Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session Z07: Hadron-Lepton Machines, Hadrons and Neutrino BeamsLive
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Sponsoring Units: DPB Chair: Todd Satogata, JLAB |
Tuesday, April 20, 2021 3:45PM - 3:57PM Live |
Z07.00001: Green Energy Future EIC Collider Dejan Trbojevic, Stephen Brooks, Scott Berg, Thomas Roser, Francois Meot, Nicholaos Tsoupas, Vladmir Litvinenko, Georg Hoffstaetter, Colwyn Gulliford, Kirsten Deitrick, David Sagan, Adam Bartnik, William Lou We call the future Electron Ion Colliders (EIC) green energy colliders as either the Superconducting Energy Recovery Linac `ERL' or Superconducting Recirculating Linacs Accelerator (RLA) are used with their energy fully recovered in the ERL case with the electron beam brought back to the linac by the single beam line without requiring electric power as it is made of permanent magnets. The single beam line transports all electron energies at once as it uses the Fixed Field Alternating Linear Gradient (FFA-LG) principle with a very strong focusing. The designs are based on experience on the very successful results from commissioning of the Cornell University and Brookhaven National Laboratory Energy Recovery Test Accelerator -- `CBETA'. Examples of the green EIC at Relativistic Heavy Ion Collider (RHIC) and of the CERN Large Hadron Collider - LHeC are presented. [Preview Abstract] |
Tuesday, April 20, 2021 3:57PM - 4:09PM Live |
Z07.00002: Review of beam dynamics issues during RHIC Beam Energy Scan Phase-II. Chuyu Liu To explore the first-order phase transition and determine the location of a possible critical point, the Beam Energy Scan Phase II (BES-II) is being performed at the Relativistic Heavy Ion Collider (RHIC) with collisions of beams in the energy range from 9.8 GeV to 3.85 GeV. The operation at such a low energy range at RHIC are very challenging due to multiple beam dynamics, of which the most significant are intra-beam scattering, space charge, beam-beam, beam instability, and persistent current effects. This presentation will review these issues and the measures being taken to combat them during the first two years of BES-II operation. A outlook of the final year BES-II operation will be presented as well. [Preview Abstract] |
Tuesday, April 20, 2021 4:09PM - 4:21PM Live |
Z07.00003: Experimental Studies of Beam Dynamics in Integrable Storage Rings Nikita Kuklev, Alexander Valishev, Alexander Romanov, Sergei Nagaitsev, Young-Kee Kim One of key challenges in increasing particle accelerator beam intensity is the limit imposed by losses due to collective instabilities. Recently, integrable optics has been proposed as a novel method to suppress these effects. It relies on a precise placement of a set of electromagnetic fields, such that the overall Hamiltonian describing beam dynamics is integrable. To experimentally test this concept, a new research storage ring, the Integrable Optics Test Accelerator (IOTA), has been constructed at the Fermilab Accelerator Science and Technology (FAST) facility. IOTA has completed scientific run 2 in 2020, incorporating many improvements - better lattice alignment, instrumentation system overhaul, and addition of sextupoles. We present run 2 results of the two integrable optics experiments - the quasi-integrable Henon-Heiles type system and the fully integrable Danilov-Nagaitsev system. Tune footprints and Poincaré surfaces of section are compared with theoretical and simulation results, and remaining disagreements highlighted. An extensive error analysis treatment is presented, quantifying impact of fundamental effects such as beam decoherence as well as experimental systematics. Related efforts in machine learning and lattice optimization are also highlighted. [Preview Abstract] |
Tuesday, April 20, 2021 4:21PM - 4:33PM Live |
