The research program of the Liquid Scintillation Detector (LSD) in the Mont Blanc Laboratory

A massive (90 tons) liquid scintillation detector (LSD) has been running since October 1984 in the Mont Blanc Laboratory at a depth of 5,200 hg/sq cm of standard rock. The research program of the experiment covers a variety of topics in particle physics and astrophysics. The performance of the detector, the main fields of research are presented and the preliminary results are discussed

THE DETECTION OF THE NECESSARY CONDITIONS OF EFFECTIVE FUNCTIONING OF THE BALL CLEANING SYSTEM OF THE TUBES OF STEAM TURBINE CONDENSERS. Part 1

A problem of an increase of the power of turbine by improving heat transfer in condensers of steam turbines is considered in the article as a topical one. The analysis of contamination of the internal surfaces of cooling tubes and of the influence of pollution on the process of heat transfer in turbine condensers has been fulfilled. The existing method of cleaning of condenser tubes with the use of porous elastic balls of sponge rubber that is implemented on a number of large thermal power plants and state region power plants of the Republic of Belarus is examined. In the operation of the ball cleaning system a significant drawback has been revealed, viz. a low efficiency of this method due to the failure to comply with preparation the system of circulating water for operation. Also, a certain imperfection of ball cleaning system technology has been determined. One of the prerequisites for the effective functioning of the ball cleaning system is a certain degree of purity of the pipe system of the condenser, characterized by the coefficient of purity. To determine the effectiveness of ball cleaning system a series of experiments on the launching of porous rubber balls in the pipe system of the main and the embedded bunches of the T-250/300-240 UTMZ turbine has been produced. Immediately before the experiments hydraulic cleaning of the tubes of the condenser by a high-pressure installation were carried out. During the experiments, records of the number of downloaded porous rubber balls, of the number of rubber balls captured in a loading chamber, and of the number of rubber balls that remained in a calibration device were kept. A large proportion of default of the balls caused by the presence of residues of the carbonate sediments, that obstruct the movement of porous rubber balls in the tubes of the condenser, was determined. The presence of carbonate deposits in the tubes of the condenser indicates a lack of effectiveness of antiscale treatment of circulating water and of hydraulic method of cleaning tubes of the condenser

ОПРЕДЕЛЕНИЕ НЕОБХОДИМЫХ УСЛОВИЙ ЭФФЕКТИВНОЙ РАБОТЫ СИСТЕМЫ ШАРИКОВОЙ ОЧИСТКИ ТРУБОК КОНДЕНСАТОРОВ ПАРОВОЙ ТУРБИНЫ. Часть 1

A problem of an increase of the power of turbine by improving heat transfer in condensers of steam turbines is considered in the article as a topical one. The analysis of contamination of the internal surfaces of cooling tubes and of the influence of pollution on the process of heat transfer in turbine condensers has been fulfilled. The existing method of cleaning of condenser tubes with the use of porous elastic balls of sponge rubber that is implemented on a number of large thermal power plants and state region power plants of the Republic of Belarus is examined. In the operation of the ball cleaning system a significant drawback has been revealed, viz. a low efficiency of this method due to the failure to comply with preparation the system of circulating water for operation. Also, a certain imperfection of ball cleaning system technology has been determined. One of the prerequisites for the effective functioning of the ball cleaning system is a certain degree of purity of the pipe system of the condenser, characterized by the coefficient of purity. To determine the effectiveness of ball cleaning system a series of experiments on the launching of porous rubber balls in the pipe system of the main and the embedded bunches of the T-250/300-240 UTMZ turbine has been produced. Immediately before the experiments hydraulic cleaning of the tubes of the condenser by a high-pressure installation were carried out. During the experiments, records of the number of downloaded porous rubber balls, of the number of rubber balls captured in a loading chamber, and of the number of rubber balls that remained in a calibration device were kept. A large proportion of default of the balls caused by the presence of residues of the carbonate sediments, that obstruct the movement of porous rubber balls in the tubes of the condenser, was determined. The presence of carbonate deposits in the tubes of the condenser indicates a lack of effectiveness of antiscale treatment of circulating water and of hydraulic method of cleaning tubes of the condenser. Рассмотрено актуальное направление – повышение мощности турбоагрегатов путем улучшения условий теплопередачи в конденсаторах паровых турбин. Проведен анализ микрозагрязнений внутренних поверхностей охлаждающих трубок и влияния загрязненности на процесс теплопередачи в конденсаторах турбин. Изучен существующий способ очистки конденсаторных трубок с помощью пористых эластичных шариков из губчатой резины, который реализован на ряде крупных ТЭЦ и ГРЭС Республики Беларусь. При эксплуатации системы шариковой очистки выявлен существенный недостаток – низкая эффективность данного способа из-за несоблюдения требований по подготовке системы циркуляционного водоснабжения к эксплуатации, а также некоторая степень несовершенства технологии системы шариковой очистки. Одним из условий эффективной работы системы шариковой очистки является определенная степень чистоты трубной системы конденсатора, которая характеризуется коэффициентом чистоты. Для определения эффективности системы шариковой очистки произведена серия опытов по запуску пористых резиновых шариков в трубную систему основных и встроенного пучков турбины Т-250/300-240 УТМЗ. Непосредственно перед опытами проводили гидравлическую очистку трубок конденсатора высоконапорной установкой. В процессе опытов вели учет количества загруженных и отловленных в загрузочной камере пористых резиновых шариков, а также оставшихся в калибровочном устройстве. В результате установлен большой процент невозврата этих шариков, причиной которого является наличие остатков карбонатных отложений, препятствующих движению пористых резиновых шариков в трубках конденсатора. Наличие карбонатных отложений в трубках конденсатора свидетельствует о недостаточной эффективности применяемой противонакипной обработки циркуляционной воды и гидравлического способа очистки трубок конденсатора.

Determination of the muon charge sign with the dipolar spectrometers of the OPERA experiment

The OPERA long-baseline neutrino-oscillation experiment has observed the direct appearance of $\nu_\tau$ in the CNGS $\nu_\mu$ beam. Two large muon magnetic spectrometers are used to identify muons produced in the $\tau$ leptonic decay and in $\nu_\mu^{CC}$ interactions by measuring their charge and momentum. Besides the kinematic analysis of the $\tau$ decays, background resulting from the decay of charmed particles produced in $\nu_\mu^{CC}$ interactions is reduced by efficiently identifying the muon track. A new method for the charge sign determination has been applied, via a weighted angular matching of the straight track-segments reconstructed in the different parts of the dipole magnets. Results obtained for Monte Carlo and real data are presented. Comparison with a method where no matching is used shows a significant reduction of up to 40\% of the fraction of wrongly determined charges.Comment: 10 pages. Improvements in the tex

Procedure for short-lived particle detection in the OPERA experiment and its application to charm decays

The OPERA experiment, designed to perform the first observation of $\nu_\mu \rightarrow \nu_\tau$ oscillations in appearance mode through the detection of the $\tau$ leptons produced in $\nu_\tau$ charged current interactions, has collected data from 2008 to 2012. In the present paper, the procedure developed to detect $\tau$ particle decays, occurring over distances of the order of 1 mm from the neutrino interaction point, is described in detail. The results of its application to the search for charmed hadrons are then presented as a validation of the methods for $\nu_\tau$ appearance detection