The Spectroscopy of Antihydrogen

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

Abstract

Understanding and explaining the origin and evolution of our Universe has been at the heart of scientific endeavour for centuries. Recent decades have seen spectacular advances, as particle physics and cosmology have combined to provide the beginnings of a coherent picture. Our Universe seems to have been born in a cataclysmic event called the Big Bang, and has continuously evolved over the 13-14 billion years since then. Though much of the visible Universe can be explained, there are still many very profound mysteries, and none more so than that posed by the existence of antimatter.Simply put, antimatter remains a mystery to Physics. Whilst the symmetry of the laws of nature, and in particular quantum mechanics, demands its existence, the Universe appears to be composed entirely of matter. Addressing this conundrum is one of the great challenges of basic science. As the hot Universe cooled shortly after the Big Bang it appears that all of the antimatter vanished, leaving a tiny excess of matter. At one part in a billion, this doesn't sound much, but the entire material Universe is created from it. The problem is we don't understand how this came to be. There are asymmetries in the behaviour of matter and antimatter, but they are too small by many orders of magnitude to account for the existence of the Universe. One way to address this problem, and the way we have chosen, is to study the antihydrogen atom - the building block of antimatter, and an atom that the Universe never got the chance to make. Recent years have seen great progress in our capabilities with low energy antiparticles (antiprotons and positrons). We can routinely collect many of them in vacuum and store them until we are ready to gently mix them to form antihydrogen under very controlled conditions.Although this capability has opened up great opportunities, there is still much work to be done before the properties of antihydrogen can be compared to those of hydrogen. In this project we will begin along this road by performing a series of experiments on antihydrogen atoms which we have manufactured and trapped in a special device. The apparatus has several parts, but the most important is a trap which can hold neutral species, such as antihydrogen. The trap is formed by magnetic fields from a complicated coil arrangement that forms a magnetic field minimum in the centre of the antihydrogen production region. Antihydrogen, like hydrogen, has a tiny magnetic moment - think of the orbiting positron as a minute current loop - which means that the energy levels shift in an applied magnetic field. Those atoms whose potential energy increases in the field will prefer to sit at the magnetic field minimum, and will be trapped.The depth of the trap is very shallow, just below the equivalent of one degree Kelvin, so we have to make our anti-atoms under very controlled conditions. Once they are trapped we will shine photons on them to interrogate their internal structure. First experiments are likely to be with microwaves, which will help us to compare with the famous 21 cm line of hydrogen. Eventually we will be able to shine laser light onto the antihydrogen.If any differences between the properties of hydrogen and antihydrogen are found, we will have discovered new physics, and perhaps come some way along the road to discovering what happened to antimatter in the early Universe.

Planned Impact

Direct academic beneficiaries have been covered elsewhere. Other beneficiaries include the stakeholders in the research and the students and staff who participate in the research. An important UK stakeholder is the EPSRC itself. Concerning publicity for the results of the antimatter research it has sponsored, in the past the interaction between investigators and the EPSRC has, by and large, been weak. Establishing more formal links between the investigators/University marketing groups might prove beneficial. Direct benefits accrue from the output of trained personnel. At postgraduate level, students are given a unique opportunity to interact with physicists from a range of sub-disciplines and to work for extended periods at CERN, the world's flagship physics laboratory. The strict scheduling and attention to detail required for the demanding antiproton shift work gives these students an edge to their repertoire of skills. They are also given the opportunity to develop leadership skills at an early stage of their career, as they are often entrusted with the charge of sub-tasks to be used by the collaboration. PDRA's are given a great opportunity to develop leadership skills. Significant sub-tasks are delegated to them, and they are given the chance to lead individual shifts and eventually to assume a temporary run coordinator position, where they are responsible for delivering the agreed scientific/technical milestones of the collaboration over a period of typically 1-2 weeks. Public interest in antimatter continues to be high. Given that grand societal aims are to raise the public awareness of what scientists do, and why, and to promote science to school children as offering a potentially exciting and fulfilling career, it would appear that our work can be of benefit here. Members of the Swansea and Liverpool teams are active in outreach in the UK. Talks on antimatter are frequently given to local scientific and astronomical societies as well as to organisations such as IoP Branches and University Physics Societies. Charlton has addressed groups of physics school teachers on several occasions and he is also on the Board of the Welsh Stimulating Physics initiative. Van der Werf is a STEM Ambassador connected with the Techniquest Science Discovery Centre, based in Cardiff. We will continue to develop these links. In particular, the Swansea-based Welsh Institute for Mathematical and Computational Sciences is the Welsh spoke in the new National HE STEM Programme, which is coordinated from Birmingham University. The roll-out of this Programme is just beginning such that there are great prospects for enhanced engagement and collaboration.

