Measurement of parity-violating γ-ray asymmetry in the capture of polarized cold neutrons on protons

M. T. Gericke, Ricardo Alarcon, S. Balascuta, L. Barrón-Palos, C. Blessinger, J. D. Bowman, R. D. Carlini, W. Chen, T. E. Chupp, C. Crawford, S. Covrig, M. Dabaghyan, N. Fomin, S. J. Freedman, T. R. Gentile, R. C. Gillis, G. L. Greene, F. W. Hersman, T. Ino, G. L. JonesB. Lauss, M. Leuschner, W. R. Lozowski, R. Mahurin, Y. Masuda, J. Mei, G. S. Mitchell, S. Muto, H. Nann, S. A. Page, S. I. Penttilä, W. D. Ramsay, A. Salas-Bacci, S. Santra, M. Sharma, P. N. Seo, E. I. Sharapov, T. B. Smith, W. M. Snow, W. S. Wilburn, V. Yuan

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Abstract

The NPDGamma collaboration reports results from the first phase of a measurement of the parity violating up-down asymmetry Aγ with respect to the neutron spin direction of γ rays emitted in the reaction n+p→d+γ using the capture of polarized cold neutrons on the protons in a liquid parahydrogen target. One expects parity-odd effects in the hadronic weak interaction between nucleons to be induced by the weak interaction between quarks. Aγ in n-+p→d+γ is dominated by a ΔI=1, 3S1-3P1 parity-odd transition amplitude in the n-p system. The first phase of the measurement was completed at the Los Alamos Neutron Science Center spallation source (LANSCE), with the result A γ=[-1.2±2.1(stat.)±0.2(sys.)]×10 -7. We also report the first measurement of an upper limit for the parity-allowed left-right asymmetry in this reaction, with the result A γ,LR=[-1.8±1.9(stat.)±0.2(sys.)]×10 -7. In this paper we give a detailed report on the theoretical background, experimental setup, measurements, extraction of parity-odd and parity-allowed asymmetries, analysis of potential systematic effects, and LANSCE results. The asymmetry has an estimated size of 5×10-8 and the aim of the NPDGamma collaboration is to measure it to 1×10-8. The second phase of the measurement will be performed at the Spallation Neutron Source at Oak Ridge National Laboratory.

Original languageEnglish (US)
Article number015505
JournalPhysical Review C - Nuclear Physics
Volume83
Issue number1
DOIs
StatePublished - Jan 31 2011

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cold neutrons
rays
parity
asymmetry
protons
spallation
neutrons
neutron sources
nucleons
ridges
quarks
liquids

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

Cite this

Measurement of parity-violating γ-ray asymmetry in the capture of polarized cold neutrons on protons. / Gericke, M. T.; Alarcon, Ricardo; Balascuta, S.; Barrón-Palos, L.; Blessinger, C.; Bowman, J. D.; Carlini, R. D.; Chen, W.; Chupp, T. E.; Crawford, C.; Covrig, S.; Dabaghyan, M.; Fomin, N.; Freedman, S. J.; Gentile, T. R.; Gillis, R. C.; Greene, G. L.; Hersman, F. W.; Ino, T.; Jones, G. L.; Lauss, B.; Leuschner, M.; Lozowski, W. R.; Mahurin, R.; Masuda, Y.; Mei, J.; Mitchell, G. S.; Muto, S.; Nann, H.; Page, S. A.; Penttilä, S. I.; Ramsay, W. D.; Salas-Bacci, A.; Santra, S.; Sharma, M.; Seo, P. N.; Sharapov, E. I.; Smith, T. B.; Snow, W. M.; Wilburn, W. S.; Yuan, V.

In: Physical Review C - Nuclear Physics, Vol. 83, No. 1, 015505, 31.01.2011.

