. Anthony, J. Asaadi, A. Ashkenazi, S. Balasubramanian, B. Baller, C. Barnes, G. Barr, V. Basque, L. Bathe-Peters, S. Berkman, A. Bhanderi, A. Bhat, M. Bishai, A. Blake, T. Bolton, L. Camilleri, D. Caratelli, I. Caro Terrazas, R. Castillo Fernandez, F. Cavanna, G. Cerati , et al. (164 additional authors not shown)

Abstract: We describe algorithms developed to isolate and accurately reconstruct two-track events that are contained within the MicroBooNE detector. This method is optimized to reconstruct two tracks of lengths longer than 5 cm. This code has applications to searches for neutrino oscillations and measurements of cross sections using quasi-elastic-like charged current events. The algorithms we discuss will b… ▽ More We describe algorithms developed to isolate and accurately reconstruct two-track events that are contained within the MicroBooNE detector. This method is optimized to reconstruct two tracks of lengths longer than 5 cm. This code has applications to searches for neutrino oscillations and measurements of cross sections using quasi-elastic-like charged current events. The algorithms we discuss will be applicable to all detectors running in Fermilab's Short Baseline Neutrino program (SBN), and to any future liquid argon time projection chamber (LArTPC) experiment with beam energies ~1 GeV. The algorithms are publicly available on a GITHUB repository. This reconstruction offers a complementary and independent alternative to the Pandora reconstruction package currently in use in LArTPC experiments, and provides similar reconstruction performance for two-track events. △ Less

Submitted 7 December, 2020; v1 submitted 21 February, 2020; originally announced February 2020.

Comments: 35 pages, 26 figures

Report number: FERMILAB-PUB-20-073-ND

Construction of precision wire readout planes for the Short-Baseline Near Detector (SBND)

Authors: R. Acciarri, C. Adams, C. Andreopoulos, J. Asaadi, M. Babicz, C. Backhouse, W. Badgett, L. F. Bagby, D. Barker, C. Barnes, A. Basharina-Freshville, V. Basque, A. Baxter, M. C. Q. Bazetto, O. Beltramello, M. Betancourt, A. Bhanderi, A. Bhat, M. R. M. Bishai, A. Bitadze, A. S. T. Blake, J. Boissevain, C. Bonifazi, J. Y. Book, D. Brailsford , et al. (170 additional authors not shown)

Abstract: The Short-Baseline Near Detector time projection chamber is unique in the design of its charge readout planes. These anode plane assemblies (APAs) have been fabricated and assembled to meet strict accuracy and precision requirements: wire spacing of 3 mm +/- 0.5 mm and wire tension of 7 N +/- 1 N across 3,964 wires per APA, and flatness within 0.5 mm over the 4 m +/- 2.5 m extent of each APA. This… ▽ More The Short-Baseline Near Detector time projection chamber is unique in the design of its charge readout planes. These anode plane assemblies (APAs) have been fabricated and assembled to meet strict accuracy and precision requirements: wire spacing of 3 mm +/- 0.5 mm and wire tension of 7 N +/- 1 N across 3,964 wires per APA, and flatness within 0.5 mm over the 4 m +/- 2.5 m extent of each APA. This paper describes the design, manufacture and assembly of these key detector components, with a focus on the quality assurance at each stage. △ Less

Submitted 24 April, 2020; v1 submitted 19 February, 2020; originally announced February 2020.

Comments: 42 pages, 45 figures. Prepared for submission to JINST

Search for heavy neutral leptons decaying into muon-pion pairs in the MicroBooNE detector

Authors: P. Abratenko, M. Alrashed, R. An, J. Anthony, J. Asaadi, A. Ashkenazi, S. Balasubramanian, B. Baller, C. Barnes, G. Barr, V. Basque, S. Berkman, A. Bhanderi, A. Bhat, M. Bishai, A. Blake, T. Bolton, L. Camilleri, D. Caratelli, I. Caro Terrazas, R. Castillo Fernandez, F. Cavanna, G. Cerati, Y. Chen, E. Church , et al. (159 additional authors not shown)

Abstract: We present upper limits on the production of heavy neutral leptons (HNLs) decaying to $μπ$ pairs using data collected with the MicroBooNE liquid-argon time projection chamber (TPC) operating at Fermilab. This search is the first of its kind performed in a liquid-argon TPC. We use data collected in 2017 and 2018 corresponding to an exposure of $2.0 \times 10^{20}$ protons on target from the Fermila… ▽ More We present upper limits on the production of heavy neutral leptons (HNLs) decaying to $μπ$ pairs using data collected with the MicroBooNE liquid-argon time projection chamber (TPC) operating at Fermilab. This search is the first of its kind performed in a liquid-argon TPC. We use data collected in 2017 and 2018 corresponding to an exposure of $2.0 \times 10^{20}$ protons on target from the Fermilab Booster Neutrino Beam, which produces mainly muon neutrinos with an average energy of $\approx 800$ MeV. HNLs with higher mass are expected to have a longer time-of-flight to the liquid-argon TPC than Standard Model neutrinos. The data are therefore recorded with a dedicated trigger configured to detect HNL decays that occur after the neutrino spill reaches the detector. We set upper limits at the $90\%$ confidence level on the element $\lvert U_{\mu4}\rvert^2$ of the extended PMNS mixing matrix in the range $\lvert U_{\mu4}\rvert^2<(6.6$-$0.9)\times 10^{-7}$ for Dirac HNLs and $\lvert U_{\mu4}\rvert^2<(4.7$-$0.7)\times 10^{-7}$ for Majorana HNLs, assuming HNL masses between $260$ and $385$ MeV and $\lvert U_{e 4}\rvert^2 = \lvert U_{τ4}\rvert^2 = 0$. △ Less

Submitted 12 February, 2020; v1 submitted 24 November, 2019; originally announced November 2019.

