Characterization of a 109Cd γ-Ray Source for the Two-Phase Argon Detector

Abstract

A: At present, a two-phase argon detector is being developed in our laboratory for dark matter search and low-energy neutrino experiments. To calibrate its energy scale a 109 Cd gammaray source was used. In this work a detailed emission spectrum of the 109 Cd source was measured using YAP:Ce scintillator and high-purity germanium (HPGe) detectors. It is shown that the 109 Cd source, equipped with a W substrate and a Cu filter, can provide a complete set of gamma-ray lines, ranging from 8 to 90 keV, for the energy calibration of two-phase detectors. These measurements allowed us to successfully quantify the shape of the amplitude spectra observed in the two-phase argon detector when irradiated with the 109 Cd source.

SiPM-matrix readout of two-phase argon detectors using electroluminescence in the visible and near infrared range

“…The detection threshold is defined as the minimum energy, deposited by a scattered particle in the noble-gas liquid, that can be detected by the detector. There are two types of particle scattering: that of electron recoil, induced by gamma-ray and minimum ioniz- Red curve is the fit by inverse root function using all data points ing particle scattering, or resulting from beta decays, such as by 39 Ar, and that of nuclear recoil, induced by neutron and dark matter particle (WIMP) scattering. Their recoil energies are expressed in terms of keVee and keVnr respectively [1].…”

“…The detector was irradiated from outside either by X-rays from a pulsed X-ray tube with Mo anode, with an average deposited energy in liquid Ar of 25 keV [38], or by gamma rays from a 109 Cd source [39]. To study the position resolution of the detector, a narrow beam of gamma-rays and X-rays was provided by a collimator with a hole diameter of 2 mm.…”

“…To measure the EL gap yield, a 109 Cd gamma-ray source was used. The emission spectrum of this source includes lowenergy (22-25 keV) and high-energy lines: namely the characteristic lines of W (59 keV), which was used as a radionuclide substrate, and the 88 keV line of 109 Cd itself [39]. Due to insufficient energy resolution, the 59 and 88 keV lines could not be separated; therefore their weighted average energy (82 keV [39]) was used in the analysis.…”

SiPM-matrix readout of two-phase argon detectors using electroluminescence in the visible and near infrared range

“…This however will not prevent in the following to assess the maximum light yields and detection thresholds that would be achieved under optimal conditions. The detector was irradiated from outside either by X-rays from a pulsed X-ray tube with Mo anode, with the average deposited energy in liquid Ar of 25 keV [32], or by gamma rays from a 109 Cd source [33]. To study the position resolution of the detector, a narrow beam of gamma-rays and X-rays was provided by a collimator with a hole diameter of 2 mm.…”

“…To measure the EL gap yield, a 109 Cd gamma-ray source was used. The emission spectrum of this source includes low-energy (22-25 keV) and high-energy lines: namely the characteristic lines of W (60 keV), which was used as a radionuclide substrate, and the 88 keV line of 109 Cd itself [33]. Due to insufficient energy resolution, the 60 and 88 keV lines could not be separated; therefore their weighted average energy (82 keV [33]) was used in the analysis.…”