Caroline Kathrin Riedl

Research Assistant Professor


Caroline Kathrin Riedl

Primary Research Area

  • Nuclear Physics
467 Loomis Laboratory


After my return to UIUC from CERN in mid-2018, I took over the scientific supervision of the sPHENIX project at the Nuclear Physics Lab (NPL). Our group is in charge of building almost 5,000 absorber blocks for the electromagnetic calorimeter of sPHENIX, an experiment at BNL scheduled to see first beam in 2023. Each block consists of an array of 2,668 manually assembled scintillating fibers in a tungsten-epoxy matrix and is constructed from scratch by our NPL technicians and student workers. Since 2019, I have been the corresponding level-3 manager with BNL. In 2020, I moved with the help of our UIUC COMPASS grad students and postdocs COMPASS data productions from Blue Waters to the next-generation NSF-funded supercomputer Frontera at TACC. I currently serve as a member of the COMPASS publication committee and help to publish physics results in a timely manner.

I joined the Department of Physics at the University of Illinois as Research Assistant Professor in 2013. In 2013-2015, I was the project coordinator for a detector upgrade for COMPASS at CERN (Geneva, Switzerland / Prevessin, France). I organized the prototyping, construction and assembly of a large-area planar drift chamber (DC5). The DC5 detector was constructed in the US, mostly at the Nuclear Physics Laboratory. This would not have been possible without a small army of undergraduate students. The detector parts were shipped to CERN in fall 2014 and assembled. DC5 was installed into COMPASS in May 2015 and has been successfully collecting valuable data since then in two Drell-Yan runs 2015 and 2018 and two GPD runs in 2016/17. In 2018, I served as the COMPASS technical coordinator. From 2016 through 2019, I was able to secure grants for COMPASS data productions on NCSA's supercomputer Blue Waters. Our team used more than 13 million Blue-Waters node hours to produce COMPASS data for high-level physics analysis, for the study of high-precision detector efficiencies and for detailed Monte-Carlo simulations.

After my PhD on HERMES data, a fellowship with INFN Frascati (Italy) and a postdoc association with DESY allowed me to continue my research at DESY. I participated in the commissioning and operation of the HERMES recoil detector and lead the analysis and publication of hard-exclusive data collected with this detector. From 2008 to 2010, I was the deputy analysis coordinator of HERMES and from 2007 through 2012 the DVCS and exclusive physics convener. In 2011 and 2012, I worked from DESY as main data quality manager for CMS, one of the LHC experiments at CERN, and contributed to the analysis of the Higgs-boson decay into two tau-leptons and successively into muons.

I received my diploma degree in physics from the University of Erlangen-Nuremberg, Germany, in 2001. My diploma thesis was on (1+1)-dimensional quantum field theoretical models and massless mesons in dense nuclear matter at zero temperature. From 2002 on, I focussed my research on experimental particle physics and worked at DESY (Hamburg, Germany) on data from the HERMES experiment. I investigated the tensor structure of polarized deuterons in deep-inelastic electron-deuteron scattering and received my PhD with the University of Erlangen-Nuremberg in 2005.

Research Interests

  • Experimental nuclear physics: spin structure of the nucleon in Drell-Yan, semi-inclusive deep-inelastic scattering (SIDIS) and hard exclusive processes using polarized nuclear targets and hadron or lepton beams
  • Transverse-momentum dependent (TMD) degrees of freedom in the hadron
  • Development and construction of detectors for nuclear-physics research.

Undergraduate Research Opportunities

In 2021, there will be plenty of opportunities for undergrad hands-on work at the Nuclear Physics Lab, where we are building absorber blocks for the sPHENIX electromagnetic calorimeter.

Research Statement

I am interested in the structure of nucleons and nuclei. Modern approaches to investigate nuclear structure involve transverse momentum dependent parton distribution functions (TMDs) and generalized parton distributions (GPDs). COMPASS at CERN collected TMD-related data in 2015 and 2018. The analysis of part of these data hints to a sign change between the Sivers TMD measured in Drell-Yan vs. that measured in semi-inclusive deep-inelastic scattering and grad students of our group currently analyze the full data set. The future sPHENIX data collected with transversely polarized proton beams will also allow for TMD-related studies. We will analyze these data while preparing the advent of the Electron Ion Collider, the future polarized electron-proton collider at BNL to start after 2030.

Selected Articles in Journals

Articles in Conference Proceedings

Related news

  • Research

The most powerful supercomputer in the world for academic research has established its mission for the coming year.The Texas Advanced Computing Center (TACC) announced that the National Science Foundation has approved allocations of supercomputing time on Frontera to 49 science projects for 2020-2021. Time on Frontera is awarded based on a project’s need for very large scale computing to make science and engineering discoveries, and the ability to efficiently use a supercomputer on the scale of Frontera.

“Our generous allocation of compute time on Frontera makes it possible to perform uniquely large-scale, data-driven simulations of key brain cell networks involved in memory with unprecedented biological realism,” Soltesz said.Another awardee, Caroline Riedl, research assistant professor of Physics at the University of Illinois, is part of a large international collaboration analyzing particle collision data from the Super Proton Synchrotron at CERN. Riedl was awarded 1.5 million hours to unravel the mass of hadrons and the quark structure of protons. Her work will analyze past particle physics experiments from the COMPASS experiment and explore new detectors for quantum chromodynamics research (COMPASS++/AMBER).”We were very excited to learn that our request for an LRAC allocation on TACC’s Frontera was approved,” Riedl said.

  • Accolades

Thirty-eight research groups at the University of Illinois at Urbana-Champaign have been allocated new computation time on the Blue Waters supercomputer at the National Center for Supercomputing Applications (NCSA), with funding from the National Science Foundation (NSF). This round of allocations provides over 17 million node-hours, equivalent to over half a billion core hours, and is valued at over $10.5 million, helping Illinois researchers push the boundaries of innovation and frontier science discovery.