Comments: 11 pages, 9 figures. Final accepted version by Phys. Rev. D, minor textual changes

Report number: FERMILAB-PUB-19-581-ND

Journal ref: Phys. Rev. D 101, 052001 (2020)

Sensitivity of the COHERENT Experiment to Accelerator-Produced Dark Matter

Authors: COHERENT Collaboration, D. Akimov, P. An, C. Awe, P. S. Barbeau, B. Becker, V. Belov, M. A. Blackston, A. Bolozdynya, B. Cabrera-Palmer, N. Chen, E. Conley, R. L. Cooper, J. Daughhetee, M. del Valle Coello, J. A. Detwiler, M. R. Durand, Y. Efremenko, S. R. Elliott, L. Fabris, M. Febbraro, W. Fox, A. Galindo-Uribarri, M. P. Green, K. S. Hansen , et al. (53 additional authors not shown)

Abstract: The COHERENT experiment is well poised to test sub-GeV dark matter models using low-energy recoil detectors sensitive to coherent elastic neutrino-nucleus scattering (CEvNS) in the $π$-DAR neutrino beam produced by the Spallation Neutron Source. We show how a planned 750-kg liquid argon scintillation detector would place leading limits on scalar light dark matter models, over two orders of magnitu… ▽ More The COHERENT experiment is well poised to test sub-GeV dark matter models using low-energy recoil detectors sensitive to coherent elastic neutrino-nucleus scattering (CEvNS) in the $π$-DAR neutrino beam produced by the Spallation Neutron Source. We show how a planned 750-kg liquid argon scintillation detector would place leading limits on scalar light dark matter models, over two orders of magnitude of dark matter mass, for dark matter particles produced through vector and leptophobic portals in the absence of other effects beyond the standard model. The characteristic timing structure of a $π$-DAR beam allows a unique opportunity for constraining systematic uncertainties on the standard model background in a time window where signal is not expected, enhancing expected sensitivity. Additionally, we discuss future prospects, further increasing the discovery potential of CEvNS detectors. Such methods would test the calculated thermal dark matter abundance for all couplings $α'\leq1$ within the vector portal model over an order of magnitude of dark matter masses. △ Less

Submitted 14 November, 2019; originally announced November 2019.

Journal ref: Phys. Rev. D 102, 052007 (2020)

Reconstruction and Measurement of $\mathcal{O}$(100) MeV Energy Electromagnetic Activity from $π^0 \rightarrow γγ$ Decays in the MicroBooNE LArTPC

Authors: MicroBooNE collaboration, C. Adams, M. Alrashed, R. An, J. Anthony, J. Asaadi, A. Ashkenazi, S. Balasubramanian, B. Baller, C. Barnes, G. Barr, V. Basque, M. Bass, F. Bay, S. Berkman, A. Bhanderi, A. Bhat, M. Bishai, A. Blake, T. Bolton, L. Camilleri, D. Caratelli, I. Caro Terrazas, R. Carr, R. Castillo Fernandez , et al. (164 additional authors not shown)

Abstract: We present results on the reconstruction of electromagnetic (EM) activity from photons produced in charged current $ν_μ$ interactions with final state $π^0$s. We employ a fully-automated reconstruction chain capable of identifying EM showers of $\mathcal{O}$(100) MeV energy, relying on a combination of traditional reconstruction techniques together with novel machine-learning approaches. These stu… ▽ More We present results on the reconstruction of electromagnetic (EM) activity from photons produced in charged current $ν_μ$ interactions with final state $π^0$s. We employ a fully-automated reconstruction chain capable of identifying EM showers of $\mathcal{O}$(100) MeV energy, relying on a combination of traditional reconstruction techniques together with novel machine-learning approaches. These studies demonstrate good energy resolution, and good agreement between data and simulation, relying on the reconstructed invariant $π^0$ mass and other photon distributions for validation. The reconstruction techniques developed are applied to a selection of $ν_μ + {\rm Ar} \rightarrow μ+ π^0 + X$ candidate events to demonstrate the potential for calorimetric separation of photons from electrons and reconstruction of $π^0$ kinematics. △ Less

Submitted 4 October, 2019; originally announced October 2019.

A Method to Determine the Electric Field of Liquid Argon Time Projection Chambers Using a UV Laser System and its Application in MicroBooNE

Authors: MicroBooNE collaboration, C. Adams, M. Alrashed, R. An, J. Anthony, J. Asaadi, A. Ashkenazi, S. Balasubramanian, B. Baller, C. Barnes, G. Barr, V. Basque, M. Bass, F. Bay, S. Berkman, A. Bhanderi, A. Bhat, M. Bishai, A. Blake, T. Bolton, L. Camilleri, D. Caratelli, I. Caro Terrazas, R. Carr, R. Castillo Fernandez , et al. (165 additional authors not shown)

Abstract: Liquid argon time projection chambers (LArTPCs) are now a standard detector technology for making accelerator neutrino measurements, due to their high material density, precise tracking, and calorimetric capabilities. An electric field (E-field) is required in such detectors to drift ionized electrons to the anode to be collected. The E-field of a TPC is often approximated to be uniform between th… ▽ More Liquid argon time projection chambers (LArTPCs) are now a standard detector technology for making accelerator neutrino measurements, due to their high material density, precise tracking, and calorimetric capabilities. An electric field (E-field) is required in such detectors to drift ionized electrons to the anode to be collected. The E-field of a TPC is often approximated to be uniform between the anode and the cathode planes. However, significant distortions can appear from effects such as mechanical deformations, electrode failures, or the accumulation of space charge generated by cosmic rays. The latter is particularly relevant for detectors placed near the Earth's surface and with large drift distances and long drift time. To determine the E-field in situ, an ultraviolet (UV) laser system is installed in the MicroBooNE experiment at Fermi National Accelerator Laboratory. The purpose of this system is to provide precise measurements of the E-field, and to make it possible to correct for 3D spatial distortions due to E-field non-uniformities. Here we describe the methodology developed for deriving spatial distortions, the drift velocity and the E-field from UV-laser measurements. △ Less

Submitted 15 October, 2019; v1 submitted 3 October, 2019; originally announced October 2019.

First Constraint on Coherent Elastic Neutrino-Nucleus Scattering in Argon

Authors: COHERENT Collaboration, D. Akimov, J. B. Albert, P. An, C. Awe, P. S. Barbeau, B. Becker, V. Belov, M. A. Blackston, A. Bolozdynya, B. Cabrera-Palmer, M. Cervantes, J. I. Collar, R. L. Cooper, J. Daughhetee, M. del Valle Coello, J. A. Detwiler, M. D'Onofrio, Y. Efremenko, E. M. Erkela, S. R. Elliott, L. Fabris, M. Febbraro, W. Fox, A. Galindo-Uribarri , et al. (55 additional authors not shown)

Abstract: Coherent elastic neutrino-nucleus scattering (CEvNS) is the dominant neutrino scattering channel for neutrinos of energy $E_ν< 100$ MeV. We report a limit for this process using data collected in an engineering run of the 29 kg CENNS-10 liquid argon detector located 27.5 m from the Oak Ridge National Laboratory Spallation Neutron Source (SNS) Hg target with $4.2\times 10^{22}$ protons on target. T… ▽ More Coherent elastic neutrino-nucleus scattering (CEvNS) is the dominant neutrino scattering channel for neutrinos of energy $E_ν< 100$ MeV. We report a limit for this process using data collected in an engineering run of the 29 kg CENNS-10 liquid argon detector located 27.5 m from the Oak Ridge National Laboratory Spallation Neutron Source (SNS) Hg target with $4.2\times 10^{22}$ protons on target. The dataset yielded $< 7.4$ observed CEvNS events implying a cross section for the process, averaged over the SNS pion decay-at-rest flux, of $<3.4 \times 10^{-39}$ cm$^{2}$, a limit within twice the Standard Model prediction. This is the first limit on CEvNS from an argon nucleus and confirms the earlier CsI non-standard neutrino interaction constraints from the collaboration. This run demonstrated the feasibility of the ongoing experimental effort to detect CEvNS with liquid argon. △ Less

Submitted 12 September, 2019; originally announced September 2019.

