External Beam Line Research Articles

The MESA physics program

In the recent past, a comprehensive experimental program has been worked out at the Mainz Energy-Recovery Superconducting Accelerator, MESA, at the Institute of Nuclear Physics in Mainz. MESA is a high-intensity, low-energy electron accelerator presently under construction and will thereby provide great opportunities to perform a new generation of high-precision scattering experiments. The versatile MAGIX experiment will use MESA’s innovative energy recovery technique, with a science focus on the study of hadron structure and few-body systems, dark sector searches, and investigations into reactions pertinent to nuclear astrophysics. An external beam line will supply spin-polarized electrons to the P2 experiment, enabling the performance of sensitive tests of the Standard Model through parity-violating electron scattering. The DarkMESA beam dump experiment, situated behind P2, is dedicated to the search for light dark matter particles.

Improvement of the quality of neutron radiography beamlines in Isfahan MNSR

Recently, two external neutron beam lines have been installed in the Isfahan MNSR. This reactor is a tank in pool type with a maximum power of 30 kW, which has been in operation since 1994, and in its original design it did not have a beam tube. These two neutron beam lines are designed and installed out of the reactor tank for irradiation experiments of large objects outside the reactor core, such as neutron radiography. The results of the evaluations in the previous researches showed that these two beam lines have acceptable quality according to the ASTM-E545 standard. However, their gamma contamination were relatively high. In this study calculations and experiments have been done to reduce the gamma content of the neutron beams and to increase the ratio of thermal neutron flux to gamma dose rate. This was done through the design and installation of gamma filters in the beam lines. The results of the evaluations showed that the quality of the neutron beams has been greatly improved in terms of reducing gamma content, so that the quality rating of the beams has increased by at least two ranks.

Commissioning the Muon Campus external beamline: first beam optics measurement

The Fermilab Mu2e experiment aims to observe charged lepton flavor violation through the direct conversion of a muon to an electron. This can be accomplished with the considerable challenge of manipulating and transporting large numbers of protons confined to a narrow phase space region without significant particle losses or deterioration of beam quality before reaching the production target. In this paper we report the first results from the commissioning the beamline upstream the Mu2e production target. We first discuss the evolution of the beam distribution in x-y plane after collecting a series of beam profiles along the line. Then, we discuss the beam evolution in phase-space by measuring the beam's Twiss parameters using two independent techniques. Finally, with the aid of numerical simulations we compare our measured data with design parameters and discuss similarities and differences observed.

Complete beam optics analysis along the Muon Campus External Beamline

The Fermilab Mu2e experiment aims to measure the event ratio of the neutrinoless coherent conversion of muons to electrons in the field of an aluminum nucleus to ordinary capture as a means to probe the possibility of charged lepton flavor violation. Since the number of muons at the Mu2e production target is highly correlated to the upstream beam Twiss parameters, knowledge of these parameters is critical. Such measurement is not trivial since the accelerator line contains several bending magnets which can induce non-negligible dispersion. We discuss a methodology that in addition to the Twiss parameters can extract dispersion, slope of dispersion and momentum spread using only a set of beam profiles. We then apply this technique along the Fermilab Muon Campus and show it can play a significant role in maximizing the muon flux of the Mu2e Experiment.

Beamline-implemented stretching devices for in situ X-ray scattering experiments

Two recently developed experimental devices for investigating soft matter deformation are presented. Both devices exploit the capabilities of a modern synchrotron beamline to enable advanced and highly precise materials-science experiments in which X-ray scattering is registered. The devices can be operated both in monotonic as well as cyclic mode and are implemented into a beamline at DESY, Hamburg (Germany). Hence, relevant experimental parameters, such as displacement, force and temperature, are recorded synchronously with the individual X-ray scattering patterns. In addition, spatial variation of materials deformation can be monitored and recorded with optical microscopy. This unique sample environment enables in situ X-ray experiments in transmission, i.e. small- or wide-angle X-ray scattering (SAXS or WAXS), and in grazing-incidence geometry, i.e. grazing-incidence (GI-) SAXS or WAXS. One device with stepper motors is designed for studies of slow, (quasi-) static deformation and the other one with pneumatic actuators can be used for fast, impact deformation. Both devices are available to external beamline users, too.

Measurement of the production cross-sections of natCd(p,x) reactions up to 45 MeV

In this experimental study, we used natCd as the target material and bombarded it with a 45-MeV energetic proton beam to study the natCd(p,x) reaction and determine the production cross-sections of 109g,110g,111g,113m,114m,115mIn, 107,109,115gCd, and 105,106m,110m,111gAg radionuclides. The external beam line of the MC-50 cyclotron installed at Korea Institute of Radiological and Medical Sciences (South Korea) was used for the activation. We applied the well-known stacked-foil activation technique to measure the excitation functions of the reaction products. The active foils were analyzed using an offline γ-ray spectrometry system to measure the production cross-sections. We also determined the thick target yield using the cross-section values. Subsequently, the measured results were compared with the theoretical model calculations using TALYS 1.9 code. In summary, the natCd(p,x) reaction is considerable because of its reaction products that have potential medical and industrial applications.

