63 research outputs found
Infrared scintillation yield in gaseous and liquid argon
The study of primary and secondary scintillations in noble gases and liquids
is of paramount importance to rare-event experiments using noble gas media. In
the present work, the scintillation yield in gaseous and liquid Ar has for the
first time been measured in the near infrared (NIR) and visible region, both
for primary and secondary (proportional) scintillations, using Geiger-mode
avalanche photodiodes (G-APDs) and pulsed X-ray irradiation. The primary
scintillation yield of the fast component was measured to be 17000 photon/MeV
in gaseous Ar in the NIR, in the range of 690-1000 nm, and 510 photon/MeV in
liquid Ar, in the range of 400-1000 nm. Proportional NIR scintillations
(electroluminescence) in gaseous Ar have been also observed; their
amplification parameter at 163 K was measured to be 13 photons per drifting
electron per kV. Possible applications of NIR scintillations in high energy
physics experiments are discussed.Comment: 6 pages, 5 figures. Submitted to Europhysics Letter. Revised Figs. 3
and
First demonstration of THGEM/GAPD-matrix optical readout in two-phase Cryogenic Avalanche Detector in Ar
The multi-channel optical readout of a THGEM multiplier coupled to a matrix
of 3x3 Geiger-mode APDs (GAPDs) was demonstrated in a two-phase Cryogenic
Avalanche Detector (CRAD) in Ar. The GAPDs recorded THGEM-hole avalanches in
the Near Infrared (NIR). At an avalanche charge gain of 160, the yield of the
combined THGEM/GAPD-matrix multiplier amounted at ~80 photoelectrons per 20 keV
X-ray absorbed in the liquid phase. A spatial resolution of 2.5 mm (FWHM) has
been measured for the impinging X-rays. This technique has potential
applications in coherent neutrino-nucleus scattering and dark matter search
experiments.Comment: 4 pages, 6 figures. Presented at Vienna Conference of Instrumentation
(Feb 15-20, 2013, Vienna, Austria). Submitted to the Proceeding
Recent results on the properties of two-phase argon avalanche detectors
The characteristic properties of two-phase Ar avalanche detectors, including
those obtained with CsI photocathode, are further studied. Such detectors are
relevant in the field of coherent neutrino-nucleus scattering and dark matter
search experiments. The detectors investigated comprised a 1 cm thick liquid Ar
layer followed by a triple-GEM multiplier. In these detectors, typical gains
reaching 10000 were obtained with good reproducibility and a stable operation
for at least one day was demonstrated. Amplitude and pulse-shape
characteristics are presented under irradiation with X-rays, gamma-rays and
neutrons from different radioactive sources. The detection of both primary
scintillation and ionization signals at higher gains, at a deposited energy of
60 keV, has been demonstrated.Comment: 6 pages, 11 figures. Presented at Xth Int. Conf. for Collid. Beam
Phys., Feb 28 - March 6, 2008, Novosibirsk, to be published in Nucl. Instr.
Meth.
On the low-temperature performances of THGEM and THGEM/G-APD multipliers in gaseous and two-phase Xe
The performances of THGEM multipliers in two-phase Xe avalanche mode are
presented for the first time. Additional results on THGEM operation in gaseous
Xe at cryogenic temperatures are provided. Stable operation of a double-THGEM
multiplier was demonstrated in two-phase Xe with gains reaching 600. These are
compared to existing data, summarized here for two-phase Ar, Kr and Xe
avalanche detectors incorporating GEM and THGEM multipliers. The optical
readout of THGEMs with Geiger-mode Avalanche Photodiodes (G-APDs) has been
investigated in gaseous Xe at cryogenic temperature; avalanche scintillations
were recorded in the Near Infrared (NIR) at wavelengths of up to 950 nm. At
avalanche charge gain of 350, the double-THGEM/G-APD multiplier yielded 0.07
photoelectrons per initial ionization electron, corresponding to an avalanche
scintillation yield of 0.7 NIR photons per avalanche electron over 4pi. The
results are compared with those of two-phase Ar avalanche detectors. The
advantages, limitations and possible applications are discussed.Comment: 22 pages, 14 figures. Revised Figs. 10,11 and Table 1. To be
published in JINS
Geiger Mode APD performance in a cryogenic two-phase Ar avalanche detector based on THGEMs
Characteristic properties of a Geiger Mode APD (G-APD) in a THGEM-based
cryogenic two-phase Ar avalanche detector were studied in view of potential
applications in rare-event experiments. G-APD signal amplitude and noise
characteristics at cryogenic temperatures turned out to be superior to those at
room temperature. The effective detection of avalanche scintillations from
THGEM-multiplier holes in two-phase Ar has been demonstrated using a G-APD
without wavelength shifter. At an avalanche gain of 60, the avalanche
scintillation yield measured by the G-APD was as high as 0.9 photoelectrons per
avalanche electron, extrapolated to 4pi acceptance.Comment: 4 pages, 8 figures. Presented at Vienna Conference on Instrumentation
(Feb 15-20, 2010, Vienna, Austria). Submitted to the Proceeding
Study of infrared scintillations in gaseous and liquid argon - Part I: methodology and time measurements
A methodology to measure Near Infrared (NIR) scintillations in gaseous and
liquid Ar, using Geiger-mode APDs (GAPDs) sensitive in the NIR and pulsed X-ray
irradiation, is described. This study has been triggered by the development of
Cryogenic Avalanche Detectors (CRADs) with optical readout in the NIR using
combined THGEM/GAPD multiplier, which may come to be in demand in coherent
neutrino-nucleus scattering and dark matter search experiments. A new approach
to measure the NIR scintillation yield at cryogenic temperatures has been
developed, namely using GAPDs in single photoelectron counting mode with time
resolution. The time structure of NIR scintillations and their light yield were
measured both for primary scintillations and that of secondary at moderate
electric fields (electroluminescence), in gaseous and liquid Ar.Comment: 17 pages, 15 figures. Submitted to JINS
Direct observation of avalanche scintillations in a THGEM-based two-phase Ar avalanche detector using Geiger-mode APD
A novel concept of optical signal recording in two-phase avalanche detectors,
with Geiger-mode Avalanche Photodiodes (G-APD) is described.
Avalanche-scintillation photons were measured in a thick Gas Electron
Multiplier (THGEM) in view of potential applications in rare-event experiments.
The effective detection of avalanche scintillations in THGEM holes has been
demonstrated in two-phase Ar with a bare G-APD without wavelength shifter, i.e.
insensitive to VUV emission of Ar. At gas-avalanche gain of 400 and under \pm
70^\circ viewing-angle, the G-APD yielded 640 photoelectrons (pe) per 60 keV
X-ray converted in liquid Ar; this corresponds to 0.7 pe per initial (prior to
multiplication) electron. The avalanche-scintillation light yield measured by
the G-APD was about 0.7 pe per avalanche electron, extrapolated to 4pi
acceptance. The avalanche scintillations observed occurred presumably in the
near infrared (NIR) where G-APDs may have high sensitivity. The measured
scintillation yield is similar to that observed by others in the VUV. Other
related topics discussed in this work are the G-APD's single-pixel and
quenching resistor characteristics at cryogenic temperatures.Comment: 21 pages, 18 figures. Submitted to JINS
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