Publications

10 25 50
 
Description During the grant period: The Spectroscopy of Antihydrogen, progress towards the ultimate goal of testing CPT using the 1S-2S transition in antihydrogen, and measuring its acceleration in a gravitational field has been made. We have improved the trapping and trapping lifetime (put to 1000 s) of the antiatom and were able to make a resonant quantum transition: using microwaves to flip the spin of the positron so to change the antihydrogen atom from a trapped to an untrapped state. Moreover, we have been able to develop new technique to measure the gravitational mass of antihydrogen and obtain a first result. We also developed a lot of experimental techniques to manipulated and cool positron and antiprotons clouds. At Swansea we developed a theory explaining the effect of a rotating dipole field on a positron plasma and a technique to manipulate the magnetron orbit of a positron cloud in a Penning trap. Furthermore, we have been able to excite positronium from the 1S to 2P state, leading the way to Rydberg excitation, and possibly to colder antihydrogen production.
Exploitation Route Our findings have been essential to make progress in checking fundamental physics theories and both other antihydrogen collaboration and theoretical physicist have been very interested in our results so far.
Sectors Other

URL http://cern.ch/alpha
 
Description Our findings have been used by many scientists to justify theoretical and experimental work in number of areas of basic physics. Organisations such as CERN and our institutions have used our work to promote their respective missions, and in the public understanding of science.
Sector Other
Impact Types Cultural

 
Description CERN teachers programme for welsh teachers
Geographic Reach Local/Municipal/Regional 
Policy Influence Type Influenced training of practitioners or researchers
Impact The welsh teachers programme at CERN, spear headed by Swansea in collaboration with Lynn Evans (former head of the LHC programme) highlighted the need to enthuse physics teachers in Wales. Funding for this programme and others has now been granted by the Welsh government under the NNEST umbrella.
URL http://gov.wales/newsroom/educationandskills/2017/welsh-teachers-return-from-cern-to-teach-what-matt...
 
Description Published Book " Trapped Charged Particles - A Graduate Textbook with Problems and Solutions"
Geographic Reach Multiple continents/international 
Policy Influence Type Influenced training of practitioners or researchers
Impact The book is used as reference material at the winter schools on "Physics with Trapped Charged Particles", the next of which will be hosted in january 2018 (the previous one was in 2015). These schools reach primarily European level post-graduates (Ph.D. students and young researchers), with a few intercontinental participants (US / Asia / Brazil). We have received good feedback on this. No further quantitative feedback available at this time.
 
Description Published Book "Trapped Charged Particles A Graduate Textbook with Problems and Solutions"
Geographic Reach Multiple continents/international 
Policy Influence Type Influenced training of practitioners or researchers
Impact We have used the text book at our winterschools on Physics with Trapped Charged Particles in 2015 and 2018 and will use it again in 2021. The students have expressed much appreciation for the quality of the book - and I'm aware of at least one lecturer who is basing their lecture-course on the book.
 
