Beam Transfer Line Research Articles

Design of a 250 MeV linac injector system for the Southern Advanced Photon Source

The Southern Advanced Photon Source (SAPS) is a 4th generation storage ring based light source under design started several years ago, which is planned to be constructed at Guangdong province at China. The equilibrium emittance of the storage ring(SR) will be below 100 pm.rad and the beam energy is determined to be 3.5 GeV. Over the past two years, the nominal current of the SR was increased from 200 to 500 mA, requiring the injector system to provide more bunch charge. Additionally, the injection beam energy for the booster has been increased from 150 to 250 MeV, which means two more accelerating cavities have to been added. This paper presents an update of the linac injector. And also a beam transfer line from linac to booster is presented.

New developments for theranostic radioisotope production with solid targets at the Bern medical cyclotron

The concept of theranostics in nuclear medicine is based on the use of a pair of radioisotopes to label radiopharmaceuticals for both diagnosis and therapy and is essential for nuclear medicine developments. The production of novel medical radioisotopes using solid target stations is challenging and new instruments and methods are needed. A research program is ongoing at the 18 MeV Bern medical cyclotron, equipped with a Solid Target Station and a 6.5 m Beam Transfer Line ending in a separate bunker. To irradiate isotope-enriched materials in form of compressed powder pellets, a novel target coin was conceived and realized together with methods to assess the beam energy and the production cross sections. To optimize the irradiation procedure, a novel ultra-compact active irradiation system based on a specific magnetic lens and a two-dimensional beam detector was conceived, constructed and tested. The system allows to control on-line the size and position of the beam and to correct its characteristics by steering and focusing it in order to keep it on target. The first results on the production of several radionuclides (43Sc, 44Sc, 47Sc, 61Cu, 64Cu, 67Cu, 68Ga, 165Er, 165Tm, 167Tm and 155Tb) are presented.

Design and optimization of a compact quasi-isochronous 180-deg transport arc with suppressed CSR-induced emittance growth

Preserving the beam quality of a high-brightness electron beam is a noteworthy issue when delivering the electron bunch through a beam transfer line. In a beam transfer line with a large deflection angle, e.g., a 180-deg transport arc comprised of a large amount of dipoles, emission of coherent synchrotron radiation (CSR) can lead to transverse emittance dilution. In addition, the longitudinal dispersion may cause undesirable bunch length variation. Both effects can degrade beam quality. Nevertheless, design and optimization of a 180-deg transport arc that can be well applied to practical applications is a challenging problem, considering the practical nonlinear effects of a real lattice and the contributions of transient CSR at the dipole edges and CSR in the subsequent drifts. In this study, we present the design and optimization of a compact 180-deg transport arc comprised of multi-triple-bend achromat (TBA) cells, aiming at suppressing the CSR-induced emittance growth and avoiding bunch length variation simultaneously. The TBA cells and optics along the arc are adjusted to suppress the CSR-induced emittance growth and bunch length variation cell by cell, after which a multi-objective optimization of the arc is conducted. Practical considerations including lattice nonlinear effects and a full one-dimensional CSR model (including transient CSR and CSR in drifts) are taken into account.

Optimized production of 67Cu based on cross section measurements of 67Cu and 64Cu using an 18 MeV medical cyclotron

RadioNuclide Therapy (RNT) in nuclear medicine is a cancer treatment based on the administration of radioactive substances that specifically target cancer cells in the patient. These radiopharmaceuticals consist of tumor-targeting vectors labeled with β−, α, or Auger electron-emitting radionuclides. In this framework, 67Cu is receiving increasing interest as it provides β−-particles accompanied by low-energy γ radiation. The latter allows to perform Single Photon Emission Tomography (SPECT) imaging for detecting the radiotracer distribution for an optimized treatment plan and follow-up. Furthermore, 67Cu could be used as therapeutic partner of the β+-emitters 61Cu and 64Cu, both currently under study for Positron Emission Tomography (PET) imaging, paving the way to the concept of theranostics. The major barrier to a wider use of 67Cu-based radiopharmaceutical is its lack of availability in quantities and qualities suitable for clinical applications. A possible but challenging solution is the proton irradiation of enriched 70Zn targets, using medical cyclotrons equipped with a solid target station. This route was investigated at the Bern medical cyclotron, where an 18 MeV cyclotron is in operation together with a solid target station and a 6-m-long beam transfer line. The cross section of the involved nuclear reactions were accurately measured to optimize the production yield and the radionuclidic purity. Several production tests were performed to confirm the obtained results.

