In this paper, we use the Monte Carlo method to calculate the fluxes of neutrons emitted from targets of different geometry and composition under the action of a low-energy (13 MeV) proton beam. The ...target is a thin beryllium layer with a thickness of 1–2 mm or a three-dimensional structure including beryllium, copper, and polyethylene. The energy spectra of neutrons are given. A comparison with the calculations of other authors is made.
A study is performed of distortions in the registration of fluxes and energy spectra of delayed neutrons by a stilbene scintillation spectrometer inside Pb shielding. The delayed neutrons are ...products of
238
U photofission on a pulsed electron linear accelerator. The dependences of these distortions on the neutron energy and wall thickness of the Pb shielding are considered. Contributions from processes in the walls of the irradiation hall are described.
In this article, we describe an experimental verification of the correctness of registration of delayed neutrons from
238
U photofission at a maximum energy of 10 MeV of bremsstrahlung γ quanta on a ...pulsed linear electron accelerator LUE-8-5 in an interval of (1–5) ms after each beam pulse at times ≳7 min from the onset of irradiation. The measurements have been carried out using the scintillation spectrometer of fast neutrons based on a single stilbene crystal with pulse shape discrimination of γ quanta and fast neutrons. The temporal dependence of the counting rate of delayed neutrons in
238
U photofission has been measured at a repetition rate of 300 s
–1
in a time interval of (1.25–3.30) ms after the beam pulse.
A special version of the SHIELD transport code has been developed intended for radiation protection purposes in space. The calculation of the fluxes of primary and secondary particles and the ...absorbed dose rate in a water phantom behind various shielding under the influence of galactic cosmic rays (GCRs) using the GCR model developed by the Institute of Nuclear Physics, Moscow State University. The code architecture is briefly described as a version of SHIELD including models of nuclear reactions. Stopping power
dE
/
dX
(
E
) is calculated in the energy range of 10 keV/nucleon–100 GeV/nucleon. The calculation was performed in spherical geometry, which allows, in a simple formulation of the problem, to compare the fluxes of particles of different types in the phantom, as well as to estimate the contribution to the dose of different GCR components depending on the protection parameters.
A stand for the irradiation of electronic integrated circuits is developed at the proton beam of the linear accelerator of the Institute for Nuclear Research, Russian Academy of Sciences. Estimation ...of secondary neutron fluxes in the experimental hall and in the surrounding medium outside the external shielding of the accelerator is performed. The issue of the impact of albedo protons and neutrons from the beam trap on the irradiated object is considered. The activation and cooling of the stand elements and the irradiated object as well as the dose rate are calculated. The data obtained allow safe operating conditions of the stand and optimal modes of irradiation to be selected. The calculations were carried out by the Monte Carlo method using the SHIELD hadron transport code for proton-beam parameters which are maximal at this time: energy of 209 MeV, current of 1 μA.
In this article, we describe an experimental verification of the correctness of registration of delayed neutrons from .sup.238U photofission at a maximum energy of 10 MeV of bremsstrahlung gamma ...quanta on a pulsed linear electron accelerator LUE-8-5 in an interval of (1-5) ms after each beam pulse at times greater-than or equivalent to7 min from the onset of irradiation. The measurements have been carried out using the scintillation spectrometer of fast neutrons based on a single stilbene crystal with pulse shape discrimination of gamma quanta and fast neutrons. The temporal dependence of the counting rate of delayed neutrons in .sup.238U photofission has been measured at a repetition rate of 300 s.sup.-1 in a time interval of (1.25-3.30) ms after the beam pulse.
Growing evidence supports a role for extracellular vesicles (EVs) in haemostasis and thrombosis due to exposure of negatively charged procoagulant phospholipids (PPL). Current commercial ...PPL-dependent clotting assays use chemically phospholipid depleted plasma to measure PPL activity. The purpose of our study was to modify the PPL assay by substituting the chemically phospholipid depleted plasma with PPL depleted plasma obtained by ultracentrifugation This in order to get readily access to a sensitive and reliable assay to measure PPL activity in human plasma and cell supernatants. The performance of the assay was tested, including the influence of individual coagulation factors and postprandial lipoproteins and compared to a commercial PPL assay (STA-Procoag-PPL). The two PPL assays displayed similar sensitivity to exogenously added standardized phospholipids. The PPL activity measured by the modified assay strongly correlates with the results from the commercial assay. The intraday- and between-days coefficients of variation ranged from 2-4% depending on the PPL activity in the sample. The modified PPL assay was insensitive to postprandial lipoprotein levels in plasma, as well as to tissue factor (TF) positive EVs from stimulated whole blood. Our findings showed that the modified assay performed equal to the comparator, and was insensitive to postprandial lipoproteins and TF
EVs.
Cryogenic setup for MJ class laser targets Rybakov, A. S.; Demikhov, E. I.; Kostrov, E. A. ...
Laser and particle beams,
03/2019, Letnik:
37, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The cryogenic system for maintaining a target at a constant temperature in the range 5–25 K after shutting off the pulse tube (PT) cryogenic refrigerator is developed and tested. The temperature ...stability at the sample is ±2 mK for at least 20 hours. The cryogenic setup consists of cryostat, PT cryocooler, liquid helium vessel, helium gas supply, thermo-radiation shield, thermal resistance. The system provides 0.25 W of cooling power at the target. The appropriate thermal resistance should be used for different temperatures. The designed operation mode is 3 minutes off and 15 minutes on. The deactivation of PT cryocooler allows to achieve the target position stability of 1 micrometer or less during the X-ray characterization. The effect of neutron-shield was estimated using Monte-Carlo simulation.
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