Description EPSRC Standard Grant (Responsive Mode)
Amount £3,824,192 (GBP)
Funding ID EP/P024734/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 03/2017 
End 03/2021
 
Description Probing the Rydberg levels of Positronium - Research Fellowship
Amount £41,138 (GBP)
Funding ID RF-2012-495 
Organisation The Leverhulme Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 10/2012 
End 09/2014
 
Title SDR-EVC 
Description We have successfully combined the known techniques of Strong Drive Rotating (SDR) wall and Evaporative Cooling (EVC) to develop a new technique that we have dubbed SDR-EVC. The technique allows tailoring non-neutral plasmas held in Penning traps on all their parameters except their temperature (i.e. you can tailor their number, density and size). The technique is particularly useful in connection with use of positrons, as it allows one to stabilize the number of particles for experiments with positrons, that are often accumulated in a fashion that cause some fluctuation in the number, density and size of what's accumulated. 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? Yes  
Impact This new tool has assisted in the development of new techniques for trapping antihydrogen that has allowed an order of magnitude increase in the rate at which we can trap antihydrogen. It has also been of great use for allowing us to accumulate antihydrogen a trap and thus reaching much larger numbers than hitherto possible. Finally the stability it engenders has made the experiments on antihydrogen more reliable and reproducible facilitating a number of recent breakthroughs in antihydrogen physics. 
 
Description ALPHA 
Organisation European Organization for Nuclear Research (CERN)
Department ALPHA Experiment
Country Switzerland 
Sector Public 
PI Contribution We have provided 20 years of leadership to antihydrogen research. We have provided expertise in positrons and positron accumulation, trap physics, atomic physics, laser physics, laser-cooling, plasma physics, cryogenics and vacuum technologies.
Collaborator Contribution Partners have provided funding and manpower and expertise in plasma physics, detector physics, analysis, laser physics, particles physics, atomic physics and physics simulation.
Impact Essentially all my outputs in the last 15 years are due to work with ALPHA. ALPHA is multi-disciplinary by nature, as we have to bring together very diverse fields of physics to do research on antihydrogen. The fields covered are accelerator physics, atomic physics, laser physics, detector physics, particle physics, plasma physics, fundamental physics as well as vacuum technology, detector technology, cryogenics and super-conducting magnet technology to mention the most prominent ones.
 
Description ALPHA Collaboration 
Organisation European Organization for Nuclear Research (CERN)
Department ALPHA Experiment
Country Switzerland 
Sector Public 
PI Contribution As co-founders of the collaboration, we have provided funding and expertise in multiple areas of key importance to this experiment : Super conducting magnets, Lasers, Plasma physics, Trap physics, Antiproton physics, Antitrapping, Positrons, Positron accumulation, Cryogenics.
Collaborator Contribution Partners and expertise (in parenthesis) are come from Brazil (Lasers), Canada (Detectors/DAQ), Denmark (Lasers, Antihydrogen), UK (Detectors, Plasma physics plus the above), US (plasma physics, Simulation). The contributations are estimated based on 10 year running of the experiment with 30 academics contributing cash for running and maintenance and about 20 FTE's per year of running plus 3M of contributions of kit.
Impact This is an enormously successful collaboration having resulted in 4 Nature papers and a large volume of other papers as well as heavy representation in the media. It is physics-multidisciplinary in that the collaboration spans several normally separate areas of physics : cryogenics, plasma physics, atomic physics, particle physics, fundamental physics, laser physics, positron physics, and spectroscopy
Start Year 2006
 
Description CERN 
Organisation European Organization for Nuclear Research (CERN)
Country Switzerland 
Sector Academic/University 
Start Year 2006
 
Description Antimatter Lectures and Tours at CERN 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Schools
Results and Impact I give antimatter related lectures on a regular basis for school groups from Wales, UK, Denmark and Finland. Typically I entertain a about 300 pupils per year this way. The lectures are followed by guided visits to the experiments, in particular the ALPHA experiment where UK is a lead contributor.
I have many repeat visits (same teacher, new students) - and both teachers and students give very enthusiastic feedback from these visits.
Year(s) Of Engagement Activity Pre-2006,2006,2007,2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018
 
