arXiv subjects

J. Perez Garcia

Publications and source records attributed to J. Perez Garcia.

4 recordsLinked to original sources

arXiv2026

A large nonmagnetic aluminum-and-Viton vacuum chamber suitable for vacuum pressures down into the extremely-high-vacuum (XHV) regime

A recently constructed large nonmagnetic vacuum chamber is described and characterized. The vacuum chamber was machined from 19-inch cubes of aluminum and are sealed using dual Viton O-rings (with the interspace between the O-rings evacuated by a separate vacuum pump). 17-inch-diameter openings on all six sides allow for easy access to the experimental apparatus and for vacuum pumps with very large pumping speeds. These 17-inch holes were bored straight through the aluminum cube, resulting in an interior volume of 100 L (almost 90\% of the total volume of the 19-inch cube). The 17-inch openings are sealed with 19-inch-diameter aluminum flanges. The system is modular in that the cubes can be connected to one another to form larger vacuum systems. The chamber is designed to allow for vacuum pressures of $10^{-12}$ torr. In many respects (including nonmagnetic properties, outgassing rate after low-temperature baking, weight, cost, ease of machining, and ease of baking due to the chamber's high thermal conductivity) this system is superior to standard stainless-steel metal-sealed CF vacuum systems and is highly recommended for use by others.

physics.atom-ph↗

arXiv2024

Matrix isolated barium monofluoride: Assembling a sample of BaF molecules for a measurement of the electron electric dipole moment

A cryogenic neon solid doped with barium monofluoride (BaF) is created on a cryogenic substrate using a stream of Ne gas and a high-intensity beam of BaF molecules produced in a cryogenic helium-buffer-gas laser-ablation source. The apparatus is designed for eventual use in a measurement of the electron electric dipole moment (eEDM). Laser-induced fluorescence is observed from transitions up to the $B\,^2Σ_{1/2}$ state. The number of BaF molecules found to be present in the solid and addressable with this laser transition is approximately 10$^{10}$ per mm$^3$, which is of the same order as the total number of BaF molecules that impact the substrate during the hour of growth time for the solid. As a result, an eventual eEDM measurement could have continual access to an accumulation of an hour's worth of molecules (all of which are contained within a 1-mm$^3$ volume and are thermalized into the ground state), compared to beam experiments which study the molecules from a single ablation during the millisecond-timescale of their passage through a much larger-scale measurement apparatus. The number of BaF molecules observed in the doped solid matches the target value for our planned eEDM measurement.

physics.atom-ph↗

arXiv2024

Specular reflection of polar molecules from a simple multi-cylinder electrostatic mirror: a method for separating BaF molecules produced in a buffer-gas-cooled laser-ablation source from other ablation products

A method for specular reflection of polar molecules is proposed. Electrostatatic potentials and forces are calculated for a low-field-seeking molecule near a series of long cylindrical electrodes of radius $r$ with dc potentials of $+V$ and $-V$ applied to alternate electrodes. A center-to-center separation of $2.9\,r$ leads to remarkably flat equipotential surfaces and thus to a nearly planar mirror for specular reflection of the polar molecules, with the angle of reflection equalling the angle of incidence to an accuracy approaching a microradian. This mirror can be used to redirect cryogenic molecular beams. Separating barium monofluoride (BaF) molecules created in a helium-buffer-gas laser-ablation source from other ablation products is a necessary step to producing a pure sample of matrix-isolated BaF, as is required by the EDM$^3$ collaboration for implementing a precise measurement of the electron electric dipole moment. The design and modelling for the BaF deflector based on this electrode geometry is presented.

physics.atom-ph↗

arXiv2024

Optical pumping of matrix-isolated barium monofluoride: dependence on the orientation of the BaF molecular axis

Optical pumping of barium monofluoride (BaF) within a cryogenic neon matrix is demonstrated. Interestingly, with an applied magnetic field of 2~G, optical pumping is found to be considerably more efficient for a laser beam with right-circular polarization compared to left-circular polarization. Calculations show that the higher efficiency is due to a constructive versus destructive interference and is dependent on the orientation of the BaF molecule relative to the magnetic field direction. The effect leads to orientation-dependent optical pumping within the matrix. As optical pumping is the first step used in our planned electron electric-dipole moment (eEDM) measurement, we intend to exploit this property to obtain the selection of molecular orientations that is required for an eEDM measurement.

physics.atom-ph↗