High-energy Particle Beams Research Articles

Focusing of a high-energy particle beam at an extremely short distance

It has recently been realized that the focusing of high-energy particle beams at a distance of about 1 cm is promising. A new idea is proposed in this work to focus the beam at a short distance by using a bent plane–parallel silicon plate whose side edges are rotated at a small angle with respect to crystallographic planes. At the U-70 accelerator (IHEP, Protvino), a 50-GeV proton beam has been focused to a narrow line with a width of no more than 30 μm at a distance of 17 cm.

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.

Splitting of a high-energy positively-charged particle beam with a bent crystal

The possibility of high-energy positively-charged particle beam splitting by means of a short bent axially oriented silicon crystal was recently reported in an experiment carried out at CERN SPS H8 extracted line with a 400GeV/c proton beam. Here, we investigate more deeply such a possibility focusing our attention on the efficiency of beam splitting and its modulation for different crystal-to-beam orientations. New experimental results confirm the possibility of modulating the 400GeV/c proton beam intensity in different planar channels by adjusting the orientation of the crystal. Furthermore, an analysis of the beam splitting efficiency vs. the curvature of the crystal was carried out through simulation, highlighting that there exists a bending radius for which the efficiency is maximal.

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.

Multicrystal undulator

Radiation of positrons passing through a set of equidistant and mutually oriented crystals is considered. The thickness of each crystal is half of the particle trajectory period at planar channeling in a thick crystal. Passing through the set of half-wave crystals the particle moves on quasi-undulator trajectory. The radiation spectrum of such “multicrystal undulator”, consists of discrete harmonics, and the frequency of each harmonic and the number of harmonics in the spectrum depend on the spacing between the crystals, and on the particle energy. Varying the spacing between crystals one can tune the frequency of the first harmonic. A multicrystal undulator should be of particular assistance when there is a need to produce relatively soft radiation by use of a high energy particle beam.

Construction and performance of the sTGC and MicroMegas chambers for ATLAS NSW upgrade

The innermost stations of the current ATLAS muon end-cap system, the Small Wheels, must be upgraded in 2019 to retain their good precision tracking and trigger capabilities in the high background environment expected with the upcoming luminosity increase of the LHC. The New Small Wheels (NSW) will employ two chamber technologies: eight layers of MicroMegas (MM) arranged in two quadruplets, sandwiched between two quadruplets of small-strip Thin Gap Chambers (sTGC) for a total of about 2400 m2 of detection planes. All quadruplets have trapezoidal shapes with surface areas between 1 and 3 m2. Both MM and sTGC systems will independently provide trigger and tracking capabilities. The readout boards are industrially produced for both technologies and an accurate quality control is needed. In order to achieve a 15% transverse momentum resolution for 1 TeV muons, in addition to an excellent intrinsic resolution (010 μm), the mechanical precision of each plane of the assembled modules must be as good as 30 μm along the precision coordinate and 80 μm perpendicular to the chamber. In 2016 the milestone to build the first module-0 prototypes for both technologies has been reached. The construction procedure of the module-0 detectors will be reviewed, along with the results of the quality control checks performed during construction. The module-0 have been measured and subjected to a thorough validation. Results obtained with high-energy particle beams, with cosmic rays and with X-rays will be presented.

Review of the Elementary Particles Physics in the External Electromagnetic Fields Studies at KEK

High Energy Accelerator Research Organization (KEK [1]) is a world class accelerator-based research laboratory. The field of its scientific interests spreads widely from the study of fundamental properties of matter, particle physics, nuclear physics to materials science, life science, technical researches, and industrial applications. Research outcomes from the laboratory achieved making use of high-energy particle beams and synchrotron radiation. Two synchrotron facilities of KEK, the Photon Factory (PF) ring and the Photon Factory Advanced Ring (PF-AR) are the second biggest synchrotron light source in Japan. A very wide range of the radiated light, from visible light to X-ray, is provided for a variety of materials science, biology, and life science [2]. KEK strives to work closely with national and international research institutions, promoting collaborative research activities. Advanced research and facilities provision are key factors to be at the frontier of the accelerator science. In this review I am going to discuss KEK overall accelerator-based science, and to consider light sources research and development. The state of arts of the current projects with respect to the elementary particles physics in the external electromagnetic fields is also stressed here.

Influence of incoherent scattering on stochastic deflection of high-energy negative particle beams in bent crystals

An investigation on stochastic deflection of high-energy negatively charged particles in a bent crystal was carried out. On the basis of analytical calculation and numerical simulation it was shown that there is a maximum angle at which most of the beam is deflected. The existence of a maximum, which is taken in the correspondence of the optimal radius of curvature, is a novelty with respect to the case of positively charged particles, for which the deflection angle can be freely increased by increasing the crystal length. This difference has to be ascribed to the stronger contribution of incoherent scattering affecting the dynamics of negative particles that move closer to atomic nuclei and electrons. We therefore identified the ideal parameters for the exploitation of axial confinement for negatively charged particle beam manipulation in future high-energy accelerators, e.g., ILC or muon colliders.

