arXiv subjects

Bradley W. Filippone

Publications and source records attributed to Bradley W. Filippone.

4 recordsLinked to original sources

arXiv2026

Electrode Design for a Cavallo High Voltage Multiplier in a Cryogenic nEDM Experiment

The Cavallo multiplier [http://archive.org/details/b28771035_0003] is an electrostatic inductance machine that can generate low-noise high voltages electrically isolated from its voltage input, making it ideally suited for precision experiments. Its in-situ production makes it especially useful in cryogenic experiments, where the use of traditional feedthroughs is challenging due to thermal, electrical, magnetic, and physical size considerations. One such experiment is a cryogenic measurement of the neutron electric dipole moment (nEDM) [arXiv:1908.09937,arXiv:2512.14975], which requires several hundred kilovolts on a measurement cell electrode in 0.4 K liquid helium (LHe). A Cavallo multiplier can generate this voltage by stepping up a smaller input (e.g., 50 kV) from a feedthrough. We designed Cavallo electrodes using finite element analysis to provide high voltage gain and low probability of electrical breakdown in the experimental apparatus. The final geometry achieves a gain of 18, providing a target of 650 kV with peak electric fields of 116 kV/cm distributed over small areas to limit breakdown risk.

physics.ins-det↗

arXiv2023

Electric Charging Effects on Insulating Surfaces in Cryogenic Liquids

This paper presents a new technique to study the adsorption and desorption of ions and electrons on insulating surfaces in the presence of strong electric fields in cryoliquids. The experimental design consists of a compact cryostat coupled with a sensitive electro-optical Kerr device to monitor the stability of the electric fields. The behavior of nitrogen and helium ions on a poly(methyl methacrylate) (PMMA) surface was compared to a PMMA surface coated with a mixture of deuterated polystyrene and deuterated polybutadiene. Ion accumulation and removal on these surfaces were unambiguously observed. Within the precision of the data, both surfaces behave similarly for the physisorbed ions. The setup was also used to measure the (quasi-)static dielectric constant of PMMA at T = 70 K. The impact of the ion adsorption on the search for a neutron permanent electric dipole moment in a cryogenic environment, like the nEDM@SNS experiment, is discussed.

physics.app-ph↗

arXiv2022

Electric dipole moments and the search for new physics

Static electric dipole moments of nondegenerate systems probe mass scales for physics beyond the Standard Model well beyond those reached directly at high energy colliders. Discrimination between different physics models, however, requires complementary searches in atomic-molecular-and-optical, nuclear and particle physics. In this report, we discuss the current status and prospects in the near future for a compelling suite of such experiments, along with developments needed in the encompassing theoretical framework.

hep-ph↗

arXiv2018

Cavallo's Multiplier for in situ Generation of High Voltage

A classic electrostatic induction machine, Cavallo's multiplier, is suggested for in situ production of very high voltage in cryogenic environments. The device is suitable for generating a large electrostatic field under conditions of very small load current. Operation of the Cavallo multiplier is analyzed, with quantitative description in terms of mutual capacitances between electrodes in the system. A demonstration apparatus was constructed, and measured voltages are compared to predictions based on measured capacitances in the system. The simplicity of the Cavallo multiplier makes it amenable to electrostatic analysis using finite element software, and electrode shapes can be optimized to take advantage of a high dielectric strength medium such as liquid helium. A design study is presented for a Cavallo multiplier in a large-scale, cryogenic experiment to measure the neutron electric dipole moment.

physics.ins-det↗