176 research outputs found
Pulse Shape Analysis with scintillating bolometers
Among the detectors used for rare event searches, such as neutrinoless Double
Beta Decay (0DBD) and Dark Matter experiments, bolometers are very
promising because of their favorable properties (excellent energy resolution,
high detector efficiency, a wide choice of different materials used as
absorber, ...). However, up to now, the actual interesting possibility to
identify the interacting particle, and thus to greatly reduce the background,
can be fulfilled only with a double read-out (i.e. the simultaneous and
independent read out of heat and scintillation light or heat and ionization).
This double read-out could greatly complicate the assembly of a huge,
multi-detector array, such as CUORE and EURECA. The possibility to recognize
the interacting particle through the shape of the thermal pulse is then clearly
a very interesting opportunity.
While detailed analyses of the signal time development in purely thermal
detectors have not produced so far interesting results, similar analyses on
macro-bolometers (10-500 g) built with scintillating crystals showed that
it is possible to distinguish between an electron or -ray and an
particle interaction (i.e. the main source of background for 0DBD
experiments based on the bolometric technique). Results on pulse shape analysis
of a CaMoO crystal operated as bolometer is reported as an example. An
explanation of this behavior, based on the energy partition in the heat and
scintillation channels, is also presented.Comment: Presented at the 14th International Workshop on Low Temperature
Detectors, proceedings to be published in the Journal of Low Temperature
Physic
Optimization of light collection from crystal scintillators for cryogenic experiments
High light collection efficiency is an important requirement in any
application of scintillation detectors. The purpose of this study is to
investigate the possibility for improving this parameter in cryogenic
scintillation bolometers, which can be considered as a promising detectors in
experiments investigating neutrinoless double beta decay and dark matter.
Energy resolutions and relative pulse amplitudes of scintillation detectors
using ZnWO4 scintillation crystals of different shapes (cylinder 20 mm in
dimater by 20 mm and hexagonal prism with diagonal 20 mm and height 20 mm),
reflector materials and shapes, optical contact and surface properties
(polished and diffused) were measured at room temperature. Propagation of
optical photons in these experimental conditions was simulated using Geant4 and
ZEMAX codes. The results of the simulations are found to be in good agreement
