Booster Accelerator Research Articles

Beam Dynamics in the Heavy Ion Injector LU2 for the Synchrotron Research Complex (SRC)

The project of the complex for studying ionizing radiation exposure from outer space based on the synchrotron accelerator of protons and various types of ions up to 209Bi is being developed at the Russian Federal Nuclear Center - All-Russian Research Institute ofExperimental Physics (FSUE RFNC - VNIIEF). The accelerator includes two injection complexes (one of which is the source of protons and light ions, the second - heavy ions), the booster accelerator and the main synchrotron. The pulsed type heavy ions linac is being developed at the NRC “Kurchatov Institute” - KCTEF (Kurchatov Complex for Theoretical and Experimental Physics). The ions with mass-to-charge ratio 4÷8 with current of 10 mA will be accelerated up to 4 MeV/u. The linac is proposed, including the RFQ and two DTL sections operating at multiple frequencies. Each DTL section is modular and consists of individually phased H-type resonators (IH-DTLs). Quadrupole lenses located between the resonators for the beam focusing. This DTL structure ensures the accelerator compactness and allows section-by-section configuration and sequential commissioning. 6D beam matching between all sections of the linac is carried out. The results ofbeam dynamics simulation in linear accelerator are presented.

Uncertainty aware machine-learning-based surrogate models for particle accelerators: Study at the Fermilab Booster Accelerator Complex

Standard deep learning methods, such as Ensemble Models, Bayesian Neural Networks, and Quantile Regression Models provide estimates of prediction uncertainties for data-driven deep learning models. However, they can be limited in their applications due to their heavy memory, inference cost, and ability to properly capture out-of-distribution uncertainties. Additionally, some of these models require post-training calibration that limits their ability to be used for continuous learning applications. In this paper, we present a new approach to provide prediction with calibrated uncertainties that includes out-of-distribution contributions and compare it to standard methods on the Fermi National Accelerator Laboratory (FNAL) Booster accelerator complex.

Real-time artificial intelligence for accelerator control: A study at the Fermilab Booster

We describe a method for precisely regulating the gradient magnet power supply (GMPS) at the Fermilab Booster accelerator complex using a neural network trained via reinforcement learning. We demonstrate preliminary results by training a surrogate machine-learning model on real accelerator data to emulate the GMPS, and using this surrogate model in turn to train the neural network for its regulation task. We additionally show how the neural networks to be deployed for control purposes may be compiled to execute on field-programmable gate arrays (FPGAs), and show the first machine-learning based control algorithm implemented on an FPGA for controls at the Fermilab accelerator complex. As there are no surprise latencies on an FPGA, this capability is important for operational stability in complicated environments such as an accelerator facility.

Developing Robust Digital Twins and Reinforcement Learning for Accelerator Control Systems at the Fermilab Booster

We describe the offline machine learning (ML) development for an effort to precisely regulate the Gradient Magnet Power Supply (GMPS) at the Fermilab Booster accelerator complex via a Field-Programmable Gate Array (FPGA). As part of this effort, we created a digital twin of the Booster-GMPS control system by training a Long Short-Term Memory (LSTM) to capture its full dynamics. We outline the path we took to carefully validate our digital twin before deploying it as a reinforcement learning (RL) environment. Additionally, we demonstrate the use of a Deep Q-Network (DQN) policy model with the capability to regulate the GMPS against realistic time-varying perturbations.

Comparison between PHITS and GEANT4 Simulations of the Heavy Ion Beams at the BEVALAC at LBNL and the Booster Accelerator at BNL

