Enhanced antihydrogen trapping for fundamental tests

Lead Research Organisation: Swansea University
Department Name: College of Science


Why does the visible universe contain almost no antimatter even though in the beginning an equal amount of antimatter and matter formed? In the ALPHA experiment at CERN we are looking for a solution to this conundrum by studying the minute details of antihydrogen, the antimatter counterpart of the most abundant element, hydrogen. In this project we will provide support to precise measurements on trapped antihydrogen which are then conducted as a team to allow a comparison with results obtained in hydrogen. According to the basic tenets of the most successful theories in physics, the properties of antihydrogen and hydrogen should be the same. Our results can confirm this prediction to a spectacular precision, but should we in our experiment find a difference, we might point the way to finding a clue to solving the antimatter conundrum.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509553/1 30/09/2016 29/06/2022
2003689 Studentship EP/N509553/1 01/01/2018 29/06/2021 Patrick Mullan
Description The Penning-Malmberg trap is one of the most common tools used in the field of antihydrogen physics research. The trap uses a combination of magnetic and electric fields to confine charged particles. The charged particles confined in the Penning-Malmberg traps of the ALPHA-experiment are electrons, positrons (anti-electrons) and antiprotons which are used to synthesise antihydrogen. Antiprotons with low enough energy to be confined in the trap are provided by CERN's Antiproton Decelerator, with limited beam-time to each user experiment. Due to the scarcity of antiprotons, capture, storage and transport in the experiment must be efficient. In the ALPHA-apparatus antiprotons are captured in one Penning-Malmberg trap and then transported to other traps for further manipulation. This process suffers from losses. If a diagnostic involving charged test particles more abundant than antiprotons is available, then preparations to reduce transport losses can be done prior to receiving antiprotons. For charged particles to be confined in this type of trap on long time scales, the internal pressure must be very low, which further places restrictions on connecting new particle sources. In this work, we investigate creating cold charged plasma of particles with a similar charge-to-mass ratio to the antiproton from the residual gas without modification of the apparatus. The plasma can then serve as a source of test particles with well-defined properties. Our first candidate for a suitable test particle to replace the antiproton is the (negative) hydrogen anion. A group based in San Diego, California, United States of America was successful in producing hydrogen anions from the molecular hydrogen in the residual gas in their room-temperature Penning-Malmberg trap by electron collisions. Repeating this study in the cryogenic trap of the ALPHA experiment by similarly using an electron plasma to generate hydrogen anions was attempted but ultimately proved unsuccessful possibly being due to the very low pressure in a cryogenic trap. The second candidate is the proton. Similarly, this relies upon the residual molecular hydrogen gas. An alternating electric field is applied onto a trapped electron plasma. This causes electrons to interact with the residual gas in such a way that ions are generated as a mixture of different species forming a plasma. Currently, purification of the protons from other ions in this plasma is under investigation.
Exploitation Route With the condition that this development of this proton generation technique is successful, such a proton source can be used in the ALPHA experiment to diagnose antiproton like transport between traps. This could also be used as a possible source for hydrogen production, whereby protons are mixed with electrons to recombine into hydrogen atoms. With further developments in fluorescence detection hardware in high magnetic fields, this could lead to precision hydrogen spectroscopy in Penning-Malmberg traps.
Sectors Other

Description ALPHA Collaboration 
Organisation European Organization for Nuclear Research (CERN)
Department ALPHA Experiment
Country Switzerland 
Sector Public 
PI Contribution I have taken part in shift work during experimental periods. This consists of operating and maintaining the two experimental apparatuses ALPHA2 and ALPHAg. During non-shift work periods, I have been fixing/replacing/assembling hardware used in both experiments.
Collaborator Contribution The collaboration gave me access to use their ALPHA2 apparatus, allowing me to take measurements. The members of the collaboration provided me with the technical knowledge and training to operate the hardware, along with insights into interpreting the various diagnostic tools available for measurements.
Impact None
Start Year 2018
Description CERN Open Day 2019 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact I was involved in distributing virtual reality hardware to the public. Along with aiding them when using the device. This was a two-day activity, lasting 8 hours each day.
The virtual reality hardware allowed the viewer to experience 3D videos, in which the purpose of the CERN facility was described and promoting interest in physics research.
Year(s) Of Engagement Activity 2019
URL https://home.cern/news/news/cern/cern-open-days-explore-future-us
Description Various tours in the Antiproton Decelerator facility 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Schools
Results and Impact This is normally be carried out with a group of 12 people. The activity involves me discussing the purpose and motivation of the Antiproton Decelerator facility. Followed by bringing the group around the facility, trying to discuss some basic physics of how in principle the facility operates. While showing them the actual decelerator ring. This usually ends with the group being brought to the region of the building where I work. This allows me to explain the research output of the collaboration I participate in. And of course, during the tour, I attempt to answer any questions raised by members of the group.
This is intended to promote awareness of this niche field of physics research that has a large physics output. Along with generally increasing interest in physics.
On separate occasions, I have given tours to school groups, the British Ambassadors to Switzerland and various postgraduate and undergraduate students.
Year(s) Of Engagement Activity 2018,2019