with each other and with direct measurements of the crystals. This could be
applied to optimize the geometry of scintillation detectors used in the
cryogenic experiments.Comment: 12 pages, 8 figures, 1 Tabl
Impact of geometry on light collection efficiency of scintillation detectors for cryogenic rare event searches
Simulations of photon propagation in scintillation detectors were performed
with the aim to find the optimal scintillator geometry, surface treatment, and
shape of external reflector in order to achieve maximum light collection
efficiency for detector configurations that avoid direct optical coupling, a
situation that is commonly found in cryogenic scintillating bolometers in
experimental searches for double beta decay and dark matter. To evaluate the
light collection efficiency of various geometrical configurations we used the
ZEMAX ray-tracing software. It was found that scintillators in the shape of a
triangular prism with an external mirror shaped as truncated cone gives the
highest light collection efficiency. The results of the simulations were
confirmed by carrying out measurements of the light collection efficiencies of
CaWO4 crystal scintillators. A comparison of simulated and measured values of
light output shows good agreemen
Influence of Annealing on the Optical and Scintillation Properties of CaWO Single Crystals
We investigate the influence of oxygen annealing on the room temperature
optical and scintillation properties of CaWO single crystals that are being
produced for direct Dark Matter search experiments. The applied annealing
procedure reduces the absorption coefficient at the peak position of the
scintillation spectrum ( nm) by a factor of and leads to an
even larger reduction of the scattering coefficient. Furthermore, the annealing
has no significant influence on the \emph{intrinsic} light yield. An additional
absorption occurring at nm suggests the formation of O hole
centers. Light-yield measurements at room temperature where one crystal surface
was mechanically roughened showed an increase of the \emph{measured} light
yield by and an improvement of the energy resolution at 59.5 keV by
for the annealed crystal. We ascribe this result to the reduction of
the absorption coefficient while the surface roughening is needed to compensate
for the also observed reduction of the scattering coefficient after annealing
Microscopic features of buccal epithelium in smokers students indo-dravidian race: by E. Hooton