Z07.00004: The Implications and Challenges of Representing the 6D Distribution of High Charge Bunches Kiersten Ruisard, Sarah Cousineau, Alexander Aleksandrov As the need for higher beam intensity grows, the challenges of space charge dynamics become more pressing. Space charge both introduces nonlinear force components into the beam evolution and creates interplane coupling, complicating dynamics in the mostly linear and un-coupled accelerator system. One consequence of coupling is that the standard method of characterizing bunches, independent imaging of three phase space projections, does not fully describe the 6D phase space distribution. This presentation will describe a method for direct 6D measurement which has been implemented at the Spallation Neutron Source (SNS) Beam Test Facility. I will describe key insights from this measurement, namely the presence of hidden but significant interplane coupling after initial bunch formation and acceleration. Finally, I will touch on the implications of the 6D shape for predicting downstream beam evolution, particularly with respect to halo growth and beam loss. [Preview Abstract] |
Tuesday, April 20, 2021 4:33PM - 4:45PM Live |
Z07.00005: Computation of the matched envelope of the Danilov distribution Austin Hoover, Nick Evans, Jeff Holmes Self-consistent beams are those which give rise to linear internal electric fields and maintain this property under any linear transport. Their analytic tractability provides valuable insights into space charge effects, and they would possess a number of ideal properties if realized in practice. Although the KV distribution is the most famous example, a larger class of self-consistent beams exists. Here we focus on a particular case which we call the Danilov distribution. The dynamical behavior of this beam is more complicated than that of the KV distribution due to the fact that it tilts in real space as it transports through the lattice. There is current interest in generating the Danilov distribution experimentally; however, the beam dynamics have not yet been studied in detail. We present an iterative method to calculate the matched envelope of the Danilov distribution in both coupled and uncoupled lattices using an existing parameterization of coupled transverse motion. We demonstrate the method in a few simple lattices and study the resulting matched beam properties, thus laying the groundwork for future calculations to optimize the injection of a self-consistent beam in more complicated lattices. [Preview Abstract] |
Tuesday, April 20, 2021 4:45PM - 4:57PM Live |
Z07.00006: Applications of the High-Current IsoDAR Cyclotron Beyond Neutrino Physics Loyd Waites The IsoDAR cyclotron is a compact, high-current, 60 MeV proton accelerator. It was originally conceived as a driver for a definitive sterile neutrino experiment. However, with its design beam current greatly exceeding the capabilities of presently available cyclotrons, the technology lends itself to a variety of applications beyond particle physics. The high current and versatility of using an H2$+$ beam makes it an ideal system for high power target development, which is a critical bottleneck in the medical isotope community. This technology would also be helpful for development of materials and in energy research. We describe the cyclotron design, including novel methods of applying machine learning to injector development, and the multiple uses of this particle accelerator. These applications demonstrate how the IsoDAR cyclotron could have an important impact on physics communities beyond particle physics, and on society. [Preview Abstract] |
Tuesday, April 20, 2021 4:57PM - 5:09PM Live |
Z07.00007: A Concept of Neutral Rich Horn Focusing System for Low-Mass Dark Matter Search in Future Neutrino Experiments. Aayush Bhattarai Next-generation neutrino experiments like the Deep Underground Neutrino Experiment (DUNE) can also help exploring the physics Beyond the Standard Model (BSM) thanks to high intensity proton beams and capable detectors. The concept of a Neutral Rich Horn Focusing system (NRHF) makes it possible for precision neutrino experiments and beam-dump style experiments to coexist. This system helps to reduce background from neutrinos to searches of BSM particles such as low-mass dark matter, axions like particles, heavy neutral leptons, and other charge-neutral particles. The most essential component of this system is the three-dimensional sign selecting dipole that provides a magnetic kick guiding the focused charged particles towards the neutrino experiment, leaving the neutral particles on their way to the beam dump. With this system, we can enhance the signal to background ratio by several orders of magnitudes. This presentation will describe the working principles of NRHF, technical issues concerning sign selecting 3D dipole, and the resulting enhancement of the signal to background ratio dependent on the parameters of the system. [Preview Abstract] |
