Proton Energy Spectra in the Nonmesonic Weak Decay of <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow></mrow><mrow><mi>Λ</mi></mrow><mrow><mn>12</mn></mrow></msubsup></mrow><mi>C</mi></math></span> and <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow></mrow><mrow><mi>Λ</mi></mrow><mrow><mn>28</mn></mrow></msubsup></mrow><mi>Si</mi></math></span> Hypernuclei

O. Hashimoto; S. Ajimura; K. Aoki; H. Bhang; T. Hasegawa; H. Hotchi; Y. D. Kim; T. Kishimoto; K. Maeda; H. Noumi; Y. Ohta; K. Omata; H. Outa; H. Park; Y. Sato; M. Sekimoto; T. Shibata; T. Takahashi; M. Youn

doi:10.1103/PhysRevLett.88.042503

Proton Energy Spectra in the Nonmesonic Weak Decay of $_{Λ}^{12} C$ and $_{Λ}^{28} Si$ Hypernuclei

O. Hashimoto, S. Ajimura, K. Aoki, H. Bhang, T. Hasegawa, H. Hotchi, Y. D. Kim, T. Kishimoto, K. Maeda, H. Noumi, Y. Ohta, K. Omata, H. Outa, H. Park, Y. Sato, M. Sekimoto, T. Shibata, T. Takahashi, and M. Youn

Phys. Rev. Lett. 88, 042503 – Published 14 January 2002

Abstract

Numbers of protons per $Γ$ hypernuclear weak decay were measured as a function of proton energy above 40 MeV, explicitly identifying production of $Γ$ hypernuclei by the $(π^{+} {, K}^{+})$ reaction. The ratios between the neutron-stimulated to proton-stimulated nonmesonic decay widths, $Γ (Λ n \to nn) / Γ (Λ p \to np) (= Γ_{n} / Γ_{p})$ were extracted by fitting the proton energy spectra. The present result claims that the proton yields are suppressed and the $Γ_{n} / Γ_{p}$ ratios are close to 1 both for $_{Λ}^{12} C$ and $_{Λ}^{28} Si$ in contradiction to theoretical expectations based on meson exchange models.

Received 28 September 2001

DOI:https://doi.org/10.1103/PhysRevLett.88.042503

Authors & Affiliations

O. Hashimoto¹, S. Ajimura⁵, K. Aoki³, H. Bhang², T. Hasegawa^4,*, H. Hotchi^4,†, Y. D. Kim^2,3,‡, T. Kishimoto⁵, K. Maeda¹, H. Noumi³, Y. Ohta⁴, K. Omata³, H. Outa³, H. Park², Y. Sato^1,3, M. Sekimoto³, T. Shibata³, T. Takahashi¹, and M. Youn^2,3

¹Department of Physics, Tohoku University, Sendai 980-8578, Japan
²Department of Physics, Seoul National University, Seoul 151-742, Korea
³High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
⁴Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan
⁵Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan

^*Present address: School of Allied Health Sciences, Kitazato University, Sagamihara 228-8555, Japan.
^†Present address: Physics Department, Brookhaven National Laboratory, Upton, NY 11973.
^‡Present address: Department of Physics, Sejong University, Seoul 143-747, Korea.