Preparation status of the hypernuclear gamma-ray spectroscopy for Λ's g-factor in a nucleus (J-PARC E63)

 Properties of baryons in nuclear matter may be changed from those in free space because of its high density.  However, nucleons deep inside a nucleus cannot be probed due to very short life time of the highly excited states. On the other hand, hyperons are free from Pauli effect from nucleons in a nucleus. Thus, hyperons can be a good probe to investigate possible modification of baryons in a nucleus.

 We plan to study modification of a Λ particle in a nucleus by measuring that of the magnetic moment. Λ's magnetic moment can be derived from the lifetime of spin flip M1 transition. Therefore we proposed a γ ray spectroscopy of hypernuclei (J-PARC E63) at the K1.1 beam line in J-PARC. We will measure the γ ray of spin flip M1 transition by Ge detectors array (Hyperball-J) to obtain the lifetime using Doppler Shift Attenuation Method (DSAM). DSAM is a method to obtain the lifetime from γ ray peak shape which is determined by lifetime and stopping time of hypernuclei in a nucleus. For this purpose, a lithium oxide target, which has uniform density, is very important. Now we are challenging to produce the crystal of lithium oxide.

  In this presentation, we will introduce about the J-PARC E63 experiment and report the preparation status.