Primary and secondary scintillation measurements in a xenon Gas Proportional Scintillation Counter

TL;DR

This study investigates primary and secondary scintillation in gaseous xenon using a specific photomultiplier, demonstrating effective energy resolution and stable primary scintillation across various pressures, relevant for high-pressure xenon TPCs.

Contribution

It provides new measurements of primary and secondary scintillation yields in gaseous xenon with a specific photomultiplier at room temperature and different pressures.

Findings

Achieved 8.0% energy resolution for secondary scintillation.

Observed negligible variation in primary scintillation with pressure and electric field.

Measured primary scintillation yield of 81 ± 7 photons for 5.9 keV X-rays.

Abstract

NEXT is a new experiment to search for neutrinoless double beta decay using a 100 kg radio-pure high-pressure gaseous xenon TPC. The detector requires excellent energy resolution, which can be achieved in a Xe TPC with electroluminescence readout. Hamamatsu R8520-06SEL photomultipliers are good candidates for the scintillation readout. The performance of this photomultiplier, used as VUV photosensor in a gas proportional scintillation counter, was investigated. Initial results for the detection of primary and secondary scintillation produced as a result of the interaction of 5.9 keV X-rays in gaseous xenon, at room temperature and at pressures up to 3 bar, are presented. An energy resolution of 8.0% was obtained for secondary scintillation produced by 5.9 keV X-rays. No significant variation of the primary scintillation was observed for different pressures (1, 2 and 3 bar) and for electric fields up to 0.8 V cm-1 torr-1 in the drift region, demonstrating negligible recombination luminescence. A primary scintillation yield of 81 \pm 7 photons was obtained for 5.9 keV X-rays, corresponding to a mean energy of 72 \pm 6 eV to produce a primary scintillation photon in xenon.