Description Antimatter Matters exhibition at the Gravity Fields Festival in Grantham 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact The Antimatter Matters Royal Society Exhibition was moved to the thirds gravity fields festival and participated in the activities in the Guildhall.
Year(s) Of Engagement Activity 2016
URL https://www.gravityfields.co.uk/CHttpHandler.ashx?id=17942&p=0
 
Description Article in Advances Wales (Welsh Government) 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact I participated in an article in Advances Wales showcasing our antihydrogen research.
Year(s) Of Engagement Activity 2016
URL https://businesswales.gov.wales/sites/business-wales/files/documents/Advances%2079%20final.pdf
 
Description CERN Open Days 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 Our experiment played a key role in antimatter outreach for the CERN open days in September 2019 that has more than 70'000 visitors.
We showed people around at the experiments and discussed the physics applied, the motivations and the outlook. We had many interesting discussions with the general public ranging from age 12 to 80.
Year(s) Of Engagement Activity 2019
URL http://opendays.cern/
 
Description CERN Open Weekend: 2 talks about Antimatter 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact A large number of question after the talks

I don't know
Year(s) Of Engagement Activity 2013
 
Description Christmas lecture in Aberystwyth 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact I was invited to give a "fun and educational" Christmas lecture of a group of local schools (sixt form / A-levels) at Aberytswyth University.
Year(s) Of Engagement Activity 2018
 
Description Guided Tours for High School Students, Visitors 
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 Guided tours are given to groups of 10's of students (6th-form and older), as well as the visiting public and professionals. Tours often spark discussions about fundamental physics and the nature of the universe. Professionals in, for example the IT industry, are always interested in seeing applications of their products. Public visitors are often surprised at the differences between "real" physics experiments and the portrayal in the media.

Nothing specific, though school groups have followed-up with requests for informational slides.
Year(s) Of Engagement Activity 2006,2007,2008,2009,2010,2011,2012,2013,2014
 
Description Hosting schools at the Antimatter Factory (both for visits and presentations) 
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 Schools
Results and Impact We should around about 30 school classes per year with about 30 students in each in the experiment. Many of them also enjoy an introductory presentation about our experiments. The feedback is always very positive to the likes of "the antimatter visit was the best part", and the teachers report really positively about it. We therefore have a number of Schools who return annually or bi-annually and pre-emptively contact us to exactly get the "antimatter experience".
Year(s) Of Engagement Activity 2012,2013,2014,2015,2016,2017,2018,2019
 
Description Lecture at E2PHI for French Highschool teachers 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact I was invited to present our activites at a summer school for french high school teachers. About 200 teachers from all of France participate in this week-long school and I had incredibly positive feedback from them. Since the school 3 of the teachers have brought their classes to CERN specifically asking for a tour and introductory talk by myself.

As mentioned above. This has caused an additional number of visits to our lab.
Year(s) Of Engagement Activity 2013
URL http://e2phy.in2p3.fr/2013/
 
Description Lectures at Aabenraa Gymnasium (Denmark) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact My presentation sparked many questions and was very well received.

I expect several students to go further towards studying physics at university as a result of my presentation.
Year(s) Of Engagement Activity 2013
 
Description Lectures at Lycée des Glières in Annemasse (France) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact My presentations sparked a lot of interest with the students and I had several stimulating discussion with the most interested students after the talk.

