WesleyTerrillLetterSpring22

Dear Colleagues,

I am writing to highly recommend my student, Wesley Terrill, for your summer program. Wes is currently in his third year of a Ph.D. program at Carnegie Mellon University and has an outstanding academic record. He has completed two years of graduate courses, has passed qualifying exams, and is now based at CERN working full time on the CMS experiment.

During his first two years at CMU, Wes completed a number of rigorous graduate courses, including Quantum Mechanics, Electricity and Magnetism, Statistical Mechanics, and Astrophysics. He received high grades in these courses, placing him in the top 25% of his class and the top 10% of experimentalists. Wes went on to pass his qualifying exams, again with high marks, and was subsequently advanced to PhD candidacy.

During his first two years at CMU, Wes began working in my group on the CMS experiment. Specifically, he was tasked with developing software to monitor the CMS b-jet trigger, which involved modifying existing code to analyze new b-tagging algorithms introduced in the LHC Run-3. Additionally, he developed an algorithm aimed at increasing the b-jet purity of the monitored jets by effectively performing a real-time top-quark analysis. His work has been highly valued by the b-tagging group, and I anticipate that Wes will be selected to lead the CMS B-jet trigger group later this year.

Wes has also starting working a search for dark matter models with compressed mass spectra using soft leptons. The analysis targets models with several new particles with similar masses. Compressed spectra is a common structure seen both in the standard model and as a part of many new physics scenarios. This situation naturally arises when the overall mass of a particle multiplet is set by one scale and the splitting between states is set by a second, parametrically-larger scale. The detector signature Wes is searching for is large missing energy plus soft (low pT) leptons arising from cascade decays between particles within the multiplet. The lepton pT is set by the mass splitting between the states; low pT thresholds are thus critical to maximize acceptance to small mass splittings. Building on a previous CMS analysis, Wes is lowering the electron pT threshold from 5 GeV down to 1 GeV. Reconstructing electrons in this pT range is not standard in CMS, and Wes has had to modify nominal reconstruction algorithms and develop dedicated methods to calibrate these ultra-soft electrons.

Wes has recently moved to CERN and will focus on his CMS research full-time. In addition to his work on the b-jet trigger and the soft lepton analysis, Wes will be involved in the High-Granularity Calorimeter (HGC) upgrade project at CERN. This upgrade is being developed in collaboration with my group at CMU, which is building silicon modules for the HGC. Wes will act as our liaison to CERN and will take part in test beams at CERN and their silicon testing facility.

In summary, I believe that Wes would make an excellent candidate for your school. He is in the top 10% of graduate students I have worked with at CMU (~20) and in the top 20% of students I have worked with on ATLAS or CMS (~100) at a similar stage in their career. I was a student of the program in 2007 (in Trest) and found it to be extremely beneficial. I made some of my closest friends in the field during the program, and I expect that Wes will have a similar experience. I believe that Wes is well-prepared for the lectures and is at a stage in his career where the school will provide valuable context for his research.

Please to not hesitate to reach out for more information.

Sincerely, John Alison