We have studied the microscopic features of buccal epithelium in smoking students of Indo-Dravidian race. In the epithelial cells of the mucous cheek surface of smoking students we revealed the scored nuclei with tongue- and broken egg-type protrusions, micronuclei, cellular dimorphism, binuclear cells, as well as a significant decrease in nuclear-cytoplasmic ratio, as compared to the control, which may indicate the presence of local inflammation resulting from the toxic effects of smoking products on the oral mucos
Detection of the Natural Alpha Decay of Tungsten
The natural alpha decay of 180W has been unambiguously detected for the first
time. The alpha peak is found in a (gamma,beta and neutron)-free background
spectrum. This has been achieved by the simultaneous measurement of phonon and
light signals with the CRESST cryogenic detectors. A half-life of T1/2 = (1.8
+- 0.2) x 10^18 y and an energy release of Q = (2516.4 +- 1.1 (stat.) +- 1.2
(sys.)) keV have been measured. New limits are also set on the half-lives of
the other naturally occurring tungsten isotopes.Comment: Submitted to Physical Review C Revised versio
Estimation of the Immunity of a Satellite Communication System Based on Wideband Signals in Relation to Impulse and Fluctuating Interferences
ΠΠΎΡΡΡΠΏΠΈΠ»Π°: 14.04.2023. ΠΡΠΈΠ½ΡΡΠ° Π² ΠΏΠ΅ΡΠ°ΡΡ: 25.04.2023.Received: 14.04.2023. Accepted: 25.04.2023.Π ΡΡΠ°ΡΡΠ΅ ΡΠ°Π·ΡΠ°Π±ΠΎΡΠ°Π½Π° ΠΌΠΎΠ΄Π΅Π»Ρ ΡΠΈΡΡΠ΅ΠΌΡ ΡΠΏΡΡΠ½ΠΈΠΊΠΎΠ²ΠΎΠΉ ΡΠ²ΡΠ·ΠΈ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΡΠΈΡΠΎΠΊΠΎΠΏΠΎΠ»ΠΎΡΠ½ΡΡ
ΡΠΈΠ³Π½Π°Π»ΠΎΠ² Ρ ΠΎΡΠ½ΠΎΡΠΈΡΠ΅Π»ΡΠ½ΡΠΌ ΡΠ°Π·ΠΎΠ²ΡΠΌ ΠΊΠΎΠ΄ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ. ΠΡΠΏΠΎΠ»ΡΠ·ΡΠ΅ΡΡΡ ΡΠΈΡΡΠ΅ΠΌΠ° ΠΈΠ· ΡΠ΅ΡΡΡΠ΅Ρ
ΡΠΈΠ³Π½Π°Π»ΠΎΠ² Ρ Π΄Π²ΠΎΠΈΡΠ½ΠΎΠΉ ΡΠ°Π·ΠΎΠ²ΠΎΠΉ ΠΌΠ°Π½ΠΈΠΏΡΠ»ΡΡΠΈΠ΅ΠΉ. Π‘ΠΏΠ΅ΠΊΡΡΡ ΡΠΈΠ³Π½Π°Π»ΠΎΠ² ΡΠ°ΡΡΠΈΡΠ΅Π½Ρ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ ΠΏΡΡΠΌΠΎΠΉ ΠΏΠΎΡΠ»Π΅Π΄ΠΎΠ²Π°ΡΠ΅Π»ΡΠ½ΠΎΡΡΠΈ. ΠΠΎΠ΄Π΅Π»ΠΈΡΡΠ΅ΡΡΡ ΡΠ°Π±ΠΎΡΡ ΡΠΈΡΡΠ΅ΠΌΡ Π² ΡΡΠ»ΠΎΠ²ΠΈΡΡ
Π΄Π΅ΠΉΡΡΠ²ΠΈΡ ΠΈΠΌΠΏΡΠ»ΡΡΠ½ΡΡ
ΡΠ°Π΄ΠΈΠΎΠΏΠΎΠΌΠ΅Ρ
ΠΈ Π² ΡΡΠ»ΠΎΠ²ΠΈΡΡ
Π΄Π΅ΠΉΡΡΠ²ΠΈΡ ΡΠ»ΡΠΊΡΡΠ°ΡΠΈΠΎΠ½Π½ΡΡ
ΠΏΠΎΠΌΠ΅Ρ
. ΠΠΎΠ»ΡΡΠ΅Π½Ρ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠΈ ΠΏΠΎΠΌΠ΅Ρ
ΠΎΡΡΡΠΎΠΉΡΠΈΠ²ΠΎΡΡΠΈ ΡΠΈΡΡΠ΅ΠΌΡ ΠΊ ΠΈΠΌΠΏΡΠ»ΡΡΠ½ΡΠΌ ΠΏΠΎΠΌΠ΅Ρ
Π°ΠΌ Ρ ΡΠ°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΠ΅ΠΌ ΠΠΆΠΎΠ½ΡΠΎΠ½Π° ΠΈ ΠΏΠΎΠΌΠ΅Ρ
Π°ΠΌ Π² Π²ΠΈΠ΄Π΅ Π±Π΅Π»ΠΎΠ³ΠΎ Π³Π°ΡΡΡΠΎΠ²ΡΠΊΠΎΠ³ΠΎ ΡΡΠΌΠ°.A model of a satellite communication system based on wideband signals with relative diphase encoding is developed in the paper. A system of four signals with binary phase shift keying is used. Spectra of the signals are spread by the direct sequence technique. The developed system operation under conditions of impulse electromagnetic interference and under the influence of fluctuation interference is simulated. The dependences of bit error rate on signal-to-interference ratio are evaluated in the cases of impulse interference with Johnson distribution and white Gaussian noise affecting the signal
