2021 CAP Virtual Congress / Congrès virtuel de l'ACP 2021

(G*) In situ magnetometry using electron plasmas for gravitational experiments with antihydrogen.

9 Jun 2021, 16:15

10m

Underline Conference System

Oral Competition (Graduate Student) / Compétition orale (Étudiant(e) du 2e ou 3e cycle) Nuclear Physics / Physique nucléaire (DNP-DPN) W3-6 Exotic Matter II (DNP) / Matière exotique II (DPN)

Speaker

Adam Powell (University of Calgary Dep. of Phys. and Astronomy (CA))

Description

The Antihydrogen Laser Physics Apparatus (ALPHA), at the European Centre for Nuclear Research (CERN) antiproton decelerator facility, uses low energy antiprotons in a bound state with a positron to produce and trap antihydrogen [1]. Given the long history of atomic physics experiments with hydrogen, spectroscopy experiments with antihydrogen offer some of the most precise tests of quantum electrodynamics and charge-parity-time symmetry [1]. A test of the weak equivalence principle is also on the horizon with a major addition to the ALPHA experiment, ALPHAg, aiming to measure the free fall of antihydrogen.

For the spectroscopy and gravity experiments in ALPHA, precise measurements of the magnetic field inside the apparatus are essential [2]. A technique developed in ALPHA determines the in situ magnetic fields by measuring the cyclotron frequency of an electron plasma. Microwave pulses on resonance with the electron cyclotron frequency, which is magnetic field dependent, heat the plasma [3]. A campaign to characterize the precision and accuracy of this technique in a high magnetic field gradient is required before a successful measurement of the effect of Earth’s gravity on antimatter can be made.

I will discuss recent progress made towards realising this goal using the ALPHA2 apparatus. This will include the first application of this measurement in a strong magnetic field gradient and methods used to experimentally distinguish the cyclotron frequency from a sideband structure. I will move on to show development the ALPHA Penning-Malmberg traps and microwave injection system ahead of the recommissioning of ALPHAg in mid 2021.

1. Characterization of the 1S–2S transition in antihydrogen, ALPHA Collaboration, Nature, 557, 71, (2018)
2. Description And First Application Of A New Technique To Measure The Gravitational Mass Of Antihydrogen, ALPHA Collaboration, Nature Communications 4, 1785 (2013)
3. Electron Cyclotron Resonance (ECR) Magnetometry with a Plasma Reservoir, E. D. Hunter and A. Christensen and J. Fajans and T. Friesen and E. Kur and J. S. Wurtele, arXiv 1912.04358 (2019)