Improved accuracy in the determination of the thermal cross section of 14N(n, p) 14C for neutron lifetime measurement

R. Kitahara, K. Hirota, S. Ieki, T. Ino, Y. Iwashita, M. Kitaguchi, J. Koga, K. Mishima, A. Morishita, N. Nagakura, H. Oide, H. Otono, Y. Seki, D. Sekiba, T. Shima, H. M. Shimizu, N. Sumi, H. Sumino, K. Taketani, T. TomitaT. Yamada, S. Yamashita, M. Yokohashi, T. Yoshioka

Research output: Contribution to journalArticle

Abstract

In a neutron lifetime measurement at the Japan Proton Accelerator Complex, the neutron lifetime is calculated from the neutron decay rate and the incident neutron flux. The flux is obtained by counting the protons emitted from the neutron absorption reaction of 3He gas, which is diluted in a mixture of working gas in a detector. Hence, it is crucial to determine the amount of 3He in the mixture. In order to improve the accuracy of the number density of the 3He nuclei, we have suggested using the 14N(n, p)14C reaction as a reference because this reaction involves similar kinetic energy to the 3He(n,p)3 H reaction and a smaller reaction cross section to introduce reasonable large partial pressure. The uncertainty of the recommended value of the cross section, however, is not satisfied with our requirement. In this paper we report the most accurate experimental value of the cross section of the 14N(n,p)14C reaction at a neutron velocity of 2200 m s-1, measured relative to the 3He(n,p)3H reaction. The result was 1.868 \pm 0.003 (stat.) ± 0.006 (sys.) b. Additionally, the cross section of the 17O(n,α)14C reaction at the neutron velocity is also redetermined as 249 ± 6 mb.

Original languageEnglish
Article number093C01
JournalProgress of Theoretical and Experimental Physics
Volume2019
Issue number9
DOIs
Publication statusPublished - Sep 26 2019

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neutrons
life (durability)
cross sections
neutron decay
protons
flux (rate)
gases
decay rates
partial pressure
Japan
counting
accelerators
kinetic energy
requirements
nuclei
detectors

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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Improved accuracy in the determination of the thermal cross section of 14N(n, p) 14C for neutron lifetime measurement. / Kitahara, R.; Hirota, K.; Ieki, S.; Ino, T.; Iwashita, Y.; Kitaguchi, M.; Koga, J.; Mishima, K.; Morishita, A.; Nagakura, N.; Oide, H.; Otono, H.; Seki, Y.; Sekiba, D.; Shima, T.; Shimizu, H. M.; Sumi, N.; Sumino, H.; Taketani, K.; Tomita, T.; Yamada, T.; Yamashita, S.; Yokohashi, M.; Yoshioka, T.

In: Progress of Theoretical and Experimental Physics, Vol. 2019, No. 9, 093C01, 26.09.2019.

Research output: Contribution to journalArticle

Kitahara, R, Hirota, K, Ieki, S, Ino, T, Iwashita, Y, Kitaguchi, M, Koga, J, Mishima, K, Morishita, A, Nagakura, N, Oide, H, Otono, H, Seki, Y, Sekiba, D, Shima, T, Shimizu, HM, Sumi, N, Sumino, H, Taketani, K, Tomita, T, Yamada, T, Yamashita, S, Yokohashi, M & Yoshioka, T 2019, 'Improved accuracy in the determination of the thermal cross section of 14N(n, p) 14C for neutron lifetime measurement', Progress of Theoretical and Experimental Physics, vol. 2019, no. 9, 093C01. https://doi.org/10.1093/ptep/ptz096
Kitahara, R. ; Hirota, K. ; Ieki, S. ; Ino, T. ; Iwashita, Y. ; Kitaguchi, M. ; Koga, J. ; Mishima, K. ; Morishita, A. ; Nagakura, N. ; Oide, H. ; Otono, H. ; Seki, Y. ; Sekiba, D. ; Shima, T. ; Shimizu, H. M. ; Sumi, N. ; Sumino, H. ; Taketani, K. ; Tomita, T. ; Yamada, T. ; Yamashita, S. ; Yokohashi, M. ; Yoshioka, T. / Improved accuracy in the determination of the thermal cross section of 14N(n, p) 14C for neutron lifetime measurement. In: Progress of Theoretical and Experimental Physics. 2019 ; Vol. 2019, No. 9.
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abstract = "In a neutron lifetime measurement at the Japan Proton Accelerator Complex, the neutron lifetime is calculated from the neutron decay rate and the incident neutron flux. The flux is obtained by counting the protons emitted from the neutron absorption reaction of 3He gas, which is diluted in a mixture of working gas in a detector. Hence, it is crucial to determine the amount of 3He in the mixture. In order to improve the accuracy of the number density of the 3He nuclei, we have suggested using the 14N(n, p)14C reaction as a reference because this reaction involves similar kinetic energy to the 3He(n,p)3 H reaction and a smaller reaction cross section to introduce reasonable large partial pressure. The uncertainty of the recommended value of the cross section, however, is not satisfied with our requirement. In this paper we report the most accurate experimental value of the cross section of the 14N(n,p)14C reaction at a neutron velocity of 2200 m s-1, measured relative to the 3He(n,p)3H reaction. The result was 1.868 \pm 0.003 (stat.) ± 0.006 (sys.) b. Additionally, the cross section of the 17O(n,α)14C reaction at the neutron velocity is also redetermined as 249 ± 6 mb.",
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AU - Kitahara, R.

