MeV Linear Accelerator Research Articles

Using basic electromagnetism to introduce LINAC4 (CERN)

The LHC is the last element of CERN’s accelerator complex, which is a succession of machines with increasingly higher energies. Everything starts in the 50 MeV linear accelerator (LINAC2), but a new linear accelerator, the 160 MeV LINAC4, will replace LINAC2 in 2018, upgrading LHC injectors to higher intensity and eventually increasing the luminosity of LHC.The aim of this article is briefly introducing this new accelerator, and presenting a simple application of some fundamental laws of magnetism to be taken to the secondary school classrooms.

Development of an easy and effective method for 10 MeV linear accelerator irradiation and its application in food process

Development of an easy and effective method for 10 MeV linear accelerator irradiation and its application in food process

Design and Simulation of Photoneutron Source by MCNPX Monte Carlo Code for Boron Neutron Capture Therapy

Introduction Electron linear accelerator (LINAC) can be used for neutron production in Boron Neutron Capture Therapy (BNCT). BNCT is an external radiotherapeutic method for the treatment of some cancers. In this study, Varian 2300 C/D LINAC was simulated as an electron accelerator-based photoneutron source to provide a suitable neutron flux for BNCT. Materials and Methods Photoneutron sources were simulated, using MCNPX Monte Carlo code. In this study, a 20 MeV LINAC was utilized for electron-photon reactions. After the evaluation of cross-sections and threshold energies, lead (Pb), uranium (U) and beryllium deuteride (BeD2)were selected as photoneutron sources. Results According to the simulation results, optimized photoneutron sources with a compact volume and photoneutron yields of 107, 108 and 109 (n.cm-2.s-1) were obtained for Pb, U and BeD2 composites. Also, photoneutrons increased by using enriched U (10-60%) as an electron accelerator-based photoneutron source. Conclusion Optimized photoneutron sources were obtained with compact sizes of 107, 108 and 109 (n.cm-2.s-1), respectively. These fluxs can be applied for BNCT by decelerating fast neutrons and using a suitable beam-shaping assembly, surrounding electron-photon and photoneutron sources.

Electron beam effect on biomaterials I: focusing on bone graft materials.

BackgroundTo develop biocompatible bony regeneration materials, allogenic, xenogenic and synthetic bones have been irradiated by an electron beam to change the basic structures of their inorganic materials. The optimal electron beam energy and individual dose have not been established for maximizing the bony regeneration capacity in electron beam irradiated bone.ResultsCommercial products consisting of four allogenic bones, six xenogenic bones, and six synthetic bones were used in this study. We used 1.0-MeV and 2.0 MeV linear accelerators (power: 100 KW, pressure; 115 kPa, temperature; -30 to 120°C, sensor sensitivity: 0.1-1.2 mV/kPa, generating power sensitivity: 44.75 mV/kPa, supply voltage: 50.25 V), and a microtrone with different individual irradiation doses such as 60 kGy and 120 kGy. Additional in vitro analyses were performed by elementary analysis using field emission scanning electron microscopy (FE-SEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and confocal laser scanning microscopy (CLSM). In vivo clinical, radiographic, and micro-computed tomography (Micro-CT) with bone marrow density (BMD) analysis was performed in 8- and 16-week-old Spraque-Dawley rats with calvarial defect grafts.ConclusionsElectron beam irradiation of bony substitutes has four main effects: the cross-linking of biphasic calcium phosphate bony apatite, chain-scissioning, the induction of rheological changes, and microbiological sterilization. These novel results and conclusions are the effects of electron beam irradiation.

Vacuum Outgassing Behavior of Carbon Nanotube Cathode with High-Intensity Pulsed Electron Emission

Experimental investigations on the vacuum outgassing of a carbon nanotube (CNT) cathode with high-intensity pulsed electron emission on a 2 MeV linear induction accelerator injector are presented. Under the 1.60 MV diode voltage, the CNT cathode could provide 1.67 kA electron beam with the amount of outgassing of about 0.51 Pa·L. It is found that the amount of outgassing, which determines the cathode emission current, depends on the diode voltage and the vacuum.

Experimental demonstration of longitudinal beam phase-space linearizer in a free-electron laser facility by corrugated structures.

