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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±14ps, 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±10ps. From the present work, it was found that the total decay width saturates according to the hypernuclear mass number even at A12. 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.