Instruments and methods for theranostic radioisotope production at the Bern medical cyclotron

Radioisotopes for theranostics are essential for nuclear medicine developments. Their production using solid target stations is challenging and new instruments and methods derived from particle physics are needed. A research program is ongoing at the 18 MeV Bern medical cyclotron, equipped with a solid target station and a 6 m long beam transfer line ending in a separate bunker. To irradiate 6 mm diameter compressed powder pellets, novel target “coins” were conceived and realized together with methods to assess the beam energy and the production cross sections. To measure the activity at End of Beam (EoB) a system based on a CdZnTe detector was installed. To accurately assess the properties of the beam, novel non-destructive one- and two-dimensional beam monitoring detectors were developed. An ultra-compact active irradiation system based on a novel magnetic lens and two-dimensional beam detectors was conceived and tested with the beamline and recently installed in an outport of the cyclotron.

Cross-section measurement for an optimized 61Cu production at an 18 MeV medical cyclotron from natural Zn and enriched 64Zn solid targets

The availability of novel medical radionuclides is a key point in the development of personalised nuclear medicine. In particular, copper radioisotopes are attracting considerable interest as they can be used to label various molecules of medical interest, such as proteins and peptides, and offer two of the most promising true theranostic pairs, namely 61Cu/67Cu and 64Cu/67Cu. Although 64Cu (t1/2 = 12.7006 h, β+: 17.6%, β−: 38.5%) is nowadays the most commonly used as a diagnostic radionuclide, 61Cu (t1/2 = 3.339 h, β+: 61%) features more favourable nuclear properties, such as a higher positron decay fraction and the absence of β− emissions. To date, the production of 61Cu has been carried out irradiating highly enriched 61Ni targets with a low energy proton beam. However, the use of the very expensive 61Ni targets requires an efficient recovery of the target material and makes this method quite inconvenient. Another promising production route is the proton irradiation of natural Zn or enriched 64Zn targets, exploiting the (p,α) nuclear reaction. Along this line, a research program is ongoing at the Bern medical cyclotron, equipped with an external beam transfer line and a solid target station. In this paper, we report on cross-section measurements of the 64Zn(p,α)61Cu nuclear reaction using natural Zn and enriched 64Zn material, which served as the basis to perform optimized 61Cu production tests with solid targets.

A facility for radiation hardness studies based on a medical cyclotron

The development of instrumentation for operation in high-radiation environments represents a challenge in various research fields, particularly in particle physics experiments and space missions, and drives an ever-increasing demand for irradiation facilities dedicated to radiation hardness studies. Depending on the application, different needs arise in terms of particle type, energy and dose rate. In this article, we present a versatile installation based on a medical cyclotron located at the Bern University Hospital (Inselspital), which is used as a controlled 18-MeV proton source. This accelerator is used for daily production of medical radioisotopes, as well as for multidisciplinary research, thanks to a 6.5-meter long beam transfer line that terminates in an independent bunker, dedicated only to scientific activities. The facility offers a wide range of proton fluxes, due to an adjustable beam current from approximately 10 pA to the micro-ampere range, together with a series of steering and focusing magnets along the beamline that allow for the beam spot to be focused down to a few mm^2. The beamline can be instrumented with a variety of beam monitoring detectors, collimators, and beam current measurement devices to precisely control the irradiation conditions. The facility also hosts a well equipped laboratory dedicated to the characterisation of samples after irradiation. An experimental validation of the irradiation setup, with proton fluxes ranging from 5×10^9 cm^-2s^-1 to 4×10^11 cm^-2s^-1, is reported.

First injector commissioning results with helium beam at MedAustron Ion Therapy Center

MedAustron is a synchrotron-based Particle Therapy Accelerator located in lower Austria which delivers clinical proton and carbon beams in the range of 62-252.7 MeV/u and 120-400 MeV/u respectively in two clinical treatment rooms. A proton Gantry was recently commissioned in a third clinical treatment room and a fourth experimental beamline is dedicated to non-clinical research activities. Within the latter, the injector commissioning has recently started for He2+ beam generation. The long-term goal is to use helium for cancer treatment due to its favourable physical and biological properties. The helium beam properties from the source up to injection further downstream into the accelerator, i.e. from the Low Energy Beam Transfer line to the Linear Accelerator are discussed in terms of beam emittance, intensity and transmission efficiency. Furthermore, a comparison with simulated data is presented.

New methods for theranostic radioisotope production with solid targets at the Bern medical cyclotron

The production of theranostic radionuclides using solid targets is challenging and requires an accurate knowledge of the production crosssections as well as the energy, positioning and focusing of the beam. A research program is ongoing at the 18 MeV Bern medical cyclotron, equipped with a Solid Target Station (STS) and a 6 m Beam Transfer Line (BTL) ending in a separate bunker with independent access. A novel target coin was designed and built to irradiate compressed powder pellets, together with a compact focalization system to optimize the irradiation procedure. Furthermore, methods were developed to measure the beam energy, the production cross-sections and the EoB-activity.

