Athira (left) and other junior NuPECC prize winners at Transversity 2024.
Athira Vijayakumar, NPL Physics graduate student, has won a NuPECC (Nuclear Physics European Collaboration Committee) prize for the best junior physicist contribution at the international Transversity workshop, which took place in Trieste, Italy, in June 2024. During her stay in Europe, she collaborated with researchers in Trieste and at CERN to establish a RICH-detector-based framework for hadron identification in COMPASS data.
“I had a great experience working with my collaborators in person in Europe, specifically those at INFN Trieste and CERN. Trieste group's expertise in RICH-1 detector has provided a great kickstart to my analysis with particle identification. I was thrilled to present recent results from our COMPASS collaboration at the Transversity workshop in June. Theorists, phenomenologists and experimentalists working on various experiments across the world came together to discuss recent developments in the respective branches in understanding the transverse structure of the nucleon. It was an incredible learning experience for a graduate student, allowing me to see the many facets of our research field.”
Athira giving her talk titled “New measurements of transverse spin asymmetries at COMPASS”.
The “Common Muon and Proton Apparatus for Structure and Spectroscopy”, or COMPASS experiment, is located in the CERN North Area and uses a muon or pion beam to scatter off a fixed nuclear target. The unique COMPASS data from semi-inclusive deep-inelastic scattering (SIDIS) or Drell-Yan production contribute to the worldwide efforts to study the transverse-spin and momentum-dependent (TMD) structure of the nucleon. Athira’s research is centered around the so-called transversity TMD parton distribution function (PDF), which describes transverse parton polarization in a transversely polarized nucleon. To that end, she analyzes the 2022 COMPASS SIDIS data from a transversely polarized deuteron target. The results of Athira’s analysis will help constrain better the transversity TMD PDF in particular for the d-quark, and the tensor charge, one of the fundamental charges of the nucleon. The COMPASS RICH-1 detector can discriminate between different hadron types such as pions, kaons, and protons. It is based on the principle that particles traveling through the detector emit Cherenkov light in a cone, the opening angle of which depends on the velocity of the particle. The particle mass can then be deduced by combining this information with the momentum measurement by the tracking detectors
Athira joined the Illinois NPL group as a graduate student in the summer of 2022, working under the supervision of Dr. Caroline Riedl. She has been working on the analysis of COMPASS data from 2022 towards understanding the transverse structure of nucleons. The recent results from COMPASS she presented in Trieste are to appear in PRL (arXiv:2401.00309). Next, she will use RICH-1 information to determine TMD azimuthal asymmetry amplitudes separately for positively and negatively charged pions, kaons, and protons.
“I will continue analyzing transverse spin asymmetries (TSAs) for hadrons in SIDIS, incorporating particle-identification information from RICH-1. Currently, I am assessing data quality, the performance of the RICH-1 detector, and the efficiency and purity of its hadron identification. These preliminary studies are essential for accurately extracting the final asymmetries. In addition to using conventional methods for particle identification from RICH-I data, I plan to implement machine learning techniques. I'm excited to see not only the results with expected higher precision but also how these different particle-identification algorithms compare. The final results could provide deeper insights into the internal structure of a proton that continues to be a mystery. In addition, these results will remain unique for many years until the EIC and future JLab measurements become available.”
This work was supported by NSF-PHY-2111046 and by an Illinois Graduate College Dissertation Travel Grant awarded to Athira.