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Imaging with SiPMs in noble-gas detectors  [PDF]
N. Yahlali,L. M. P. Fernandes,K. González,A. N. C. Garcia,A. Soriano
Physics , 2012, DOI: 10.1088/1748-0221/8/01/C01003
Abstract: Silicon photomultipliers (SiPMs) are photosensors widely used for imaging in a variety of high energy and nuclear physics experiments. In noble-gas detectors for double-beta decay and dark matter experiments, SiPMs are attractive photosensors for imaging. However they are insensitive to the VUV scintillation emitted by the noble gases (xenon and argon). This difficulty is overcome in the NEXT experiment by coating the SiPMs with tetraphenyl butadiene (TPB) to convert the VUV light into visible light. TPB requires stringent storage and operational conditions to prevent its degradation by environmental agents. The development of UV sensitive SiPMs is thus of utmost interest for experiments using electroluminescence of noble-gas detectors. It is in particular an important issue for a robust and background free neutrinoless double-beta experiment with xenon gas aimed by NEXT. The photon detection efficiency (PDE) of UV-enhanced SiPMs provided by Hamamatsu was determined for light in the range 250-500 nm. The PDE of standard SiPMs of the same model (S10362-33-50C), coated and non-coated with TPB, was also determined for comparison. In the UV range 250-350 nm, the PDE of the standard SiPM is shown to decrease strongly, down to about 3%. The UV-enhanced SiPM without window is shown to have the maximum PDE of 44% at 325 nm and 30% at 250 nm. The PDE of the UV-enhanced SiPM with silicon resin window has a similar trend in the UV range, although it is about 30% lower. The TPB-coated SiPM has shown to have about 6 times higher PDE than the non-coated SiPM in the range 250-315 nm. This is however below the performance of the UV-enhanced prototypes in the same wavelength range. Imaging in noble-gas detectors using UV-enhanced SiPMs is discussed.
CsI-THGEM gaseous photomultipliers for RICH and noble-liquid detectors  [PDF]
A. Breskin,V. Peskov,M. Cortesi,R. Budnik,R. Chechik,S. Duval,D. Thers,A. E. C. Coimbra,J. M. F. dos Santos,J. A. M. Lopes,C. D. R. Azevedo,J. F. C. A. Veloso
Physics , 2010, DOI: 10.1016/j.nima.2010.10.034
Abstract: The properties of UV-photon imaging detectors consisting of CsI-coated THGEM electron multipliers are summarized. New results related to detection of Cherenkov light (RICH) and scintillation photons in noble liquid are presented.
Liquid noble gas detectors for low energy particle physics  [PDF]
Vitaly Chepel,Henrique Araújo
Physics , 2012, DOI: 10.1088/1748-0221/8/04/R04001
Abstract: We review the current status of liquid noble gas radiation detectors with energy threshold in the keV range, wich are of interest for direct dark matter searches, measurement of coherent neutrino scattering and other low energy particle physics experiments. Emphasis is given to the operation principles and the most important instrumentation aspects of these detectors, principally of those operated in the double-phase mode. Recent technological advances and relevant developments in photon detection and charge readout are discussed in the context of their applicability to those experiments.
Evaluation of various planar gaseous detectors with CsI photocathodes for the detection of primary scintillation light from noble gases  [PDF]
L. Periale,V. Peskov,P. Carlson,T. Francke,C. Iacobaeus,P. Pavlopoulos,F. Pietropaolo,T. Sokolova
Physics , 2001, DOI: 10.1016/S0168-9002(02)01918-6
Abstract: Noble gases and liquids are excellent scintillators and this opens a unique opportunity to directly detect the primary scintillation light produced in these media by photons or particles. This signal can be used for several purposes, for example as a start signal for TPCs or for particles identification. Usually photomultipliers (PMs) are used for the detection of the scintillation light. In our previous work we have demonstrated that costly PMs could be replaced by gaseous detectors with CsI photocathodes . Such detectors have the same quantum efficiency as the best PMs but at the same time are cheap, simple and have high position and time resolutions. The aim of this work is to evaluate various planar type gaseous detectors with CsI photocahodes in order to choose the best one for the detection of the primary scintillation light from noble gases and liquids.
Recent results in the search for dark matter with noble liquid detectors  [PDF]
Aaron Manalaysay
Physics , 2011,
Abstract: The field of dark matter direct detection has seen important contributions in recent years from experiments involving liquid noble gases, specifically liquid argon and liquid xenon. These detection media offer many properties deemed useful in this search, including fast scintillation response, charge readout, 3-D position reconstruction, and nuclear recoil discrimination. Part of the very rapid emergence and dominance of noble liquids is due to the fact that these technologies are easily scalable to nearly arbitrary size and mass. However, the physics impact of recent results has called into question our understanding of the low-energy response of these detection media, in light of apparent contradictions with a possible low-mass WIMP signal observed in the DAMA/LIBRA and CoGeNT experiments. I discuss recent results and examine the details of this inconsistency.
