Measured cross sections of the production of tritium in thin
27
Al,
nat
Ni, and
nat
W targets irradiated with protons with energies ranging from 40 to 2600 MeV are presented. The targets in the form ...of single and double metal-aluminum “sandwiches” were irradiated at the ITEP-based U-10 accelerator. Tritium was extracted from the irradiated targets using the Sample Oxidizer system, and its activity was measured using a low-background liquid scintillation spectrometer. To calculate the cross sections of tritium production in the
27
Al,
nat
Ni, and
nat
W targets, its losses in the process of irradiation (geometrical correction due to target dimensions) and storage from the end of irradiation to the start of extraction (diffusion correction) were estimated. The obtained data on the tritium production cross section were used to assess the prognostic capacity of the CEM03.03 nuclear model.
This paper presents the results of an experiment determining (n,2n), (n,p), (n,pn), (n,α), (n,n'γ), and (n,γ) reaction rates in 15 test samples of both natural and high-enriched composition:
nat
Mg,
...27
Al,
nat
Ti,
nat
Fe,
59
Co,
nat
Ni,
63
Сu (99.5%),
65
Cu (99.7%),
64
Zn (99.4%),
nat
Zr,
93
Nb,
nat
Cd,
nat
In,
169
Tm, and
197
Au. Computer simulations in the NG-24M neutron generator spectrum were carried out using the MCNP5 and KIR2 radiation transport codes with different nuclear data libraries (JEFF-3.2, JEFF-3.3, JENDL-4.0, ENDF/B-VII.0, ENDF/B-VII.1, ENDF/B-VIII.0, ROSFOND-2010, FENDL-3.0, TENDL-2019, and IRDFF-II). The elaborated full-scale model for neutron transport analysis included the geometry and composition of the neutron generator, experimental samples, and laboratory room. The mean square deviation factor was used to compare the experimental and the simulated results. The best predictive results for both the MCNP5 code and the KIR2 code were obtained with the FENDL-3.0 and ENDF/B-VIII.0 libraries.
The results obtained by determining the flux density of neutrons produced with energies of up to 20 MeV upon the irradiation of a beryllium target 1.3 mm thick with a beam of 21.3-MeV protons are ...presented. The proton flux density was determined by means of standard instruments and was controlled with the aid of the monitoring reactions
Cu
Zn and
Cu
Zn, while the neutron flux density was determined using the reactions
Al
Mg and
Al
Na. The proton and neutron spectra at the center of experimental samples were calculated using the PHITS code.
The possibility of verifying benchmark experiments which are necessary for design validation of the blankets of the TIN-ST thermonuclear neutron source based on the I-2 proton accelerator using ...neutrons from the reaction
7
Li(p, n) is analyzed. It is shown that modern software and databases are effective in calculating the neutron spectra for two types of thorium blankets: solid-state and molten-salt. The hardware and procedures used to develop an adequate idea of the spectral characteristics of the neutron fluxes from plasma and accelerator sources are examined. The results can become the basis for designing micromodels of blankets for subsequent verification benchmark experiments.
The problems of the metrological certification of beams of high-energy heavy charged particles (HCPs) and protons that will be used in the study—as well as testing for radiation resistance—of ...promising products of semiconductor micro- and nanoelectronics, solid-state microwave electronics, and micromechanical systems are considered. One of the main requirements for such beams is ensuring the desired range of linear energy transfer (LET). Two methods for changing the LET are considered, one of which is based on using the ions of various types (
16
O,
22
Ne,
40
Ar,
56
Fe,
84
Kr,
136
Xe,
209
Bi), and the other is based on using ion of the same type (
197
Au), but with different energies. The advantages of using both methods are considered and the problems arising when using the second method are analyzed.
A variant of the target unit based on tungsten rods cooled by molten-salt coolant (alkali-metal fluorides) in a subcritical electronuclear facility is examined. The results of calculations of its ...main parameters are presented: the neutron yield, neutron spectrum on the lateral surface, top and bottom ends of the target, total energy release, specific energy release and induced activity. The calculations are performed using the three codes MCNPX 2.6B, SHIELD and KATRIN-2.5 and the codes ORIHET3 and DCHAIN-SP for calculating the changes in the radioactivity of the main units. The discrepancies in the parameters of the target unit of a subcritical electronuclear facility were determined by calculating the standard deviation factors. Apparently, the uncertainties in the computational results for the differential and integral parameters are due to the nuclear models and libraries in the programs used.
A new species of the genus Chrysina Kirby, 1828 is decribed from Panama. Chrysina valentini sp.n. is related to Chrysina tricolor (Ohaus, 1922) and Chrysina optima (H. W. Bates, 1888) in morphology ...and mtDNA COX I molecular marker. Three related species differ in elytra colour, elytral striae, and number of tubercles on foreleg femur. The morphological divergence of the compared species is supported by distances in mtDNA COI molecular marker.
A method for solving boundary value problems for irregular waveguides that combines the generalized Lorentz lemma with a collocation technique is proposed. The method allows one to reduce boundary ...value problems to systems of integro-differential equations, which are algebraized by identifying collocation points with the points of localization of auxiliary sources.
It is shown that the source function on the right-hand side of the Helmholtz equation, which is a solution of a homogeneous boundary value problem for this equation, provides the excitation of an ...associated wave (oscillation). Since this wave (oscillation) exists only in the presence of a source of the specified type, it is proposed to classify them (wave and oscillation) as associated with the source, and to consider the problem “generating” them as self-consistent, because the excited wave (oscillation) is in synchronism with the source in all wave numbers and energy balance.
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