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Title: Measurement of the scintillation time spectra and pulse-shape discrimination of low-energy β and nuclear recoils in liquid argon with DEAP-1

Abstract

The DEAP-1 low-background liquid argon detector has been used to measure scintillation pulse shapes of beta decays and nuclear recoil events and to demonstrate the feasibility of pulse-shape discrimination down to an electron-equivalent energy of 20 keV ee. The relative intensities of singlet/triplet states in liquid argon have been measured as a function of energy between 15 and 500 keVee for both beta and nuclear recoils. Using a triple-coincidence tag we find the fraction of beta events that are misidentified as nuclear recoils to be less than 6 x 10 -8 between 43-86 keV ee and that the discrimination parameter agrees with a simple analytic model. The discrimination measurement is currently limited by nuclear recoils induced by cosmic-ray generated neutrons, and is expected to improve by operating the detector underground at SNOLAB. The analytic model predicts a beta misidentification fraction of 10 -10 for an electron-equivalent energy threshold of 20 keV ee. This reduction allows for a sensitive search for spin-independent scattering of WIMPs from 1000 kg of liquid argon with a WIMP-nucleon cross-section sensitivity of 10 -46 cm 2.

Authors:
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Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25); National Science and Engineering Research Council of Canada (NSERC); Canada Foundation for Innovation (CFI); Ontario Ministry of Research and Innovation (MRI); David and Lucille Packard Foundation
OSTI Identifier:
1368371
Report Number(s):
FERMILAB-PUB-16-697-AE; arXiv:0904.2930
Journal ID: ISSN 0927-6505; 818299
Grant/Contract Number:
AC02-07CH11359
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Astroparticle Physics
Additional Journal Information:
Journal Volume: 85; Journal Issue: C; Journal ID: ISSN 0927-6505
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY

