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The possibility of increasing the current density of a charged particle beam (focusing) by means of tapered glass channels without the use of external energy sources is actively translated into action today for positively charged ions. For electron beams, this possibility is not realized due to the lack of experimental data on the sliding interaction between electron beams and a dielectric surface. It is necessary to examine the compression of an electron beam by tapered capillaries depending on their geometrical parameters, as well as to study the temporal characteristics of the focusing process. In this work, the authors experimentally studied the compression of a 10 keV electron beam using a 15-mm-long tapered glass channel with an inlet-to-outlet inside diameter ratio of 1.15 mm/0.30 mm. The beam current density is shown to increase at the outlet of the capillary with the specified parameters by up to a factor of 2.7 for the position where the channel axis is parallel to that of the initial beam. This density increase is estimated for electrons that have lost no more than 1 keV of initial energy. It is also shown that the process of electron transmission by a tapered capillary is stable regardless of the orientation of the capillary with respect to the direction of the initial beam.

Transmission of 10-keV electrons through a ceramic macrocapillary in the geometry, where the channel axis is oriented parallel to the incident-beam axis, has been studied experimentally. The current and energy spectrum of electrons passing through the channel have been measured depending on the incident beam current and the channel irradiation time. It is demonstrated that the transmission of electrons through a sample depends on the time that has passed after the formation of a conducting carbon deposit on the inner surfaces of both end faces of the channel.

The results of experimental studies of the transmission of 12 and 15 keV electron beams through tapered glass macro-capillaries are presented. Measurements showed that there is no explicit dependence of the output current on the electron energy. The time dependence of the beam current at the output from the capillaries was measured.

The possibility of controlling charged-particle beams by the use of dielectric channels (guiding) is an urgent task because of the potential of developing inexpensive autonomous controlling and focusing devices. At present, experiments with the use of ions with an energy on the order of MeV are intended for the application of radiation with a spot size of about one micrometer for material analysis, surface modification, and cell surgery. In the case of using electron beams, such a possibility is still under study. In this work, the possibility of controlling a beam of accelerated electrons by using a ceramic channel in the case of its inclination both in the vertical and in horizontal planes is demonstrated. Data about the control are obtained for the channel after irradiation of both its end faces for no less than 5 h. After such treatment, an inhomogeneous carbon-containing deposit is formed on the interior surface of the channel near its end faces. It is demonstrated that the formed deposit has no influence on the guiding properties of the channel.

AbstractThe results of the study of the 10-keV electron beam transmission through cylindrical dielectric macrochannels with various lengths. All channels made of polyethylene terephthalate had an identical inner diameter of 1.55 mm and lengths of 20, 30, 35, 40, 45, and 50 mm. The dependence of the current passed through beam channels on their tilt angle relative to the incident electron beam is measured. The electron beam fraction suffered energy losses no more than 1 keV after passing through the dielectric channel is estimated. The dependence of the maximum electron transport through channels on their length is also studied. The data obtained show that the passed current intensity weakly depends on channel lengths in the length range of 20–50 mm under study. These results can be explained by the fact that such a dynamic charge distribution is formed on channel walls, which provides the best conditions of electron transport through the dielectric channel.

The results of spectral analysis of the surface of polysulfone fiber (channel) after transmission of a 10-keV electron beam through it are presented in this work. This work is a continuation of the study of the dependence of the quantity of electrons transmitted without loss of energy through the array formed of polysulfone hollow fibers, on the angle of rotation of the array about the vertical axis. Data of the analysis demonstrates significant modification of the internal surface of the channel after its electron irradiation. It is made clear that, in the case of the long-term irradiation of polysulfone tubes by charged-particle beams, a dark coating is formed on the surface layer of the channel which can have a significant impact on the transmission capacity and controllability of the channels in the context of the control of charged particles. Comparison of the elemental composition of the surface of the fiber before and after the grazing interaction of a beam of electrons with an energy of 10 keV with it reveals an increase in the carbon concentration in the irradiated fiber of 50 wt %, and an oxygen content increase of 40 wt %. The sulphur amount does not change, and remains at the level of about 10 wt % both in the irradiated and in nonirradiated sample.

New NICA accelerator complex at JINR (Dubna), based on the existing upgraded Nuclotron accelerator, will allow conducting all types of research in the field of high-energy physics. The main tasks of this project are study of the properties of the deconfinement phase transition, experimental investigation on medium modification of vector mesons, and search for the QCD critical end point. Thus, two interaction points are foreseen in the NICA collider: one for studying the collision of heavy ions on the Multipurpose detector MPD, the other for polarized beams for the experiment on the SPD installation. The ambitious physical goals of MPD require excellent particle identification at the maximum possible range of phase space. Identification of charged hadrons is achieved by combining time-of-flight measurements and energy loss measurements from the time-projection camera TPC. The Time-of-Flight system is based on multigap resistive plate chambers (MRPC), which are successfully used to identify particles in similar experiments around the world. A production site has been organized at the Laboratory of High Energy Physics of JINR for serial production of TOF MPD modules including 10 MRPCs. This site includes the entire cycle of work from preparing materials for the assembly of detectors to testing the assembled modules on cosmic radiation. This report presents the structure of the TOF system, its main parameters, the current state and the results of decoding and processing data obtained at the module testing facility.

Identification of particles generated by ion collisions in the NICA collider is one of the basic functions of the Multipurpose Detector (MPD). The main means of identification in MPD are the time-of-flight system (TOF) and the time-projection chamber (TPC). The article considers the optimization of the algorithms of particles identification by these systems. Under certain conditions, the use of the statistical Bayesian approach has made it possible to achieve an optimal ratio of the efficiency of particle identification and contamination by incorrectly defined particles.