Upgrade of the external beamline at the microanalytical center of the Jožef Stefan Institute

The existing external beamline at the Microanalytical Centre of the Jožef Stefan Institute (JSI) in Ljubljana has been upgraded in order to extend the capabilities towards in-air PIXE imaging across relatively large sample surface area (∼1 cm2) with lateral resolution of sub 100 µm. For that purpose, a doublet of magnetic quadrupole lenses was installed on the beamline together with the newly designed exit nozzle with a 200 nm Si3N4 exit window resulting finally in ∼ 50 × 50 μm2 lateral resolution. Additionally, an in-vacuum beam chopper was installed before the exit nozzle to measure the proton dose deposited on the sample. The beam characterization results are presented together with the first application from the field of biology, namely quantitative concentration maps of a longitudinal section of a whole thick wheat grain.

Microdosimetry in low energy proton beam at therapeutic-equivalent fluence rate with silicon 3D-cylindrical microdetectors

In this work we show the first microdosimetry measurements on a low energy proton beam with therapeutic-equivalent fluence rates by using the second generation of 3D-cylindrical microdetectors. The sensors belong to an improved version of a novel silicon-based 3D-microdetector design with electrodes etched inside silicon, which were manufactured at the National Microelectronics Centre (IMB-CNM, CSIC) in Spain. A new microtechnology has been employed using quasi-toroid electrodes of 25 μm diameter and a depth of 20 μm within the silicon bulk, resulting in a well-defined cylindrical radiation sensitive volume. These detectors were tested at the 18 MeV proton beamline of the cyclotron at the National Accelerator Centre (CNA, Spain). They were assembled into an in-house low-noise readout electronics to assess their performance at a therapeutic-equivalent fluence rate. Microdosimetry spectra of lineal energy were recorded at several proton energies starting from 18 MeV by adding 50 μm thick tungsten foils gradually at the exit-window of the cyclotron external beamline, which corresponds to different depths along the Bragg curve. The experimental values in silicon cover from (5.7 ± 0.9) to (8.5 ± 0.4) keV μm−1 in the entrance to (27.4 ± 2.3) keV μm−1 in the distal edge. Pulse height energy spectra were crosschecked with Monte Carlo simulations and an excellent agreement was obtained. This work demonstrates the capability of the second generation 3D-microdetectors to assess accurate microdosimetric distributions at fluence rates as high as those used in clinical centers in proton therapy.

Neutron production with particle accelerators

Neutron beams have been produced at Laboratory of High Energy Physics (LHEP) of University of Bern. LEHP is equipped with an 18 MeV cyclotron with an external beam line. Simulations, analytical calculations and kinematics studies have been carried out, in order to produce several neutron beam configurations with characteristics suited for specific applications. Furthermore, a procedure for energy modulation has been developed to match the fixed cyclotron energy to the needed requirements. The technique described in this work is of general application and can be applied to more intense beams up to 1010 pps.

Measurement of the proton beam energy of a medical cyclotron based on Rutherford Back-scattering Analysis

For the first time the Rutherford Back-Scattering Spectroscopy (RBS) technique has been successfully exploited for the measurement of the energy of a proton beam accelerated by the IBA Cyclone 18/18 medical cyclotron in operation at the Bern University Hospital. This accelerator, routinely used for radioisotope production for Positron Emission Tomography (PET) imaging is equipped with an external beam line devoted to research activities in several fields such as detector physics, medical applications of particle physics, accelerator physics. Recently a widespread request has raised for the availability of well characterized proton and neutron beams, particularly for radiation hardness studies and the development of new neutron detectors. A feasibility study for a future upgrade of the Bern cyclotron towards a neutron facility was started, which requires a complete and precise characterization of the proton beam. Along this line, the measurement of fundamental parameters of the primary proton beam, such as the maximum proton energy and its spread have been performed by means of the RBS technique with two different targets, namely gold and graphite foils.

