We have measured the lifetimes of the weak decay of 12ΛC, 28ΛSi, and 56ΛFe 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 12ΛC, 28ΛSi, and ΛFe are 231 ±15, 206±11, and 215±14 ps, respectively. The lifetimes of 11ΛB and 27ΛA1 with the application of the gate to the pΛ state of the formation spectra of 12ΛC and 28ΛSi 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 A hypernuclei.
|ジャーナル||Physical Review C - Nuclear Physics|
|出版ステータス||Published - 2000 1月 1|
ASJC Scopus subject areas