Pepan Letters
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Preprints and Communications

Here you can find JINR preprints and communications in pdf format starting from 1999.
File size is given in bytes in round brackets.

Subject Categories for JINR Publications Archive (1999 - 2021)

P3-2022-13 (496.940)
Dubois M. et al.
Enhanced Directional Extraction of Very Cold Neutrons Using a Diamond Nanoparticle Powder Reflector

For more than a decade, Detonation NanoDiamond (DND) powders have been actively studied as a material for efficient reflectors of Very Cold Neutrons (VCNs) and Cold Neutrons (CNs). During this time, the storage of VCNs in traps with walls made of DND powder and the quasi-specular reflection of CNs from layers of DND powder have been experimentally demonstrated. The quality of DND powder has been improved by reducing the fraction of impurities causing neutron losses, as well as by choosing the powder parameters that correspond to the most efficient reflection of neutrons. Methods for calculating the transport of neutrons in real powders have been developed. In this work, we experimentally demonstrate the possibility of shaping a VCN beam using a reflector made of fluorinated DND (F-DND) powder. With respect to the flux from an isotropic source located at the bottom of the reflector cavity, the gain in the VCN flux density along the beam axis is ∼ 10 for the neutron velocities of 57 m/s and 75 m/s. The gain in the total flux at the exit from the reflector cavity is ∼ 14 for the fastest VCNs from the interval 4692 m/s and increases with decreasing VCN velocity, reaching ∼ 33 for the slowest VCNs.

E7-2022-12 (413.769)
Isaev A. V. et al.
Spontaneous Fission of 246Fm

An experiment on the study of the 246Fm spontaneous fission was conducted using the SHELS separator. The isotope was synthesized in the complete fusion reaction of 40Ar beam ions and 208Pb target nuclei. The neutron yields of 246Fm spontaneous fission (¯ν = 3,79±0,30, σ2nu = 2,1) were obtained using the SFiNx detector system. The multiplicity distribution of emitted prompt neutrons was restored using the Tikhonov method of statistical regularisation (¯νr = 3,79 ± 0,20, σ2νr= 2,8). The spontaneous fission branching ratio (bSF = 0,061 ± 0,005) and the half-life (T1/2 = 1,50+0,08-0,07 s) of the isotope were determined. The experimental data were compared with scission point model predictions. Excellent convergence was observed in the average number of neutrons per spontaneous fission process. However, the forms of the experimental and model prompt neutron multiplicity distributions differ significantly.

9-2022-10 (927.586)
Teterev Yu. G. et al.
Estimation of the Yield and Angular Distribution of Neutrons for Calculating the Biological Protection of Reconstructed Heavy Ion Accelerators with Energies from 1 to 6 MeV/nucleon

Simple analytical formulas are presented for the operational estimation of the yield and angular distribution of neutrons, which are necessary for calculating the biological protection of heavy ion accelerators with energies from 1 to 6 MeV/nucleon. The results of the calculation were compared with the results of calculations using the LIZE++ and FLUKA programs and with the available experimental data in the literature. As a result of the comparisons, it can be argued that the proposed method for calculating the yield and angular distribution of neutrons from thick targets can be used to quickly assess the necessary biological protection of heavy ion accelerators under construction and reconstruction with energies from 1 to 6 MeV/nucleon. The deviation of the results of these calculations from the more accurate ones does not exceed a factor of two, which is comparable with the results of deviations in the calculation of biological shielding associated with a certain variety of spectra of produced neutrons and deviations in the protective properties of the materials used or their thickness.

P10-2022-5 (496.940)
Kirilov A.S., Murashkevich S.M.
Adaptation of the Sonix+ Software Package to Work with DAQ Controllers DeLiDAQ-2 and Digitizer N6730 by CAEN

Before the use of DeLiDAQ-2 controllers and Digitizer N6730 on the IBR-2 reactor instruments, the main form of DAQ output data was spectral distributions of intensities in matrix form, which, in particular, was used in the Sonix$+$ software package for online visualization. Due to the fact that output data from considered controllers are available only in the events list form, the construction of spectral distributions (histogramming) must be done by programs.The work is devoted to adaptation of the complex for use of the controllers specified, algorithms of data histogramming for them, as well as to tests results carried out at the GRAINS instrument (beam 10 of the IBR-2) in October 2021 consideration.

P10-2022-4 (496.940)
Kirilov A. S., Truntova L. A.
Enhancement of Experiment Control in the Sonix+ Software Package

The work is devoted to enhancing the Sonix+ software package at the IBR-2 instruments to minimize the loss of measurement time when including mathematical operations (summing matrices, building spectral distributions of intensity based on data from the list of events, etc.) directly in the experimental procedure in the Python language (script). For this purpose, the execution of all such operations was separated from the main script into one or more background scripts. A special device class has been added to the complex structure to execute background scripts. Besides this, the checkpoint mechanism previously used to connect the user interface with the script has been replaced by a new one based on Python language decorators and context managers. This significantly simplified the script, improved its reliability, and reduced the time of its development or modification.

2022-2 (20.032.428)
Brief Review of Topmost Scientific Results Obtained in 2021 at the Joint Institute for Nuclear Research

9-2022-1 (2.030.431)
Kozlov O. S. et al.
Actual Tasks of Beam Dynamics Analysis in the NICA Collider

The NICA project is under development at the Joint Institute for Nuclear Research (Dubna). The accelerator complex is in the stage of step-by-step assembly and commissioning. The complex consists of two superconducting synchrotrons and a superconducting ion collider. Numerous studies of beam dynamics, performed at the design stage, formed the basis of R&D of the collider systems. Most part of tasks was done in detail and totally completed. However, a number of tasks are not finished and actual to date. Some of them, being fundamental, need detailed analysis using three-dimensional particle tracing with taking into account all the main physical effects and nonlinearities of electromagnetic fields of the structure. Key task in the NICA collider is study of collective phenomena, to which this work is mainly devoted. The paper describes the current status of numerical and analytical calculations of beam stability in the NICA collider and possible plans of solution of noncompleted tasks.