Removal of the undesired time-energy correlations in the electron beam is of paramount importance for efficient lasing of a high-gain free-electron laser. Recently, it has been theoretically and experimentally demonstrated that the longitudinal wakefield excited by the electrons themselves in a corrugated structure allows for precise control of the electron beam phase space. In this Letter, we report the first utilization of a corrugated structure as a beam linearizer in the operation of a seeded free-electron laser driven by a 140MeV linear accelerator, where a gain of ∼10 000 over spontaneous emission was achieved at the second harmonic of the 1047nm seed laser, and a free-electron laser bandwidth narrowing by 50% was observed, in good agreement with the theoretical expectations.

Beam dump for 10 kW 10 Mev LINAC

Raja Ramanna Centre for Advanced Technology has developed a 10 kW, 10 MeV linear particle accelerator (LINAC) for the Agricultural Radiation Processing Facility for radiation processing of agricultural products and medical sterilization. This paper presents an improved design for the existing beam dump of this accelerator. The new design is more efficient, safer, economical and compact than the previous design [1]. The new design is investigated both for maximum stress and maximum temperature. The material selection is done keeping in mind the radiation damage, thermal conductivity, corrosion in the ozone environment, mechanical strength and manufacturability. The estimated maximum temperature is 85.8 °C which is less than the boiling point of water at 1 bar pressure (100 °C). The maximum stress intensity is estimated to be 42.60 N/mm2 which is less than the yield strength of the material [2].

Mechanistic aspects of the radiation-chemical reduction of graphene oxide to graphene-like materials

Purpose: The aim of the work was to investigate mechanistic details of the preparation of graphene-like materials (GLM) via reduction of graphene oxide (GO) in aqueous dispersions by electron beam (EB) generated reducing free radicals.Materials and methods: A 10 MeV linear accelerator was employed to irradiate aqueous GO dispersions at ambient temperatures. The kinetics of GO reduction was followed using UV-Vis spectroscopy. The resulting GLM were characterized by X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM), Raman spectroscopy and conductivity measurements.Results: The reduction of GO could be afforded with high efficiency within minutes at room temperature via the reaction of GO with reducing radicals generated by EB irradiation. The detailed investigation of the reduction mechanism allowed a selection of the best reducing free radicals in terms of both their efficiency and environmental impact of their precursors and final products.Conclusions: The EB-treatment of aqueous GO dispersions is a highly efficient, environmentally friendly, cost-effective and easily up-scalable method for the preparation of GLM. The efficiency of the new reduction approach is comparable with the best existing methods.

수산화인회석과 인산삼칼슘 및 1형 콜라젠 혼합골의 전자빔 조사 효과

Purpose: The aim of this study is to evaluate the effect and potential of electron beam (E-beam) irradiation treatment to the synthetic bony mixtures composed of hydroxyapatite (HA; Bongros<TEX>$^{(R)}$</TEX>, Bio@ Co., Korea) and tricalcium phosphate (<TEX>${\beta}$</TEX>-TCP, Sigma-Aldrich Co., USA), mixed at various ratios and of type I collagen (Rat tail, BD Biosciences Co., Sweden) as an organic matrix. Methods: We used 1.0~2.0 MeV linear accelerator and 2.0 MeV superconductive linear accelerator (power 100 KW, pressure 115 kPa, temperature <TEX>$-30{\sim}120^{\circ}C$</TEX>, sensor sensitivity 0.1~1.2 mV/kPa, generating power sensitivity 44.75 mV/kPa, supply voltage <TEX>$5{\pm}0.25$</TEX> V) with different irradiation dose, such as 1, 30 and 60 kGy. Structural changes in this synthetic bone material were studied in vitro, by scanning electron microscopy (SEM), elementary analysis and field emission scanning electron microscope (FE-SEM), attenuated total reflection (ATR), and electron spectroscopy for chemical analysis (ESCA). Results: The large particular size of HA was changed after E-beam irradiation, to which small particle of TCP was engaged with organic collagen components in SEM findings. Conclusion: The important new in vitro data to be applicable as the substitutes of artificial bone materials in dental and medical fields will be able to be summarized.

Design, Manufacture and Measurements of Permanent Quadrupole Magnets for Linac4

Compact quadrupole magnets are required for the CCDTL (Cell-Coupled Drift Tube Linac) of Linac 4, a 160 MeV linear accelerator of negative hydrogen ions which will replace the old 50 MeV proton Linac2 at CERN. The magnets, of an overall physical length of 140 mm and an aperture diameter of 45 mm, are based on Sm <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Co <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sub> blocks and can provide an integrated gradient of up to 1.6 Tesla. The magnetic field quality is determined by 4 ferromagnetic pole tips, aligned together with the permanent magnets blocks inside a structure made in a single piece. Tuning bars allow to individually trim the magnetic flux provided by each pole, to correct possible differences between blocks and to modify the field gradient intensity within about 20% of the nominal value. The paper describes and discusses the design, manufacture and magnetic measurements of a first prototype magnet.

