My two weeks with CMS

Guest post by Daniele Doronzo. "Daniele is an eighteen-year-old high-school student from Italy, who came to CERN for a two-weeks internship with the CMS team. He recounts his experience below. Those of us who met him were charmed by his enthusiasm." – Gabriella Pugliese, CMS

Daniele in front of the CMS detector


Looking outside my airplane window, seeing Geneva replace the vista of alpine glaciers, I suddenly began to distinguish the well-known underground path of the Large Hadron Collider (LHC) – lying between Lake Geneva and the Jura mountains. It suddenly dawned on me that, regardless of how much I had attempted to prepare myself for my two weeks internship at CERN, I was about to confront much bigger things than I had imagined.

Upon my arrival physicist Marcello Maggi picked me up at the airport and my preconceptions about this experience vanished, as the feelings I had had on the plane turned out to be true. Being driving in green-plate diplomatic cars multiple times a day, crossing the Swiss-French border to the experimental sites and laboratories, sitting next to Nobel laureates at lunch, or simply going from one building to another spread out much like a city, is not normal for most people. On the contrary, you are likely to feel dazed, just as I did when Marcello pointed out Samuel Ting to me in the central car park. My bewilderment turned into enthusiasm, as I received my badge; seeing the CERN symbol alongside my face and name somehow cemented the reality of me having arrived and being part of a very different world for two weeks.

I then had one of the most interesting lunches of my life, not because of the fish obviously, but because of the conversation. “Why do you need to detect muons? After all, they are not the most cutting edge physics right now,” I asked Marcello. “Because they provide us with a clear signature that is often a sign for interesting physics,” he replied, engaging in an hour-long explanation of various things ranging from symmetry breaking in the very first instants of our Universe and the Higgs mechanism to the prevalence of matter over antimatter.

“A Higgs can decay into a di-boson and then into four high-energy muons. That’s why we need them.” I will always remember this as one of the most incredible sentences I have ever heard, because it led me to reflect on my previous assumptions on how scientific research is conducted and how difficult it may be; it involves a lot more intermediate steps than you usually learn in a high-school science class. One of these involves organising data and this is what I engaged in after my first visit to Point 5 in Cessy, where the CMS detector lies 100 metres below the control room. This is where Marcello showed me the Web Based Monitoring (WBM) of the 912 Resistive Plate Chambers (RPC) held within the barrel and endcaps of the “cylindrical onion” for a total surface of 3500 m2 and 110,000 electronic channels. After having me download the raw data in text form from WBM, Marcello challenged me to arrange UNIX times and high voltage (HV) data in a plot programmed from the ground up. This actually marked the beginning of my Python odyssey, at the end of which I even mastered advanced topics in this powerful language and one of its graphing tools.

By the end of my first week, I got to do my first full shift alongside PhD student Andres and physicist Anton Dimitrov, who taught us about the Detector Control System (DCS) of the RPCs after the run meeting we had attended. It was very exciting to actually monitor the commissioning of the whole CMS detector during the global runs and learn about the trigger system for which RPC does a wonderful job. Moreover, I spent many hours discussing the next aims of the restless hunt for new particles at CERN. Andres is interested in Vector Boson Fusion (VBF) processes – involving the likely observation of SUSY particles – and he is looking forward to collecting data in the LHC's Run 2, starting in the spring of 2015.

The second week of my internship coincided with both the CMS Upgrade Week and the celebration of CERN's 60th anniversary. I had the opportunity to attend several meetings about the High Luminosity LHC (HL-LHC) – giving me an insight into CERN projects – alongside colloquiums, lectures and seminars. On one day I even got to attend two lectures in different languages, the former in English and the latter in French, about particle accelerators and their applications by Dr. Philippe Lebrun. In particular, I found the one about quantum communication and computation, given by Wolf laureate Anton Zeilinger, fascinating. It was of great personal satisfaction for me to raise questions to him, the answers to which kept me up reading till late at night, in order to understand as much as I could about the complex material.

There were many memorable lunchtime discussions with everyone – from doctoral students to theoretical physicist John Ellis – about the most recent findings in particle physics and its applications. Furthermore, thanks to physicist Gabriella Pugliese, I had the occasion to attend meetings about RPC and even visit the Gamma Irradiation Facility (GIF) that has been used for 15 years to simulate the effects of aging on the detectors.

On my final working day at CERN – after having completed all the necessary courses and getting my dosimeter – I finally joined Gabriella to descend 100 metres underground and see the majestic CMS detector: a horizontal seven-storey device, heavier than the Eiffel Tower, with a solenoid generating 100,000 times the Earth's magnetic field, and several million cables packed in gigantic racks. Not to mention the mainframe made up by thousands of computers, roughly the same size as my laptop, each boosted by 64 processors. It was so exciting seeing CMS physicists working hands-on on the two chambers that experienced minor errors during my shift!

At the end of the day, I have to admit that CERN is unlike anything I expected. For as unusual and spread-out as it may seem at a first glance, after two weeks that I thoroughly enjoyed, I found it to be permeated by a very strong force. Not one of the four they are trying to put together here, but a more macroscopic and thus human one: the passion for physics. Everybody who shares it is welcomed to join and this creates a place that is “warm” somehow; so much so that even an eighteen-years-old high-school student like me feels like he belongs.

I would also like to thank physicists Dave Barney of CMS and Fabiola Gianotti of ATLAS for valuable and enjoyable conversations, and my supervisors Marcello Maggi and Gabriella Pugliese to whom I shall always be grateful.

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