Last month, the High Energy and Particle Physics division of the European Physical Society announced the 2015 prizes for outstanding contributions in the field of high energy physics. The 2015 Young Experimental Physicist Prize was awarded to Jan Fiete Grosse-Oetringhaus, a member of the ALICE Collaboration, and Giovanni Petrucciani, a CMS researcher. Jan Fiete has been awarded this year’s prize for “his outstanding contribution to the investigation of particle collisions at the LHC through the analysis of jet quenching and multiparticle correlations in the ALICE Experiment".
Jan Fiete arrived at CERN as a summer student in 2003. He was an undergraduate student at the University of Munster and though he was not yet familiar with ultra-relativistic heavy-ion physics, he decided to apply for CERN’s summer student programme given the challenges that it presented for summer students. Soon after receiving his acceptance letter, he started working with Predrag Buncic – presently the chair of ALICE’s computing board – on developing parts of the AliEn software.
Jan Fiete recalls: “I enjoyed my time as a summer student, as it gave me the opportunity to deepen my knowledge in computing, as well as to have a first-hand experience of the research done at CERN, while at the same time it offered a very stimulating international environment”. The intellectual stimulus that Jan Fiete gained from his experience made it easy to decide and apply for a technical studentship.
At that time, an interesting coincidence happened, affecting his later career in ALICE. The current ALICE Deputy Spokesperson, Hannes Wessels, had joined the University of Munster to become active in the ALICE Collaboration with his group; following their discussion about interesting physics questions they both agreed on a research strategy. Looking back, one can say that it led to a fruitful collaboration.
Jan Fiete in the ALICE Control Room during the first collisions recorded by ALICE in 2009
We asked Jan Fiete whether he faced the dilemma of moving to computer science instead of pursuing a career in physics. His answer is straightforward: “my programming skills offered me the possibility to efficiently conduct analysis of data”. The balance between the two is also reflected in his PhD thesis that combines a computing topic – the development of the Shuttle framework which extracts conditions data from the experiment needed for Offline reconstruction – with the development of the analyses for the first data of ALICE. He prepared the measurement of the pseudorapidity density distribution and the multiplicity distribution. Unfortunately, due to the LHC incident in 2008, Jan Fiete could not include the data he wished for in his thesis, but continued as a research fellow in ALICE where his pseudorapidity density measurement became the first LHC physics publication. “During the pp data-taking, I was following these topics and three papers came out shedding more light on particle production at the LHC”, before continuing with the study of more complex observables.
Jan Fiete, now a CERN staff, has contributed to important discoveries made by ALICE. He participated in the direct observation of triangular flow (v3) in Pb-Pb collisions, already suggested by data from RHIC, clearly observed by ALICE in the 1% most central collisions. Furthermore, his analysis of p-Pb collisions revealed a double-ridge structure in high-multiplicity collisions.
Such structures have been seen earlier in Pb-Pb and Au-Au collisions and are typically understood as effects of a hydrodynamic behaviour of the system. In p-Pb collisions the result came as a surprise and its origin is still under debate in the theoretical community although many see it as a strong hint for a hydrodynamical evolution also in p-Pb collisions.
More studies are needed to understand what causes this structure, and physicists working in the field are looking forward to the next p-Pb collisions near the end of Run 2. As Jan Fiete adds: “one should be patient and wait for more results that may tell us the truth”.
We hope you will join us to congratulate Jan Fiete for this distinction that also reflects the importance of the field of ultra-relativistic heavy-ion collisions and wish him the best of success in his future steps.