Characterization of photo-multiplier tubes for the Cryogenic Avalanche Detector

Abstract

New Cryogenic Avalanche Detector (CRAD) with ultimate sensitivity, that will be able to detect one primary electron released in the cryogenic liquid, is under development in the Laboratory of Cosmology and Particle Physics of the Novosibirsk State University jointly with the Budker Institute of Nuclear Physics. The CRAD will use two sets of cryogenic PMTs in order to get trigger signal either from primary scintillations in liquid Ar or from secondary scintillations in high field gap above the liquid. Two types of cryogenic PMTs produced by Hamamatsu Photonics were tested and the results are presented in this paper. Low background 3 inch PMT R11065-10 demonstrated excellent performance according to its specifications provided by the producer. The gain measured with single electron response (SER) in liquid Ar reached 10 7 , dark count rate rate did not exceed 300 Hz and pulse height resolution of single electron signals was close to 50%(FWHM). However, two R11065-10 PMTs out of 7 tested stopped functioning after several tens minutes of operation immersed completely into liquid Ar. The remaining 5 devices and one R11065-MOD were operated successfully for several hours each with all the parameters according to the producer specifications. Compact 2 inch PMT R6041-506-MOD with metal-channel dynode structure is a candidate for side wall PMT system that will look at electroluminescence in high field region above liquid. Four of these PMTs were tested in liquid Ar and demonstrated gain up to 2x10 7 , dark count rate rate below 100 Hz and pulse height resolution of single electron signals of about 110% (FWHM).

Further studies of proportional electroluminescence in two-phase argon

“…The present study was performed in the course of the development of two-phase Cryogenic Avalanche Detectors (CRADs) of ultimate sensitivity for rare-event experiments [13][14][15][16][17][18][19].…”

Measurement of the ionization yield of nuclear recoils in liquid argon using a two-phase detector with electroluminescence gap

“…All regions had an active area of 10×10 cm 2 . The EL gap was viewed by four compact cryogenic 2-inch PMTs R6041-506MOD [12], located on the perimeter of the gap and separated from the high-field region by an acrylic box with WLS (wavelength shifter) films deposited in front of each PMT. The WLS films were needed to convert the VUV emission of pure Ar into visible light.…”

“…The present study was performed in the course of the development of two-phase Cryogenic Avalanche Detectors (CRADs) of ultimate sensitivity for rare-event experiments [10][11][12][13][14][15][16][17].…”

Two-phase Cryogenic Avalanche Detector with electroluminescence gap operated in argon doped with nitrogen

“…The EL gap was viewed by four compact cryogenic 2-inch PMTs R6041-506MOD [21], located on the perimeter of the gap. The PMTs were electrically insulated from the gap by a grounded mesh and an acrylic protective box of a rectangular shape.…”