## Summary

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.

## E566 Proposal

·  KEK-PS Proposal (E566) (0.6 MB)
"Hypernuclear gamma Spectroscopy on 12C target "

KEK-PS PAC presentation file (E566) (0.7 MB)
--- submitted on August 11, 2004; approved on December 21, 2004.

·  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.

## Information for E566 Members

·  Drawings

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Hyperball2 base for KEK

## Photos

#### Strangness Nuclear Physics group in Tohoku Univ.

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Correspondence

Hirokazu Tamura
e-mail: tamura@lambda.phys.tohoku.ac.jp
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Department of Physics, Tohoku University
Aramaki, Aoba-ku, Sendai 980-8578, Japan
phone: +81-22-795-6454
FAX: +81-22-795-6455
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