14-17 September 2021
America/Los_Angeles timezone

Preliminary studies towards spectroscopic-based particle discrimination in Ar

14 Sep 2021, 11:30
Light/charge response in noble elements Light/Charge Response (1B)


Vicente Pesudo Fortes (CIEMAT)


Noble elements are the active medium of choice for several among the most important neutrino and dark matter experiments being built now. The foreseen next generation, besides going bigger, would benefit from any feature not-yet exploited of this technology.

With this goal, we performed a time-resolved spectroscopic study of the VUV/UV scintillation of gaseous argon as a function of pressure and electric field, by means of a wavelength sensitive detector operated with different radioactive sources.

Our work conveys new evidence of distinctive features of the argon light which are in contrast with the general assumption that, for particle detection purposes, the scintillation can be considered to be largely monochromatic at 128 nm (second continuum).
The wavelength and time-resolved analysis of the photon emission reveal that the dominant component of the argon scintillation during \blue{the} first tens of ns is in the range [160, 325] nm. This light is consistent with the third continuum emission from highly charged argon ions/molecules. This component of the scintillation is field-independent up to 25 V/cm/bar and shows a very mild dependence with pressure in the range [1, 16] bar. The dynamics of the second continuum emission is dominated by the excimer formation time, whose variation as a function of pressure has been measured. Additionally, the time and pressure-dependent features of electron-ion recombination, in the second continuum band, have been measured. This study opens new paths toward a novel particle identification technique based on the spectral information of the noble-elements scintillation light.

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