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Details of Grant 

EPSRC Reference: EP/R025320/1
Title: Antiparticle beamline for experiments on matter antimatter symmetry
Principal Investigator: Madsen, Professor N
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department: College of Science
Organisation: Swansea University
Scheme: Standard Research
Starts: 01 February 2018 Ends: 31 January 2023 Value (£): 486,613
EPSRC Research Topic Classifications:
Atoms & Ions
EPSRC Industrial Sector Classifications:
No relevance to Underpinning Sectors
Related Grants:
EP/R025363/1
Panel History:
Panel DatePanel NameOutcome
06 Dec 2017 EPSRC Strategic Equipment Interview Panel December 2017 (1) Announced
Summary on Grant Application Form
The virtual absence of antimatter and preponderance of matter in the Universe today remains one of the biggest conundrums facing physics. Already in 1967, the famous Sakharov conditions described how this asymmetric Universe could come about by requiring symmetry violations (i.e. differences) between matter and antimatter. Until now, no sufficient symmetry violations have been found to resolve this question, thus the puzzle remains. This project aims to seek answers to this question by directly testing the supposition that atoms made of antimatter are indistinguishable from their matter counterparts.

This grant proposes the construction of a beamline which will improve the performance of the existing apparatus and enable significant expansion of the ALPHA antihydrogen experiment. In this project we have set out to apply the greatest tools of precision measurements to this problem. Our approach is to trap antihydrogen atoms, (atoms made of antiprotons and positrons), and study their internal states using spectroscopic techniques from atomic physics, the same techniques that have given us atomic-clocks, the basis for the global positioning system (GPS) and the most precise gauges in the human toolbox to date. Specifically, (ALPHA-2) we will investigate the ground to first excited state transition in antihydrogen held in a magnetic trap to test the hypothesis that the frequency of this transition is exactly the same as that of hydrogen (matter). This transition has been investigated with a staggering 15 decimal places of precision in hydrogen. In this project we plan to be the first to investigate this transition in antihydrogen, expecting around 10 decimal places of precision for this initial experiment

In the second thread of this project (ALPHA-g) we exploit our expertise in antihydrogen trapping to perform a text book measurement of the gravitational acceleration of antimatter. This is a feat that is only possible because we can use charge neutral antihydrogen: no measurements of gravitational acceleration have been accomplished on charged particles due to systematic errors arising from the size of electrostatic interactions that swamp all gravitational effects. While the fundamental symmetries discussed above both require that antihydrogen is identical to hydrogen and that there are equal amounts of matter and antimatter in the Universe (hence the conundrum), the gravitational question is of a different nature. Our current understanding of gravity relies on Einstein's general theory of relativity, which is based on the postulate that inertial (movement) mass is equal to gravitational mass. This postulate is called the weak equivalence principle. A given mass of antimatter should also obey this principle if our understanding of gravity is correct. Testing this principle experimentally is therefore of great interest to further our knowledge of gravity.

The antimatter research in this project tests the very foundations of physics, foundations that have, through decades of success, given us many insights into the physical world. In spite of these successes, we still do not understand why there appears to be no bulk antimatter in the Universe. In this project we apply the most precise tools available to physics, to look for tiny deviations from our current understanding. Past experience demonstrates that careful observation of Nature is the way to make breakthroughs and antihydrogen properties are compelling subjects because of the very specific and thus far untested predictions of their values. The risk of finding no clues on this path (though no clues would of course mean the exclusion of some optional explanations, and so are not devoid of interest) is outweighed by the spectacular and unquantifiable consequences any measured difference between antihydrogen and hydrogen would imply.
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Organisation Website: http://www.swan.ac.uk