Feasibility Study of a Proton Irradiation Facility for Radiobiological Measurements at an 18 MeV Cyclotron

A feasibility study of an experimental setup for the irradiation of biological samples at the cyclotron facility installed at the National Centre of Accelerators (Seville, Spain) is presented. This cyclotron, which counts on an external beam line for interdisciplinary research purposes, produces an 18 MeV proton beam, which is suitable for the irradiation of mono-layer cultures for the measurement of proton cell damages and Relative Biological Effectiveness (RBE) at energies below the beam nominal value. Measurements of this kind are of interest for proton therapy, since the variation of proton RBE at the distal edge of the Bragg curve may have implications in clinical proton therapy treatments. In the following, the characteristics of the beam line and the solutions implemented for the irradiation of biological samples are described. When dealing with the irradiation of cell cultures, low beam intensities and broad homogeneous irradiation fields are required, in order to assure that all the cells receive the same dose with a suitable dose rate. At the cyclotron, these constraints have been achieved by completely defocusing the beam, intercepting the beam path with tungsten scattering foils and varying the exit-window-to-sample distance. The properties of the proton beam thus obtained have been analysed and compared with Monte Carlo simulations. The results of this comparison, as well as the experimental measurement of the lateral dose profiles expected at the position of samples are presented. Meaningful dose rates of about 2–3 Gy/min have been obtained. Homogeneous lateral dose profiles, with maximum deviations of 5%, have been measured at a distance of approximately 50 cm in air from the exit window, placing a tungsten scattering foil of 200 μm in the beam path.

Timing in a FLASH

A prototype detector, called FLASH (Fast Light Acquiring Start Hodoscope), was built to provide precise Time-of-Flight (TOF) measurements and reference timestamps for detector setups at external beam lines. Radiator bars, made of synthetic fused silica, were coupled to a fast MCP-PMT with 64 channels and read out with custom electronics using Time-over-Threshold (TOT) for signal characterization. The TRB3 system, a high-precision TDC implemented in an FPGA, was used as data acquisition system. The performance of a system consisting of two FLASH units was investigated at a dedicated test experiment at the Mainz Microtron (MAMI) accelerator using its 855MeV electron beam. The TOT measurement enabled time walk corrections and an overall TOF resolution of ∼70ps could be achieved which translates into a resolution of ∼50ps per FLASH unit. The intrinsic resolution of the frontend electronics including the TDC was measured to be less than 25ps.

Design of cryo-refrigerator assisted HTS steering magnet for K500 cyclotron beam line

The steering magnet is required for the external beam line of K-500 cyclotron to provide corrective steering capabilities. A conventional copper based steering magnet for high rigidity beam (maximum up to 3.3 T-m) becomes very bulky and difficult to integrate in beam line if large steering (±3 degree horizontal (X) and ±1.5 degree vertical (Y)) is required. Recently, commercial availability of long length (more than 100 m) high temperature superconductor (HTS) tape along with availability of high power cryo-refrigerator has given opportunity to develop compact conduction-cooled HTS magnet operating at temperature of 20 K or even higher. Although many prototype magnets using HTS tape have been fabricated and evaluated, there are only few applications in the particle accelerator fields. The paper describes the physics design aspect of the X-Y steering magnet along with details of cryostat.

Accelerator and detector physics at the Bern medical cyclotron and its beam transport line

Abstract The cyclotron laboratory for radioisotope production and multi-disciplinary research at the Bern University Hospital (Inselspital) is based on an 18-MeV proton accelerator, equipped with a specifically conceived 6-m long external beam line, ending in a separate bunker. This facility allows performing daily positron emission tomography (PET) radioisotope production and research activities running in parallel. Some of the latest developments on accelerator and detector physics are reported. They encompass novel detectors for beam monitoring and studies of low current beams.

X-ray and gamma-ray based spectroscopic analysis of a millefiori Roman glass fragment: degradation of sunken glass from a shipwreck

Particle induced X-ray and gamma-ray techniques (PIXE and PIGE) carried out on an external beam line, combined with X-ray dose monitoring and a helium atmosphere, have been performed in this work.

Emittance Measurement for Beamline Extension at the PET Cyclotron

Particle-induced X-ray emission is used for determining the elemental composition of materials. This method uses low-energy protons (of several MeV), which can be obtained from high-energy (of tens MeV) accelerators. Instead of manufacturing an accelerator for generating the MeV protons, the use of a PET cyclotron has been suggested for designing the beamline for multipurpose applications, especially for the PIXE experiment, which has a dedicated high-energy (of tens MeV) accelerator. The beam properties of the cyclotron were determined at this experimental facility by using an external beamline before transferring the ion beam to the experimental chamber. We measured the beam profile and calculated the emittance using the pepper-pot method. The beam profile was measured as the beam current using a wire scanner, and the emittance was measured as the beam distribution at the beam dump using a radiochromic film. We analyzed the measurement results and are planning to use the results obtained in the simulations of external beamline and aligned beamline components. We will consider energy degradation after computing the beamline simulation. The experimental study focused on measuring the emittance from the cyclotron, and the results of this study are presented in this paper.

