Physics Major 

Carlos Sierra will be going to CERN, the European Organization for Nuclear Research, for the second summer in a row.  If you had told the Berkeley physics major that he would be doing this two years ago, he wouldn’t have believed you.  “I always figured that if I went to college, I’d be studying history or something similar, as that was really the only subject I had ever been good at in school. I had never taken a physics class before college so I knew very little about the subject other than it being notoriously difficult. I think it was the allure of a challenge, along with the desire to understand the universe a little better, that led to that spontaneous choice to major in physics. In hindsight, I wish I knew what I was getting myself into.” 


His high school didn’t have many math courses so Carlos had to start almost from the beginning.  “I had to start with high school algebra at Fullerton College.  My first two years were spent taking a ton of math classes, something I was never good at, before I could even take my first physics class.” 


His perseverance started paying off when he transferred to Cal.  While the academics were much more rigorous, Carlos quickly found help when he enrolled in the Junior Transfer Course.  The two-unit class is offered through a partnership between The Compass Project in the Physics Department and Cal NERDS.  “Right away it was made clear to me that struggling in upper division physics classes at Cal is completely normal. It was really encouraging to learn the experiences of the facilitators and the other transfer students, and the information and studying methods they shared with us have been very helpful in getting me through classes.”  


After completing the transfer course, Carlos joined two Cal NERDS programs.  He is a NSF CAMP Research Scholar and a UC LEADS Scholar.  Through the latter program students spend two years doing research.  Most of them work in a Berkeley lab with professors and graduate students the first summer and then go to another UC campus for their second summer.  Instead, Carlos headed to Switzerland.  “I emailed Professor Joel Fajans about working with him at Berkeley.”  Fajans is one of the collaborators at the ALPHA experiment, a project based at CERN.  “He said he was going to CERN for the summer and I was welcome to come if I had funding.  Thanks to NERDS, I did.”  


At CERN, he worked on a number of different projects to improve the ALPHA apparatus, including designing stabilizing mounts for a camera and implementing a relay system.  “It turns off electronics that aren’t being used in any particular run to prevent noise from coupling into the experiment.” The workdays were long and hours often reversed.  It wasn’t unusual for Carlos to work from midnight to seven in the morning because that’s when the anti-proton beam was available.  “I think my favorite part of that experience was seeing some of the concepts that I had learned about in classes, like in quantum mechanics where everything seems so abstract, being applied to real experiments.” 


Carlos presented his summer research at the recent NSF CAMP Symposium at UC Irvine and the UC LEADS Symposium at UC Davis, where his work was awarded an Honorable Mention.  “I don’t think I would have ever done research if not for the two NERDS programs.  In physics the research opportunities here are pretty competitive.  I tried emailing professors before and I never got any responses until I told them I was fully funded.  Doing that research, actually doing hands-on physics has also played a role in motivating me to do better in my classes. I’m much more inclined to learn something if I can understand it within the context of an experimental setting.” 


Since returning to campus, Carlos has continued doing research in Professor Fajan’s lab.  “I’ve been working with a device called a silicon photomultiplier, which is capable of detecting light at the single photoelectron level and has a number of advantages over the typical photomultiplier tube. In the lab we work with very cold electron plasmas, which can be converted into light by sending them into a phosphor screen, a process known as luminescence.  After taking a picture of that light, the photons hit the photomultiplier and are converted back into electrons.  We can then measure the arrival time of each individual photoelectron as a way of getting the temperature of the original electron plasma.” Carlos is now working on figuring out how to implement this new photomultiplier into the ALPHA experiment at CERN.   


While he doesn’t know exactly what path he’ll pursue after graduating next fall, Carlos is sure of one thing, “I’ve come to genuinely love the process of doing scientific research, and would really like to continue on that path. I always thought I’d go to graduate school, that’s what people in physics do, get their Ph.D.  I wouldn’t mind teaching, but I really want to continue doing research for as long as I can manage.”