Characterization of large area photomultipliers and its application to dark matter search with noble liquid detectors  [PDF]
A. Bueno,J. Lozano,A. J. Melgarejo,F. J. Munoz,J. L. Navarro,S. Navas,A. G. Ruiz
Physics , 2007, DOI: 10.1088/1748-0221/3/01/P01006
Abstract: There is growing interest in the use of noble liquid detectors to study particle properties and search for new phenomena. In particular, they are extremely suitable for performing direct searches for dark matter. In this kind of experiments, the light produced after an interaction within the sensitive volume is usually read-out by photomultipliers. The need to go to masses in the tonne scale to explore deeper regions of the parameter space, calls for the use of large area photomultipliers. In this paper we address the need to perform laboratory calibration measurements of these large photomultipliers, in particular to characterize its behaviour at cryogenic temperatures where no reference from the manufacturer is available. We present comparative tests of phototubes from two companies. The tests are performed in conditions similar to those of operation in a real experiment. Measurements of the most relevant phototube parameters (quantum efficiency, gain, linearity, etc.) both at room and liquid Argon temperatures are reported. The results show that the studied phototubes comply with the stringent requirements posed by current dark matter searches performed with noble-liquid detectors.
Dark Matter Search with liquid Noble Gases  [PDF]
Marc Schumann
Physics , 2012,
Abstract: Dark matter detectors using the liquid noble gases xenon and argon as WIMP targets have evolved rapidly in the last decade and will continue to play a major role in the field. Due to the possibility to scale these detectors to larger masses relatively easily, noble liquids will likely be the first technology realizing a detector with a ton-scale target mass. In this article, we summarize the basic concepts of liquid noble gas dark matter detectors and review the current experimental status.
Quartz fiber calorimetry and calorimeters  [PDF]
G. Mavromanolakis
Physics , 2004,
Abstract: Quartz fiber calorimetry is a technique the signal generation mechanism of which is based on the Cherenkov effect. In this article we try to give a comprehensive overview of the subject. We start with a general introduction to calorimetry where the basic elements that characterize the development of electromagnetic and hadronic showers are discussed. Then we describe in detail the operation principle and the properties of calorimeters equipped with quartz fibers. The main advantages of this type of calorimeters are the radiation hardness, the fast response and the compact detector dimensions, features that derive from the quartz material and the specific mechanism of operation. A section is devoted to presenting the quartz fiber calorimeters that have been built or planned to in various experiments to operate as centrality detectors, trigger detectors, luminosity monitors or general purpose very forward calorimeters.
Further studies of GEM performance in dense noble gases  [PDF]
V. Aulchenko,A. Bondar,A. Buzulutskov,L. Shekhtman,R. Snopkov,Yu. Tikhonov
Physics , 2002, DOI: 10.1016/j.nima.2003.08.042
Abstract: 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.
Luminescence of alpha-quartz  [PDF]
Anatoly Trukhin,Kaspars Truhins
Physics , 2012,
Abstract: Among the host materials luminescence the luminescence of the self-trapped exciton (STE) is reviewed. This luminescence, which band is situated at 2.6 to 2.7 eV, could be observed mainly under ionising radiation with energetic yield about 0.2. The STE does not participate in pure recombination processes. Host material defect luminescence at 5 eV appears in alpha-quartz after heavy irradiation. It is constituted of permanent defect after neutron irradiation and transient defect after dens electron beam irradiation. This luminescence could be observed well at temperatures below 60 K. All another luminescence are of impurity nature. The Ge impurity luminescence in alpha-quartz explained as STE near Ge. The aluminium and alkali complexes. One of them is with UV band at 6 eV, appears at low temperatures and could be excited only in tunnelling recombination process between pairs (AlO4 Me), where Me is an alkali ion captured an electron and a hole remains on aluminium tetrahedron. Another luminescence with band at 3.4 eV is also luminescence of complexes (AlO4 Me), which behaviour is similar to the luminescence of alkali alumosilicate glass. The third luminescence with band at 3 eV could be observed mainly in natural alpha-quartz, bright at temperatures below 200 K and is interpreted as STE like luminescence at alumosilicate clasters. The exchange of alkali ions to noble ions of copper of silver reduces original luminescence of alumo alkali complexes and luminescence of noble ions appears. The main band of copper related luminescence is at 3.4 eV and that of silver is at 4.75 eV, both could be observed up to 500 K. their nature could be well described in terms of intraions transition. Exchange of noble ions back to alkali ions renews initial luminescence of the samples.
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