Experimental Study of Hypernuclei Electroproduction by High Precision Spectroscopy

Abstract

Jlab experiment E01-011, carried out in 2005 in JLab Hall C, is the second generation of the hypernuclear spectroscopy experiments by the (e,e'K+) reaction. The (e,e'K+) reaction is complimentary to the associated production reactions (K-,π-), (π+,K+) since, due to a larger momentum transfer to a hyperon, excitations of both spin-non-flip and spin-flip states are possible. The experiment uses high quality and continuous primary electron beam to produce neutron rich hypernuclei on various targets by the electroproduction. The experimental setup consists of splitter magnet, high resolution kaon spectrometer (HKS) and electron spectrometer (Enge) implemented in new configuration, the so called 'Tilt Method'. Production data was taken on multiple targets: CH2, 6Li, 7Li, 9Be, 10B, 12C and 28Si. In present study the analysis of CH2, 12C and 28Si is presented. The elementary processes of p(e,e'K+)Λ/Σ from CH2 data were used for calibration of the spectrometer optics and kinematics. The hypernuclear spectra of 12ΛB was obtained with ground state resolution of 0.47 ± 0.07 MeV (FWHM), the best ever achieved. Feasibility of the electroproduction reaction to study medium to heavy targets has been proven with the first high resolution beyond p-shell hypernuclear spectra from 28ΛAl hypernuclei. The obtained results of the E01-011 experiment confirmed that hypernuclear spectroscopy by the (e,e'K+) reaction is a very useful technique.