PSI, Villigen PSI, Switzerland
We perform beamline design optimization for the High Intensity Muon Beams (HIMB) project at the Paul Scherrer Institute (PSI), which will deliver muon beams at the unprecedented rate of 1·1010 muons/s to next-generation intensity frontier particle physics and material science experiments. For optimization of the design and operational parameters to maximize the beamline transmission, we use the asynchronous Bayesian optimization package DeepHyper and a custom build of G4beamline with variance reduction and measured cross sections. We minimize the beam spot size at the final foci using a COSY INFINITY model with differential-algebraic system knobs, where we minimize the respective transfer map elements using the Levenberg-Marquardt and simulated annealing optimizers. We obtained a transmission of 1.34·1010 muons/s in a G4beamline model of HIMB’s MUH2 beamline into the experimental area.
Fermilab, Batavia, Illinois, USA
LBNL, Berkeley, California, USA
The use of high temperature superconductors for accelerator dipole has been discussed for about twenty years and maybe a little more. Conductors that can potentially be used for accelerator magnets have been available for about fifteen years. These conductors are REBCO tape conductors, which can be wound into coils with no reaction after winding, and BISSCO cable conductors, which require reaction after winding and insulation after reaction in a process similar to Nb3Sn cables. Both conductors are expensive and the process after reacting is expensive. Some unknown factors that remain: Will either conductor degrade in current carrying capacity with repeated cycling like Nb3Sn cables do? The other two issues are problems for both types of HTS conductors and they are; 1) quench protection in the event of a normal region run-away and 2) dealing with the superconducting magnetization inherent with HTS cables and tapes. This paper will discuss the last two issues and maybe will provide a partial solution to these problems.
Northern Illinois University, DeKalb, Illinois, USA
JLab, Newport News, Virginia, USA
ANL, Lemont, Illinois, USA
LBNL, Berkeley, California, USA
Beamlines capable of merging beams with different energies are critical to many applications related to advanced accelerator concepts and energy-recovery linacs (ERLs). In an ERL, a low-energy "fresh" bright bunch is generally injected into a superconducting linac for acceleration using the fields established by a decelerated "spent" beam traveling on the same axis. A straight-merger system composed of a selecting cavity with a superimposed dipole magnet was proposed and recently test at AWA. This paper reports on the experimental results obtained so far along with detailed beam dynamics investigations of the merger concept and its ability to conserve the beam brightness associated with the fresh bunch.
MSU, East Lansing, Michigan, USA
Fermilab, Batavia, Illinois, USA
The Integrable Optics Test Accelerator (IOTA) is a research storage ring constructed and operated at Fermilab to demonstrate the advantages of nonlinear integrable lattices. One of the nonlinear lattice configurations with one integral of motion is based on a string of short octupoles. The results of the individual magnet’s characterizations, which were necessary to determine their multipole composition and magnetic centers, are presented. This information was used to select and align the best subset of octupoles for the IOTA run 4.
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
Exact transport equations for a pure dipole bend (a bend with a dipole field and nothing else) have been derived and formulated to avoid singularities when evaluated. The transport equations include finite edge angles and no assumption is made in terms of the bending field being matched to the curvature of the coordinate system.
ANL, Lemont, Illinois, USA
Fringe fields effects in dipoles can give rise to important linear and nonlinear contributions. This paper describes how to extend the classic results of Brown [1] and the more recent calculations of Hwang and Lee [2] to Cartesian dipoles with transverse and/or longitudinal gradients. We do this by 1) introducing a more general definition of the fringe field that can be applied to longitudinal gradient dipoles, 2) allowing for quadrupole and/or sextupole content in the magnet body, and 3) showing how to employ the resulting fringe field maps as a symplectic transformation of the coordinates. We compare our calculation results with tracking for longitudinal and transverse gradient dipoles planned for the APS-U.
[1] K.L. Brown, Report SLAC-75, 1982.
[2] K. Hwang and S.Y. Lee, Phys. Rev. Accel. Beams, vol. 18, p. 122401 2015.
