Study of cryogenic photomultiplier tubes for the future two-phase cryogenic avalanche detector

Abstract

A: We report the results of a characterization study of several types of cryogenic photomultipliers manufactured by Hamamatsu Photonics and intended for operation in liquid Ar conditions, namely: compact 2-inch R6041-506MOD tubes, 3-inch R11065-10 and R11065-MOD tubes for operation in liquid Ar and 3-inch R11410-20 tubes originally designed for operation in liquid Xe. These types of PMT are proposed for installation into the future two-phase cryogenic avalanche detector that is developed in the Laboratory of Cosmology and Particle Physics of the Novosibirsk State University jointly with the Budker Institute of Nuclear Physics. Eight R11065 PMTs and seven R11410-20 tubes were tested and all demonstrated excellent performance in liquid Ar in terms of gain and relative single electron efficiency. All 3-inch PMTs showed a maximal gain in liquid Ar above 5x10 6 and relative single electron efficiency higher than 95%. Compact R6041-506MOD tubes have dynode system different from that of the 3-inch photomultipliers and thus their single electron energy resolution and relative efficiency is much worse than that of 3-inch tubes. From 21 2-inch PMTs only 12 tubes were selected with acceptable, i.e. higher than 75%, relative single electron efficiency and the maximal gain higher than 5x10 6 . However, these PMTs are very attractive because they are the only compact type of tubes that can operate in liquid Ar.

Revealing neutral bremsstrahlung in two-phase argon electroluminescence

“…The N 2 content was below 1 ppm (with the measurement accuracy of 1 ppm); it was constantly monitored before and after each cryogenic run using gas analyzer "SVET" [48], which employed emissionspectrum-measurement technique. The detector was operated in a two-phase mode in the equilibrium state, at a saturated vapor pressure of 1.000±0.005 atm and at a temperature of 87.3 K. The EL gap, formed by the liquid surface and a THGEM plate (THGEM1 in the figure), was viewed by four compact 2inch PMTs R6041-506MOD [49,50], located on the perimeter of the gap. The PMTs were electrically insulated from the gap by an acrylic box.…”

Neutral bremsstrahlung in two-phase argon electroluminescence: further studies and possible applications

“…1 shows the experimental setup for the present measurement session, of 2019; it was modified compared to the previous measurement session, of 2018, described in [1] (see below). The setup comprised a two-phase TPC with EL gap, filled with liquid Ar and operated in the two-phase mode at a saturated vapor pressure of 1.0 atm and temperature of 87.3 K. The EL gap, formed by the liquid surface and THGEM1 electrode, was viewed by four compact PMTs R6041-506MOD [6], located on the perimeter of the gap. The PMTs were electrically insulated from the gap by an acrylic box.…”

Measurement of the Ionization Yields of Nuclear Recoils in Liquid Argon Using a Two-Phase Detector with Optical Readout

“…В Видно, что ионизационный выход зависит от энергии нетривиальным образом: ионизационный выход сначала уменьшается, а затем растет с энергией, проходя через минимум. Следует отметить, что подобная энергетическая зависимость для электронов отдачи в жидком Ar наблюдалась ранее [14] (рис. 7).…”

“…Ионизационные выходы электронов отдачи в жидком Ar при электрическом поле 2,4 кВ/см как функция энергии. Данные взяты из Sangiorgio et al [29] (при 0,27, 2,8 и 5,9 кэВ), из Bondar et al [14] (при 35 кэВ), из Scallettar et al [30] (при 364 кэВ) и из Shibamura et al [31] (при 976 кэВ) и аппроксимированы сплайн-кривой (рисунок приводится по: [14]) зависимость для ядер отдачи в жидком Xe является монотонной в диапазоне от 1 до 300 keVnr [32].…”