Speaker
Description
Cold-charged particles play an essential role in interstellar molecular formation, are present in many high-precision experiments, antimatter physics, and chemistry, and are also relevant for studies on the origin of biological homochirality. In this contribution, I will describe a system based on the Matrix Isolation Sublimation (MISu) technique [1],[2] to generate and trap these species in the laboratory. After growing a thin film of Neon upon a cold (4 K) sapphire subtract, we implant different species inside this film via laser ablation of a solid target. With a heat pulse to the sapphire surface, we sublimate the solid neon at low temperatures, and the inert gas carries the particles that were confined inside the solid, producing a beam at low energies. We guide the charged particles using the magnetic field produced by two perpendicular coils and trap the particles in a Penning-Malmberg trap using low voltages (~1 V) and weak magnetic fields (~0.1 T).
We have measured energy distribution for positive and negative trapped charge particles whose peak was below 25 meV. Using an on-trap-time-of-flight scheme, we demonstrate the presence of electrons, hydrogen anions, protons, lithium cations and anions, and light molecular ions.
The hydrogen anions can be used to produce a cold sample of neutral trappable hydrogen by near-threshold photodetachment (0.754 eV). For example, a laser at 1575 nm will leave 0.2 K of recoil energy, less than the ion sample's typical temperature or energy dispersion, to the neutral H. The fraction of resulting atoms with energy below 0.5 K can remain trapped in a 1 T trap depth superposed magnetic trap and could be detected using the sensitive technique [3]. These cold H can loaded into the ALPHA [4] antihydrogen trap at CERN toward direct spectroscopic comparison of both conjugated species beyond 13 significant figures. The production is scalable and adaptable to different species, including deuterium and tritium, which is relevant for neutrino mass and fusion research.
[1] - Azevedo, L.O.A., Costa, R.J.S., Wolff, W. et al. Adaptable platform for trapped cold electrons, hydrogen and lithium anions and cations. Commun Phys6, 112 (2023).
[2] - Sacramento, R. L. et al. Matrix Isolation Sublimation: an apparatus for producing cryogenic beams of atoms and molecules. Rev. Sci. Instrum.86, 073109 (2015).
[3] - Cesar, C. L. A sensitive detection method for high resolution spectroscopy of trapped antihydrogen, hydrogen and other trapped species. J. Phys. B49, 074001 (2016).
[4] - Ahmadi, M. et al. Characterization of the 1S-2S transition in antihydrogen. Nature557, 71 (2018).
