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Xenon scintillation has been widely used in recent particle physics experiments [1-3]. However, information on primary scintillation yield in the absence of recombination is still scarce and dispersed. The mean energy required to produce a VUV scintillation photon (Wsc) in gaseous Xe has been measured in the range of 30-120 eV [4-7]. Lower Wsc-values are often reported for alpha particles compared to electrons produced by gamma or x-rays, being this difference still not fully understood.
We carried out a systematic study of the absolute primary scintillation yield in Xe at 1.2 bar, using a Gas Proportional Scintillation Counter. The simulation model of the detector's geometric efficiency was benchmarked through the primary and secondary scintillation produced at different distances from the photosensor. Wsc-values were obtained for gamma and x-rays with energies in the range 5.9-60 keV, and for 2-MeV alpha particles. No significant differences were found between alpha particles and electrons.
[1] E. Aprile et al. (XENON), The XENON1T Dark Matter Experiment, Eur. Phys. J. C 77 (2017), 881
[2] D. S. Akerib et al. (LUX-ZEPLIN), Projected WIMP sensitivity of the LUX-ZEPLIN dark matter experiment, Phys. Rev. D 101 (2020), 052002
[3] P. Ferrario et al. (NEXT), Demonstration of the event identification capabilities of the NEXT-White detector, JHEP 10 (2019), 052
[4] M. Mimura et al., Average Numbers of Scintillation Photons and Electrons Produced by an Alpha Particle in High-Density Xenon Gas, Japan. J. Appl. Phys. 48 (2009), 076501
[5] S. J. C. do Carmo et al., Absolute primary scintillation yield of gaseous xenon under low drift electric fields for 5.9 keV X-rays, J. Instrum. 3 (2008), P07004.
[6] L. M. P. Fernandes et al., Primary and secondary scintillation measurements in a Xenon Gas Proportional Scintillation Counter, J. Instrum. 5 (2010), P09006.
[7] L. Serra et al. (NEXT), An improved measurement of electron-ion recombination in high-pressure xenon gas, J. Instrum. 10 (2015), P03025.