LANL, Los Alamos, New Mexico, USA
LANL, Los Alamos, New Mexico, USA
The Los Alamos National Laboratory electromagnetic isotope separator (EMIS) utilizes a Freeman ion source to generate beams of various elements which are accelerated to 40 keV and passed through a 75-degree bend using a large dipole magnet with a radius of 1.2 m. The isotope mass differences translate directly to a spread in momentum, dp, relative to the design momentum p0. Momentum spread is converted to spread in the horizontal arrival location dx at a target chamber by the dispersion of the dipole magnet: dx = D(s)dp/p0. By placing a thin slit leading to a collection chamber at a location xc specific isotope mass is isolated by adjusting the dipole magnet strength or the beam energy. The arriving beam current at xc is associated with average isotope atomic mass, giving an isotope mass spectrum I(m) measured in mA. Although the EMIS is a compact system (5 m) setting up and automatically running at an optimal isotope separation profile I(m) profile is challenging due to time-variation of the complex source as well as un-modeled disturbances. We present preliminary results of developing adaptive machine learning-based tools for the EMIS beam and for the accelerator components.
LANL, Los Alamos, New Mexico, USA
We report our comparison study on the first stage electron bunch compression schemes at 750 MeV using a conventional and a double C-chicane for the X-ray free electron laser (XFEL) under development for the Matter-Radiation Interactions in Extremes (MaRIE) initiative at Los Alamos National Laboratory. Compared to the performance of the conventional C-chicane bunch compressor, the double C-chicane scheme exhibits the capability of utilizing the transverse momentum shift induced by the coherent synchrotron radiation in the second C-chicane to compensate that generated in the first C-chicane, resulting in a compressed electron bunch with minimized transverse momentum shift along the beam. It is also found that the double C-chicane scheme can be designed to significantly better preserve the beam emittance in the course of the bunch compression. This is particularly beneficial for the MaRIE XFEL whose lasing performance critically depends on the preservation of the ultralow beam emittance.
ANL, Lemont, Illinois, USA
We have developed a set of tools to simulate particle dynamics in the full magnetic field using the generalized gradients representation. Generalized gradients provide accurate and analytic representations of the magnetic field that allow for symplectic tracking [1]. We describe the tools that convert magnetic field data into generalized gradients representations suitable for tracking in Elegant, and discuss recent results based upon tracking with the full field representations for all magnets in the APS-U storage ring.
[1] A. Dragt. Lie Methods for Nonlinear Dynamics with Applications to Accelerator Physics. University of Maryland (2019).
JLab, Newport News, Virginia, USA
ORNL RAD, Oak Ridge, Tennessee, USA
We will present a new design of a two-energy storage ring for low energy (0.2 to 2 MeV) polarized electron bunches [1]. The new design is based on the transparent spin methodology that cancels the spin precession due to the magnetic dipole moment at any energy while allowing for spin precession induced by the fundamental physics of interest to accumulate. The buildup of the vertical component of beam polarization can be measured using standard Mott polarimetry that is optimal at low electron energy. These rings can be used to measure the permanent electric dipole moment of the electron, relevant to CP violation and matter-antimatter asymmetry in the universe, and to search for dark energy and ultra-light dark matter.
[1] R. Suleiman, V.S. Morozov, and Y.S. Derbenev, On possibilities of high precision experiments in fundamental physics in storage rings of low energy polarized electron beams, arXiv:2105.11575 (2021)
ORNL, Oak Ridge, Tennessee, USA
Beam dynamics of charged particles in the fringe field of a quadrupole and a dipole magnet is considered. An effective method for solving symplectic Lie map exp(:f:) in such cases has been developed. A precise analytic solution for nonlinear transverse beam dynamics in a quadrupole magnet with hard-edge fringe field has been obtained. The method of Lie map calculation considered here can be applied for other magnets and for soft edge type of fringe field.
RadiaBeam, Santa Monica, California, USA
FRIB, East Lansing, Michigan, USA
Rare isotope beams are produced at FRIB via fragmentation of a primary heavy ion beam in a thin target. The isotope beam of interest is contaminated with other fragments, which must be filtered out to ensure the delivery of rare isotopes with desired rates and purities. One of the stages of fragment separation uses an RF deflecting cavity to provide time-of-flight separation. However, to avoid neighboring bunches overlapping with each other and with the contaminants, it is necessary to increase the inter-bunch distance by a factor of four, corresponding to a 20.125 MHz rate. To solve this problem, we have developed an RF chopper system for the 500 keV/u primary heavy-ion beams. The system consists of a deflecting quarter wave resonator (QWR) cavity operating at 60.375 MHz, two dipole steering magnets, and a beam dump. In this paper, we present and discuss the optimization of the electromagnetic design of the QWR cavity and magnets, as well as some aspects, related to beam dynamics and conceptual engineering design.
BNL, Upton, New York, USA
Fermilab, Batavia, Illinois, USA
SBU, Stony Brook, New York, USA
ANL, Lemont, Illinois, USA