AU - Hirota, K.

AU - Ieki, S.

AU - Ino, T.

AU - Iwashita, Y.

AU - Kitaguchi, M.

AU - Koga, J.

AU - Mishima, K.

AU - Morishita, A.

AU - Nagakura, N.

AU - Oide, H.

AU - Otono, H.

AU - Seki, Y.

AU - Sekiba, D.

AU - Shima, T.

AU - Shimizu, H. M.

AU - Sumi, N.

AU - Sumino, H.

AU - Taketani, K.

AU - Tomita, T.

AU - Yamada, T.

AU - Yamashita, S.

AU - Yokohashi, M.

AU - Yoshioka, T.

PY - 2019/9/26

Y1 - 2019/9/26

N2 - In a neutron lifetime measurement at the Japan Proton Accelerator Complex, the neutron lifetime is calculated from the neutron decay rate and the incident neutron flux. The flux is obtained by counting the protons emitted from the neutron absorption reaction of 3He gas, which is diluted in a mixture of working gas in a detector. Hence, it is crucial to determine the amount of 3He in the mixture. In order to improve the accuracy of the number density of the 3He nuclei, we have suggested using the 14N(n, p)14C reaction as a reference because this reaction involves similar kinetic energy to the 3He(n,p)3 H reaction and a smaller reaction cross section to introduce reasonable large partial pressure. The uncertainty of the recommended value of the cross section, however, is not satisfied with our requirement. In this paper we report the most accurate experimental value of the cross section of the 14N(n,p)14C reaction at a neutron velocity of 2200 m s-1, measured relative to the 3He(n,p)3H reaction. The result was 1.868 \pm 0.003 (stat.) ± 0.006 (sys.) b. Additionally, the cross section of the 17O(n,α)14C reaction at the neutron velocity is also redetermined as 249 ± 6 mb.

AB - In a neutron lifetime measurement at the Japan Proton Accelerator Complex, the neutron lifetime is calculated from the neutron decay rate and the incident neutron flux. The flux is obtained by counting the protons emitted from the neutron absorption reaction of 3He gas, which is diluted in a mixture of working gas in a detector. Hence, it is crucial to determine the amount of 3He in the mixture. In order to improve the accuracy of the number density of the 3He nuclei, we have suggested using the 14N(n, p)14C reaction as a reference because this reaction involves similar kinetic energy to the 3He(n,p)3 H reaction and a smaller reaction cross section to introduce reasonable large partial pressure. The uncertainty of the recommended value of the cross section, however, is not satisfied with our requirement. In this paper we report the most accurate experimental value of the cross section of the 14N(n,p)14C reaction at a neutron velocity of 2200 m s-1, measured relative to the 3He(n,p)3H reaction. The result was 1.868 \pm 0.003 (stat.) ± 0.006 (sys.) b. Additionally, the cross section of the 17O(n,α)14C reaction at the neutron velocity is also redetermined as 249 ± 6 mb.

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