Citation Formats

Amaudruz, P. -A., Batygov, M., Beltran, B., Bonatt, J., Boudjemline, K., Boulay, M. G., Broerman, B., Bueno, J. F., Butcher, A., Cai, B., Caldwell, T., Chen, M., Chouinard, R., Cleveland, B. T., Cranshaw, D., Dering, K., Duncan, F., Fatemighomi, N., Ford, R., Gagnon, R., Giampa, P., Giuliani, F., Gold, M., Golovko, V. V., Gorel, P., Grace, E., Graham, K., Grant, D. R., Hakobyan, R., Hallin, A. L., Hamstra, M., Harvey, P., Hearns, C., Hofgartner, J., Jillings, C. J., Kuźniak, M., Lawson, I., La Zia, F., Li, O., Lidgard, J. J., Liimatainen, P., Lippincott, W. H., Mathew, R., McDonald, A. B., McElroy, T., McFarlane, K., McKinsey, D. N., Mehdiyev, R., Monroe, J., Muir, A., Nantais, C., Nicolics, K., Nikkel, J., Noble, A. J., O’Dwyer, E., Olsen, K., Ouellet, C., Pasuthip, P., Peeters, S. J. M., Pollmann, T., Rau, W., Retière, F., Ronquest, M., Seeburn, N., Skensved, P., Smith, B., Sonley, T., Tang, J., Vázquez-Jáuregui, E., Veloce, L., Walding, J., and Ward, M. Measurement of the scintillation time spectra and pulse-shape discrimination of low-energy β and nuclear recoils in liquid argon with DEAP-1. United States: N. p., 2016. Web. doi:10.1016/j.astropartphys.2016.09.002.
Amaudruz, P. -A., Batygov, M., Beltran, B., Bonatt, J., Boudjemline, K., Boulay, M. G., Broerman, B., Bueno, J. F., Butcher, A., Cai, B., Caldwell, T., Chen, M., Chouinard, R., Cleveland, B. T., Cranshaw, D., Dering, K., Duncan, F., Fatemighomi, N., Ford, R., Gagnon, R., Giampa, P., Giuliani, F., Gold, M., Golovko, V. V., Gorel, P., Grace, E., Graham, K., Grant, D. R., Hakobyan, R., Hallin, A. L., Hamstra, M., Harvey, P., Hearns, C., Hofgartner, J., Jillings, C. J., Kuźniak, M., Lawson, I., La Zia, F., Li, O., Lidgard, J. J., Liimatainen, P., Lippincott, W. H., Mathew, R., McDonald, A. B., McElroy, T., McFarlane, K., McKinsey, D. N., Mehdiyev, R., Monroe, J., Muir, A., Nantais, C., Nicolics, K., Nikkel, J., Noble, A. J., O’Dwyer, E., Olsen, K., Ouellet, C., Pasuthip, P., Peeters, S. J. M., Pollmann, T., Rau, W., Retière, F., Ronquest, M., Seeburn, N., Skensved, P., Smith, B., Sonley, T., Tang, J., Vázquez-Jáuregui, E., Veloce, L., Walding, J., & Ward, M. Measurement of the scintillation time spectra and pulse-shape discrimination of low-energy β and nuclear recoils in liquid argon with DEAP-1. United States. doi:10.1016/j.astropartphys.2016.09.002.
Amaudruz, P. -A., Batygov, M., Beltran, B., Bonatt, J., Boudjemline, K., Boulay, M. G., Broerman, B., Bueno, J. F., Butcher, A., Cai, B., Caldwell, T., Chen, M., Chouinard, R., Cleveland, B. T., Cranshaw, D., Dering, K., Duncan, F., Fatemighomi, N., Ford, R., Gagnon, R., Giampa, P., Giuliani, F., Gold, M., Golovko, V. V., Gorel, P., Grace, E., Graham, K., Grant, D. R., Hakobyan, R., Hallin, A. L., Hamstra, M., Harvey, P., Hearns, C., Hofgartner, J., Jillings, C. J., Kuźniak, M., Lawson, I., La Zia, F., Li, O., Lidgard, J. J., Liimatainen, P., Lippincott, W. H., Mathew, R., McDonald, A. B., McElroy, T., McFarlane, K., McKinsey, D. N., Mehdiyev, R., Monroe, J., Muir, A., Nantais, C., Nicolics, K., Nikkel, J., Noble, A. J., O’Dwyer, E., Olsen, K., Ouellet, C., Pasuthip, P., Peeters, S. J. M., Pollmann, T., Rau, W., Retière, F., Ronquest, M., Seeburn, N., Skensved, P., Smith, B., Sonley, T., Tang, J., Vázquez-Jáuregui, E., Veloce, L., Walding, J., and Ward, M. 2016. "Measurement of the scintillation time spectra and pulse-shape discrimination of low-energy β and nuclear recoils in liquid argon with DEAP-1". United States. doi:10.1016/j.astropartphys.2016.09.002. https://www.osti.gov/servlets/purl/1368371.
@article{osti_1368371,
title = {Measurement of the scintillation time spectra and pulse-shape discrimination of low-energy β and nuclear recoils in liquid argon with DEAP-1},
author = {Amaudruz, P. -A. and Batygov, M. and Beltran, B. and Bonatt, J. and Boudjemline, K. and Boulay, M. G. and Broerman, B. and Bueno, J. F. and Butcher, A. and Cai, B. and Caldwell, T. and Chen, M. and Chouinard, R. and Cleveland, B. T. and Cranshaw, D. and Dering, K. and Duncan, F. and Fatemighomi, N. and Ford, R. and Gagnon, R. and Giampa, P. and Giuliani, F. and Gold, M. and Golovko, V. V. and Gorel, P. and Grace, E. and Graham, K. and Grant, D. R. and Hakobyan, R. and Hallin, A. L. and Hamstra, M. and Harvey, P. and Hearns, C. and Hofgartner, J. and Jillings, C. J. and Kuźniak, M. and Lawson, I. and La Zia, F. and Li, O. and Lidgard, J. J. and Liimatainen, P. and Lippincott, W. H. and Mathew, R. and McDonald, A. B. and McElroy, T. and McFarlane, K. and McKinsey, D. N. and Mehdiyev, R. and Monroe, J. and Muir, A. and Nantais, C. and Nicolics, K. and Nikkel, J. and Noble, A. J. and O’Dwyer, E. and Olsen, K. and Ouellet, C. and Pasuthip, P. and Peeters, S. J. M. and Pollmann, T. and Rau, W. and Retière, F. and Ronquest, M. and Seeburn, N. and Skensved, P. and Smith, B. and Sonley, T. and Tang, J. and Vázquez-Jáuregui, E. and Veloce, L. and Walding, J. and Ward, M.},
abstractNote = {The DEAP-1 low-background liquid argon detector has been used to measure scintillation pulse shapes of beta decays and nuclear recoil events and to demonstrate the feasibility of pulse-shape discrimination down to an electron-equivalent energy of 20 keVee. The relative intensities of singlet/triplet states in liquid argon have been measured as a function of energy between 15 and 500 keVee for both beta and nuclear recoils. Using a triple-coincidence tag we find the fraction of beta events that are misidentified as nuclear recoils to be less than 6 x 10-8 between 43-86 keVee and that the discrimination parameter agrees with a simple analytic model. The discrimination measurement is currently limited by nuclear recoils induced by cosmic-ray generated neutrons, and is expected to improve by operating the detector underground at SNOLAB. The analytic model predicts a beta misidentification fraction of 10-10 for an electron-equivalent energy threshold of 20 keVee. This reduction allows for a sensitive search for spin-independent scattering of WIMPs from 1000 kg of liquid argon with a WIMP-nucleon cross-section sensitivity of 10-46 cm2.},
doi = {10.1016/j.astropartphys.2016.09.002},
journal = {Astroparticle Physics},
number = C,
volume = 85,
place = {United States},
year = 2016,
month = 9
}

