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

16 páginas, 10 figuras, 1 tabla.-- El PDF es la versión post-print.-- et al.
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 ± 7 photons was obtained for 5.9 keV X-rays, corresponding to a mean energy of 72 ± 6 eV to produce a primary scintillation photon in xenon.
This work was supported by FCT (Portugal) and FEDER through project PTDC/FIS/103860/2008. E.D.C. Freitas acknowledges grant SFRH/BD/46711/2008 from FCT. C.M.B. Monteiro acknowledges grant SFRH/BD/25569/2005 from FCT. M. Ball, J.J. Gómez-Cadenas and N. Yahlali acknowledge the Spanish MICINN for the Consolider-Ingenio grants CSD2008-00037 and CSD2007-00042 and the research grants FPA2009-13697-C04-04 and FPA2009-13697-C04-B23/12. D.R. Nygren acknowledges support by the Director, Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under contract DE-AC02-05CH11231.