Sam Hobbeheydar Rec Letter

Q: The committee wondered if you could also speak a bit on Sam's graduate program of choice at Cambridge. For instance, what is your professional opinion on his "fit"/how his future career would benefit from his chosen program and research direction?

A: Cambridge good fit: they strong ATLAS group that is well matched to Sams hardware and analysis experinnce. I have spoke with the head of the ATLAS group at Cambridge Prof Potter (who I know from my time on ATLAS) She is impressed with Sams expertiice and excited for him to be a part of the Cambridge group

Q: Any commentary on the alignment of his skill set and future goals with his chosen graduate program, or any other thoughts about Sam's potential for succeeding in graduate school at Cambridge, could be a compelling addition.

A: Sam will excell at graduate school in Cambridge. He is prepared and well on his way to bright career in particle physics

https://docs.google.com/document/d/1LlSmUFmL8-SXeSAEDfRNtKBOoJtHD65YkkGxKYLxxkI/edit?tab=t.0

Dear Members of the Selection Committee,

I am writing to enthusiastically support Sam Hobbeheydar's application to the Churchill Scholarship. I am an experimental particle physicist working on the CMS experiment at the Large Hadron Collider. I first got to know Sam in the fall of 2023, when he began working as a researcher in my group. Sam came to me highly recommended by Prof. Chris Meyer (Indiana University), with whom he had collaborated as a high-school student on several high-energy physics projects in the ATLAS collaboration. He has since worked closely with me on two very different projects: analyzing LHC data already taken, and building new detectors for the future.

At CMU, we are constructing an upgrade to the CMS detector called the High-Granularity Calorimeter, which requires assembling 5,000 eight-inch silicon modules—essentially radiation-hard digital cameras. Each module consists of a silicon sensor attached to a printed circuit board containing the readout electronics, together with a base plate that provides cooling and structural stability. To support this, we have established a small manufacturing center on campus capable of producing up to 24 modules per day.

Module production is currently limited by our ability to test modules. International collaborators were to design, build, and ship us a multi-module test system ("MMTS") that would test 24 modules at once, thermally cycling them and verifying their electrical properties at the design operating temperature of −30 °C. It was supposed to be "plug and play." Unfortunately, it did not go as planned: what we received was little more than an incomplete parts list, and it arrived late, with little or no instruction on what to do.

Sam quickly took charge of what could have been a major disaster. Working with a postdoc in our group, he took responsibility for critical aspects of getting the MMTS operational. This required him to become an expert, on the fly, in a wide range of systems—an industrial chiller and thermal unit, custom hardware interlocks, and HV/LV distribution—none of which he had any prior background in.

Sam has turned a potential show-stopper into a success story. Our MMTS is now operational, and we are starting to clear the backlog of modules waiting to be tested.

Sam has also contributed to our search for HH→bbWW with the CMS detector. This channel is promising but faces a substantial background from top-quark production. Working closely with a graduate student in my group, Sam optimized the signal selection: he implemented a baseline selection using engineered features and then developed a multivariate selection using machine learning. From the outset, he has excelled at translating rough ideas into well-posed problems and solving them efficiently.

Throughout both projects, Sam has operated at the level of an advanced graduate student—in my experience exceptional for an undergraduate, and among the strongest undergraduate researchers I have worked with at CMU.

Sam's choice of Cambridge is an excellent fit. Cambridge has a strong ATLAS group whose research program is well matched to Sam's experience in both detector hardware and data analysis; he even brings prior ATLAS experience from his work with Prof. Meyer. I know the Cambridge group from my own time on ATLAS, and I recently spoke with its head, Prof. Potter, about Sam. She was impressed by his expertise and is excited for him to join the group. The skills Sam has developed in my group—commissioning complex detector systems and building machine-learning-based analyses—are precisely the skills that drive modern collider physics, and his chosen program will let him deepen both while embedding him in one of the leading groups in the field. I have no doubt Sam will excel in graduate study at Cambridge; he is fully prepared and well on his way to a bright career in particle physics.

What impresses me most, though, is his initiative. With the MMTS, Sam saw a problem that threatened the whole project and simply took the lead in solving it—teaching himself what he needed to know and bringing others along with him. That combination of ability, drive, and leadership is exactly what the Churchill Scholarship is meant to identify.

In summary, Sam grasps new concepts quickly and is unafraid of hard work. He has excellent intuition and strong, practical problem-solving skills. Sam Hobbeheydar is exactly the kind of student you are looking for in the Churchill program: creative, productive, and fun to work with.

Sincerely,

I am writing to enthusiastically support Sam Hobbeheydar's application to the Rhodes scholarship. I am an experimental particle physicist working on the CMS experiment at the Large Hadron Collider. I first got to know Sam in the fall of 2023, when he began working as a researcher in my group. Sam came to me highly recommended by Prof. Chris Meyer (Indiana University), with whom he had collaborated as a high school student on several high-energy physics projects within the ATLAS collaboration. Sam has worked closely with me on two very different projects: analyzing data that we have already taken and building new detectors for the future.

At CMU, we are constructing an upgrade to the CMS detector called the High-Granularity Calorimeter, which involves assembling 5,000 8-inch silicon modules – essentially radiation-hard digital cameras. Each module consists of a silicon sensor attached to a printed circuit board containing readout electronics and a base plate that provides cooling and structural stability. To facilitate this, we have established a small manufacturing center on campus that is capable of producing up to 24 modules per day.

Module production is currently limited by our ability to test modules. A multi-module test system (or "MMTS") was planned to be designed, built, and shipped to our module assembly center by international collaborators. The system would test 24 modules simultaneously, thermally cycling them and verifying their electrical properties at the designed operating temperature of -30°C. It was supposed to be "plug and play". Unfortunately, this did not work as advertised. What we received was little more than an incomplete parts list. This all arrived late and with little to no instructions on what was to be done.

Sam quickly took charge of what could have been a major disaster. In coordination with a postdoc in our group, he has been responsible for critical aspects of getting the MMTS operational. This required him to quickly become an expert in a wide range of areas: an industrial chiller and thermal unit, custom hardware interlocks, and HV/LV distribution systems. He picked all of this up on the fly without any specific prior knowledge.

Sam has turned a potential show-stopper into a success story. Our MMTS is now operational and we are starting to clear the backlog of modules to be tested.

Sam has also contributed to our search for HH→bbWW with the CMS detector. This channel is promising, but faces substantial background from top quark production. Sam has worked closely with a graduate student in my group to optimize the signal selection. He has implemented a simple baseline selection using engineered features and developed a multivariate selection using machine learning. From the outset, he has excelled at translating rough ideas into well-posed problems and then solving them efficiently.

Throughout both projects Sam has operated at a level comparable to that of a graduate student.

In summary, Sam is quick to grasp new concepts and unafraid of hard work. He has a strong work ethic, practical problem-solving skills, and excellent intuition. It seems to me that Sam Hobbeheydar is the exact type of student that you are looking for in the Rhodes program. He is creative, productive, and fun to work with.

john

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The letter may progress as follows: ●​ Details on how you know the applicant ●​ Discussion of the award and why, based on your experiences with the applicant, they are a good fit ●​ Discussion of why the applicant is a good “investment,” with details about their potential and promise ●​ Discussion of how the applicant stands in relation to others you have worked with (e.g., “I would place her in the top 1% of undergraduates I have taught at Carnegie Mellon” or “His work in the lab is at the level of an advanced graduate student.”)