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  • We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow band neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We also report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.3 keV and for median applied electric fields from 0more » to 970 V/cm. For the ionization yields, we report measurements from 16.9 to 57.3 keV and for electric fields from 96.4 to 486 V/cm. Furthermore, we report the observation of an anticorrelation between scintillation and ionization from nuclear recoils, which is similar to the anticorrelation between scintillation and ionization from electron recoils. Assuming that the energy loss partitions into excitons and ion pairs from 83mKr internal conversion electrons is comparable to that from 207Bi conversion electrons, we obtained the numbers of excitons (N ex) and ion pairs (N i) and their ratio (N ex/N i) produced by nuclear recoils from 16.9 to 57.3 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.« less
  • We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow band neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.3 keV and for median applied electric fields from 0 tomore » 970 V / cm . For the ionization yields, we report measurements from 16.9 to 57.3 keV and for electric fields from 96.4 to 486 V / cm . We also report the observation of an anticorrelation between scintillation and ionization from nuclear recoils, which is similar to the anticorrelation between scintillation and ionization from electron recoils. Assuming that the energy loss partitions into excitons and ion pairs from 83 m Kr internal conversion electrons is comparable to that from 207 Bi conversion electrons, we obtained the numbers of excitons ( N ex ) and ion pairs ( N i ) and their ratio ( N ex / N i ) produced by nuclear recoils from 16.9 to 57.3 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.« less
  • Using a single-phase liquid argon detector with a signal yield of 4.85 photoelectrons per keV of electronic-equivalent recoil energy (keVee), we measure the scintillation time dependence of both electronic and nuclear recoils in liquid argon down to 5 keVee. We develop two methods of pulse shape discrimination to distinguish between electronic and nuclear recoils. Using one of these methods, we measure a background- and statistics-limited level of electronic recoil contamination to be 7.6x10{sup -7} between 52 and 110 keV of nuclear recoil energy (keVr) for a nuclear recoil acceptance of 50% with no nuclear recoil-like events above 62 keVr. Finally,more » we develop a maximum likelihood method of pulse shape discrimination based on the measured scintillation time dependence.« less
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