Pulse Shape Analysis with scintillating bolometers

Among the detectors used for rare event searches, such as neutrinoless Double Beta Decay (0$\nu$DBD) 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 ($\sim$10-500 g) built with scintillating crystals showed that it is possible to distinguish between an electron or $\gamma$-ray and an $\alpha$ particle interaction (i.e. the main source of background for 0$\nu$DBD experiments based on the bolometric technique). Results on pulse shape analysis of a CaMoO$_4$ 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 CaWO4_4 Single Crystals

We investigate the influence of oxygen annealing on the room temperature optical and scintillation properties of CaWO$_4$ 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 ($\sim430$ nm) by a factor of $\sim6$ 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 $\sim400$ 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 $\sim40$ and an improvement of the energy resolution at 59.5 keV by $\sim12$ 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

Поступила: 14.04.2023. Принята в печать: 25.04.2023.Received: 14.04.2023. Accepted: 25.04.2023.В статье разработана модель системы спутниковой связи на основе широкополосных сигналов с относительным фазовым кодированием. Используется система из четырех сигналов с двоичной фазовой манипуляцией. Спектры сигналов расширены методом прямой последовательности. Моделируется работы системы в условиях действия импульсных радиопомех и в условиях действия флуктуационных помех. Получены характеристики помехоустойчивости системы к импульсным помехам с распределением Джонсона и помехам в виде белого гауссовского шума.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

Особенности микробиологического состава вод реки Раздольной (южное Приморье)

Произведена оценка численности и ее сезонной изменчивости для различных индикаторных групп микроорганизмов в поверхностных водах р. Раздольной. Результаты исследования показали, что они подвержены высокому комплексному органическому, техногенному и микробиологическому загрязнению. В поверхностных водах р. Раздольной были выявлены эколого-трофические группы микроорганизмов, которые принимали участие в очищении вод реки. Однако из-за постоянного притока сточных вод бактерии не успевали перерабатывать поступающее органическое вещество, что указывает на неспособность данной экосистемы к полному самоочищению. Согласно классификатору качества вод, воды р. Раздольной по микробиологическим показателям отнесены к грязным в летний сезон, к загрязненным в весенний и осенний периоды и к чистым в зимний сезон

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