The KEK E566 is an experiment for high-precision $\gamma$-ray spectroscopy of 12-Lambda-C and 11-Lambda-B by the (pi+,K+) reaction on 12C target. It is carried out at the K6 beam line employing Superconducting Kaon Spectrometer (SKS) and a Ge detector array ``Hyperball-2'', an upgraded version of Hyperball with a doubled efficiency. One of the purposes of the experiment is to produce 11-Lambda-B(7/2+) from proton emission of the p_Lambda states of 12-Lambda-C(2+) and to measure the Lambda-spin-flip transition probability B(M1) of 11-Lambda-B (7/2+ -> 5/2+) with the Doppler shift attenuation method. The effective g-factor of a Lambda in a nucleus is derived from the measured B(M1) value. It allows us to investigate a possible modification of the magnetic moment of a Lambda in a nucleus for the first time. The other purpose is to investigate the Sigma N - Lambda N coupling force in the Lambda N interaction from the 12-Lambda-C level energies and to solve the ``puzzle'' of the Lambda N spin-dependent interaction strengths which has emerged from a recent Hyperball data on 10-Lambda-B. In particular, the 12-Lambda-C ground-state doublet (1-,2-) spacing, which will be measured from the 1_2^- -> 1_1^- and 1_2^- -> 2_1^- transitions around 2.6 MeV, provides invaluable information on the Sigma Lambda coupling force and the consistency of the spin-dependent interaction strengths determined from previous Hyperball data. The experiment will be performed in September-October, 2005, for the approved beam time of 80 shifts.
· Letter of Intent to KEK PS PAC (in Japanese) (pdf, 1.1 MB)
"Gamma Spectroscopy of 12-Lambda-C and 4-Lambda-He "
--- submitted on April 13, 2004.
Department of Physics,
Adderess at KEK:
E566, Institute for Particle and Nuclear Study, KEK
1-1 Oho, Tsukuba, 305-0801 Japan
phone: +81-29-864-5449, 5599