Journal ref: Phys. Rev. D 100, 115020 (2019)

Calibration of the charge and energy loss per unit length of the MicroBooNE liquid argon time projection chamber using muons and protons

Authors: MicroBooNE collaboration, C. Adams, M. Alrashed, R. An, J. Anthony, J. Asaadi, A. Ashkenazi, S. Balasubramanian, B. Baller, C. Barnes, G. Barr, V. Basque, M. Bass, F. Bay, S. Berkman, A. Bhanderi, A. Bhat, M. Bishai, A. Blake, T. Bolton, L. Camilleri, D. Caratelli, I. Caro Terrazas, R. Carr, R. Castillo Fernandez , et al. (164 additional authors not shown)

Abstract: We describe a method used to calibrate the position- and time-dependent response of the MicroBooNE liquid argon time projection chamber anode wires to ionization particle energy loss. The method makes use of crossing cosmic-ray muons to partially correct anode wire signals for multiple effects as a function of time and position, including cross-connected TPC wires, space charge effects, electron a… ▽ More We describe a method used to calibrate the position- and time-dependent response of the MicroBooNE liquid argon time projection chamber anode wires to ionization particle energy loss. The method makes use of crossing cosmic-ray muons to partially correct anode wire signals for multiple effects as a function of time and position, including cross-connected TPC wires, space charge effects, electron attachment to impurities, diffusion, and recombination. The overall energy scale is then determined using fully-contained beam-induced muons originating and stopping in the active region of the detector. Using this method, we obtain an absolute energy scale uncertainty of 2\% in data. We use stopping protons to further refine the relation between the measured charge and the energy loss for highly-ionizing particles. This data-driven detector calibration improves both the measurement of total deposited energy and particle identification based on energy loss per unit length as a function of residual range. As an example, the proton selection efficiency is increased by 2\% after detector calibration. △ Less

Submitted 24 February, 2020; v1 submitted 26 July, 2019; originally announced July 2019.

Comments: Accepted version

Report number: FERMILAB-PUB-19-357-ND

Journal ref: JINST 15, P03022 (2020)

First Measurement of Inclusive Muon Neutrino Charged Current Differential Cross Sections on Argon at $E_ν\sim 0.8$ GeV with the MicroBooNE Detector

Authors: P. Abratenko, C. Adams, M. Alrashed, R. An, J. Anthony, J. Asaadi, A. Ashkenazi, M. Auger, S. Balasubramanian, B. Baller, C. Barnes, G. Barr, M. Bass, F. Bay, A. Bhat, K. Bhattacharya, M. Bishai, A. Blake, T. Bolton, L. Camilleri, D. Caratelli, I. Caro Terrazas, R. Carr, R. Castillo Fernandez, F. Cavanna , et al. (156 additional authors not shown)

Abstract: We report the first measurement of the double-differential and total muon neutrino charged current inclusive cross sections on argon at a mean neutrino energy of 0.8 GeV. Data were collected using the MicroBooNE liquid argon time projection chamber located in the Fermilab Booster neutrino beam and correspond to $1.6 \times 10^{20}$ protons on target of exposure. The measured differential cross sec… ▽ More We report the first measurement of the double-differential and total muon neutrino charged current inclusive cross sections on argon at a mean neutrino energy of 0.8 GeV. Data were collected using the MicroBooNE liquid argon time projection chamber located in the Fermilab Booster neutrino beam and correspond to $1.6 \times 10^{20}$ protons on target of exposure. The measured differential cross sections are presented as a function of muon momentum, using multiple Coulomb scattering as a momentum measurement technique, and the muon angle with respect to the beam direction. We compare the measured cross sections to multiple neutrino event generators and find better agreement with those containing more complete treatment of quasielastic scattering processes at low $Q^2$. The total flux integrated cross section is measured to be $0.693 \pm 0.010 \, (\text{stat}) \pm 0.165 \, (\text{syst}) \times 10^{-38} \, \text{cm}^{2}$. △ Less

Submitted 30 September, 2019; v1 submitted 23 May, 2019; originally announced May 2019.

Comments: 7 pages, 2 figures

Report number: FERMILAB-PUB-19-235-ND

Journal ref: Phys. Rev. Lett. 123, 131801 (2019)

Design and construction of the MicroBooNE Cosmic Ray Tagger system

Authors: MicroBooNE collaboration, C. Adams, M. Alrashed, R. An, J. Anthony, J. Asaadi, A. Ashkenazi, M. Auger, S. Balasubramanian, B. Baller, C. Barnes, G. Barr, M. Bass, F. Bay, A. Bhat, K. Bhattacharya, M. Bishai, A. Blake, T. Bolton, L. Camilleri, D. Caratelli, I. Caro Terrazas, R. Carr, R. Castillo Fernandez, F. Cavanna , et al. (149 additional authors not shown)

Abstract: The MicroBooNE detector utilizes a liquid argon time projection chamber (LArTPC) with an 85 t active mass to study neutrino interactions along the Booster Neutrino Beam (BNB) at Fermilab. With a deployment location near ground level, the detector records many cosmic muon tracks in each beam-related detector trigger that can be misidentified as signals of interest. To reduce these cosmogenic backgr… ▽ More The MicroBooNE detector utilizes a liquid argon time projection chamber (LArTPC) with an 85 t active mass to study neutrino interactions along the Booster Neutrino Beam (BNB) at Fermilab. With a deployment location near ground level, the detector records many cosmic muon tracks in each beam-related detector trigger that can be misidentified as signals of interest. To reduce these cosmogenic backgrounds, we have designed and constructed a TPC-external Cosmic Ray Tagger (CRT). This sub-system was developed by the Laboratory for High Energy Physics (LHEP), Albert Einstein center for fundamental physics, University of Bern. The system utilizes plastic scintillation modules to provide precise time and position information for TPC-traversing particles. Successful matching of TPC tracks and CRT data will allow us to reduce cosmogenic background and better characterize the light collection system and LArTPC data using cosmic muons. In this paper we describe the design and installation of the MicroBooNE CRT system and provide an overview of a series of tests done to verify the proper operation of the system and its components during installation, commissioning, and physics data-taking. △ Less

Submitted 15 March, 2019; v1 submitted 9 January, 2019; originally announced January 2019.