Heavy charged particles have been discussed for clinical use due to their superior dose-depth distribution compared to conventional radiation such as X-rays. In addition, high-charge and energy (HZE) ions in galactic cosmic rays (GCR) present important health risks for crewed space missions to the Earth's moon or Mars. Experiments at heavy ion accelerators are used in radiobiology studies; however, numerical simulations of track segment or Bragg peak irradiations are complicated by the details of the beam-line and dosimetry systems. The goal of the present work is in support of biophysics modeling of historical radiobiology data at Lawrence Berkeley National Laboratory (LBNL) and more recent results from the Brookhaven National Lab (BNL) facility (NASA Space Radiation Lab (NSRL)). In this work, the Spread-Out Bragg Peak (SOBP) of 4He, 12C, and 20Ne particles, and a Bragg curve of 56Fe ion have been simulated numerically in the geometries of LBNL and BNL using the Monte-Carlo based PHITS and GEANT4 simulation toolkits. The dose contributions of primary particles and secondary particles, including neutrons and photons, in the target material are computed and discussed as well. Comparisons suggest more contributions of secondaries in GEANT4 simulations compared to PHITS simulations, and less statistical fluctuation and better prediction of neutrons in PHITS simulations. Neutrons and gamma-rays are estimated to make minor contributions to absorbed doses for these beams.

Cycling Equipment for the NICA Booster Accelerator

Cycling equipment was developed for the Booster accelerator of the NICA complex in the form of a VME3U crate with a set of digital and optical input/output modules, which are controlled using the FPGA module.

Magnetic system of a superconducting separated-sector cyclotron for hadron therapy

The development of a cyclotron magnetic system based on superconducting sector magnets is discussed. The cyclotron is conceived as a booster accelerator of a source of 12С6+ ions with energy of 400MeV/nucleon for the purposes of hadron therapy. The results of preliminary investigations aimed at developing such a facility have been reported in our previous papers. In this paper, we consider various configurations of the booster’s magnetic system for various field levels. We also analyze the effects of the positions and shapes of superconducting coils on the magnetic field and select the optimum configuration for the cyclotron’s magnetic system.

Development of the beam extraction synchronization system at the Fermilab Booster

The new beam extraction synchronization control system called “Magnetic Cogging” was developed at the Fermilab Booster and it replaces a system called “RF Cogging” as part of the Proton Improvement Plan (PIP).[1] The flux throughput goal for the PIP is 2.2×1017 protons per hour, which is double the present flux. The flux increase will be accomplished by doubling the number of beam cycles which, in turn, will double the beam loss in the Booster accelerator if nothing else is done.The Booster accelerates beam from 400MeV to 8GeV and extracts it to the Main Injector (MI) or Recycler Ring (RR). Cogging controls the beam extraction gap position which is created early in the Booster cycle and synchronizes the gap to the rising edge of the Booster extraction kicker and the MI/RR injection kicker.The RF Cogging system controls the gap position by changing only the radial position of the beam thus limiting the beam aperture and creating beam loss due to beam scraping. The Magnetic Cogging system controls the gap position with the magnetic field of the dipole correctors while the radial position feedback keeps the beam on a central orbit. Also with Magnetic Cogging the gap creation can occur earlier in the Booster cycle when the removed particles are at a lower energy. Thus Magnetic Cogging reduces the deposited energy of the lost particles (beam energy loss) and results in less beam loss activation. Energy loss was reduced by 40% by moving the gap creation energy from 700MeV to 400MeV when the Booster Cogging system was switched from RF Cogging to Magnetic Cogging in March 2015.

The NASA Space Radiation Laboratory at Brookhaven National Laboratory: Preparation and delivery of ion beams for space radiation research

The NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL) was commissioned in October 2002 and became operational in July 2003. The NSRL was constructed in collaboration with NASA for the purpose of performing space radiation research as part of the NASA space program. The NSRL can accept a wide variety of ions from BNL’s Collider Accelerator Department (CAD) Booster accelerator. These ion beams are extracted from the accelerator with kinetic energies ranging from 0.05 to 3 GeV/nucleon. Many different beam conditions have been produced for experiments at NSRL. The facilities at BNL and the design of the NSRL facility permit a wide variety of beams to be produced with a great degree of flexibility in the delivery of ion beams to experiments. In this report we will describe the facility and its performance over the eight experimental run periods that have taken place since it became operational. We will also describe the current and future capabilities of the NSRL.

