Joey Sorenson, a Ph.D. student in the Department of Physics & Astronomy at The University of New Mexico, has been awarded the U.S. Department of Energy and the Istituto Nazionale de Fisica Nucleare (DOE-INFN) Summer Students Exchange Scholarship. He is one of only 11 recipients in 2023.

The DOE and INFN collaborate to promote interactions between student scientists from the United States and Italy. INFN is an organization that is well-known globally for promoting basic scientific research, and has close ties with DOE in many areas of interest, such as particle physics.

Joey Sorenson
UNM Ph.D. student Joey Sorenson Joey Sorenson

Sorenson will travel to Genoa, Italy, in September and October 2023 to work with INFN's Large Hadron Collider (LHC) and ATLAS group. He will be involved in the assembly and testing of 3D modules, developing a system test for module electrical qualification on a support structure, and optimizing the mechanical and thermal qualification of the support structure.

Sorenson is using ATLAS data to search for physics processes beyond the Standard Model and developing new detectors for particle tracking. Analyzing the recorded particle collision events resulting from the LHC requires complex data-acquisition and computing systems.

ATLAS is one of two general-purpose detectors in the LHC. Weighing in at 7,000 tons, ATLAS detector is the largest volume particle detector ever constructed. The European Council for Nuclear Research houses ATLAS in an underground cavern near the small village of Meyrin, Switzerland. More than 5,500 scientists from 245 institutes in 42 countries work on the ATLAS experiment.

Here's how LHC and ATLAS work together: Beams of particles from the LHC collide at the ATLAS detector's center. New collision debris forms in new particles, which fly out in all directions from where they've collided. Several detecting subsystems record the paths, movement, and energy of the particles so they can be individually identified. 

Their momenta are measured by a huge magnet system that bends the paths of the charged particles. The interactions in the ATLAS detectors create so much data that in order to digest it all, ATLAS uses an advanced trigger system to single out certain events for the detector to either record or ignore.

Sorenson studies the radiation tolerance of 4D tracking sensors. Sensors give an accurate time of arrival for particles that will go into the High-Luminosity LHC upgrade, Sorenson explained.

“To do so, we irradiate the sensors with protons, neutrons, and gamma to the expected HL-LHC fluences (stream of particles) at neighboring facilities like Los Alamos National Laboratory and Sandia National Laboratories,” Sorenson said.

“Then we measure the timing, charge collection, and other characteristics that are important for high precision tracking or particles in the HL-LHC upgrade. We use the results of these studies and measurements to optimize the sensor design.”

Sorenson's analysis project studies rare decays of B0 mesons into two muons using the ATLAS Run 2 data set (2015-2018). Only about one in 10 billion B10 particles decay into two muons. The Standard Model stifles this decay, so contributions and resources from this fellowship will make a measurable impact on the number of decays that can be observed, according to Sorenson.

"I have been studying 4D tracking sensors at UNM. The fellowship will allow me to work with our colleagues in Genoa, Italy to assemble and test modules of these 4D tracking sensors," Sorenson said, "It's a very natural extension of the research I've already been performing! I will get to develop a test system for the electrical qualification of several modules and optimize the mechanical and thermal qualification of the structures supporting the modules."