Low current performance of the Bern medical cyclotron down to the pA range

A medical cyclotron accelerating H− ions to 18 MeV is in operation at the Bern University Hospital (Inselspital). It is the commercial IBA 18/18 cyclotron equipped with a specifically conceived 6 m long external beam line ending in a separate bunker. This feature is unique for a hospital-based facility and makes it possible to conduct routine radioisotope production for PET diagnostics in parallel with multidisciplinary research activities, among which are novel particle detectors, radiation biophysics, radioprotection, radiochemistry and radiopharmacy developments. Several of these activities, such as radiobiology experiments for example, require low current beams down to the pA range, while medical cyclotrons are designed for high current operation above 10 μA. In this paper, we present the first results on the low current performance of a PET medical cyclotron obtained by ion source, radio-frequency and main coil tuning. With this method, stable beam currents down to () pA were obtained and measured with a high-sensitivity Faraday cup located at the end of the beam transport line.

Large areas elemental mapping by ion beam analysis techniques

The external beam line of the Laboratory for Material Analysis with Ion Beams (LAMFI) is a versatile setup for multi-technique analysis. X-ray detectors for Particle Induced X-rays Emission (PIXE) measurements, a Gamma-ray detector for Particle Induced Gamma- ray Emission (PIGE), and a particle detector for scattering analysis, such as Rutherford Backscattering Spectrometry (RBS), were already installed. In this work, we present some results, using a large (60-cm range) XYZ computer controlled sample positioning system, completely developed and build in our laboratory. The XYZ stage was installed at the external beam line and its high spacial resolution (better than 5 μm over the full range) enables positioning the sample with high accuracy and high reproducibility. The combination of a sub-millimeter beam with the large range XYZ robotic stage is being used to produce elemental maps of large areas in samples like paintings, ceramics, stones, fossils, and all sort of samples. Due to its particular characteristics, this is a unique device in the sense of multi-technique analysis of large areas. With the continuous development of the external beam line at LAMFI, coupled to the robotic XYZ stage, it is becoming a robust and reliable option for regular analysis of trace elements (Z > 5) competing with the traditional in-vacuum ion-beam-analysis with the advantage of automatic rastering.

Fast mapping of gold jewellery from ancient Egypt with PIXE: Searching for hard-solders and PGE inclusions

A new PIXE setup at the external beamline of the AGLAE accelerator is assessed for fast mapping the joining regions and the PGE inclusions of nine Egyptian gold items from the Louvre museum collection, dated to the end of the 2nd Intermediate Period and to the New Kingdom. The setup is composed of a cluster of SDD detectors divided in two “super detectors” dedicated to analyse the matrix and the trace elements. It provides the possibility to realise large and/or fast maps on artefacts by scanning the beam over the sample surface. Different softwares have been developed or updated to visualise, process, and quantify the data.By using this setup, we could determine the elemental distribution of major elements Au, Ag and Cu on the different joining regions, estimate the composition of the brazes, and show that they were produced by adding Cu to the base gold alloy. By fast mapping the PGE inclusions we could reveal a large variety of compositions within a single object. In addition to the expected Ir–Os–Ru system inclusions, we could also show for several inclusions the presence of another element, Pt. For a region where PGE inclusions overlap the joining area we could show that fast mapping allows to determine the compositions of the inclusion, the brazing alloy, and the base-alloy.

Aifira: An ion beam facility for multidisciplinary research

During the last decade, the CENBG (Centre d’Études Nucléaires de Bordeaux Gradignan) commissioned a new facility called AIFIRA (Applications Interdisciplinaires des Faisceaux d’ions en Région Aquitaine). It allowed the development of a multidisciplinary activity based on the “in-house” expertise of CENBG in ion beam analysis. The great flexibility offered by the five beam lines confers a lot of possibilities for chemical analysis and nuclear physics. Indeed, not only the macrobeam and the external beam lines provide the full set of IBA techniques for routine sample analysis but an additional beam line is devoted to the production of monoenergetic neutrons through the interaction of the incoming ion with selected targets. In addition, the two high-resolution microbeam lines are used for chemical analyses, 2D/3D imaging, and targeted cell irradiation. Besides, the combination of the nanobeam line flexibility, the uniqueness of the micro-irradiation design completed by the internal CENBG expertise confers a great specificity to AIFIRA in biomedical field. After a detailed technical overview of the platform, the article focuses on the two high-resolution lines as they tap most of the activity. Thus a quick overview of the most significant results concerning biomedical samples is proposed in order to highlight the analytical possibilities of AIFIRA microbeam lines. A summary of the development status of the micro-irradiation line is also done.