Jun 18 – 23, 2023
University of New Brunswick
America/Halifax timezone
Welcome to the 2023 CAP Congress Program website! / Bienvenue au siteweb du programme du Congrès de l'ACP 2023!

Detecting Anti-Hydrogen in the ALPHA-g Antimatter-Gravity Experiment

Jun 19, 2023, 5:15 PM
15m
UNB Tilley Hall (Rm. 205 (max. 85))

UNB Tilley Hall

Rm. 205 (max. 85)

Oral not-in-competition (Graduate Student) / Orale non-compétitive (Étudiant(e) du 2e ou 3e cycle) Symposia Day (DNP - DPN) - Precision Physics and Tests of Fundamental Symmetries | Physique de précision et tests des symétries fondamentales (DNP) M3-4 Testing the Standard Model at low and intermediate energies | Tester le modèle standard à des énergies faibles et intermédiaires (DPN)

Speaker

Gareth Smith (TRIUMF (CA))

Description

Performing measurements on anti-matter atoms is an alluring proposition for studying the symmetries between matter and anti-matter; however, it presents a number of technical challenges. The ALPHA group has met these challenges and successfully trapped large numbers of anti-hydrogen atoms, opening the door for many such measurements. The new ALPHA-g experiment has the ability to measure the gravitational force exerted by the Earth on these anti-hydrogen atoms, by counterbalancing this force with precisely controlled magnetic fields. By relaxing only the confinement along the gravitational axis, the anti-atoms are released into two “up” and “down” regions separated by tens of centimetres. Here they annihilate, and the ratio of counts in the two regions describes the overall – magnetic plus gravitational – bias.
Charged pions resulting from these annihilations are tracked in a time projection chamber; these tracks are fit and extrapolated back to a common annihilation vertex. Our ability to reconstruct the position of these annihilation vertices into the correct region was previously one of the limiting factors of the experiment. Here I present the steps taken to improve our position resolution beyond that necessary for the experiment.
Furthermore, due to the low number of anti-atoms produced and slow experiment timescale, cosmic rays produce a sizeable background in our time projection chamber. To mitigate this, a second plastic scintillator-based detector system was implemented, called the “barrel veto”. This was used to discriminate against the cosmic ray background based on event topology in the first data-taking run in 2022. It has the additional possibility of using time-of-flight to further identify background events. Here I present the usage of the barrel veto to reject the cosmic ray background, and demonstrate the overall effectiveness of the ALPHA-g detector system.

Keyword-1 ALPHA
Keyword-2 Anti-hydrogen

Primary author

Gareth Smith (TRIUMF (CA))

Presentation materials