Synergia: An accelerator modeling tool with 3-D space charge

High precision modeling of space-charge effects, together with accurate treatment of single-particle dynamics, is essential for designing future accelerators as well as optimizing the performance of existing machines. We describe Synergia, a high-fidelity parallel beam dynamics simulation package with fully three-dimensional space-charge capabilities and a higher order optics implementation. We describe the computational techniques, the advanced human interface, and the parallel performance obtained using large numbers of macroparticles. We also perform code benchmarks comparing to semi-analytic results and other codes. Finally, we present initial results on particle tune spread, beam halo creation, and emittance growth in the Fermilab Booster accelerator.

Simulation of the Fermilab Booster using Synergia

High precision modeling of space-charge effects is essential for designing future accelerators as well as optimizing the performance of existing machines. Synergia is a high- fidelity parallel beam dynamics simulation package with fully three dimensional space-charge capabilities and a higher-order optics implementation. We describe the Synergia framework, developed under the auspices of the DOE SciDAC program, and present Synergia simulations of the Fermilab Booster accelerator and comparisons with experiment. Our studies include investigation of coherent and incoherent tune shifts and halo formation.

Photoinjector design for the LCLs

The design of the Linac Coherent Light Source assumes that a low-emittance, 1 nC, 10 ps beam will be available for injection into the 15 GeV linac. The proposed rf photocathode injector that will meet this requirement is based on a 1.6-cell S-band rf gun equipped with an emittance-compensating solenoid. The booster accelerator with a gradient of 25 MV/m is positioned at the beam waist coinciding with the first emittance maximum, i.e., the “new working point.” The uv pulses required for cathode excitation will be generated by tripling the output of a Ti:sapphire laser system. Details of the design and the supporting simulations are presented.

RoSiB – a 4π silicon ball for charged-particle detection in EUROBALL

A 4π silicon ball for detection and identification of light charged particles in large multidetector γ-arrays as EUROBALL is presented. The design is based on a N=42 ball with 12 pentagons and 30 hexagons as used in the GASP array. The absorptive material for γ-rays is minimized to the detector thickness of 300 or 500 μm and a 0.63 mm ceramic backing. The geometrical coverage is designed for about 90% of 4π. A pulse shape discrimination method with totally depleted detectors working in the reverse mount allows identifying protons and α-particles above an energy threshold of about 2 MeV. The performances of the ball were tested at the tandem – booster accelerator combination of the MPI Heidelberg in two experiments using the high-recoil reaction of 228 MeV 58 Ni+ 46Ti and the low-recoil reaction of 95 MeV 16 O+ 58Ni . The two-dimensional spectra of zero-crossing (ZC) versus energy confirmed an excellent discrimination of protons and α-particles in all the detectors at different angles. The energy spectra of protons and α-particles measured in the experiments are presented, too. The γ-spectra measured in coincidence with various combinations of emitted particles showed a high selectivity of the ball. The reduced total efficiency for protons of 59% and 55% and α-particles of 44% and 32% measured in a nuclear spectroscopy application is analyzed in a Monte-Carlo simulation (GEANT). It is due to a combined influence of a thick target needed to stop the recoiling residual nuclei and thick absorbers needed to protect the Si-detectors from scattered beam. The results along with the GEANT extrapolation to optimum experimental conditions confirm that RoSiB is a highly efficient and selective device for identification of rare reaction channels with heavy ions.

A proposal for antiproton physics at Brookhaven

A report is presented of the plans developed by the Working Group for Antiproton Physics at the AGS 2000 Workshop held at the Brookhaven National Laboratory. A multi-stage development of a vigorous program of antiproton physics, using both the existing beam lines and the Booster accelerator, was developed and presented. International cooperation is invited in order to design the facility, propose the best physics, and help transform the proposal into reality.

An achromat for the ANU 14UD linac

A compact magnetic achromat has been designed and constructed to deliver the horizontal output beam of the ANU 14UD Pelletron tandem accelerator to a superconducting booster accelerator to be located in part of the experimental hall of the laboratory. The achromat provides 90° deflection of the ion beam and is fully achromatic with respect to energy spread in the beam. Due to space constraints in the laboratory, it has been necessary to locate the beam chopping device and bunching cryostat upstream of the 90° bend, thereby requiring that the beam trajectory following the bend be independent of beam energy. The optical performance of the achromat has been investigated in first order using the matrix transfer beam calculation code TRANSPORT, and in high order using the particle tracking code RAYTRACE. In first order, the achromat is shown to have precise achromatism and to be isochronous with the exception of small and predictable time waist shifts. High order calculations lead to an expectation of less than 6% worsening of the transverse beam emittance and less than 9 ps timing degradation for 170 MeV 59Ni 13+, an isotope of interest in accelerator mass spectrometry. The effect on the transmission of this isotope through the subsequent acceleration stages and beam-optical elements is negligible.

