Spectroscopic study of Λ hypernuclei in the medium - heavy mass region and p - shell region using the ( e , e ′

We propose an extension of the beamtime for the approved experiment E05-115 which is in preparation for beam and will be ready by the end of 2008. This experiment has been proposed and approved by PAC28 while we were taking data for it’s precursor, E01-011. Meanwhile, the data analysis for E01-011 has matured and further strengthened our confidence in the proposed experimental procedure. Furthermore, we believe that recent progress in theoretical studies support our request to strengthen the impact of E05-115 by increasing the number of targets to be investigated. If approved this will increase the return on the necessary investment in time and manpower to install E05-115. The second generation (e,e′K+) hypernuclear experiment E01-011 proved the effectiveness of the (e, e′K+) reaction by employing the “tilt method” for the electron arm, and by installing a new high-resolution kaon spectrometer (HKS) for the kaon arm. The E01-011 experiment performed a spectroscopic study of Λ hypernuclei for 28 Λ Al with the (e, e ′K+) reaction, as the first step beyond the p-shell region. As a natural extension of the successful second generation experiment, the third generation experiment E05-115 with newly developed high-resolution electron spectrometer (HES) was proposed to PAC28 in order to study Λ hypernuclei in a wide mass region and 20 days of beamtime including commission time for a new spectrometer was accepted. This proposal requests additional beamtime to the approved E05-115 based on recent progresses in the theoretical and experimental investigations of hypernuclei as follows: 1. Recent progresses in precise few body calculations demonstrated the importance of studying ΛHe and 10 Λ Be. 2. A new calculation for a 40Ca target became available and a precise mass spectrum of 40 Λ K would be needed to obtain complete A dependence of Λ single energies in the 7 ≤ A ≤ 52 region. 3. Progress of the analysis/calibration methods of (e,e′K+) reaction with E01-011 data suggested us to plan for more calibration data than we expected at the time of PAC28. Therefore, we request an additional beamtime to the approved E05-115 experiment in order to carry out precision spectroscopy of ΛHe, 10 Λ Be, and