Measurement of gamma-rays from Λ 11B and Λ 12C

From the 12C(π +, K +) 12 ΛC reaction, the γ-rays of 261.60.24keV (7/2 +5/2 +) and 1481.70.7keV (1/2 +5/2 +) of 11 ΛB, and 2667.32.8keV (1 2 -2 1 -) of 12 ΛC hypernuclei have been identified using a large germanium detector array Hyperball2 at K6 beam line of KEK. The observed energies of the transitions 1481.7keV and 261.6keV are significantly different from the values predicted by the shell model using the Δ and S N parameters determined from the 7 ΛLi data. © 2007 Chinese Physical Society and IOP Publishing Ltd.