High Energy Charged Particle Beams Research Articles

Remarkable reduction in thermal contact resistance between target and heat exchanger using TIMs in isotope neutron source accelerator

The high thermal contact resistance (TCR) between the target and the heat exchanger in the Isotope Neutron Source Accelerator will cause the high-energy charged particle beam to stay in the target, resulting in a remarkable increase of temperature which affects the production of stable isotopes. At present, the usage of thermal interface materials (TIMs) can fill the gap at the contact surface and thus reduces the TCR. In this paper, aiming at the actual working condition of neutron source, the steady-state TCR measurement experiment is designed under vacuum and high temperature environment. The TCR at the contact surface was reduced after adding graphite films, thermal greases, liquid metals and preloads. The improvement of TCR of the contact surface between palladium (Pd), copper (Cu) and graphite (Gr) were measured respectively. The results show that the TCR between palladium and graphite is reduced by 95 % by adding liquid metal (Gallium alloy). The TCR between copper and graphite was reduced by 91 % by brazing method. Compared with other TIMs, graphite film has the advantages of high thermal conductivity, high temperature resistance and no fluidity. Adding 0.08 mm thick graphite film between Pd/Gr and Cu/Gr contact surface can reduce the TCR by 50 % and 70 %, respectively. The improvement effect between the two contact surfaces was not obvious when 15.9–318.3 kPa preload was applied.

High precision real-time insertion device and monochromator synchronization at NSLS-II

Insertion devices have become the dominant photon source at synchrotron and free electron laser light source facilities the world over. Undulators, characterized by their small deflection parameter, exhibit a high degree of constructive interference in photon production from high energy charged particle beams leading to very high photon rates at specific harmonics of the fundamental frequency with relatively narrow spectral widths. Spectroscopic measurements of interest typically span several of these harmonic widths, which requires precision adjustment of an undulator’s magnetic gap to maintain peak flux within the much narrower bandwidth of a beamline monochromator at the desired energy. High precision insertion device controls are developed at NSLS-II including real-time linked control of monochromator hardware allowing for fast, high precision, hardware triggered, spectroscopic measurements. This fast fly scan method is described, compared statistically for self consistency, and shown to be far superior in both efficiency and accuracy as compared to standard step scan measurements.

Measuring the self-generated magnetic field and the velocity of plasma flow in a pulsed plasma accelerator

In phase of radial compression the unsteady plasma flow at the exit of a pulsed plasma accelerators is related to the generation of fast high-energy charged particle beams, to plasma density perturbations, to the internal plasma pressure is opposite to the external magnetic pressure (B2/2μ0) associated with plasma column’s self-generated magnetic field. The last one listed above is of particular interest. The investigation of the magnetic field of plasma flow relatively gives information about the above mutually close factors cause to plasma flow instability.In this paper a miniature high-frequency magnetic probe are made for measuring and further investigating the pulsed self-generated magnetic field of plasma flow, in particular, at the exit of the accelerator in an experimental setup of PPA (located in KazNU, IETP). The magnetic probe dimensions are following: coil diameter is 2,12 mm, number of turns is 7, copper wire diameter is 150 μm, and winding length is 1, 1 mm. The coil inductance is about 0,113 μH and the temporal resolution of the magnetic probe is 2,3 ns. The magnetic probe was calibrated using a Hall sensor on the magnetic field of a multi-layered solenoid connected to an alternating power source of 15 A. Thus, the evaluated measurement error of the probe was no more than 10%.

Shaping ion beams into hollow profiles using sextupole magnets

It is essential to properly shape the intensity distribution or irradiation field of high-energy charged-particle beams to improve their utilization, e.g., high energy density physics and heavy-ion fusion. Recently, unique beam profile shaping that cannot be realized through conventional linear focusing (i.e., the formation of hollow transverse profiles) was achieved through nonlinear focusing using octupole magnets. In this paper, we experimentally demonstrate hollow profile shaping using sextupole magnets, and numerically and analytically verify the beam dynamics of second-order sextupole focusing. We found that both triangular and elliptical-shaped hollow beams can be formed despite the three-fold symmetry of transverse beam cross-sections and asymmetric phase-space evolution. The characteristics of the sextupole-focused beams are compared with those of octupole-focused beams.

Combined Effects of Three High-Energy Charged Particle Beams Important for Space Flight on Brain, Behavioral and Cognitive Endpoints in B6D2F1 Female and Male Mice.

