Experiments with the High Resolution Kaon Spectrometer at JLab Hall C and the new spectroscopy of Λ12 B hypernuclei

Since the pioneering experiment E89-009 studying hypernuclear spectroscopy using the (e,e′K+) reaction was completed, two additional experiments, E01-011 and E05-115, were performed at Jefferson Lab. These later experiments used a modified experimental design, the "tilt method," to dramatically suppress the large electromagnetic background, and allowed for a substantial increase in luminosity. Additionally, a new kaon spectrometer, HKS (E01-011), a new electron spectrometer, HES, and a new splitting magnet (E05-115) were added to produce new data sets of precision, high-resolution hypernuclear spectroscopy. All three experiments obtained a spectrum for Λ12B, which is the most characteristic p-shell hypernucleus and is commonly used for calibration. Independent analyses of these different experiments demonstrate excellent consistency and provide the clearest level structure to date of this hypernucleus as produced by the (e,e′K+) reaction. This paper presents details of these experiments, and the extraction and analysis of the observed Λ12B spectrum.