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Phys. Rev. C 61, 054004 (2000) [11 pages]

Lifetime measurements of medium-heavy Λ hypernuclei

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H. Park *, H. Bhang, and M. Youn †
Department of Physics, Seoul National University, Seoul 151-742, Korea

O. Hashimoto, K. Maeda, Y. Sato, and T. Takahashi
Department of Physics, Tohoku University, Aoba-ku, Sendai, Miyagi 980-77, Japan

K. Aoki, Y. D. Kim ‡, H. Noumi, K. Omata, H. Outa, M. Sekimoto, and T. Shibata
High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan

T. Hasegawa §, H. Hotchi, and Y. Ohta
Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan

S. Ajimura and T. Kishimoto
Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan

Received 10 December 1999; published 21 April 2000

We have measured the lifetimes of the weak decay of Λ12C, Λ28Si, and Λ56Fe hypernuclei which were produced via a (π+,K+) reaction at KEK 12-GeV PS. The lifetimes were obtained by direct measurement of the production and decay time of the hypernucleus using a fast timing counter system whose time resolution was about 83 ps. Our results for the lifetimes of Λ12C, Λ28Si, and ΛFe are 231±15, 206±11, and 215±14 ps, respectively. The lifetimes of Λ11B and Λ27Al with the application of the gate to the pΛ state of the formation spectra of Λ12C and Λ28Si were also determined to be 211±13 and 203±10 ps. From the present work, it was found that the total decay width saturates according to the hypernuclear mass number even at A∼12. This suggests the importance of the proper treatment of the short range nature of the nonmesonic decay of Λ hypernuclei.


©2000 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevC.61.054004
DOI: 10.1103/PhysRevC.61.054004
PACS: 21.80.+a, 13.30.Eg, 13.75.Ev, 21.10.Tg

* Present address: High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan.
† Present address: University of Houston, Houston, TX 77004.
‡ Present address: Department of Physics, Sejong University, Seoul 144-747, Korea.
§ Present address: School of Allied Health Sciences, Kitasato University, Sagamihara 228-8555, Japan.

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