Development of high-voltage pulse-slicer unit with variable pulse duration for pulse radiolysis system

A high-voltage pulse-slicer unit with variable pulse duration has been developed and integrated with a 7 MeV linear electron accelerator (LINAC) for pulse radiolysis investigation. The pulse-slicer unit provides switching voltage from 1 kV to 10 kV with rise time better than 5 ns. Two MOSFET based 10 kV switches were configured in differential mode to get variable duration pulses. The high-voltage pulse has been applied to the deflecting plates of the LINAC for slicing of electron beam of 2 μs duration. The duration of the electron beam has been varied from 30 ns to 2 μs with the optimized pulse amplitude of 7 kV to get corresponding radiation doses from 6 Gy to 167 Gy.

Libera Brilliance Single Pass束流位置处理器性能测试

In the upgrade of Hefei Light Source (HLS), Libera Brilliance Single Pass is chosen to constitute a signal processing system in order to enhance the overall performance of the injector beam position monitor (BPM) system. The characterization test of the apparatus was made. The mapping of stripline BPM was carried out on a workbench with Libera Brilliance Single Pass. The beam position was tested at HLSs existing 200 MeV linear accelerator using Libera Brilliance Single Pass. The results show that the offline resolution is 4 m to 17 m, better than that of the original logarithmic processing system. The online horizontal and vertical resolution is better than 26 m and 19 m, respectively, also better than the existing systems 58 m and 33 m.

Plasma-induced field emission study of carbon nanotube cathode

An investigation on the plasma-induced field emission (PFE) properties of a large area carbon nanotube (CNT) cathode on a 2 MeV linear induction accelerator injector is presented. Experimental results show that the cathode is able to emit intense electron beams. Intense electron beams of $14.9--127.8\text{ }\text{ }\mathrm{A}/{\mathrm{cm}}^{2}$ are obtained from the cathode. The CNT cathode desorbs gases from the CNTs during the PFE process. The fast cathode plasma expansion affects the diode perveance. The amount of outgassing is estimated to be $0.06--0.49\text{ }\text{ }\mathrm{Pa}\ifmmode\cdot\else\textperiodcentered\fi{}\mathrm{L}$, and the ratio of outgassing and electron are roughly calculated to be within the range of 170--350 atoms per electron. The effect of the outgassing is analyzed, and the outgassing mass spectrum of the CNT cathode has been studied during the PFE. There is a significant desorption of ${\mathrm{CO}}_{2}$, ${\mathrm{N}}_{2}(\mathrm{CO})$, and ${\mathrm{H}}_{2}$ gases, which plays an important role during the PFE process. All the experiments demonstrate that the outgassing plays an important role in the formation of the cathode plasma. Moreover, the characteristic turn-on time of the CNT cathode was measured to be 39 ns.

Characteristics of the beam injection system in an electron LINAC

The main characteristics of an electron beam injection system are described; the system is used for injecting and focusing electron beams into the acceleration structure of an 10 MeV linear electron accelerator. The beam injection system consists of a Pierce convergent diode-type electron gun with pulse modulator for power supply and a thin axially symmetric lens. The perveance and the capture coefficient were optimized by the analogical resistors network. This type of injection system was used in the linear electron accelerators: ALIN – 3 MeV, ALIN – 10 MeV and ALID − 8 MeV, performed at NILPRP ∗ Bucharest, Romania.

Feasibility study on the use of uranium in photoneutron target and BSA optimization for Linac based BNCT

A hybrid photoneutron target including natural uranium has been studied for a 20 MeV linear electron accelerator (Linac) based Boron Neutron Capture Therapy (BNCT) facility. In this study the possibility of using uranium to increase the neutron intensity has been investigated by focusing on the time dependence behavior of the build-up and decay of the delayed gamma rays from fission fragments and activation products through photo-fission reactions in the BSA (Beam Shaping Assembly) configuration design. Delayed components of neutrons and photons were calculated. The obtained BSA parameters are in agreement with the IAEA recommendation and compared to the hybrid photoneutron target without U. The epithermal flux in the suggested design is 2.67E9 (n/cm 2s/mA).