Research output: Contribution to journalArticle

Gericke, MT, Alarcon, R, Balascuta, S, Barrón-Palos, L, Blessinger, C, Bowman, JD, Carlini, RD, Chen, W, Chupp, TE, Crawford, C, Covrig, S, Dabaghyan, M, Fomin, N, Freedman, SJ, Gentile, TR, Gillis, RC, Greene, GL, Hersman, FW, Ino, T, Jones, GL, Lauss, B, Leuschner, M, Lozowski, WR, Mahurin, R, Masuda, Y, Mei, J, Mitchell, GS, Muto, S, Nann, H, Page, SA, Penttilä, SI, Ramsay, WD, Salas-Bacci, A, Santra, S, Sharma, M, Seo, PN, Sharapov, EI, Smith, TB, Snow, WM, Wilburn, WS & Yuan, V 2011, 'Measurement of parity-violating γ-ray asymmetry in the capture of polarized cold neutrons on protons', Physical Review C - Nuclear Physics, vol. 83, no. 1, 015505. https://doi.org/10.1103/PhysRevC.83.015505
Gericke, M. T. ; Alarcon, Ricardo ; Balascuta, S. ; Barrón-Palos, L. ; Blessinger, C. ; Bowman, J. D. ; Carlini, R. D. ; Chen, W. ; Chupp, T. E. ; Crawford, C. ; Covrig, S. ; Dabaghyan, M. ; Fomin, N. ; Freedman, S. J. ; Gentile, T. R. ; Gillis, R. C. ; Greene, G. L. ; Hersman, F. W. ; Ino, T. ; Jones, G. L. ; Lauss, B. ; Leuschner, M. ; Lozowski, W. R. ; Mahurin, R. ; Masuda, Y. ; Mei, J. ; Mitchell, G. S. ; Muto, S. ; Nann, H. ; Page, S. A. ; Penttilä, S. I. ; Ramsay, W. D. ; Salas-Bacci, A. ; Santra, S. ; Sharma, M. ; Seo, P. N. ; Sharapov, E. I. ; Smith, T. B. ; Snow, W. M. ; Wilburn, W. S. ; Yuan, V. / Measurement of parity-violating γ-ray asymmetry in the capture of polarized cold neutrons on protons. In: Physical Review C - Nuclear Physics. 2011 ; Vol. 83, No. 1.
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abstract = "The NPDGamma collaboration reports results from the first phase of a measurement of the parity violating up-down asymmetry Aγ with respect to the neutron spin direction of γ rays emitted in the reaction n+p→d+γ using the capture of polarized cold neutrons on the protons in a liquid parahydrogen target. One expects parity-odd effects in the hadronic weak interaction between nucleons to be induced by the weak interaction between quarks. Aγ in n-+p→d+γ is dominated by a ΔI=1, 3S1-3P1 parity-odd transition amplitude in the n-p system. The first phase of the measurement was completed at the Los Alamos Neutron Science Center spallation source (LANSCE), with the result A γ=[-1.2±2.1(stat.)±0.2(sys.)]×10 -7. We also report the first measurement of an upper limit for the parity-allowed left-right asymmetry in this reaction, with the result A γ,LR=[-1.8±1.9(stat.)±0.2(sys.)]×10 -7. In this paper we give a detailed report on the theoretical background, experimental setup, measurements, extraction of parity-odd and parity-allowed asymmetries, analysis of potential systematic effects, and LANSCE results. The asymmetry has an estimated size of 5×10-8 and the aim of the NPDGamma collaboration is to measure it to 1×10-8. The second phase of the measurement will be performed at the Spallation Neutron Source at Oak Ridge National Laboratory.",
author = "Gericke, {M. T.} and Ricardo Alarcon and S. Balascuta and L. Barr{\'o}n-Palos and C. Blessinger and Bowman, {J. D.} and Carlini, {R. D.} and W. Chen and Chupp, {T. E.} and C. Crawford and S. Covrig and M. Dabaghyan and N. Fomin and Freedman, {S. J.} and Gentile, {T. R.} and Gillis, {R. C.} and Greene, {G. L.} and Hersman, {F. W.} and T. Ino and Jones, {G. L.} and B. Lauss and M. Leuschner and Lozowski, {W. R.} and R. Mahurin and Y. Masuda and J. Mei and Mitchell, {G. S.} and S. Muto and H. Nann and Page, {S. A.} and Penttil{\"a}, {S. I.} and Ramsay, {W. D.} and A. Salas-Bacci and S. Santra and M. Sharma and Seo, {P. N.} and Sharapov, {E. I.} and Smith, {T. B.} and Snow, {W. M.} and Wilburn, {W. S.} and V. Yuan",
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AU - Gericke, M. T.

AU - Alarcon, Ricardo

AU - Balascuta, S.

AU - Barrón-Palos, L.

AU - Blessinger, C.

AU - Bowman, J. D.

AU - Carlini, R. D.

AU - Chen, W.

AU - Chupp, T. E.

AU - Crawford, C.

AU - Covrig, S.

AU - Dabaghyan, M.

AU - Fomin, N.

AU - Freedman, S. J.

AU - Gentile, T. R.

AU - Gillis, R. C.

AU - Greene, G. L.

AU - Hersman, F. W.

AU - Ino, T.

AU - Jones, G. L.

AU - Lauss, B.

AU - Leuschner, M.

AU - Lozowski, W. R.

AU - Mahurin, R.

AU - Masuda, Y.

AU - Mei, J.

AU - Mitchell, G. S.

AU - Muto, S.

AU - Nann, H.

AU - Page, S. A.

AU - Penttilä, S. I.

AU - Ramsay, W. D.

AU - Salas-Bacci, A.

AU - Santra, S.

AU - Sharma, M.

AU - Seo, P. N.

AU - Sharapov, E. I.

AU - Smith, T. B.

AU - Snow, W. M.

AU - Wilburn, W. S.

AU - Yuan, V.

PY - 2011/1/31

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