Charge‐State Distributions of Highly Charged Lead Ions at Relativistic Collision Energies

AbstractThis study describes the charge‐state evolution of relativistic lead ions passing through a thin aluminum stripper foil. It is motivated by the Gamma Factory project at CERN, where optical laser pulses will be converted into intense gamma‐ray beams with energies up to a few hundred MeV, achieved via excitation of atomic transitions in few‐electron heavy‐ions at highly relativistic velocities. The recently developed BREIT code is employed together with theoretical cross‐sections for single‐electron loss and capture of the projectile ions. All charge‐states starting from Pb54 + up to bare ions are considered at kinetic projectile energies of 4.2 and 5.9 GeV u−1. During recent Gamma Factory beam tests, the calculated preparatory predictions allow to effectively produce Pb80 + and Pb81 + ions from Pb54 + in the transfer beam line between the PS and SPS synchrotron accelerators at CERN and consequently, to store partially stripped ions in the LHC for the very first time. Reasonable agreement is found between the calculations and the very few experimental data available. The study lays the groundwork to optimize the yields of charge states of interest for experiments within the future Gamma Factory project, including the upcoming Gamma Factory Proof‐of‐Principle experiment for which predictions for the production of Pb79 + are presented.

Calculation and Optimization of High-Energy Beam Transfer Lines by the Monte Carlo Method

Calculation and Optimization of High-Energy Beam Transfer Lines by the Monte Carlo Method

Development and Operation of Vacuum System for Rapid Cycling Synchrotron to Target Beam Transfer Line of China Spallation Neutron Source

Development and Operation of Vacuum System for Rapid Cycling Synchrotron to Target Beam Transfer Line of China Spallation Neutron Source

Radiation-induced effects in glass windows for optical readout GEM-based detectors

In this paper we present irradiation measurements performed to select a transparent anode substrate that best meets the requirements of an optical readout for a novel detector, the LaGEMPix. The modification of the optical properties of the material due to proton irradiation were studied in soda-lime, fused quartz and fused silica glasses coated with an Indium Tin Oxide layer. The irradiations were performed using the research Beam Transfer Line (BTL) of the IBA Cyclone 18 MeV cyclotron of the Bern University Hospital (Inselspital). We recorded visible scintillation light generated by proton irradiation in the soda-lime and fused quartz samples. We also investigated the darkening of these three glasses and observed radiation-induced colour centres in the soda-lime glass sample. The optical transmission spectra of the samples were measured before and after irradiation. Reductions of 45%, 1% and 0.4% were observed for soda-lime glass, fused quartz and fused silica, respectively (with an associated error of 0.25%). We conclude that the best option for our specific application is the fused silica substrate, which will be the transparent anode for the next generation of the LaGEMPix detector.

Quasi-isochronous triple-bend achromat with periodic stable optics and negligible coherent-synchrotron-radiation effects

In modern high-brightness electron accelerators, the goal of preserving the beam quality from the source has long been pursued to ensure the fulfillment of their scientific missions. However, when delivering the electron beam through a beam transfer line, which may consist of bending magnets, the performance of a high-brightness electron beam may be degraded by the coherent synchrotron radiation (CSR) and the residual longitudinal dispersion. It is of critical importance to preserve the transverse emittance and control the bunch length variation as well as maintain the longitudinal phase space distribution in such a beam transfer line. For a multipass beam transfer line, the achromatic cell designs with stable optics would bring great convenience. In this study, for the periodic stable symmetric triple-bend achromat designs with identical dipoles, it is discovered that the CSR-induced emittance growth and the longitudinal dispersion up to high orders can be minimized simultaneously when a certain transfer matrix relation is satisfied; to be specific, the matrix entries between the first two dipoles should follow $[{m}_{11},{m}_{21}({\mathrm{m}}^{\ensuremath{-}1})]\ensuremath{\approx}(\ensuremath{-}2,0)$. Numerical optimizations demonstrate that the normalized transverse emittance, the bunch length, and the longitudinal phase space distribution are well preserved. In addition, such a design strategy shows the potential merit of effectively mitigating the microbunching instability.