Rejecting cosmic background for exclusive neutrino interaction studies with Liquid Argon TPCs; a case study with the MicroBooNE detector

Authors: MicroBooNE collaboration, C. Adams, M. Alrashed, R. An, J. Anthony, J. Asaadi, A. Ashkenazi, M. Auger, S. Balasubramanian, B. Baller, C. Barnes, G. Barr, M. Bass, F. Bay, A. Bhat, K. Bhattacharya, M. Bishai, A. Blake, T. Bolton, L. Camilleri, D. Caratelli, I. Caro Terrazas, R. Carr, R. Castillo Fernandez, F. Cavanna , et al. (150 additional authors not shown)

Abstract: Cosmic ray (CR) interactions can be a challenging source of background for neutrino oscillation and cross-section measurements in surface detectors. We present methods for CR rejection in measurements of charged-current quasielastic-like (CCQE-like) neutrino interactions, with a muon and a proton in the final state, measured using liquid argon time projection chambers (LArTPCs). Using a sample of… ▽ More Cosmic ray (CR) interactions can be a challenging source of background for neutrino oscillation and cross-section measurements in surface detectors. We present methods for CR rejection in measurements of charged-current quasielastic-like (CCQE-like) neutrino interactions, with a muon and a proton in the final state, measured using liquid argon time projection chambers (LArTPCs). Using a sample of cosmic data collected with the MicroBooNE detector, mixed with simulated neutrino scattering events, a set of event selection criteria is developed that produces an event sample with minimal contribution from CR background. Depending on the selection criteria used a purity between 50% and 80% can be achieved with a signal selection efficiency between 50% and 25%, with higher purity coming at the expense of lower efficiency. While using a specific dataset from the MicroBooNE detector and selection criteria values optimized for CCQE-like events, the concepts presented here are generic and can be adapted for various studies of exclusive νμ interactions in LArTPCs. △ Less

Submitted 2 January, 2019; v1 submitted 9 December, 2018; originally announced December 2018.

Comments: 12 pages, 10 figures, 1 table

Report number: FERMILAB-PUB-18-677-E

First Measurement of $ν_μ$ Charged-Current $π^{0}$ Production on Argon with a LArTPC

Authors: MicroBooNE collaboration, C. Adams, M. Alrashed, R. An, J. Anthony, J. Asaadi, A. Ashkenazi, M. Auger, S. Balasubramanian, B. Baller, C. Barnes, G. Barr, M. Bass, F. Bay, A. Bhat, K. Bhattacharya, M. Bishai, A. Blake, T. Bolton, L. Camilleri, D. Caratelli, I. Caro Terrazas, R. Carr, R. Castillo Fernandez, F. Cavanna , et al. (150 additional authors not shown)

Abstract: We report the first measurement of the flux-integrated cross section of $ν_μ$ charged-current single $π^{0}$ production on argon. This measurement is performed with the MicroBooNE detector, an 85 ton active mass liquid argon time projection chamber exposed to the Booster Neutrino Beam at Fermilab. This result on argon is compared to past measurements on lighter nuclei to investigate the scaling as… ▽ More We report the first measurement of the flux-integrated cross section of $ν_μ$ charged-current single $π^{0}$ production on argon. This measurement is performed with the MicroBooNE detector, an 85 ton active mass liquid argon time projection chamber exposed to the Booster Neutrino Beam at Fermilab. This result on argon is compared to past measurements on lighter nuclei to investigate the scaling assumptions used in models of the production and transport of pions in neutrino-nucleus scattering. The techniques used are an important demonstration of the successful reconstruction and analysis of neutrino interactions producing electromagnetic final states using a liquid argon time projection chamber operating at the earth's surface. △ Less

Submitted 6 November, 2018; originally announced November 2018.

Journal ref: Phys. Rev. D 99, 091102 (2019)

A Deep Neural Network for Pixel-Level Electromagnetic Particle Identification in the MicroBooNE Liquid Argon Time Projection Chamber

Authors: MicroBooNE collaboration, C. Adams, M. Alrashed, R. An, J. Anthony, J. Asaadi, A. Ashkenazi, M. Auger, S. Balasubramanian, B. Baller, C. Barnes, G. Barr, M. Bass, F. Bay, A. Bhat, K. Bhattacharya, M. Bishai, A. Blake, T. Bolton, L. Camilleri, D. Caratelli, I. Caro Terrazas, R. Carr, R. Castillo Fernandez, F. Cavanna , et al. (148 additional authors not shown)

Abstract: We have developed a convolutional neural network (CNN) that can make a pixel-level prediction of objects in image data recorded by a liquid argon time projection chamber (LArTPC) for the first time. We describe the network design, training techniques, and software tools developed to train this network. The goal of this work is to develop a complete deep neural network based data reconstruction cha… ▽ More We have developed a convolutional neural network (CNN) that can make a pixel-level prediction of objects in image data recorded by a liquid argon time projection chamber (LArTPC) for the first time. We describe the network design, training techniques, and software tools developed to train this network. The goal of this work is to develop a complete deep neural network based data reconstruction chain for the MicroBooNE detector. We show the first demonstration of a network's validity on real LArTPC data using MicroBooNE collection plane images. The demonstration is performed for stopping muon and a $ν_μ$ charged current neutral pion data samples. △ Less

Submitted 22 August, 2018; originally announced August 2018.

Journal ref: Phys. Rev. D 99, 092001 (2019)

Dark Matter Search in Nucleon, Pion, and Electron Channels from a Proton Beam Dump with MiniBooNE

Authors: MiniBooNE-DM Collaboration, A. A. Aguilar-Arevalo, M. Backfish, A. Bashyal, B. Batell, B. C. Brown, R. Carr, A. Chatterjee, R. L. Cooper, P. deNiverville, R. Dharmapalan, Z. Djurcic, R. Ford, F. G. Garcia, G. T. Garvey, J. Grange, J. A. Green, E. -C. Huang, W. Huelsnitz, I. L. de Icaza Astiz, G. Karagiorgi, T. Katori, W. Ketchum, T. Kobilarcik, Q. Liu , et al. (20 additional authors not shown)

