High Resolution Λ Hypernuclear Spectroscopy by the (e,e'K+) Reaction at Jlab Hall C
by
Tomislav Ševa(University of Zagreb)
→
Europe/Brussels
IIHE (ULB-VUB) (Large seminar room)
IIHE (ULB-VUB)
Large seminar room
VUB - Building G - 1G003
Description
A hypernucleus contains a hyperon, which contains a strange quark, implanted as an impurity within the nuclear medium. The Jefferson Lab HKS/HES Collaboration has been studying the electroproduction of Λ hypernuclei by the (e,e′K+) reaction at JLab Hall C since 2000. The (e,e'K+) reaction is complementary to the widely studied associated production reactions (K-,π-), (π+,K+) because it produces neutron-rich and mirror hypernuclei and due to a larger momentum transfer to a hyperon, excitations of both spin-non-flip and spin-flip states are possible.
The first experiment, JLab E89-009, demonstrated the possibility of the (e,e′K+) reaction for hypernuclear spectroscopy by achieving an energy resolution of better than 1 MeV (FWHM).
Jlab experiment E01-011, carried out in 2005, is the second generation of the hypernuclear spectroscopy experiments by the (e,e'K+) reaction. The experiment uses high quality and continuous primary electron beam, a key factor in high resolution energy spectra. 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. The tilt method of the electron spectrometer greatly reduced the rate of the background electrons due to Bremsstrahlung and Møller scattering. The experiment measured spectra of various Λ hypernuclei with high resolution and sufficient statistics for the first time by this reaction.
The third experiment, JLab E05-115, was performed in 2009 with employing newly constructed high resolution electron spectrometer and a new charge-separation magnet. The higher beam energy and brand new electron spectrometer makes the tilt method work more effectively. With the fully customized third generation experimental setup, we have studied a variety of targets up to medium-heavy ones such as 52Cr.
The talk will outline the experimental techniques and conditions, present results from JLab E89-009 and E01-011 and (very) preliminary data from the just completed E05-115 run.