An Active Irradiation System with Automatic Beam Positioning and Focusing for a Medical Cyclotron

A novel active focusing system was developed for enhancing the irradiation performance of the 18 MeV medical cyclotron in operation at the Bern University Hospital in view of the production of non-conventional medical radioisotopes using solid targets. In several cases, such as the production of 43Sc and 44Sc, the beam has to be kept stable within a very small target of about 5 mm diameter. For this purpose, we conceived and realized an apparatus based on a compact focusing and steering magnet system followed by a two-dimensional beam monitoring detector and a specific feedback software that drives the magnet to optimize the beam for a given irradiation set-up. We report on the design, realization and validation beam tests performed using the research beam transfer line of the Bern cyclotron. We demonstrated that the beam spot can be kept on target thanks to the fact that the system automatically reacts to perturbations. Compactness is one of the key features of this system, allowing its use in accelerator facilities with limited space, such as medical cyclotrons for radioisotope production.

A state of the art Lambertson septum magnet of the RHIC beam injection system

The beam injection system of the Relativistic Heavy Ion Collider (RHIC) is the last section of the beam transfer line which transports the beam from the Alternating Gradient Synchrotron (AGS) to RHIC and comes under the acronym AtR (AGS to RHIC) (https://ieeexplore.ieee.org/document/749599, https://ieeexplore.ieee.org/abstract/document/749594). The Lambertson septum magnet is one of the magnetic elements of the RHIC injection system (https://ieeexplore.ieee.org/abstract/document/749594). This paper presents results from the 2D and 3D electromagnetic design of the RHIC Lambertson septum magnet which has unique design features to minimize the magnetic field at the circulated beam region including the fringe field regions at the entrance and exit of the magnet.

Study of the Extracted Beam Energy as a Function of Operational Parameters of a Medical Cyclotron

The medical cyclotron at the Bern University Hospital (Inselspital) is used for both routine 18 F production for Positron Emission Tomography (PET) and multidisciplinary research. It provides proton beams of variable intensity at a nominal fixed energy of 18 MeV. Several scientific activities, such as the measurement of nuclear reaction cross-sections or the production of non-conventional radioisotopes for medical applications, require a precise knowledge of the energy of the beam extracted from the accelerator. For this purpose, a study of the beam energy was performed as a function of cyclotron operational parameters, such as the magnetic field in the dipole magnet or the position of the extraction foil. The beam energy was measured at the end of the 6 m long Beam Transfer Line (BTL) by deflecting the accelerated protons by means of a dipole electromagnet and by assessing the deflection angle with a beam profile detector.

The Signal Processing Electronics for the Beam Position Monitors of Russian Fourth Generation Synchrotron Radiation Source

The project of fourth-generation Ultimate Source for Synchrotron Radiation (USSR-4) is under development in Russia by leading of National Research Center “Kurchatov institute”. Some of diagnostic systems required for the new facility have to be developed or redeveloped to satisfy the features of the new facility. Hundreds beam position monitors (BPM) are installed along beam transfer lines, booster and storage rings to control the electron beam position. In booster and storage ring the electronics of BPM has to provide both the normally beam circulation and the first beam turn operation. It has to provide beam position monitoring in the bunch-by-bunch option for all operational modes [1]. In this manuscript we discuss the architecture of the BPM electronics, important aspects of the analog front-end, available components and a resulting performance of designed electronic module.

Electrodes for Beam Position Monitors for Fourth Generation Synchrotron Radiation Source

Fourth-generation synchrotron radiation sources demand new quality for the electron beam diagnostic systems. Some of diagnostic system elements have to be accurately developed or redeveloped due to match the new requirements. Beam position monitor (BPM) is a most used detector and tens (even hundreds) BPMs are installed in numerous positions along beam transfer lines, booster and storage rings. Modern approach to this device development assumes such features as short transient time, wide bandwidth, high sampling rate, low noise architecture and reasonable production and maintenance price. As a part of the system, the BPM electrodes should meet all those requirements. In this article we describe a development procedure for high quality capacitive electrodes for the BPM. 3D electromagnetic model allows estimation of the sensitivity, frequency response and tolerance requirements for the manufacturing of hundreds of monitors. Presented here equivalent scheme for the electrodes is a basis for the BPM electronics design.

Measuring longitudinal beam parameters in the low energy section of the Oak Ridge Spallation Neutron Source accelerator

Knowledge of the longitudinal beam parameters is important for understanding beam dynamics in hadron linacs. Recently, a noninterceptive method suitable for measuring the longitudinal rms Twiss parameters in the high energy part of a hadron linac was developed and experimentally verified at the Spallation Neutron Source (SNS). This work presents an extension and modification of the method to allow measurements in the low energy part of a linac. Like the original method, amplitude of the beam rf harmonic measured by the beam position monitor is used to derive the information on the bunch length. The new method was tested at the medium energy beam transfer line of the SNS accelerator. The results are in good agreement with an independent measurement of the bunch length using the longitudinal acceptance scan of the drift tube linac. The suggested method is fast, and it can be a useful part of the initial longitudinal beam tuning at the front end of hadron linacs.