Study of the one-way speed of light anisotropy with particle beams

Concepts of high precision studies of the one-way speed of light anisotropy are discussed. The high energy particle beam allows measurement of a one-way speed of light anisotropy (SOLA) via analysis of the beam momentum variation with sidereal phase without the use of synchronized clocks. High precision beam position monitors could provide accurate monitoring of the beam orbit and determination of the particle beam momentum with relative accuracy on the level of $10^{-10}$, which corresponds to a limit on SOLA of $10^{-18}$ with existing storage rings. A few additional versions of the experiment are also presented.

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.

Comparison of 30 THz impulsive burst time development to microwaves, Hα, EUV, and GOES soft X-rays

The recent discovery of impulsive solar burst emission in the 30 THz band is raising new interpretation challenges. One event associated with a GOES M2 class flare has been observed simultaneously in microwaves, H-alpha, EUV, and soft X-ray bands. Although these new observations confirm some features found in the two prior known events, they exhibit time profile structure discrepancies between 30 THz, microwaves, and hard X-rays (as inferred from the Neupert effect). These results suggest a more complex relationship between 30 THz emission and radiation produced at other wavelength ranges. The multiple frequency emissions in the impulsive phase are likely to be produced at a common flaring site lower in the chromosphere. The 30 THz burst emission may be either part of a nonthermal radiation mechanism or due to the rapid thermal response to a beam of high-energy particles bombarding the dense solar atmosphere.

Mass production of fluorescent nanodiamonds with a narrow emission intensity distribution

Fluorescent diamond nanocrystals are attracting increasing interest for a broad range of applications, from biolabeling and single particle tracking to nanoscale magnetic field sensing. Their fluorescence stems from nitrogen-vacancy color centers created within synthetic diamond nanoparticles by high-temperature annealing, which results in the association of pre-existing nitrogen impurities and vacancies generated by high-energy particle (electron, proton, or helium ion) beam irradiation. Up to now, diamond nanocrystals have been irradiated as dry powder in a container or deposited as a thin layer on a flat substrate, depending on the type and energy of the irradiating particles. However, these techniques suffer from intrinsic inhomogeneities: the fluence of particles may vary over the whole sample area, as well as the thickness and density of the nanodiamond layer. Here, we present an approach based on direct large-scale irradiation of nanodiamonds in aqueous colloidal solution by high-energy protons. This approach results in a larger fraction of fluorescent particles, with a more homogenous distribution of nitrogen-vacancy centers per particle and less severe lattice damages compared to dry powder irradiation.

Extreme light

By the compression of petawatt pulses to multi-exawatt, a new route for the generation of Schwinger intensities capable of producing highenergy radiation and particle beams with extremely short time structure down to the attosecond-zeptosecond regime is being presented. Far from the traditional laser investigation in the eV regime, this laser-based approach offers a new paradigm to investigate the structure of vacuum and applications to subatomic physics.

Detection efficiency of microchannel plates for e(-) and π(-) in the momentum range from 17.5 to 345 MeV/c.

High-energy e(-) and π(-) were measured by the multichannel plate (MCP) detector at the PiM1 beam line of the High Intensity Proton Accelerator Facilities located at the Paul Scherrer Institute, Villigen, Switzerland. The measurements provide the absolute detection efficiencies for these particles: 5.8% ± 0.5% for electrons in the beam momenta range 17.5-300 MeV/c and 6.0% ± 1.3% for pions in the beam momenta range 172-345 MeV/c. The pulse height distribution determined from the measurements is close to an exponential function with negative exponent, indicating that the particles penetrated the MCP material before producing the signal somewhere inside the channel. Low charge extraction and nominal gains of the MCP detector observed in this study are consistent with the proposed mechanism of the signal formation by penetrating radiation. A very similar MCP ion detector will be used in the Neutral Ion Mass (NIM) spectrometer designed for the JUICE mission of European Space Agency (ESA) to the Jupiter system, to perform measurements of the chemical composition of the Galilean moon exospheres. The detection efficiency for penetrating radiation determined in the present studies is important for the optimisation of the radiation shielding of the NIM detector against the high-rate and high-energy electrons trapped in Jupiter's magnetic field. Furthermore, the current studies indicate that MCP detectors can be useful to measure high-energy particle beams at high temporal resolution.

Phase field modelling of dynamic thermal fracture in the context of irradiation damage

This work presents a continuum mechanics approach to model fracturing processes in brittle materials that are subjected to rapidly applied high-temperature gradients. Such a type of loading typically occurs when a solid is exposed to an intense high-energy particle beam that deposits a large amount of energy into a small sample volume. Given the rapid energy deposition leading to a fast temperature increase, dynamic effects have to be considered. Our existing phase field model for dynamic fracture is thus extended in a way that allows modelling of thermally induced fracture. A finite element scheme is employed to solve the governing partial differential equations numerically. Finally, the functionality of our model is illustrated by two examples.

