Science

Particle physics – nine to five

Science talks to Chris Tuckley, a summer research student at CERN about a typical day at the “office” of the world’s leading particle research laboratory

How did you get involved with CERN?

I applied for their annual summer student program, but in the end I cancelled my application for this as I had got an offer to work with a group from Purdue University (Indiana, USA) through a professor at my old university who spends a lot of time in CERN.

 

What department/project did you work on?

I was part of the Purdue University CMS group. This group work as part of the CMS collaboration, analysing data from the Compact Muon Solenoid experiment. CMS is one two large multi-purpose detectors on the LHC, although there are seven experiments in total, with four large detectors.

Within each experiment (by experiment I mean detector) there are many “sub-departments” which look at more specific events in the detector – this is especially true in CMS and ATLAS. One of these “sub-departments” concerns quarkonia, which is the study of bound quark matter.

[…] We look at things like quark-antiquark bound states, where a quark and its anti-particle are “orbiting” one another in its bound state. One of these particles is known as an Upsilon particle. This consists of a b-quark and anti-b-quark. My group specialises in the study of these particles, and my work concerned them too.

What did your day to day jobs include?

To carry out the analysis I used a programming framework called ROOT, developed at CERN, along with an additional package called RooFit (developed at Stanford). So the actual programming I did was in C++ and over my time there I wrote about 25,000 lines of code. But obviously just writing the code isn’t good enough, you need to be able to interpret the results you get back and find where any problems in the data you get may lie.

 

How long were you there for? 

I lived in Geneva for about three months, but am still helping in the finishing touches to the analysis and the preparation of it for publication.

What attracted you to work for them?

They’re one of the most advanced scientific research labs in the world, and now is an especially exciting time to be there. I didn’t need much persuasion to go there!

 

Have you always been interested in this branch of science?

Originally I was more interested in astronomy and astrophysics, and just a year before my time at CERN I worked for the European Space Agency, but during my last undergraduate year of university I became more interested in more theoretical work (especially in high energy physics), mostly as a result of my project.

How did it feel to be part of such an immense organisation?

Humbling. It’s quite nice to think that you’re part of an organisation where around 10,000 people work from approximately 100 different countries. Although the admin difficulties can get a bit wearisome sometimes!

 

How was it to work with such distinguished scientists, engineers and leading thinkers?

They always keep you on your toes. You’re expected to work very hard if you manage to get there.

 

Are there any moments that particularly stand out when you think of your time there?

Visiting CMS itself was incredible. The magnet was still on when we went in the cavern, so all electrical items as well as credit cards, watches etc. had to be left outside to avoid breaking them.

The magnetic field was strong enough to make small keys float up to point at the detector and make coins stick to each other (one person got some to stick together edge-to-edge and then they rolled over each other until they made a line pointing at the detector). This is even though the maximum magnetic field outside the detector is about 1/10,000th that inside the detector.

The room is also at a lower temperature and pressure than normal, so the whole sensory experience in there was fantastic. You also have to pass through an airlock to get in which is designed to only let in one person at a time (it detects footfall, outlines of people and scans your iris) so that no-one can be left in the cavern when the LHC’s turned on.

 

Would you encourage other scientists to get involved with the organisation?

Definitely, it’s a great place to work. And the nearby mountains are a good way of getting away from it all over the weekends!

 

CERN is a non-profit organisation. Do you think the working atmosphere would be different if there was a more commercial aspect to their work?

Undoubtedly. With commercial considerations comes even more bureaucracy and admin-related headaches (and there’s plenty of admin to consider as it is!). At CERN (at least among lower level staff) there’s a satisfying sense of not having to worry about external politics of funding etc., so one can focus on the work more.

What are your future career aspirations?

Touchy topic here; I would love to become a physicist. However, due to several factors it’s not a viable career option for me in the current climate. The recent budget cuts to science funding, although not as severe as they could have been, resulted in a massive cut in the number of post-doctoral research positions in the UK (so that large subscriptions to things like ESA, CERN, ESO, etc. could be maintained). However, the number of PhD studentships remained comparatively constant.   While this isn’t necessarily a problem in itself, as many physics and maths PhDs go into finance careers anyway, I certainly wouldn’t like a career in finance.

There is also the option of going abroad, which I have seriously considered having been offered a PhD in the USA, but this too doesn’t suit me. Further to this there’s the inherent assumption that one is prepared to have to move around the country (or even world) every 3 years to a different post-doc, being unable to settle down until the age of ~35-40 and have no job security beyond your current postdoc until this age either.

For me it’s too much of a risk so I have decided to pursue other career options.

 

Tuckley on the search for the Higgs boson and the exclusion of the minimal version of Supersymmetry:

The Higgs absence isn’t a problem until the Higgs is excluded altogether. And even then the LHC will soon explain its absence.

[The Higgs] is not absent until the full mass range has been excluded. At the moment about 80% of the mass range has been, but the remaining 20% might still contain the Higgs. However, if it is fully excluded it would mean that our current ideas of how particles gain mass is wrong. However, the LHC will probe energies at which the alternative mechanism (whatever it may be) will show up.

A more significant, confirmed problem is the exclusion of the Minimal Suspersymmetric extension to the Standard Model (MSSM). Supersymmetry (SUSY) is a rather nice theory which explains many phenomena which the Standard Model (SM) cannot (for example, dark matter).

In SUSY models each SM particle has a supersymmetric partner, which differs from the SM particle in spin and mass alone. Although most SUSY particles would be very unstable and decay in very short times, the lightest supersymmetric particle is stable. This is usually taken to be a neutralino. This neutralino would only interact through the weak and gravitational interactions, and thus makes a very good candidate for dark matter.

 

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