Hypernuclear weak decay experiments at KEK: n-n and n-p coincidence measurement

H. Outa; S. Ajimura; K. Aoki; A. Banu; H. C. Bhang; T. Fukuda; O. Hashimoto; J. I. Hwang; S. Kameoka; B. H. Kang; E. H. Kim; J. H. Kim; M. J. Kim; T. Maruta; Y. Miura; Y. Miyake; T. Nagae; M. Nakamura; S. N. Nakamura; H. Noumi; S. Okada; Y. Okayasu; H. Park; P. K. Saha; Y. Sato; M. Sekimoto; T. Takahashi; H. Tamura; K. Tanida; A. Toyoda; K. Tsukada; T. Watanabe; H. J. Yim

doi:10.1016/j.nuclphysa.2005.03.007

Hypernuclear weak decay experiments at KEK: n-n and n-p coincidence measurement

H. Outa, S. Ajimura, K. Aoki, A. Banu, H. C. Bhang, T. Fukuda, O. Hashimoto, J. I. Hwang, S. Kameoka, B. H. Kang, E. H. Kim, J. H. Kim, M. J. Kim, T. Maruta, Y. Miura, Y. Miyake, T. Nagae, M. Nakamura, S. N. Nakamura, H. NoumiS. Okada, Y. Okayasu, H. Park, P. K. Saha, Y. Sato, M. Sekimoto, T. Takahashi, H. Tamura, K. Tanida, A. Toyoda, K. Tsukada, T. Watanabe, H. J. Yim

School of Earth System Sciences

Research output: Contribution to journal › Article › peer-review

35 Scopus citations

Abstract

We performed a coincidence measurement of two nucleons emitted from the nonmesonic weak decay (NMWD) of _Λ⁵He and _Λ¹²C formed via the (π⁺, K⁺) reaction. In both of n + p and n + n pair coincidence spectra, we observed a clean back-to-back correlation coming from the two-body decay of Λp → np and Λn → nn, respectively. We obtained the ratio of the nucleon pair numbers, N_nn/N_np (_Λ⁵He) = 0.45 ± 0.11 (stat) ± 0.03 (syst) in the kinematic region of cos θ_NN < -0.8. Since each decay mode was exclusively detected, the measured ratio should be close to the ratio of Γ(Λp → nn)/Γ (Λp → np). The Γ_n/Γ_p ratio was measured also for the NMWD of _Λ¹²C. It is also close to 0.5. Those ratios are consistent with recent theoretical calculations based on the heavy meson/direct quark exchange picture.

Original language	English
Pages (from-to)	157-167
Number of pages	11
Journal	Nuclear Physics A
Volume	754
Issue number	1-4 SPEC. ISS.
DOIs	https://doi.org/10.1016/j.nuclphysa.2005.03.007
State	Published - 30 May 2005

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Outa, H., Ajimura, S., Aoki, K., Banu, A., Bhang, H. C., Fukuda, T., Hashimoto, O., Hwang, J. I., Kameoka, S., Kang, B. H., Kim, E. H., Kim, J. H., Kim, M. J., Maruta, T., Miura, Y., Miyake, Y., Nagae, T., Nakamura, M., Nakamura, S. N., ... Yim, H. J. (2005). Hypernuclear weak decay experiments at KEK: n-n and n-p coincidence measurement. Nuclear Physics A, 754(1-4 SPEC. ISS.), 157-167. https://doi.org/10.1016/j.nuclphysa.2005.03.007

@article{70d7d94e2033448584b7fb1c613b1b51,

title = "Hypernuclear weak decay experiments at KEK: n-n and n-p coincidence measurement",

abstract = "We performed a coincidence measurement of two nucleons emitted from the nonmesonic weak decay (NMWD) of Λ5He and Λ12C formed via the (π+, K+) reaction. In both of n + p and n + n pair coincidence spectra, we observed a clean back-to-back correlation coming from the two-body decay of Λp → np and Λn → nn, respectively. We obtained the ratio of the nucleon pair numbers, Nnn/Nnp (Λ5He) = 0.45 ± 0.11 (stat) ± 0.03 (syst) in the kinematic region of cos θNN < -0.8. Since each decay mode was exclusively detected, the measured ratio should be close to the ratio of Γ(Λp → nn)/Γ (Λp → np). The Γn/Γp ratio was measured also for the NMWD of Λ12C. It is also close to 0.5. Those ratios are consistent with recent theoretical calculations based on the heavy meson/direct quark exchange picture.",

author = "H. Outa and S. Ajimura and K. Aoki and A. Banu and Bhang, {H. C.} and T. Fukuda and O. Hashimoto and Hwang, {J. I.} and S. Kameoka and Kang, {B. H.} and Kim, {E. H.} and Kim, {J. H.} and Kim, {M. J.} and T. Maruta and Y. Miura and Y. Miyake and T. Nagae and M. Nakamura and Nakamura, {S. N.} and H. Noumi and S. Okada and Y. Okayasu and H. Park and Saha, {P. K.} and Y. Sato and M. Sekimoto and T. Takahashi and H. Tamura and K. Tanida and A. Toyoda and K. Tsukada and T. Watanabe and Yim, {H. J.}",

