Estimations of electron-positron pair production at high-intensity laser interaction with high-Z targets

Electron-positron pairs' generation occuring in the interaction of $10^{18}$-$10^{20}$~W/cm$^2$ laser radiation with high-Z targets are examined. Computational results are presented for the pair production and the positron yield from the target with allowance for the contribution of pair production processes due to electrons and bremsstrahlung photons. Monte-Carlo simulations using the PRIZMA code confirm the estimates obtained. The possible positron yield from high-Z targets irradiated by picosecond lasers of power $10^2$-$10^3$~TW is estimated to be $10^9$-$10^{11}$

Hot Electron and Pair Production from the Texas Petawatt Laser Irradiating Thick Gold Targets

We present data for relativistic hot electron production by the Texas Petawatt Laser irradiating solid Au targets with thickness between 1 and 4 mm. The experiment was performed at the short focus target chamber TC1 in July 2011, with laser energies around 50 J. We measured hot electron spectra out to 50 MeV which show a narrow peak around 10 - 20 MeV plus high energy exponential tail. The hot electron spectral shape differs from those reported for other PW lasers. We did not observe direct evidence of positron production above background.Comment: HEDLA 2012 Conference Paper. submitted to HEDP. revised 1/28/2013. 18 pages. 10 figure

Analysis of the emotional strain influence on the indicators of the heart rhythm variability in students

To determine the features of the cardiovascular system functional state in students using some indicators of heart rate variability under emotional strain. The research involved 67 male students with an average level of daily motor activity. The age range corresponded to 18 - 23 years. All the examined in the personal history had no deviations in health status and were considered to belong to the main medical group. The tonic activity of the autonomic nervous system in the normal condition was determined using the rhythmocardiographic method on the “Varicard 2.51” hardware-software complex according to the indicators of heart rate variability mathematical analysis. Cardio intervals were recorded in the normal condition and under conditions of emotional stress (the examination session was a model of stress). The analysis of heart rate variability was carried out on the basis of the statistical analysis indicators evaluation - SDNN, pNN50 and variational pulsometry - Mo, AMo, MxDMn, IN. Depending on the initial tonicity of the autonomic nervous system, all examined students were divided into groups: vagotonics, normotonics and sympathotonics. Among the determined values, the examination stress had the greatest impact on the stress index and the share of neighboring RR intervals, which differ by more than 50 ms. If the stress index significantly increased in students with vago- and normotonia, the proportion of neighboring RR intervals, differing by more than 50 ms, decreased in all the studied groups Taking an exam led to psycho-emotional stress of the body. It caused autonomic provision restructuring of cardiac activity due to an increase in the sympathetic effect. The results of the research may be of interest to all participants of the educational process

Change of the liquid-electrolyte balance of the digestive glands under muscle tension and during rehabilitation

Изучали изменение баланса водной и электролитной части секрета пищеварительных желез у лиц, не занимающихся спортом, и спортсменов высокой квалификации, развивающих скоростно-силовые качества, борцов. Применяли гастродуоденальное зондирование, собирали биологические жидкости: слюну, мочу, желудочный и панкреатический секреты. Исследовали их объемы, содержание электролитов. В качестве модели острого мышечного напряжения предлагалась 60-минутная велоэргометрическая нагрузка, выполнявшаяся на уровне 60-70 % от уровня МПК. Определено, что различный уровень повседневной двигательной активности оказывает влияние на электролитный состав слюны, желудочного и поджелудочного сока. Установлено перераспределение в объемах пищеварительных соков и мочи в условиях относительного мышечного покоя как в условиях базальной секреции, так и в условиях введения в дуоденум 0,5%-го раствора соляной кислоты. Определено, что при высоком уровне слюноотделения и выделения поджелудочного сока в условиях базальной секреции, при высоком уровне выделения желудочного сока в условиях стимуляции двенадцатиперстной кишки параллельно наблюдались низкие значения диуреза. При выполнении физической нагрузки концентрация натрия и калия в слюне и желудочном соке снижается у обследованных контрольной группы; у спортсменов-борцов подобного угнетения не выявлено, что связано с адаптированностью организма к выполнению физических нагрузок. Концентрация электролитов в дуоденальном содержимом при выполнении физической нагрузки увеличивается.We have investigated the shift in balance of the liquid and electrolytic parts in secretion of digestive glands of persons not engaged in sports and sportsmen of high qualification, developing high speed and power qualities, (wrestlers). We employed gastroduodenal sounding and collected biological fluids: saliva, urine, gastric, pancreatic secrets. We studied their volume and electrolyte content. As a model of acute muscle strain we offered a 60-minute bicycle stress load performed at a level of 60-70% of the maximum oxygen consumption. It was revealed that different levels of everyday motor activity influence the electrolyte composition of saliva, gastric and pancreatic juice, which is connected with the adaptation to the effects of physical exercise. We registered redistribution of the volumes of digestive juices and urine in muscle rest time, both in terms of basal secretion and application of duodenum 0.5% solution of hydrochloric acid. It was determined that at high salivation and secretion of pancreatic juice in basal conditions, and at a high level of gastric juice while simultaneous stimulation of the duodenum the values of diuresis are low. During exercise, the concentration of sodium and potassium in the saliva and gastric juice in the surveyed control group was reduced. Such oppression was not registered with the athletes - wrestlers due to adaptability of their bodies to perform physical activities. The concentration of electrolytes in the duodenal contents during exercise increases

PRIZMA Status

For more than thirty years the code PRIZMA has been used at RFNC-VNIITF for solving radiation transport problems with the Monte Carlo method. The code models the separate and coupled transport of neutrons, photons, electrons, positrons and ions in one-, two-, and three-dimensional geometry. For criticality calculations the code implements the method of generations with a constant number of fission sites in one generation. Now the code is extending its capabilities for nuclear reactor calculations. The paper describes the current status of the code and gives examples of its application to particle transport in nuclear reactors and other physical facilities