CAREER: Jets measurements at the Relativistic Heavy Ion Collider

Lehigh University, Bethlehem PA

Investigators

Abstract

This award supports the investigation of the strong nuclear force by the PI and her research group, and also supports several initiatives to increase the participation of under-represented minorities in the field of high energy nuclear physics. The nuclei of atoms are made up of nucleons, which can be either protons or neutrons. These, in turn, consist of quarks, and are bound together by gluons. These quarks and gluons are confined to the protons and neutrons and cannot be observed individually. In order to study the strong nuclear force that holds the quarks and gluons together, heavy ions such as gold or lead nuclei are collided with each other at ultra-relativistic speeds. This forms an extremely hot and dense liquid drop of matter, where the quarks and gluons are no longer confined into normal matter as we know it. This new state of matter is called the Quark Gluon Plasma (QGP). Understanding the QGP allows for a better understanding of the strong nuclear force, which is necessary to discern how sub-atomic matter organizes itself. There are two facilities in the world that can create this matter, the Large Hadron Collider (LHC) in Europe and the Relativistic Heavy Ion Collider (RHIC) located in Brookhaven National Lab, in Long Island, New York. In some of the heavy ion collisions, two nucleons will strike each other hard enough to knock a quark or gluon out at a high rate of speed. This quark or gluon will travel through the QGP, losing energy to it via its interactions, and then produce a spray of particles called a "jet". The jets created in this fashion can then be used as probes of the QGP, by comparisons with collisions where QGP was not formed. This award supports studying this phenomenon at the Solenoidal Tracker at RHIC (STAR) experiment, which has recorded several large data sets ideal for jet measurements. Additionally, it will support measuring jet results using a new experiment, called sPHENIX, which will start taking data in the last few years of the award. This experiment has a central hadronic calorimeter (HCal), which allows nearly all the energy within a jet to be measured and will increase the precision of all jet-based measurements. In addition to the jet related analysis, this award includes testing electronic components of the Electromagnetc Calorimeter (EMCal) and HCal and helping with the final assembly. A dedicated test stand will be set up at the PI's institution, which will allow the electronic boards used by both calorimeters to be characterized by undergraduate and graduate students at Lehigh. These students will then spend some time at Brookhaven, assisting with the final assembly so that they can see how detectors are designed, tested, and assembled. Additionally, the students will continue to assist with the installation, commissioning and calibration of the STAR Event Plane Detector. This detector was constructed with the help of a previous award and forms a vital part of the STAR experiment by determining the impact parameter of the colliding nuclei within the STAR experiment. The diverse undergraduate and graduate students involved in this project will gain skills in the analysis of big data, develop hardware skills, and be able to network within the large experimental collaborations at RHIC. These will be important for both preparing and mentoring the next generation of STEM workers. Additionally, this award will be used to continue the K-12 outreach program at Lehigh University, which will allow the younger students to work with a diverse group of scientists. This will encourage a diverse population to pursue STEM careers. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.