Hydrogen pellet acceleration with a two-stage system consisting of a gas gun and a fuseless electromagnetic railgun

Hydrogen pellets are successfully accelerated for the first time using a two-stage system consisting of a pneumatic gun and an electromagnetic railgun. The pneumatic gun preaccelerator forms cylindrical hydrogen ice pellets (1.6-mm diam×2.15-mm long) and accelerates them with high-pressure helium gas to velocities in excess of 500 m/s. The booster accelerator, which is a fuseless, circular-bore electromagnetic railgun, derives its propulsive force from a plasma arc armature. The plasma arc armature is formed by electrically breaking down the propellant gas which follows the pellet from the gas gun into the railgun. The diagnostics are for the monitoring of the main capacitor bank and rail currents, for the pellet detection and velocity measurements at the breech and muzzle ends of the railgun, for the recording of the plasma-arc-armature movement inside the railgun bore, and for the photographing of the hydrogen pellet exiting the railgun. Using the system, which is a 60-cm long proof-of-principle machine for refueling magnetic fusion devices, hyrogen pellet velocities exceeding 1 km/s have been achieved for pellets exiting the gas gun at velocities of ∼500 m/s.

The Holifield Heavy Ion Research Facility - Phase II

The Holifield Heavy Ion Research Facility, with the completion of Phase I in late 1979, will include the Oak Ridge Isochronous Cyclotron (ORIC) and associated research areas, the new 25 MV tandem accelerator with new research areas for tandem beams, and modifications to utilize the ORIC as a booster accelerator. The combination of the tandem and ORIC will provide beam energies of 25 MeV/A for light heavy ions and 6 MeV/A up to A = 160. This paper discusses plans for a Phase II expansion of the facility to include an isochronous cyclotron with superconducting magnet and reconfiguration of the existing research areas and the ORIC vault to handle the higher energy beams from the new cyclotron. The new booster cyclotron is a low-flutter high-spiral design patterned after the MSU K = 800 design, with a central magnetic field of about 5 tesla and an extraction radius of 1 meter. The new beam transport system will incorporate an rf beamsplitter system that will be able to deliver successive beam pulses to two or three experiment areas.

Stripping Foils for Multiturn Charge Exchange Injection into the Fermilab Booster

Carbon foils with surface densities of 200 μgcm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> were selected as the stripping medium for the charge exchange injection system into the Fermilab Booster accelerator. These foils have extremely long lifetimes. The criteria leading to their selection and the preparation method are discussed.

Measurement of the Electron Loss Cross Sections for Negative Hydrogen Ions on Carbon at 200 MeV

The beam diagnostic equipment in the injection area of the Fermilab Booster accelerator has been used to measure the cross sections of electron loss for H- ions on carbon. The details of the method are described. Preliminary results and comparison to theoretical calculations are presented.

A Proposed Multi-Purpose Separated-Sector Cyclotron at IPCR

A new research facility including an accelerator complex to provide all heavy ions up to uranium has been proposed at the Institute of Physical and Chemical Research. A separated-sector cyclotron (SSC) with K=620 MeV is being designed as a booster accelerator for a variable-frequency heavy-ion linac now under construction. For the injection of relatively light ions up to neon into the above SSC, the existing ordinary cyclotron will be converted into an AVF machine with K=90 MeV to be used as another preaccelerator. The maximum beam energy provided by this accelerator system will range from 120 MeV/u for fully stripped ions to 15 MeV/u for very heavy ions such as uranium. Acceleration of light particles like deuterons and ? particles is also possible. The basic design and some model studies of the proposed machine are described.