56 research outputs found
Further studies of GEM performance in dense noble gases
We further study the performance of single, double and triple Gas Electron
Multiplier (GEM) detectors in pure noble gases at high pressures, in the range
of 1-10 atm. We confirm that light noble gases, in particular He and its
mixtures with Kr, have the highest gain, reaching 10^6, and an unusual gain
dependence on pressure. Effects of the number of GEMs, GEM hole diameter and
pitch are investigated in detail. In He, avalanche-induced secondary
scintillations are observed at high gains, using the metal photocathode. These
results are relevant in the field of avalanche mechanism in noble gases and
X-ray, neutron and cryogenic particle detectors.Comment: 4 pages, 4 figures. Presented at the 6th Int. Conf. on Position
Sensitive Detectors, Leicester, Sept 9-13, 200
GEM operation in helium and neon at low temperatures
We study the performance of Gas Electron Multipliers (GEMs) in gaseous He, Ne
and Ne+H2 at temperatures in the range of 2.6-293 K. In He, at temperatures
between 62 and 293 K, the triple-GEM structures often operate at rather high
gains, exceeding 1000. There is an indication that this high gain is achieved
by Penning effect in the gas impurities released by outgassing. At lower
temperatures the gain-voltage characteristics are significantly modified
probably due to the freeze-out of impurities. In particular, the double-GEM and
single-GEM structures can operate down to 2.6 K at gains reaching only several
tens at a gas density of about 0.5 g/l; at higher densities the maximum gain
drops further. In Ne, the maximum gain also drops at cryogenic temperatures.
The gain drop in Ne at low temperatures can be reestablished in Penning
mixtures of Ne+H2: very high gains, exceeding 10000, have been obtained in
these mixtures at 50-60 K, at a density of 9.2 g/l corresponding to that of
saturated Ne vapor near 27 K. The results obtained are relevant in the fields
of two-phase He and Ne detectors for solar neutrino detection and electron
avalanching at low temperatures.Comment: 13 pages, 14 figures. Accepted for publishing in Nucl. Instr. and
Meth.
A two-phase argon avalanche detector operated in a single electron counting mode
The performance of a two-phase Ar avalanche detector in a single electron
counting mode was studied, with regard to potential application in coherent
neutrino-nucleus scattering and dark matter search experiments. The detector
comprised of a 1 cm thick liquid Ar layer and a triple-GEM multiplier operated
in the saturated vapour above the liquid phase. Successful operation of the
detector in single electron counting mode, in the gain range from 6000 to
40000, has for the first time been demonstrated.Comment: 9 pages, 9 figures. Submitted to JINS
Measurement of the Pion Form Factor in the Energy Range 1.04-1.38 GeV with the CMD-2 Detector
The cross section for the process is measured in the
c.m. energy range 1.04-1.38 GeV from 995 000 selected collinear events
including 860000 events, 82000 events, and 33000
events. The systematic and statistical errors of measuring the
pion form factor are equal to 1.2-4.2 and 5-13%, respectively.Comment: 5 pages, 2 figure
Hadron Energy Reconstruction for the ATLAS Calorimetry in the Framework of the Non-parametrical Method
This paper discusses hadron energy reconstruction for the ATLAS barrel
prototype combined calorimeter (consisting of a lead-liquid argon
electromagnetic part and an iron-scintillator hadronic part) in the framework
of the non-parametrical method. The non-parametrical method utilizes only the
known ratios and the electron calibration constants and does not require
the determination of any parameters by a minimization technique. Thus, this
technique lends itself to an easy use in a first level trigger. The
reconstructed mean values of the hadron energies are within of the
true values and the fractional energy resolution is . The value of the ratio
obtained for the electromagnetic compartment of the combined calorimeter is
and agrees with the prediction that for this
electromagnetic calorimeter. Results of a study of the longitudinal hadronic
shower development are also presented. The data have been taken in the H8 beam
line of the CERN SPS using pions of energies from 10 to 300 GeV.Comment: 33 pages, 13 figures, Will be published in NIM
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