Measurement of double longitudinal asymmetries, A_{LL}, for pi0 production in polarized pp scattering at low Bjorken-x

The gluon contribution to the spin of the proton, G, can be extracted from double spin asymmetries for inclusive 0 production in polarized pp collisions at RHIC. The combined analysis of RHIC data taking runs through 2009 indicates that G is positive for relative gluon momenta x > 0:05. The analysis of new data at center of mass energies of 510 GeV will improve the statistical signi cance of the result at low x. During Run 13 at the PHENIX experiment, a total integrated luminosity of 155 pb⁻¹ and polariations of 50% and 53% were achieved for the two beams. In this thesis a double spin asymmetry for electromagnetic clusters from photons resulting from 0 and meson decays will be measured with an electromagnetic calorimeter, the Muon Piston Calorimeter, MPC, covering forward scattering angles corresponding to pseudorapidities 3.1 < η < 3.9. This measurement will extend the sensitivity for spin contributions from gluons with small momenta reaching 0.001. For the high luminosity run in 2013, the MPC was upgraded with new, waveform sampling front-end electronics from the decommissioned PHENIX HBD. The new electronics makes it possible to suppress backgrounds in the MPC both online and at the trigger level. As part of this thesis waveform fitting algorithms for the new HBD electronics were developed to make it possible to separate electromagnetic and hadronic showers as well as backgrounds resulting from direct energy deposits in the Avalanche Photodiodes (APDs) which are reading the light from the MPC PbWO4 crystals. Using new scaler boards developed by Lawrence Berkley Laboratory, methods to determine relative luminosities were further refined resulting in systematic errors below 10⁻⁴ and well below the statistical errors expected from the 2013 high statistics data sample in PHENIX.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2017

Author dc:creator

• Montuenga, Pedro Juan

Contributors dc:contributor

• Grosse-Perdekamp, Matthias
• Peng, Jen-Chieh
• Gollin, George
• Willenbrock, Scott

• Spin
• Nuclear
• Particle

Statement dc:rights

• Copyright 2017 Pedro Montuenga

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/97441

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/97441