The radiation environment in deep space includes the galactic cosmic radiation with different proportions of all naturally occurring ions from protons to uranium. Most experimental animal studies for assessing the biological effects of charged particles have involved acute dose delivery for single ions and/or fractionated exposure protocols. Here, we assessed the behavioral and cognitive performance of female and male C57BL/6J × DBA2/J F1 (B6D2F1) mice 2 months following rapidly delivered, sequential irradiation with protons (1 GeV, 60%), 16O (250 MeV/n, 20%), and 28Si (263 MeV/n, 20%) at 0, 25, 50, or 200 cGy at 4–6 months of age. Cortical BDNF, CD68, and MAP-2 levels were analyzed 3 months after irradiation or sham irradiation. During the dark period, male mice irradiated with 50 cGy showed higher activity levels in the home cage than sham-irradiated mice. Mice irradiated with 50 cGy also showed increased depressive behavior in the forced swim test. When cognitive performance was assessed, sham-irradiated mice of both sexes and mice irradiated with 25 cGy showed normal responses to object recognition and novel object exploration. However, object recognition was impaired in female and male mice irradiated with 50 or 200 cGy. For cortical levels of the neurotrophic factor BDNF and the marker of microglial activation CD68, there were sex × radiation interactions. In females, but not males, there were increased CD68 levels following irradiation. In males, but not females, there were reduced BDNF levels following irradiation. A significant positive correlation between BDNF and CD68 levels was observed, suggesting a role for activated microglia in the alterations in BDNF levels. Finally, sequential beam irradiation impacted the diversity and composition of the gut microbiome. These included dose-dependent impacts and alterations to the relative abundance of several gut genera, such as Butyricicoccus and Lachnospiraceae. Thus, exposure to rapidly delivered sequential proton, 16O ion, and 28Si ion irradiation significantly affects behavioral and cognitive performance, cortical levels of CD68 and BDNF in a sex-dependent fashion, and the gut microbiome.

Evolution of the Pinched Column During Hard X-ray and Neutron Emission in a Dense Plasma Focus

The paper summarizes important results of the recent experimental studies performed on the plasma-focus PF-1000 facility operated in Warsaw, Poland, mainly with the pure deuterium filling. Attention is focused on the evolution of toroidal and plasmoidal self-organized structures formed by internal closed currents inside the dense plasma column. The production of hard x-rays and neutrons corresponds with the formation and decay of plasmoids, in which charged particles can be accelerated effectively to high energies, during a release of the magnetic energy from current filaments of high energy density. It is noticed that the studies of laboratory fusion and cosmic plasmas deal with similar problems, e.g., the fast release of the magnetic energy in a form of high-energy charged particle beams.

Механізми відхилення пучків високоенергетичних заряджених частинок зігнутими криста-лами. Теорія та експерименти ЦЕРН

Механізми відхилення пучків високоенергетичних заряджених частинок зігнутими криста-лами. Теорія та експерименти ЦЕРН

Improving of RPC for Muon System of CMS experiment

In the Endcap regions, CMS Muon spectrometer is using Cathode Strip Chambers (CSCs) as muon tracking and trigger detectors, also Resistive Plate Chambers (RPCs) serve as dedicated trigger detectors and improve the muon reconstruction by providing the excellent timing resolution for identification of muon particles. At the present, the four Endcap discs are not fully equipped: RPCs are covering only Endcap disks up to |ŋ| = 1.8. During the Long Shutdown 3 (from 2023 to 2026) of the Large Hadron Collider, Endcap stations 3 and 4 will be further instrumented with new improved RPCs (iRPCs) that will be covering the pseudorapidly region 1.8 < |ŋ| < 2.4, increasing the redundancy in this region. Nowadays, the final design of RPC chambers has been developed and the RPC double gap prototypes with a gas thickness 1.4mm are being tested. The performance and stability of iRPCs at the future HL-LHC upgrades have been studied (detection efficiency, cluster size, rate capability) at the Gamma-Irradiation Facility (GIF++) at CERN, where high energy charged particle beams (mainly muons) are combined with gammas from a 14 TBq 137Cesium source which simulates the background expected at the CMS experiments. In this paper, the main results obtained during the test at GIF ++ are presented.

Estimation of the R134a gas refractive index for use as a Cherenkov radiator, using a high energy charged particle beam

Abstract Gases with relatively high refractive index, n - 1 ≥ 500 × 10 - 6 at atmospheric pressure, giving a satisfactory photoelectron yield at relatively low pressures ( ≤ 5 bar ) are rare. These gases are often the only practical solution for low momentum particle identification in conventional secondary beam lines. The refractive index of R134a, one of the most common gases available to the physics community, has never been measured or reported. In the present note, the results of a dedicated experiment to estimate the refractive index of R134a, using mixed hadron/electron beams in the range 0.5–10 GeV are presented.