Tuesday, April 20, 2021 5:09PM - 5:21PM Live |
Z07.00008: Study for Alternative Cavity wall and Inductive Insert Material Charles Taylor, Sandra Biedron The goal of this proposed work is to develop a solution to the problem of longitudinal beam instability. Beam instability has been a significant problem with storage rings' performance for many decades . The proton storage ring (PSR) at the Los Alamos Neutron Science Center (LANCE) is no exception]. To mitigate the instability, it was found that ferrite inductive inserts can be used to bunch the protons that are diverging due to the electron background. The PSR was the first to successfully use these inductive inserts to mitigate the instabilities. However, years later new machine upgrades facilitate shorter, more intense beams to meet the needs of researchers. The ferrite inserts used to reduce the transverse instabilities now induce a new longitudinal (axis of the beam trajectory) instability. A multilayer ferrite structure, Finemet, was proposed as a replacement of the PSR Toshiba ferrite inserts because of its very stable magnet flux density. Yet in Japan, J-PARC has found complications with its use. It was difficult to cool Finemet, with poor contact between the core and cooling plate causing electrical discharges around it. This study will investigate alternative magnetic materials for inductive inserts in particle beam storage rings, including the necessary engineering for maintaining the ideal temperature during operation. \textbf{LA-UR-21-20189 APPROVED FOR FOR UNLIMITED RELEASE} [Preview Abstract] |
Tuesday, April 20, 2021 5:21PM - 5:33PM Live |
Z07.00009: Development of a Very Compact High-Current Cyclotron Injector System for Future Neutrino Physics and Medical Applications Daniel Koser, Daniel Winklehner, Loyd Hoyt Waites, Joseph Smolsky, Janet Conrad For the IsoDAR experiment, which aims to perform a definitive search for sterile neutrinos, a high-current, 60 MeV driver cyclotron is being developed which, besides particle physics, might also enable advances in other high-current beam applications such as the production of medical isotopes. To cope with the high space-charge forces at injection into the cyclotron, a novel scheme for pre-bunching is applied that includes a compact radio-frequency quadrupole (RFQ) of the split-coaxial type. This choice of RF structure enables a small transverse RFQ diameter at the comparatively low operating frequency of 32.8 MHz, which is crucial for the integration of the RFQ into the cyclotron yoke. Beam is injected into the cyclotron central region axially through the RFQ and an electrostatic spiral inflector. The scheme of the compact high-current injector system is described with an emphasis on the technical and beam dynamics design of the newly developed split-coaxial RFQ. At a nominal beam current of up to 10 mA this will constitute a significant advancement for compact high-current pre-accelerator and bunching systems, also in view of other types of hadron accelerators. [Preview Abstract] |
Tuesday, April 20, 2021 5:33PM - 5:45PM Live |
Z07.00010: Efficient outcoupling of terahertz radiation from relativistic beam driven dielectric lined waveguides Monika Yadav, Walter Lynn, Nathan Majernik, Gerard Andonian, Oliver Williams, Brian Naranjo, Carsten Welsch, James Rosenzweig Wakefields in dielectric structures are a useful tool for beam diagnostics and manipulation with applications including acceleration, shaping, chirping, and THz radiation generation. Simulations have been conducted using CST Studio for a 10 GeV beam (with FACET-II parameters) in a slab-symmetric, dielectric waveguide. Various termination geometries were studied to effectively out-couple the THz radiation including flat cuts, metal horns, and the ``Vlasov antenna''. Simulations indicate that the Vlasov antenna geometry is optimal and detailed studies were conducted on a variety of dielectrics including quartz, diamond, and silicon. Multiple modes were excited and coherent Cherenkov radiation (CCR) was computationally generated for both symmetric and asymmetric beams. This study is important to achieve efficient outcoupling of terahertz radiation. Finally, we include witness beams to study transport and acceleration dynamics as well as the achievable field gradients. [Preview Abstract] |
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