KEK-PS E518 Home Page

Gamma spectroscopy of 11-Lambda-B


Collaboration List


The main purpose of the E518 experiment is to measure the transition probability, B(M1), of the Lambda spin-flip M1 transition 11-Lambda-B(3/2+ -> 1/2+). From the B(M1) value, we can extract the magnetic moment of \Lambda in a nucleus for the first time.

Bound states of 11-Lambda-B are produced by the (pi+,K+) reaction at 1.04 GeV/c with the K6 beam line and SKS, and gamma rays are detected using Hyperball. We aim at measurement of the B(M1) value for 11-Lambda-B in accuracy less than 14%, which corresponds to an accuracy less than 7% for the effective g-factor of Lambda in a nucleus.

In addition, we can also observe eight or nine transitions in 11-Lambda-B and determine the level scheme. The level energies provide us with quantitative information on the Lambda-N interaction, particularly, the strength of the spin-spin force (Delta) and that of the nucleon-spin-dependent spin-orbit force (S_N). The values of Delta and S_N are compared with those obtained from the 7-Lambda-Li structure in the previous Hyperball experiment (E419), and their consistency confirms validity of the theoretical framework.

The experiment was performed in September-October, 2002, for the approved beam time of 80 shifts. Data analysis is in progress. We have observed several gamma rays from 11-Lambda-B for the first time.

E518 Proposal

KEK-PS Proposal (E518) (gzipped ps, 0.8 MB)
"Gamma Spectroscopy of 11-Lambda-B "
--- submitted on 2002-June-18, approved on 2002-July-18

Letter of Intent to KEK PS PAC (gzipped ps (0.8 MB))
--- submitted on March 18, 2002.

Setup (K6+SKS+Hyperball)

·  K6+SKS+Hyperball Setup (pdf)

·  Hyperball(schematic) , Hyperball(photo)

Information for E518 Members

·  Beam schedule

·  Job schedule

·  Shift table

·  Run Summary


·  photos


Hyperball Home Page (including the publication list)


Hirokazu Tamura
Department of Physics, Tohoku University
Aramaki, Aoba-ku, Sendai 980-8578, Japan
phone: +81-22-217-6454
FAX: +81-22-217-6455
Adderess at KEK:
E518, Institute for Particle and Nuclear Study, KEK
1-1 Oho, Tsukuba, 305-0801 Japan
phone: +81-298-64-5449, 5599
FAX: +81-298-64-7831