Abstract: A search for sub-GeV dark matter produced from collisions of the Fermilab 8 GeV Booster protons with a steel beam dump was performed by the MiniBooNE-DM Collaboration using data from $1.86 \times 10^{20}$ protons on target in a dedicated run. The MiniBooNE detector, consisting of 818 tons of mineral oil and located 490 meters downstream of the beam dump, is sensitive to a variety of dark matter in… ▽ More A search for sub-GeV dark matter produced from collisions of the Fermilab 8 GeV Booster protons with a steel beam dump was performed by the MiniBooNE-DM Collaboration using data from $1.86 \times 10^{20}$ protons on target in a dedicated run. The MiniBooNE detector, consisting of 818 tons of mineral oil and located 490 meters downstream of the beam dump, is sensitive to a variety of dark matter initiated scattering reactions. Three dark matter interactions are considered for this analysis: elastic scattering off nucleons, inelastic neutral pion production, and elastic scattering off electrons. Multiple data sets were used to constrain flux and systematic errors, and time-of-flight information was employed to increase sensitivity to higher dark matter masses. No excess from the background predictions was observed, and 90$\%$ confidence level limits were set on the vector portal and leptophobic dark matter models. New parameter space is excluded in the vector portal dark matter model with a dark matter mass between 5 and 50$\,\mathrm{MeV}\,c^{-2}$. The reduced neutrino flux allowed to test if the MiniBooNE neutrino excess scales with the production of neutrinos. No excess of neutrino oscillation events were measured ruling out models that scale solely by number of protons on target independent of beam configuration at 4.6$σ$. △ Less

Submitted 29 March, 2019; v1 submitted 16 July, 2018; originally announced July 2018.

Comments: 19 pages, 25 figures, Data release: http://www-boone.fnal.gov/for_physicists/data_release/dark_matter_prd/ v2 Updated to published version

Report number: LA-UR-18-26421, FERMILAB-PUB-18-334-ND

Journal ref: Phys. Rev. D 98, 112004 (2018)

Significant Excess of ElectronLike Events in the MiniBooNE Short-Baseline Neutrino Experiment

Authors: MiniBooNE Collaboration, A. A. Aguilar-Arevalo, B. C. Brown, L. Bugel, G. Cheng, J. M. Conrad, R. L. Cooper, R. Dharmapalan, A. Diaz, Z. Djurcic, D. A. Finley, R. Ford, F. G. Garcia, G. T. Garvey, J. Grange, E. -C. Huang, W. Huelsnitz, C. Ignarra, R. A. Johnson, G. Karagiorgi, T. Katori, T. Kobilarcik, W. C. Louis, C. Mariani, W. Marsh , et al. (23 additional authors not shown)

Abstract: The MiniBooNE experiment at Fermilab reports results from an analysis of $ν_e$ appearance data from $12.84 \times 10^{20}$ protons on target in neutrino mode, an increase of approximately a factor of two over previously reported results. A $ν_e$ charged-current quasielastic event excess of $381.2 \pm 85.2$ events ($4.5 σ$) is observed in the energy range $200<E_ν^{QE}<1250$~MeV. Combining these da… ▽ More The MiniBooNE experiment at Fermilab reports results from an analysis of $ν_e$ appearance data from $12.84 \times 10^{20}$ protons on target in neutrino mode, an increase of approximately a factor of two over previously reported results. A $ν_e$ charged-current quasielastic event excess of $381.2 \pm 85.2$ events ($4.5 σ$) is observed in the energy range $200<E_ν^{QE}<1250$~MeV. Combining these data with the $\bar ν_e$ appearance data from $11.27 \times 10^{20}$ protons on target in antineutrino mode, a total $ν_e$ plus $\bar ν_e$ charged-current quasielastic event excess of $460.5 \pm 99.0$ events ($4.7 σ$) is observed. If interpreted in a two-neutrino oscillation model, $ν_μ \rightarrow ν_e$, the best oscillation fit to the excess has a probability of $21.1\%$, while the background-only fit has a $χ^2$ probability of $6 \times 10^{-7}$ relative to the best fit. The MiniBooNE data are consistent in energy and magnitude with the excess of events reported by the Liquid Scintillator Neutrino Detector (LSND), and the significance of the combined LSND and MiniBooNE excesses is $6.0 σ$. A two-neutrino oscillation interpretation of the data would require at least four neutrino types and indicate physics beyond the three neutrino paradigm.Although the data are fit with a two-neutrino oscillation model, other models may provide better fits to the data. △ Less

Submitted 26 October, 2018; v1 submitted 30 May, 2018; originally announced May 2018.

Comments: Improved some of the figures and improved the correlation between neutrino and antineutrino data

Report number: LA-UR-18-24586

Journal ref: Phys. Rev. Lett. 121, 221801 (2018)

Comparisons and challenges of modern neutrino scattering experiments (TENSIONS2016 report)

Authors: M. Betancourt, S. Bolognesi, J. Calcutt, R. Castillo, A. Cudd, S. Dytman, B. Eberly, A. P. Furmanski, R. Fine, J. Grange, L. Jiang, T. Katori, J. Kleckner, J. Kleyklamp, K. Mahn, B. Messerly, G. Perdue, L. Pickering, J. P. Stowell, J. Sobczyk, N. Suarez, H. Tanaka, R. Tayloe, R. T. Thornton, M. Wilking , et al. (3 additional authors not shown)

Abstract: Over the last decade, there has been enormous effort to measure neutrino interaction cross sections important to oscillation experiments. However, a number of results from modern experiments appear to be in tension with each other, despite purporting to measure the same processes. The TENSIONS2016 workshop was held at University of Pittsburgh July 24-31, 2016 and was sponsored by the Pittsburgh Hi… ▽ More Over the last decade, there has been enormous effort to measure neutrino interaction cross sections important to oscillation experiments. However, a number of results from modern experiments appear to be in tension with each other, despite purporting to measure the same processes. The TENSIONS2016 workshop was held at University of Pittsburgh July 24-31, 2016 and was sponsored by the Pittsburgh High Energy Physics, Astronomy, and Cosmology Center (PITT-PACC). The focus was on bringing experimentalists from three experiments together to compare results in detail and try to find the source of tension by clarifying and comparing signal definitions and the analysis strategies used for each measurement. A set of comparisons between the measurements using a consistent set of models was also made. This paper summarizes the main conclusions of that work. △ Less

Submitted 18 May, 2018; originally announced May 2018.

