Phys. Rev. C 61, 054004 (2000) [11 pages]Lifetime measurements of medium-heavy Λ hypernucleiReceived 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
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