High-energy particle beam and gamma radiation exposure, familial relatedness and cancer in mice

Background:Some highly penetrant familial cancer syndromes exhibit elevated leukaemia risk, and there is evidence for familial clustering of lung cancer and other common cancers. Lung cancer and leukaemia are strongly radiogenic, but there are few indications that high-energy beam irradiation is markedly more effective than lower-energy radiation.Methods:We used a Cox model with familially structured random effects to assess 16 mortality end points in a group of 1850 mice in 47 families maintained in a circular-breeding scheme, exposed to accelerated Si or Fe ions (0.4 Gy) or 137Cs gamma rays (3 Gy).Results:There is periodicity in the effect of familial relatedness, which is most pronounced for pulmonary adenoma, Harderian-gland adenoma, Harderian-gland tumour, ectodermal tumour, pulmonary adenocarcinoma and hepatocellular carcinoma (P=0.0001/0.0003/0.0017/0.0035/0.0257/0.0340, respectively) with families that are 3–4 generations apart most strongly correlated; myeloid leukaemia also exhibited a striking periodic correlation structure. The relative risks of high-energy Si or Fe ions are not significantly different and are less than for 137Cs gamma-rays for most end points at the doses used.Conclusions:There is periodicity in the effect of familial relatedness for various cancer sites. The effects per unit dose of high-energy charged particle beams are no higher than ninefold those of lower-energy gamma radiation.

Bent silicon strip crystals for high-energy charged particle beam collimation

For applications in high energy particles accelerators, such as the crystal-assisted beam collimation, several strip crystals exploiting anticlastic curvature were produced in the last decade at the Sensor and Semiconductor Laboratory (SSL) of Ferrara by means of revisited techniques for silicon micromachining, such as photolitography and wet etching. Those techniques were recently enhanced by introducing a further treatment called Magnetorheological Finishing (MRF), which allowed to fabricate crystals with ultraflat surface and miscut very close to zero. The technology of the mechanical devices used to hold and bend crystals has been also improved by employing a titanium alloy to realize the holders. Characterization method were also improved: the usage of a high resolution X-rays diffractometer was introduced to directly measure crystal bending and torsion. Accuracy of the diffractometer was furtherly enhanced with an autocollimator, which found an important application in miscut characterization. A new infrared light interferometer was used to map the thickness of the starting swafers with sub-micrometric precision, as well as to measure the length along the beam of the strips. Crystals were characterized at the H8 external lines of CERN-SPS with various hundreds-GeV ion beams, which gave results in agreement with the precharacterization performed at SSL. One strip was selected among the crystals to be installed in the LHC beam pipe during the Long Shutdown 1 in 2014. These crystals were very recently tested in a crystal-assisted collimation experiment with a 6.5TeV proton beam, resulting in the first observation of channeling at this record energy, being also the first observation of channeling of the beam circulating in the LHC.

Interactive design environment transportation channel of relativistic charged particle beams

Considered a modern implementation of a computer environment for the design of channels of transportation of high-energy charged particle beams. The environment includes a software package for the simulation of the dynamics of charged particles in the channel, operating means for changing parameters of the channel, the elements channel optimization and processing of the output characteristics of the beam with the graphical output the main output parameters.

Electrostatic energy analyzers for high energy charged particle beams

The electrostatic energy analyzers for high energy charged particle beams emitted from extended large-size objects as well as from remote point sources are proposed. Results of the analytical trajectory solutions in ideal cylindrical field provide focusing characteristics for both configurations. The instruments possess of simple compact design, based on an ideal cylindrical field with entrance window arranged in the end-boundary between electrodes and can be used for measurements in space technologies, plasma and nuclear physics.

The role of the Wigner function in charged-particle beam transport

The role of the Wigner function in the dynamics of charged particle beams in high-energy accelerating machines is discussed. This is done within the quantum-like de- scription of the thermal wave model (TWM). A brief review of the numerical experiments showing satisfactory agreement between TWM and the particle tracking simulations is presented. A simple analysis in phase space in terms of the Wigner quasidistribution, showing that TWM is capable of reproducing the beam dynamics in the presence of the space charge effects, is put froward. The branch of electron optics describing the transport of non-laminar paraxial high-energy charged-particle beams involves the dynamics of an extremely large number of charged particles that is mainly dominated by the electromagnetic interactions, while the effects of the temperature cannot be neglected. The behavior of such a system is collective and affected by the thermal spreading among the particles (thermal regime). This discipline has been strongly developed in particle accelerator physics (1). A peculiar aspect of the electron optics of non-laminar beams is the mixing of the particle tra- jectories, i.e., mixing among the electron rays (1). In paraxial beams, this effect causes a slight random deviation of the electron rays slopes (with respect to the propagation direction). In vacuo, the electron ray slopes are Boltzmann-distributed, hence the instantaneous transverse momentum spread (normalized to the longitudinal relativistic particle momentum) is σp ∼ vT /c � 1( vT and c being the transverse thermal velocity and the speed of light, respectively). However, it is a matter of fact, both theoretically predicted and experimentally observed, that during the beam motion the instantaneous spread of the electron rays positions in the transverse plane, say σ, is related to σp by the following inequality:

Fabrication of large area silicon nanothickness membranes for channeling experiments