Comments: 35 pages, 20 figures

COHERENT Collaboration data release from the first observation of coherent elastic neutrino-nucleus scattering

Authors: COHERENT Collaboration, D. Akimov, J. B. Albert, P. An, C. Awe, P. S. Barbeau, B. Becker, V. Belov, M. A. Blackston, A. Bolozdynya, A. Brown, A. Burenkov, B. Cabrera-Palmer, M. Cervantes, J. I. Collar, R. J. Cooper, R. L. Cooper, C. Cuesta, J. Daughhetee, D. J. Dean, M. del Valle Coello, J. Detwiler, M. D'Onofrio, A. Eberhardt, Y. Efremenko , et al. (69 additional authors not shown)

Abstract: This release includes data and information necessary to perform independent analyses of the COHERENT result presented in Akimov et al., arXiv:1708.01294 [nucl-ex]. Data is shared in a binned, text-based format, including both "signal" and "background" regions, so that counts and associated uncertainties can be quantitatively calculated for the purpose of separate analyses. This document describes… ▽ More This release includes data and information necessary to perform independent analyses of the COHERENT result presented in Akimov et al., arXiv:1708.01294 [nucl-ex]. Data is shared in a binned, text-based format, including both "signal" and "background" regions, so that counts and associated uncertainties can be quantitatively calculated for the purpose of separate analyses. This document describes the included information and its format, offering some guidance on use of the data. Accompanying code examples show basic interaction with the data using Python. △ Less

Submitted 25 April, 2018; originally announced April 2018.

COHERENT 2018 at the Spallation Neutron Source

Authors: D. Akimov, J. B. Albert, P. An, C. Awe, P. S. Barbeau, B. Becker, V. Belov, M. A. Blackston, A. Bolozdynya, A. Brown, A. Burenkov, B. Cabrera-Palmer, M. Cervantes, J. I. Collar, R. J. Cooper, R. L. Cooper, J. Daughhetee, D. J. Dean, M. del Valle Coello, J. A. Detwiler, M. D'Onofrio, Y. Efremenko, S. R. Elliott, E. Erkela, A. Etenko , et al. (54 additional authors not shown)

Abstract: The primary goal of the COHERENT collaboration is to measure and study coherent elastic neutrino-nucleus scattering (CEvNS) using the high-power, few-tens-of-MeV, pulsed source of neutrinos provided by the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). The COHERENT collaboration reported the first detection of CEvNS [Akimov:2017ade] using a CsI[Na] detector. At present th… ▽ More The primary goal of the COHERENT collaboration is to measure and study coherent elastic neutrino-nucleus scattering (CEvNS) using the high-power, few-tens-of-MeV, pulsed source of neutrinos provided by the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). The COHERENT collaboration reported the first detection of CEvNS [Akimov:2017ade] using a CsI[Na] detector. At present the collaboration is deploying four detector technologies: a CsI[Na] scintillating crystal, p-type point-contact germanium detectors, single-phase liquid argon, and NaI[Tl] crystals. All detectors are located in the neutron-quiet basement of the SNS target building at distances 20-30 m from the SNS neutrino source. The simultaneous measurement in all four COHERENT detector subsystems will test the $N^2$ dependence of the cross section and search for new physics. In addition, COHERENT is measuring neutrino-induced neutrons from charged- and neutral-current neutrino interactions on nuclei in shielding materials, which represent a non-negligible background for CEvNS as well as being of intrinsic interest. The Collaboration is planning as well to look for charged-current interactions of relevance to supernova and weak-interaction physics. This document describes concisely the COHERENT physics motivations, sensitivity, and next plans for measurements at the SNS to be accomplished on a few-year timescale. △ Less

Submitted 2 April, 2018; v1 submitted 24 March, 2018; originally announced March 2018.

Comments: 22 pages, 14 figures

Measurement of the normalized $^{238}$U(n,f)/$^{235}$U(n,f) cross section ratio from threshold to 30 MeV with the fission Time Projection Chamber

Authors: R. J. Casperson, D. M. Asner, J. Baker, R. G. Baker, J. S. Barrett, N. S. Bowden, C. Brune, J. Bundgaard, E. Burgett, D. A. Cebra, T. Classen, M. Cunningham, J. Deaven, D. L. Duke, I. Ferguson, J. Gearhart, V. Geppert-Kleinrath, U. Greife, S. Grimes, E. Guardincerri, U. Hager, C. Hagmann, M. Heffner, D. Hensle, N. Hertel , et al. (39 additional authors not shown)

Abstract: The normalized $^{238}$U(n,f)/$^{235}$U(n,f) cross section ratio has been measured using the NIFFTE fission Time Projection Chamber from the reaction threshold to $30$~MeV. The fissionTPC is a two-volume MICROMEGAS time projection chamber that allows for full three-dimensional reconstruction of fission-fragment ionization profiles from neutron-induced fission. The measurement was performed at the… ▽ More The normalized $^{238}$U(n,f)/$^{235}$U(n,f) cross section ratio has been measured using the NIFFTE fission Time Projection Chamber from the reaction threshold to $30$~MeV. The fissionTPC is a two-volume MICROMEGAS time projection chamber that allows for full three-dimensional reconstruction of fission-fragment ionization profiles from neutron-induced fission. The measurement was performed at the Los Alamos Neutron Science Center, where the neutron energy is determined from neutron time-of-flight. The $^{238}$U(n,f)/$^{235}$U(n,f) ratio reported here is the first cross section measurement made with the fissionTPC, and will provide new experimental data for evaluation of the $^{238}$U(n,f) cross section, an important standard used in neutron-flux measurements. Use of a development target in this work prevented the determination of an absolute normalization, to be addressed in future measurements. Instead, the measured cross section ratio has been normalized to ENDF/B-VIII.$β$5 at 14.5 MeV. △ Less

Submitted 23 February, 2018; originally announced February 2018.

First Measurement of Monoenergetic Muon Neutrino Charged Current Interactions

Authors: A. A. Aguilar-Arevalo, B. C. Brown, L. Bugel, G. Cheng, E. D. Church, J. M. Conrad, R. L. Cooper, R. Dharmapalan, Z. Djurcic, D. A. Finley, R. S. Fitzpatrick, R. Ford, F. G. Garcia, G. T. Garvey, J. Grange, W. Huelsnitz, C. Ignarra, R. Imlay, R. A. Johnson, J. R. Jordan, G. Karagiorgi, T. Katori, T. Kobilarcik, W. C. Louis, K. Mahn , et al. (24 additional authors not shown)

Abstract: We report the first measurement of monoenergetic muon neutrino charged current interactions. MiniBooNE has isolated 236 MeV muon neutrino events originating from charged kaon decay at rest ($K^+ \rightarrow μ^+ ν_μ$) at the NuMI beamline absorber. These signal $ν_μ$-carbon events are distinguished from primarily pion decay in flight $ν_μ$ and $\overlineν_μ$ backgrounds produced at the target stati… ▽ More We report the first measurement of monoenergetic muon neutrino charged current interactions. MiniBooNE has isolated 236 MeV muon neutrino events originating from charged kaon decay at rest ($K^+ \rightarrow μ^+ ν_μ$) at the NuMI beamline absorber. These signal $ν_μ$-carbon events are distinguished from primarily pion decay in flight $ν_μ$ and $\overlineν_μ$ backgrounds produced at the target station and decay pipe using their arrival time and reconstructed muon energy. The significance of the signal observation is at the 3.9$σ$ level. The muon kinetic energy, neutrino-nucleus energy transfer ($ω=E_ν-E_μ$), and total cross section for these events is extracted. This result is the first known-energy, weak-interaction-only probe of the nucleus to yield a measurement of $ω$ using neutrinos, a quantity thus far only accessible through electron scattering. △ Less

Submitted 7 May, 2018; v1 submitted 11 January, 2018; originally announced January 2018.

