Speaker
Akira Hitachi
(Kochi Medical School)
Description
The scintillation efficiency for low energy recoil ions in liquid argon has been evaluated for WIMP searches. the track structure and the excitation density for recoil ions are calculated then the prescribed diffusion equation for biexcitonic quenching has been solved and the total quenching factor qT for 5-240 keV recoil ions in liquid Ar at zero electric field are obtained. All the constants necessary for the calculation are carefully determined and the quenching model include no free fitting parameters. The result slows that qT is nearly constant and agrees well with experimental values by WARP and micro-CLEAN, except at very low energy where the measured values have large error bars.
It has been observed that quenching can be influenced by the external electric filed. The scintillation efficiency, e.g., for 30 MeV/n O and Ar ions increases more than 15 percent at a few kV/cm. This phenomenon is explained as the reduction of the high-excitation-density quenching by the electronic field. The amount of increase very much depend on the kind of ions and energy. The possibility of the increase in the scintillation efficiency for recoil ions in liquid Ar and Xe due to the electric field will be discussed.
Author
Akira Hitachi
(Kochi Medical School)