Nothing specific. But I expect that the interest in physics has been heightened by my presentations.
Year(s) Of Engagement Activity 2014
 
Description Manchester Science Festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact As part of the Manchester Science Festival the royal society invited us to present our Antimatter Matters exhibit. This was a great opportunity to reach further audiences with this activity that we had already tuned for schools and the general public.
Year(s) Of Engagement Activity 2016
URL https://royalsociety.org/science-events-and-lectures/science-exhibition-manchester/exhibits/
 
Description Royal Society Summer Science Exhibition 2016 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact We presented the stand "Antimatter Matters" at the Royal Society's Summer Science exhibition in London in 2016. This certainly was an eye-opener for all the very appreciative visitors.
Year(s) Of Engagement Activity 2016
URL https://royalsociety.org/science-events-and-lectures/2016/summer-science-exhibition/
 
Description Royal Society Summer Science Exhibition : Antimatter Matters 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact In collaboration with about 10 other UK institutions members of the LHCb collaboration at CERN the UK ALPHA members (Swansea, Liverpool and Manchester) organised (Responsible organisers Prof. N. Madsen (Swansea), C. Lazzaroni (Birmingham), T. Shears (Liverpool) and C. Parkes (Manchester)) a stand/exhibit at the annual Royal Society Summer Science Exhibition. This is a competition based invitees-only exhibition (i.e. you compete to get invited to exhibit) and it's very professional (in both presentation and organisation).
A great number of schools visit the exhibit and also many members of the general public. A number of special events were also hosted,with MEP's as wells FRS.
The RS and well as ourselves collected feedback from participants who greatly appreciated and reported increased interest in science thanks to our exhibit.

We continue to tour the exhibit at various UK science events - so more events will be reported here.
Year(s) Of Engagement Activity 2016
URL https://royalsociety.org/science-events-and-lectures/summer-science-exhibition/exhibits/antimatter-m...
 
Description Royal society summer exhibition 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Exhibition about physics at CERN
Year(s) Of Engagement Activity 2016
 
Description School visits to Antimatter Factory with tours and presentaitons 
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 Schools
Results and Impact We engage with school classes coming to CERN to visit the Antimatter Factory though presentations and tours of the facilities. This is a good opportunity for them to add some spice to their education and they often ask pertinent questions and express much appreciation for in particular the antimatter part of the programme.
Year(s) Of Engagement Activity Pre-2006,2006,2007,2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018,2019,2020
URL http://visit.cern/tours
 
Description Times Cheltenham Science Festival: Particle Physics: An Introduction" co-presented with Dr Tom Whyntie 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact A number of questions after the talk were answered

None
Year(s) Of Engagement Activity 2013
URL http://www.cheltenhamfestivals.com/science/whats-on/2013/particle-physics-an-introduction/
 
Description Welsh and UK teachers programmes @ CERN 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact In collaboration with CERN's teachers programmes I deliver presentations and discussions on the subjects of our research (Antimatter) to UK high school teachers. Each year there are currently three teachers programmes (one week each, with about 25 participants) of which one has been focussed on physics teachers in Welsh Schools (A and AS levels).
These programmes help enthuse teachers to bring modern and contemporary physics into the class room as well as show them how they can bring their own students to CERN in an effort to highten their interest in STEM subjects.
In collaboration with CERN we have received very very positive feedback on this.
Year(s) Of Engagement Activity 2016,2017,2018,2019
URL https://home.cern/students-educators/teacher-programmes
 
Description Winter School on Physics with Trapped Charged Particles 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact In collaboration with Profs. Richard Thompson and Martina Knoop of Imperial College London and Aix-Marseille Universities respectively I have organised and chaired a winter school on physics with trapped charge particles in January 2012, 2015 and 2018. Each school is 10 days long with presentations and workshops by internationally recognized leaders in the field give to about 55 participants who are mainly Ph.D. students and some PDRAs. The school has been a great success each time and we will repeat it in January 2021. So far only limited external support has been received for this but we're organising it that L'ecole de Physique des Houches, which is a sort of charitable organisation for physics events.
Year(s) Of Engagement Activity 2012,2015,2018
URL http://indico.cern.ch/event/315947/