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. Jones & 21 others B. 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

Y1 - 2011/1/31

N2 - 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.

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