ΠΡΠΎΠ±Π΅Π½Π½ΠΎΡΡΠΈ ΠΌΠΈΠΊΡΠΎΠ±ΠΈΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠΎΡΡΠ°Π²Π° Π²ΠΎΠ΄ ΡΠ΅ΠΊΠΈ Π Π°Π·Π΄ΠΎΠ»ΡΠ½ΠΎΠΉ (ΡΠΆΠ½ΠΎΠ΅ ΠΡΠΈΠΌΠΎΡΡΠ΅)
ΠΡΠΎΠΈΠ·Π²Π΅Π΄Π΅Π½Π° ΠΎΡΠ΅Π½ΠΊΠ° ΡΠΈΡΠ»Π΅Π½Π½ΠΎΡΡΠΈ ΠΈ Π΅Π΅ ΡΠ΅Π·ΠΎΠ½Π½ΠΎΠΉ ΠΈΠ·ΠΌΠ΅Π½ΡΠΈΠ²ΠΎΡΡΠΈ Π΄Π»Ρ ΡΠ°Π·Π»ΠΈΡΠ½ΡΡ
ΠΈΠ½Π΄ΠΈΠΊΠ°ΡΠΎΡΠ½ΡΡ
Π³ΡΡΠΏΠΏ ΠΌΠΈΠΊΡΠΎΠΎΡΠ³Π°Π½ΠΈΠ·ΠΌΠΎΠ² Π² ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠ½ΡΡ
Π²ΠΎΠ΄Π°Ρ
Ρ. Π Π°Π·Π΄ΠΎΠ»ΡΠ½ΠΎΠΉ. Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΠΏΠΎΠΊΠ°Π·Π°Π»ΠΈ, ΡΡΠΎ ΠΎΠ½ΠΈ ΠΏΠΎΠ΄Π²Π΅ΡΠΆΠ΅Π½Ρ Π²ΡΡΠΎΠΊΠΎΠΌΡ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ½ΠΎΠΌΡ ΠΎΡΠ³Π°Π½ΠΈΡΠ΅ΡΠΊΠΎΠΌΡ, ΡΠ΅Ρ
Π½ΠΎΠ³Π΅Π½Π½ΠΎΠΌΡ ΠΈ ΠΌΠΈΠΊΡΠΎΠ±ΠΈΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠΌΡ Π·Π°Π³ΡΡΠ·Π½Π΅Π½ΠΈΡ. Π ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠ½ΡΡ
Π²ΠΎΠ΄Π°Ρ
Ρ. Π Π°Π·Π΄ΠΎΠ»ΡΠ½ΠΎΠΉ Π±ΡΠ»ΠΈ Π²ΡΡΠ²Π»Π΅Π½Ρ ΡΠΊΠΎΠ»ΠΎΠ³ΠΎ-ΡΡΠΎΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ Π³ΡΡΠΏΠΏΡ ΠΌΠΈΠΊΡΠΎΠΎΡΠ³Π°Π½ΠΈΠ·ΠΌΠΎΠ², ΠΊΠΎΡΠΎΡΡΠ΅ ΠΏΡΠΈΠ½ΠΈΠΌΠ°Π»ΠΈ ΡΡΠ°ΡΡΠΈΠ΅ Π² ΠΎΡΠΈΡΠ΅Π½ΠΈΠΈ Π²ΠΎΠ΄ ΡΠ΅ΠΊΠΈ. ΠΠ΄Π½Π°ΠΊΠΎ ΠΈΠ·-Π·Π° ΠΏΠΎΡΡΠΎΡΠ½Π½ΠΎΠ³ΠΎ ΠΏΡΠΈΡΠΎΠΊΠ° ΡΡΠΎΡΠ½ΡΡ
Π²ΠΎΠ΄ Π±Π°ΠΊΡΠ΅ΡΠΈΠΈ Π½Π΅ ΡΡΠΏΠ΅Π²Π°Π»ΠΈ ΠΏΠ΅ΡΠ΅ΡΠ°Π±Π°ΡΡΠ²Π°ΡΡ ΠΏΠΎΡΡΡΠΏΠ°ΡΡΠ΅Π΅ ΠΎΡΠ³Π°Π½ΠΈΡΠ΅ΡΠΊΠΎΠ΅ Π²Π΅ΡΠ΅ΡΡΠ²ΠΎ, ΡΡΠΎ ΡΠΊΠ°Π·ΡΠ²Π°Π΅Ρ Π½Π° Π½Π΅ΡΠΏΠΎΡΠΎΠ±Π½ΠΎΡΡΡ Π΄Π°Π½Π½ΠΎΠΉ ΡΠΊΠΎΡΠΈΡΡΠ΅ΠΌΡ ΠΊ ΠΏΠΎΠ»Π½ΠΎΠΌΡ ΡΠ°ΠΌΠΎΠΎΡΠΈΡΠ΅Π½ΠΈΡ. Π‘ΠΎΠ³Π»Π°ΡΠ½ΠΎ ΠΊΠ»Π°ΡΡΠΈΡΠΈΠΊΠ°ΡΠΎΡΡ ΠΊΠ°ΡΠ΅ΡΡΠ²Π° Π²ΠΎΠ΄, Π²ΠΎΠ΄Ρ Ρ. Π Π°Π·Π΄ΠΎΠ»ΡΠ½ΠΎΠΉ ΠΏΠΎ ΠΌΠΈΠΊΡΠΎΠ±ΠΈΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΌ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»ΡΠΌ ΠΎΡΠ½Π΅ΡΠ΅Π½Ρ ΠΊ Π³ΡΡΠ·Π½ΡΠΌ Π² Π»Π΅ΡΠ½ΠΈΠΉ ΡΠ΅Π·ΠΎΠ½, ΠΊ Π·Π°Π³ΡΡΠ·Π½Π΅Π½Π½ΡΠΌ Π² Π²Π΅ΡΠ΅Π½Π½ΠΈΠΉ ΠΈ ΠΎΡΠ΅Π½Π½ΠΈΠΉ ΠΏΠ΅ΡΠΈΠΎΠ΄Ρ ΠΈ ΠΊ ΡΠΈΡΡΡΠΌ Π² Π·ΠΈΠΌΠ½ΠΈΠΉ ΡΠ΅Π·ΠΎΠ½
The CRESST Dark Matter Search
We present first competitive results on WIMP dark matter using the
phonon-light-detection technique. A particularly strong limit for WIMPs with
coherent scattering results from selecting a region of the phonon-light plane
corresponding to tungsten recoils. The observed count rate in the neutron band
is compatible with the rate expected from neutron background. CRESST is
presently being upgraded with a 66 channel SQUID readout system, a neutron
shield and a muon veto system. This results in a significant improvement in
sensitivity.Comment: 6 pages, 3 figures, to be published in the proceedings of the 5th
International Workshop on the Identification and Detection of Dark Matter IDM
2004, Edinburgh, Sept. 2004, World Scientifi
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