The Development of a Sampling Hadronic Calorimeter for the sPHENIX Collaboration and the Detection of Event Pile-up at PHENIX

Vazquez-Carson, Sebastian F.

Undergraduate Honors Thesis

The Development of a Sampling Hadronic Calorimeter for the sPHENIX Collaboration and the Detection of Event Pile-up at PHENIX Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/undergraduate_honors_theses/6108vb674

Abstract

The sPHENIX detector at RHIC will contain an electromagnetic and a hadronic calorimeter used for the detection of particles in jets from heavy ion collisions. The hadronic calorimeter will be composed of layers of steel plates that are alternated with plastic scintillators. Within the scintillator panels, wavelength shifting fiber optic cables are embedded and coupled to silicon photo multipliers (SiPMs). The signal from the SiPMs pass through a preamp that shapes and amplifies the signal before passing it to an analog to digital converter (ADC) from which the energy deposited in the scintillator is determined. The scintillator panels are manufactured with a diffusive coating to improve reflection and increase sensitivity. With the test setup at the University of Colorado at Boulder, I explored the correlation between light uniformity and fiber geometry, fiber cladding, and diffusive coating density. Many measurements made in Heavy Ion experiments such as PHENIX at RHIC rely on knowledge of the geometrical configuration of the colliding nuclei to describe the evolution of collisions and gain insight into the quark-gluon plasma and the strong nuclear force. As part of this investigation, PHENIX has taken data in 2016 for deuteron on gold collisions at several energies. An acceptable collision frequency is achieved by injecting up to 120 separate bunches each with billions of ions into the storage ring, from which two, separate beams are made to collide. This method has a drawback as there is a chance for multiple pairs of nuclei to collide in a single bunch crossing. Data taken in a double event can not be separated into two independent events and has no clear interpretation. I develop an algorithm to flag multiple interaction events by examining the time dependence of data from the two Beam-Beam Counters – detectors surrounding the beam pipe on opposite ends of the interaction region. The algorithm is tested with data, in which events with double interactions are artificially produced.

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