Comments: 6 pages, 4 figures

Journal ref: Phys. Rev. Lett. 120, 141802 (2018)

Observation of Coherent Elastic Neutrino-Nucleus Scattering

Authors: D. Akimov, J. B. Albert, P. An, C. Awe, P. S. Barbeau, B. Becker, V. Belov, A. Brown, A. Bolozdynya, B. Cabrera-Palmer, M. Cervantes, J. I. Collar, R. J. Cooper, R. L. Cooper, C. Cuesta, D. J. Dean, J. A. Detwiler, A. Eberhardt, Y. Efremenko, S. R. Elliott, E. M. Erkela, L. Fabris, M. Febbraro, N. E. Fields, W. Fox , et al. (56 additional authors not shown)

Abstract: The coherent elastic scattering of neutrinos off nuclei has eluded detection for four decades, even though its predicted cross-section is the largest by far of all low-energy neutrino couplings. This mode of interaction provides new opportunities to study neutrino properties, and leads to a miniaturization of detector size, with potential technological applications. We observe this process at a 6.… ▽ More The coherent elastic scattering of neutrinos off nuclei has eluded detection for four decades, even though its predicted cross-section is the largest by far of all low-energy neutrino couplings. This mode of interaction provides new opportunities to study neutrino properties, and leads to a miniaturization of detector size, with potential technological applications. We observe this process at a 6.7-sigma confidence level, using a low-background, 14.6-kg CsI[Na] scintillator exposed to the neutrino emissions from the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. Characteristic signatures in energy and time, predicted by the Standard Model for this process, are observed in high signal-to-background conditions. Improved constraints on non-standard neutrino interactions with quarks are derived from this initial dataset. △ Less

Submitted 3 August, 2017; originally announced August 2017.

Dark Matter Search in a Proton Beam Dump with MiniBooNE

Authors: A. A. Aguilar-Arevalo, M. Backfish, A. Bashyal, B. Batell, B. C. Brown, R. Carr, A. Chatterjee, R. L. Cooper, P. deNiverville, R. Dharmapalan, Z. Djurcic, R. Ford, F. G. Garcia, G. T. Garvey, J. Grange, J. A. Green, W. Huelsnitz, I. L. de Icaza Astiz, G. Karagiorgi, T. Katori, W. Ketchum, T. Kobilarcik, Q. Liu, W. C. Louis, W. Marsh , et al. (18 additional authors not shown)

Abstract: The MiniBooNE-DM collaboration searched for vector-boson mediated production of dark matter using the Fermilab 8 GeV Booster proton beam in a dedicated run with $1.86 \times 10^{20}$ protons delivered to a steel beam dump. The MiniBooNE detector, 490~m downstream, is sensitive to dark matter via elastic scattering with nucleons in the detector mineral oil. Analysis methods developed for previous M… ▽ More The MiniBooNE-DM collaboration searched for vector-boson mediated production of dark matter using the Fermilab 8 GeV Booster proton beam in a dedicated run with $1.86 \times 10^{20}$ protons delivered to a steel beam dump. The MiniBooNE detector, 490~m downstream, is sensitive to dark matter via elastic scattering with nucleons in the detector mineral oil. Analysis methods developed for previous MiniBooNE scattering results were employed, and several constraining data sets were simultaneously analyzed to minimize systematic errors from neutrino flux and interaction rates. No excess of events over background was observed, leading to a 90\% confidence limit on the dark-matter cross section parameter, $Y=ε^2α_D(m_χ/m_V)^4 \lesssim10^{-8}$, for $α_D=0.5$ and for dark-matter masses of $0.01<m_χ<0.3~\mathrm{GeV}$ in a vector portal model of dark matter. This is the best limit from a dedicated proton beam dump search in this mass and coupling range and extends below the mass range of direct dark matter searches. These results demonstrate a novel and powerful approach to dark matter searches with beam dump experiments. △ Less

Submitted 23 August, 2017; v1 submitted 8 February, 2017; originally announced February 2017.

Comments: 6 pages, 7 figures, Version consistent with final PRL

Journal ref: Phys. Rev. Lett. 118, 221803 (2017)

The COHERENT Experiment at the Spallation Neutron Source

Authors: COHERENT Collaboration, D. Akimov, P. An, C. Awe, P. S. Barbeau, P. Barton, B. Becker, V. Belov, A. Bolozdynya, A. Burenkov, B. Cabrera-Palmer, J. I. Collar, R. J. Cooper, R. L. Cooper, C. Cuesta, D. Dean, J. Detwiler, A. G. Dolgolenko, Y. Efremenko, S. R. Elliott, A. Etenko, N. Fields, W. Fox, A. Galindo-Uribarri, M. Green , et al. (42 additional authors not shown)

Abstract: The COHERENT collaboration's primary objective is to measure coherent elastic neutrino-nucleus scattering (CEvNS) using the unique, high-quality source of tens-of-MeV neutrinos provided by the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). In spite of its large cross section, the CEvNS process has never been observed, due to tiny energies of the resulting nuclear recoils… ▽ More The COHERENT collaboration's primary objective is to measure coherent elastic neutrino-nucleus scattering (CEvNS) using the unique, high-quality source of tens-of-MeV neutrinos provided by the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). In spite of its large cross section, the CEvNS process has never been observed, due to tiny energies of the resulting nuclear recoils which are out of reach for standard neutrino detectors. The measurement of CEvNS has now become feasible, thanks to the development of ultra-sensitive technology for rare decay and weakly-interacting massive particle (dark matter) searches. The CEvNS cross section is cleanly predicted in the standard model; hence its measurement provides a standard model test. It is relevant for supernova physics and supernova-neutrino detection, and enables validation of dark-matter detector background and detector-response models. In the long term, precision measurement of CEvNS will address questions of nuclear structure. COHERENT will deploy multiple detector technologies in a phased approach: a 14-kg CsI[Na] scintillating crystal, 15 kg of p-type point-contact germanium detectors, and 100 kg of liquid xenon in a two-phase time projection chamber. Following an extensive background measurement campaign, a location in the SNS basement has proven to be neutron-quiet and suitable for deployment of the COHERENT detector suite. The simultaneous deployment of the three COHERENT detector subsystems will test the $N^2$ dependence of the cross section and ensure an unambiguous discovery of CEvNS. This document describes concisely the COHERENT physics motivations, sensitivity and plans for measurements at the SNS to be accomplished on a four-year timescale. △ Less

Submitted 3 April, 2016; v1 submitted 29 September, 2015; originally announced September 2015.