First results from the Telescope Array

The Telescope Array Project is a successor to the High Resolution Flyʼs Eye (HiRes) and AGASA (Akeno Giant Air Shower Array) experiments. It is the largest ultra high energy cosmic ray experiment in the northern hemisphere. The Telescope Array observatory has been collecting data since 2008 using a hybrid of fluorescence telescopes and scintillator surface detectors. Some of the first results from the experiment are presented including the monocular spectrum from the Middle Drum fluorescence site and the spectrum from the scintillator array. These are in good agreement with the spectrum from the High Resolution Flyʼs Eye. In addition, a first pass at a composition measurement is made and indicates a predominantly light composition in the 10 19 eV region. Finally, some of the ongoing work of the group is presented including a novel technique for an end to end calibration of the telescopes involving a 40 MeV linear accelerator.

Outgassing mass spectrum analysis with intense pulsed emission of carbon nanotube cathode

The outgassing mass spectrum property with intense pulsed emission of the carbon nanotube(CNT) cathode is investigated on a 2 MeV linear induction accelerator injector by using the quadrupole mass spectrometer. The results show that the cathode has a capability of desorbing gases from the CNT cathode under pulsed high voltage. There are significant CO2, N2(CO) and H2 desorbing gases which play an important role in the formation of the cathode plasma. The mechanism of electron emission of CNT cathode is plasma-induced field emission, rather than explosive field emission, which is proved by analyzing the desorbed gases component.

Generation, transport, and detection of linear accelerator based femtosecond-terahertz pulses

The generation and detection of intense terahertz (THz) radiation has drawn a great attention recently. The dramatically enhanced energy and peak electric field of the coherent THz radiation can be generated by coherent superposition of radiated fields emitted by ultrafast electron bunches. The femtosecond (fs)-THz beamline construction at the Pohang Accelerator Laboratory (PAL) was completed in the end of 2009. The fs-THz beamline at PAL can supply ultrafast and intense fs-THz radiation from a 75 MeV linear accelerator. The radiation is expected to have frequency up to 3 THz (∼100 cm(-1)) and the pulse width of <200 fs with pulse energy up to 10 μJ. This intense THz source has great potential for applications in nonlinear optical phenomena and fields such as material science, biomedical science, chemistry, and physics, etc.

Measurement with Hp(10) and H*(10) secondary standard chambers at NILPRP 7 MeV linear accelerator

A secondary standard chamber for measuring the conventionally true value of the personal dose equivalent, Hp(10), was developed by Arckerhold et al. at Physikalisch Technische Bundesanstalt (PTB). This type of chamber together with a secondary standard ionization chamber for direct measurement of ambient dose equivalent, H*(10), both outfitting the Secondary Standard Dosimetry Laboratory (SSDL), were used for area monitoring at the NILPRP 7 MeV Linear Accelerator. Measurement results, for both ICRU operational quantities, are presented in this paper.

High duty factor plasma generator for CERN’s Superconducting Proton Linac

CERN's Linac4 is a 160 MeV linear accelerator currently under construction. It will inject negatively charged hydrogen ions into CERN's PS-Booster. Its ion source is a noncesiated rf driven H(-) volume source directly inspired from the one of DESY and is aimed to deliver pulses of 80 mA of H(-) during 0.4 ms at a 2 Hz repetition rate. The Superconducting Proton Linac (SPL) project is part of the luminosity upgrade of the Large Hadron Collider. It consists of an extension of Linac4 up to 5 GeV and is foreseen to deliver protons to a future 50 GeV synchrotron (PS2). For the SPL high power option (HP-SPL), the ion source would deliver pulses of 80 mA of H(-) during 1.2 ms and operate at a 50 Hz repetition rate. This significant upgrade motivates the design of the new water cooled plasma generator presented in this paper. Its engineering is based on the results of a finite element thermal study of the Linac4 H(-) plasma generator that identified critical components and thermal barriers. A cooling system is proposed which achieves the required heat dissipation and maintains the original functionality. Materials with higher thermal conductivity are selected and, wherever possible, thermal barriers resulting from low pressure contacts are removed by brazing metals on insulators. The AlN plasma chamber cooling circuit is inspired from the approach chosen for the cesiated high duty factor rf H(-) source operating at SNS.