year = "2005",

month = may,

day = "30",

doi = "10.1016/j.nuclphysa.2005.03.007",

language = "English",

volume = "754",

pages = "157--167",

journal = "Nuclear Physics A",

issn = "0375-9474",

publisher = "Elsevier B.V.",

number = "1-4 SPEC. ISS.",

}

Outa, H, Ajimura, S, Aoki, K, Banu, A, Bhang, HC, Fukuda, T, Hashimoto, O, Hwang, JI, Kameoka, S, Kang, BH, Kim, EH, Kim, JH, Kim, MJ, Maruta, T, Miura, Y, Miyake, Y, Nagae, T, Nakamura, M, Nakamura, SN, Noumi, H, Okada, S, Okayasu, Y, Park, H, Saha, PK, Sato, Y, Sekimoto, M, Takahashi, T, Tamura, H, Tanida, K, Toyoda, A, Tsukada, K, Watanabe, T & Yim, HJ 2005, 'Hypernuclear weak decay experiments at KEK: n-n and n-p coincidence measurement', Nuclear Physics A, vol. 754, no. 1-4 SPEC. ISS., pp. 157-167. https://doi.org/10.1016/j.nuclphysa.2005.03.007

TY - JOUR

T1 - Hypernuclear weak decay experiments at KEK

T2 - n-n and n-p coincidence measurement

AU - Outa, H.

AU - Ajimura, S.

AU - Aoki, K.

AU - Banu, A.

AU - Bhang, H. C.

AU - Fukuda, T.

AU - Hashimoto, O.

AU - Hwang, J. I.

AU - Kameoka, S.

AU - Kang, B. H.

AU - Kim, E. H.

AU - Kim, J. H.

AU - Kim, M. J.

AU - Maruta, T.

AU - Miura, Y.

AU - Miyake, Y.

AU - Nagae, T.

AU - Nakamura, M.

AU - Nakamura, S. N.

AU - Noumi, H.

AU - Okada, S.

AU - Okayasu, Y.

AU - Park, H.

AU - Saha, P. K.

AU - Sato, Y.

AU - Sekimoto, M.

AU - Takahashi, T.

AU - Tamura, H.

AU - Tanida, K.

AU - Toyoda, A.

AU - Tsukada, K.

AU - Watanabe, T.

AU - Yim, H. J.

PY - 2005/5/30

Y1 - 2005/5/30

N2 - We performed a coincidence measurement of two nucleons emitted from the nonmesonic weak decay (NMWD) of Λ5He and Λ12C formed via the (π+, K+) reaction. In both of n + p and n + n pair coincidence spectra, we observed a clean back-to-back correlation coming from the two-body decay of Λp → np and Λn → nn, respectively. We obtained the ratio of the nucleon pair numbers, Nnn/Nnp (Λ5He) = 0.45 ± 0.11 (stat) ± 0.03 (syst) in the kinematic region of cos θNN < -0.8. Since each decay mode was exclusively detected, the measured ratio should be close to the ratio of Γ(Λp → nn)/Γ (Λp → np). The Γn/Γp ratio was measured also for the NMWD of Λ12C. It is also close to 0.5. Those ratios are consistent with recent theoretical calculations based on the heavy meson/direct quark exchange picture.

AB - We performed a coincidence measurement of two nucleons emitted from the nonmesonic weak decay (NMWD) of Λ5He and Λ12C formed via the (π+, K+) reaction. In both of n + p and n + n pair coincidence spectra, we observed a clean back-to-back correlation coming from the two-body decay of Λp → np and Λn → nn, respectively. We obtained the ratio of the nucleon pair numbers, Nnn/Nnp (Λ5He) = 0.45 ± 0.11 (stat) ± 0.03 (syst) in the kinematic region of cos θNN < -0.8. Since each decay mode was exclusively detected, the measured ratio should be close to the ratio of Γ(Λp → nn)/Γ (Λp → np). The Γn/Γp ratio was measured also for the NMWD of Λ12C. It is also close to 0.5. Those ratios are consistent with recent theoretical calculations based on the heavy meson/direct quark exchange picture.

UR - http://www.scopus.com/inward/record.url?scp=17644410338&partnerID=8YFLogxK

U2 - 10.1016/j.nuclphysa.2005.03.007

DO - 10.1016/j.nuclphysa.2005.03.007

M3 - Article

AN - SCOPUS:17644410338

SN - 0375-9474

VL - 754

SP - 157

EP - 167

JO - Nuclear Physics A

JF - Nuclear Physics A

IS - 1-4 SPEC. ISS.

ER -

Hypernuclear weak decay experiments at KEK: n-n and n-p coincidence measurement

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