Comments: 19 pages, 12 figures: corrections to author list

Accelerator-Produced Dark Matter Search using MiniBooNE

Authors: R. T. Thornton, MiniBooNE-DM collaboration

Abstract: Cosmology observations indicate that our universe is composed of 25% dark matter (DM), yet we know little about its microscopic properties. Whereas the gravitational interaction of DM is well understood, its interaction with the Standard Model is not. Direct detection experiments, the current standard, have a nuclear recoil interaction, low-mass sensitivity edge of order 1 GeV. To detect DM with m… ▽ More Cosmology observations indicate that our universe is composed of 25% dark matter (DM), yet we know little about its microscopic properties. Whereas the gravitational interaction of DM is well understood, its interaction with the Standard Model is not. Direct detection experiments, the current standard, have a nuclear recoil interaction, low-mass sensitivity edge of order 1 GeV. To detect DM with mass below 1 GeV, either the sensitivity of the experiments needs to be improved or use of accelerators producing boosted low-mass DM are needed. Using neutrino detectors to search for low-mass DM is logical due to the similarity of the DM and $ν$ signatures in the detector. The MiniBooNE experiment, located at Fermilab on the Booster Neutrino Beamline, has produced the world's largest collection of $ν$ and $\barν$ samples and is already well understood, making it desirable to search for accelerator-produced boosted low-mass DM. A search for DM produced by 8.9 GeV/c protons hitting a steel beamdump has finished, collecting $1.86\times10^{20} \mathrm{POT}$. Analysis techniques along with predicted sensitivity will be presented. △ Less

Submitted 31 December, 2014; v1 submitted 16 November, 2014; originally announced November 2014.

Comments: 6 pages, 8 figures, for Physics In Collision 2014 conference proceedings

Report number: FERMILAB-CONF-14-537-ND

A Time Projection Chamber for High Accuracy and Precision Fission Cross Section Measurements

Authors: NIFFTE Collaboration, M. Heffner, D. M. Asner, R. G. Baker, J. Baker, S. Barrett, C. Brune, J. Bundgaard, E. Burgett, D. Carter, M. Cunningham, J. Deaven, D. L. Duke, U. Greife, S. Grimes, U. Hager, N. Hertel, T. Hill, D. Isenhower, K. Jewell, J. King, J. L. Klay, V. Kleinrath, N. Kornilov, R. Kudo , et al. (25 additional authors not shown)

Abstract: The fission Time Projection Chamber (fissionTPC) is a compact (15 cm diameter) two-chamber MICROMEGAS TPC designed to make precision cross section measurements of neutron-induced fission. The actinide targets are placed on the central cathode and irradiated with a neutron beam that passes axially through the TPC inducing fission in the target. The 4$π$ acceptance for fission fragments and complete… ▽ More The fission Time Projection Chamber (fissionTPC) is a compact (15 cm diameter) two-chamber MICROMEGAS TPC designed to make precision cross section measurements of neutron-induced fission. The actinide targets are placed on the central cathode and irradiated with a neutron beam that passes axially through the TPC inducing fission in the target. The 4$π$ acceptance for fission fragments and complete charged particle track reconstruction are powerful features of the fissionTPC which will be used to measure fission cross sections and examine the associated systematic errors. This paper provides a detailed description of the design requirements, the design solutions, and the initial performance of the fissionTPC. △ Less

Submitted 26 March, 2014; originally announced March 2014.

Report number: LLNL-JRNL-651187

A New Method for Measuring Coherent Elastic Neutrino Nucleus Scattering at an Off-Axis High-Energy Neutrino Beam Target

Authors: S. J. Brice, R. L. Cooper, F. DeJongh, A. Empl, L. M. Garrison, A. Hime, E. Hungerford, T. Kobilarcik, B. Loer, C. Mariani, M. Mocko, G. Muhrer, R. Pattie, Z. Pavlovic, E. Ramberg, K. Scholberg, R. Tayloe, R. T. Thornton, J. Yoo, A. Young

Abstract: We present a new experimental method for measuring the process of Coherent Elastic Neutrino Nucleus Scattering (CENNS). This method uses a detector situated transverse to a high energy neutrino beam production target. This detector would be sensitive to the low energy neutrinos arising from pion decays-at-rest in the target. We discuss the physics motivation for making this measurement and outline… ▽ More We present a new experimental method for measuring the process of Coherent Elastic Neutrino Nucleus Scattering (CENNS). This method uses a detector situated transverse to a high energy neutrino beam production target. This detector would be sensitive to the low energy neutrinos arising from pion decays-at-rest in the target. We discuss the physics motivation for making this measurement and outline the predicted backgrounds and sensitivities using this approach. We report a measurement of neutron backgrounds as found in an off-axis surface location of the Fermilab Booster Neutrino Beam (BNB) target. The results indicate that the Fermilab BNB target is a favorable location for a CENNS experiment. △ Less

Submitted 22 November, 2013; originally announced November 2013.

Report number: FERMILAB-PUB-13-522-E

Targets for Precision Measurements

Authors: W. Loveland, L. Yao, David M. Asner, R. G. Baker, J. Bundgaard, E. Burgett, M. Cunningham, J. Deaven, D. L. Duke, U. Greife, S. Grimes, M. Heffer, T. Hill, D. Isenhower, J. L. Klay, V. Kleinrath, N. Kornilov, A. B. Laptev, T. N. Massey, R. Meharchand, H. Qu, J. Ruz, S. Sangiorgio, B. Selhan, L. Snyder , et al. (9 additional authors not shown)

Abstract: The general properties needed in targets (sources) for high precision, high accuracy measurements are reviewed. The application of these principles to the problem of developing targets for the Fission TPC is described. Longer term issues, such as the availability of actinide materials, improved knowledge of energy losses and straggling and the stability of targets during irradiation are also discu… ▽ More The general properties needed in targets (sources) for high precision, high accuracy measurements are reviewed. The application of these principles to the problem of developing targets for the Fission TPC is described. Longer term issues, such as the availability of actinide materials, improved knowledge of energy losses and straggling and the stability of targets during irradiation are also discussed. △ Less

Submitted 9 March, 2013; originally announced March 2013.