arXiv subjects

Loyd Waites

Publications and source records attributed to Loyd Waites.

6 recordsLinked to original sources

arXiv2023

Axion-Like Particle Production at Beam Dump Experiments with Distinct Nuclear Excitation Lines

Searches for axion-like particles (ALPs) are motivated by the strong CP problem in particle physics and by unexplained dark matter in astrophysics. In this letter, we discuss novel ALP searches using monoenergetic nuclear de-excitation photons from a beam dump, using IsoDAR as an example. We show that IsoDAR can set limits that close a gap in traditional QCD axion searches using the ALP-photon coupling, as well as provide sensitivity to large regions of new parameter space in models where ALPs couple to nucleons and electrons. We also show how isotope decay-at-rest experiments may be designed to improve potential ALP production and optimize detection sensitivity.

hep-ph↗

arXiv2022

High Power Cyclotrons: The Bridge Between Beyond the Standard Model Physics, Computation, and Medical Applications

The IsoDAR cyclotron is a 60 MeV cyclotron designed to output 10mA of protons in order to be a driver for a neutrino experiment. Coupling the high flux generated by the IsoDAR system with a kiloton neutrino detector will provide sterile neutrino exclusion searches covering anomalous regions indicated by short baseline experiments. Simultaneously, the coupling of a high power target and kiloton detector allows for the investigation of dark matter candidates, namely axion-like particles. We have shown that nuclear excitations within the IsoDAR target create a unique opportunity to produce axions and detect monoenergetic peaks with the nearby kiloton detector. Beyond this, the high power produced by the IsoDAR cyclotron can be used for applications beyond particle physics. The IsoDAR cyclotron accelerates and extracts H$_2^+$, which allows the beam to be split downstream, a versatile and important development to alleviate the problem of producing high-power targets for the medical isotope community. This thesis presents a proposal for production of an more than an order of magnitude higher rates than are available at present for certain highly-need medical isotopes, including Ac-225. In this thesis, we report results from a multi-cusp ion source that meets these requirements and produces a record level of high purity, low emittance H$_2^+$ current. The second has been to design a radio-frequency quadrupole (RFQ) that will allow for gentle bunching of the high current before injection. This is the first use of axial direct injection with a compact cyclotron. This thesis reports the first application of machine learning to the RFQ design. These tools enable the high currents required by IsoDAR cyclotron, leading to important impact on the accelerator, medical, and physics communities.

physics.acc-ph↗

arXiv2021

Input Beam Matching and Beam Dynamics Design Optimization of the IsoDAR RFQ using Statistical and Machine Learning Techniques

We present a novel machine learning-based approach to generate fast-executing virtual radiofrequency quadrupole (RFQ) particle accelerators using surrogate modelling. These could potentially be used as on-line feedback tools during beam commissioning and operation, and to optimize the RFQ beam dynamics design prior to construction. Since surrogate models execute orders of magnitude faster than corresponding physics beam dynamics simulations using standard tools like PARMTEQM and RFQGen, the computational complexity of the multi-objective optimization problem reduces significantly. Ultimately, this presents a computationally inexpensive and time efficient method to perform sensitivity studies and an optimization of the crucial RFQ beam output parameters like transmission and emittances. Two different methods of surrogate model creation (polynomial chaos expansion and neural networks) are discussed and the achieved model accuracy is evaluated for different study cases with gradually increasing complexity, ranging from a simple FODO cell example to the full RFQ optimization. We find that variations of the beam input Twiss parameters can be reproduced well. The prediction of the beam with respect to hardware changes, e.g. of the electrode modulation, are challenging on the other hand. We discuss possible reasons.

physics.acc-ph↗

arXiv2021

High current $\mathrm{H}_2^+$ beams from a filament-driven multicusp ion source

Recently, the use of $\mathrm{H}_2^+$ ions instead of protons to overcome space charge challenges in compact cyclotrons has received much attention. This technique has the potential to increase the available beam current from compact cyclotrons by an order of magnitude, paving the way for applications in energy research, medical isotope production, and particle physics, e.g. a decisive search for sterile neutrinos through the IsoDAR experiment. For IsoDAR we go a step beyond just using $\mathrm{H}_2^+$ and add pre-bunching through a Radio-Frequency Quadrupole (RFQ) embedded in the cyclotron yoke. This puts beam purity and beam quality constraints on the ion source that no published ion source has simultaneously demonstrated so far. Here, we report results from a new multicusp ion source (MIST-1) that produces the world's highest steady-state current of $\mathrm{H}_2^+$ from this type of ion source (1 mA), with exceptionally low emittance (0.05 $π$-mm-mrad, RMS, normalized) and high purity (80% $\mathrm{H}_2^+$). This result shows the feasibility of using a multicusp ion source for IsoDAR and the RFQ direct injection prototype, and paves the way to record breaking continuous wave (cw) beam currents of 5 mA $\mathrm{H}_2^+$ (equivalent to 10 mA protons) from compact cyclotrons, ideal for underground installation. This represents a significant advance, with impact on neutrino physics specifically and high power cyclotron design in general.

physics.acc-ph↗

arXiv2018

High intensity cyclotrons for neutrino physics

In recent years, the interest in high intensity proton beams in excess of several milli-Amperes has risen. Potential applications are in neutrino physics, materials and energy research, and isotope production. Continuous wave proton beams of five to ten milli-Amperes are now in reach due to advances in accelerator technology and through improved understanding of the beam dynamics. As an example application, we present the proposed IsoDAR experiment, a search for so-called sterile neutrinos and non-standard interaction using the KamLAND detector located in Japan. We present updated sensitivities for this experiment and describe in detail the design of the high intensity proton driver that uses several novel ideas. These are: accelerating H2+ instead of protons, directly injecting beam into the cyclotron via a Radio Frequency Quadrupole (RFQ), and carefully matching the beam to achieve so-called vortex motion. The preliminary design holds up well in PIC simulation studies and the injector system is now being constructed, to be commissioned with a 1 MeV test cyclotron.

physics.acc-ph↗

arXiv2018

First Commissioning Results of the Multicusp Ion Source at MIT (MIST-1) for H$_2^+$

IsoDAR is an experiment under development to search for sterile neutrinos using the isotope Decay-At-Rest (DAR) production mechanism, where protons impinging on $^9$Be create neutrons which capture on $^7$Li which then beta-decays producing $\barν_e$. As this will be an isotropic source of $\barν_e$, the primary driver current must be large (10 mA cw) for IsoDAR to have sufficient statistics to be conclusive within 5 years of running. H$_2^+$ was chosen as primary ion to overcome some of the space-charge limitations during low energy beam transport and injection into a compact cyclotron. The H$_2^+$ will be stripped into protons before the target. At MIT, a multicusp ion source (MIST-1) was designed and built to produce a high intensity beam with a high H$_2^+$ fraction. MIST-1 is now operational at the Plasma Science and Fusion Center (PSFC) at MIT and under commissioning.

physics.acc-ph↗