Membranes of micrometer lateral sizes and nanometer thickness are nowadays routinely fabricated through silicon micromachining processes, while more difficult is the fabrication of large areas membranes. In this paper we describe a method for fabrication of large area nanothickness silicon crystalline membranes starting from a SIMOX wafer. The realized structures have been characterized by means of high resolution X-ray diffraction and planar channeling of a 2MeV proton beam. This last analyses demonstrates a very interesting phenomenon: As the beam direction is inclined by less than the planar channelling critical angle with respect to the crystal planes, channeled particles undergo half a “channeling oscillation” and exit the crystal with reversed transverse momenta, i.e., the protons trajectories are ‘‘mirrored’’ by the crystal planes. Over-barrier particles are deflected of a minor extent in the opposite direction with respect to the “mirroring” direction. Observation of such effects not only proves the high crystalline quality of the Si membrane, but open new ways to manipulate high energy charged particle beams through crystals.

Vacuum System for Large-Scale Particle Accelerators —In the case of KEKB B-factory—

Main features and key issues of the vacuum system for large-scale particle accelerators are presented, taking the KEKB vacuum system as an example. Other than its large scale and complexity, a distinctive difference of the accelerator vacuum system from other vacuum systems is the presence of high-energy charged-particle beams in the vacuum chamber (beam pipe). This brings troublesome but interesting problems into the system, such as the gas desorption by the synchrotron radiation from beams, the electro-magnetic interaction between beams and vacuum components and the interaction between beams and electrons or ions. These problems are more obvious on the KEKB vacuum system due to the unprecedented high stored beam current. The vacuum system will become increasingly important in future high-performance accelerators.

Fundamental processes in relativistic laser plasmas

A review is given of processes fundamental for current relativistic regimes of laser matter interaction such as the generation and evolution of relativistic coherent nonlinear electromagnetic structures; generation of extremely high intensity electromagnetic waves and extremely high energy charged particle beams; novel regimes of electromagnetic wave interaction with matter and of the prospects for using laser accelerators for the high energy physics and for the laboratory relativistic astrophysics with relativistic laser plasmas.

Spectrometry of linear energy transfer and its use in high-energy particle beams

A new method to determine the spectra of linear energy transfer (LET) based on track-etch detectors has been developed. It is based on chemically etched polyallyldiglycolcarbonate (PADC) track detector. LET spectra are calculated using the track parameters measured with an automatic optical image analyzer. This method has been recently improved; the calibration curves have been upgraded on the basis of evaluating the detectors exposed in heavier high-energy charged particle beams. The LET spectrometer has been used to determine LET spectra and integral dosimetry characteristics along the range of protons, resp. 12C ions with primary energies of 205 MeV, resp. about 480 MeV/amu; and to study the importance of the fragmentation and nuclear reactions in carbon and other heavier ion beams. The results obtained are analyzed and discussed; the possible advantages of this type of equipment are outlined.

Track etch and thermo luminescent detectors response to high energy charged particles

Charged particles can be registered in a track etch detector (TED) when the linear energy transfer (LET) of a particle is higher than a threshold. Relative response of thermo luminescent detectors (TLDs) generally decreases with increasing LET of radiation depositing in them energy. The exposure of both these detectors in high energy charged particle beams permits to improve knowledge concerning the possibility of theirs use. Two types of poly allyldiglycolcarbonate (PADC) TED and two different TLDs have been exposed since several past years to high energy charged particles with energies up to 1 GeV/amu, and LET up to 600 keV / μ m in water. Some unknown (“blind”) exposures were also realised. Basic results like LET spectra, relative response of TLDs as the function of LET, etc., are presented. Particular attention is devoted to the results of evaluation of both detectors after blind exposures, theirs analysis and discussion.

A method and setup for studying the energy dependence of delayed neutron characteristics in nuclear fission induced by neutrons from the T(p, n), D(d, n), and T(d, n) reactions

A method and a setup based on this method are described, with which it has for the first time become possible to measure the energy dependence of the absolute total and relative yields of delayed neutrons and the half-fives of their precursors from neutron-induced fission of heavy nuclei in the course of one experiment. T(p, n)3He, D(d, n)3He, and T(d, n)4He nuclear reactions induced by high-energy charged-particle beams from the KΓ-2.5 electrostatic accelerator at the Institute of Physics and Power Engineering are used as sources of monoenergetic neutrons. The measured total delayed neutron yields from neutron-induced fission of 233U and 239Pu nuclei in the energy range of 0.37–4.7 MeV, as well as the relative yields of delayed neutrons and the half-lives of their precursors from neutron-induced fission of 239Pu in the range of 15.8–17.9 MeV, are presented as an illustration of the method. The uncertainties of the data obtained by means of this method are shown to be significantly lower than the uncertainties of similar data measured using other techniques.