Orientational Coherent Effects of High-Energy Particles in a LiNbO3 Crystal.

A bent lithium niobate strip was exposed to a 400-GeV/c proton beam at the external lines of CERN Super Proton Synchrotron to probe its capabilities versus coherent interactions of the particles with the crystal such as channeling and volume reflection. Lithium niobate (LiNbO3) exhibits an interplanar electric field comparable to that of Silicon (Si) and remarkable piezoelectric properties, which could be exploited for the realization of piezo-actuated devices for the control of high-energy particle beams. In contrast to Si and germanium (Ge), LiNbO3 shows an intriguing effect; in spite of a low channeling efficiency (3%), the volume reflection maintains a high deflection efficiency (83%). Such discrepancy was ascribed to the high concentration (10(4) per cm2) of dislocations in our sample, which was obtained from a commercial wafer. Indeed, it has been theoretically shown that a channeling efficiency comparable with that of Si or Ge would be attained with a crystal at low defect concentration (less than ten per cm2). To better understand the role of dislocations on volume reflection, we have worked out computer simulation via dynecharm++ Monte Carlo code to study the effect of dislocations on volume reflection. The results of the simulations agree with experimental records, demonstrating that volume reflection is more robust than channeling in the presence of dislocations.

Benchmark of the FLUKA model of crystal channeling against the UA9-H8 experiment

Channeling in bent crystals is increasingly considered as an option for the collimation of high-energy particle beams. The installation of crystals in the LHC has taken place during this past year and aims at demonstrating the feasibility of crystal collimation and a possible cleaning efficiency improvement. The performance of CERN collimation insertions is evaluated with the Monte Carlo code FLUKA, which is capable to simulate energy deposition in collimators as well as beam loss monitor signals. A new model of crystal channeling was developed specifically so that similar simulations can be conducted in the case of crystal-assisted collimation. In this paper, most recent results of this model are brought forward in the framework of a joint activity inside the UA9 collaboration to benchmark the different simulation tools available. The performance of crystal STF 45, produced at INFN Ferrara, was measured at the H8 beamline at CERN in 2010 and serves as the basis to the comparison. Distributions of deflected particles are shown to be in very good agreement with experimental data. Calculated dechanneling lengths and crystal performance in the transition region between amorphous regime and volume reflection are also close to the measured ones.

Exploring the Origin of High‐Energy Particle Beams in the Atmosphere

High‐energy processes in the magnetosphere and atmosphere such as thunderstorm ground enhancements (TGEs), terrestrial gamma ray flashes (TGFs), and transient luminous events (TLEs) and recently discovered relativistic electron acceleration in the Earth's outer radiation belt trigger various dynamic processes in the Earth's environments and have broad astrophysical relevance. Investigation of the accelerated structures in the geospace plasmas can shed light on particle acceleration to much higher energy in the similar structures of space plasmas in the most distant objects in the universe. The Earth's broad environment is a real laboratory for high‐energy astrophysics.

Radiation tests for a single-GEM-loaded gaseous detector

We report on a systematic study of a single-gas-electron-multiplier (GEM)-loaded gaseous detector developed for precision measurements of high-energy particle beams and for dose verification in particle therapy. In the present study, a 256-channel prototype detector having an active area of 16 × 16 cm2 and operating using a continuous current-integration-mode signal-processing method was manufactured and tested with X-rays emitted from a 70-kV X-ray generator and 43-MeV protons provided by the MC50 proton cyclotron at the Korea Institute of Radiological and Medical Science (KIRAMS). The amplified detector response was measured for X-rays with an intensity of about 5 × 106 Hz cm−2. The linearity of the detector response to the particle flux was examined and validated by using 43-MeV proton beams. The non-uniform development of the amplification for the gas electrons in space was corrected by applying a proper calibration to the channel responses of the measured beam-profile data. We conclude from the radiation tests that the detector developed in the present study will allow us to perform quality measurements of various high-energy particle beams and to apply the technology to dose-verification measurements in particle therapy.

Development of a PIXE method at high energy with the ARRONAX cyclotron

The high energy PIXE (HEPIXE) method is a multi-elemental non-destructive ion beam analysis technique. It is based on the detection of the X-ray emitted due to the interaction of high energy particle beam with a sample. This technique is fast and allows the analysis of heavy and medium elements in thin (lm), thick (mm) and multilayer samples. At the ARRONAX facility (Nantes, France), the HEPIXE method has been used to determine the composition of natural and synthetic sodalites. Photochromic properties of these samples are supposed to come from the trace elements (concentration in the ppm range) present in the samples. Taking advantage of the 70 MeV proton beam available at our facility, the HEPIXE method has been also used to study multilayer samples. It has been shown that it is possible to determine the composition of each layer, their thicknesses and their depth position by analyzing the recorded X-ray spectra.