Table-top setup for investigating the scintillation properties of liquid argon

Abstract

Abstract. The spectral and temporal light emission properties of liquid argon have been studied in the context of its use in large liquid rare-gas detectors for detecting Dark Matter particles in astronomy. A table-top setup has been developed. Continuous and pulsed low energy electron beam excitation is used to stimulate light emission. A spectral range from 110 to 1000 nm in wavelength is covered by the detection system with a time resolution on the order of 1 ns.

Near-infrared scintillation of liquid argon: recent results obtained with the NIR facility at Fermilab

“…The Munich group continued their studies now with an improved purification system added to their apparatus [23] and the possibility of adding Xe in a controlled way, with the result that they no longer see any relevant emission in pure liquid argon in the range 500 to 3,000 nm [23]. They therefore revise their previous result ( [16], [19]) stating that they now believe the observed signal was an "artifact due to the normalization of the spectrum with the response function of the spectrometer used for that spectral range" [23]. .…”

Near-infrared scintillation of liquid argon

“…More recently, the Munich group has published new results of their on-going studies of the scintillation of pure liquid argon and liquid Ar-Xe mixtures, stating that they no longer see any relevant emission in pure liquid argon in the range 500 to 3,000 nm [23]. They therefore revise their previous result ( [19,20]) saying that they now believe the observed signal was an "artifact due to the normalization of the spectrum with the response function of the spectrometer used for that spectral range". • Exciting the media with radiation more akin to the radiation that will be encountered in real applications such as in DM and/or neutrino physics detectors.…”

“…Recent results. In the last five years, two groups have pursued the investigation of NIR scintillation in LAr, one based in Novosibirsk, Russia [18] and the other at the Technical University of Munich, Germany [19]. Both groups use table-top setups, with volumes of a few cubic centimeters of LAr excited by very intense, low-energy beams: 12 keV electrons (pulsed or continuous) for the Munich experiments and pulsed X-rays with energies between 30 and 40 keV for the Novosibirsk setup.…”

“…The normalization of the scintillation spectrum is thus obtained by matching the number of counted photoelectrons in the SiPMs. Bondar [19,20] as this leads us to review a recent result from the Munich group that points out to the difficulties intrinsic to this kind of measurement and its interpretation.…”

Ion-beam excitation of liquid argon

“…In addition, they can be cleaned chemically to a high level of purity, which is important in terms of background: radioactive impurities can be removed from the LRg efficiently, as well as even some of the long-lived radioisotopes of other rare gases like 85 Kr from xenon [5]. Also impurities like oxygen or water which alter the light yield [6] or light-emission time constants [6][7][8][9] can be removed.…”