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Hemmick, Thomas K.

Publications and source records attributed to Hemmick, Thomas K..

Photons from thermalizing matter in heavy ion collisions

Here, we investigate the production of direct photons in heavy ion collisions within the modified bottom-up thermalization scenario, which we show to be related to the thermalizing Glasma framework. The dynamics of the parton system up to thermalization/ equilibration can be described by two momentum scales, by means of which we express the photon invariant yield excluding the prompt pQCD contribution. We derive an analytic formula, which provides an estimate of photon production from thermalizing matter for a wide range of collision systems and energies.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Performance of a Quintuple-GEM Based RICHDetector Prototype

Cerenkov technology is often the optimal choice for particle identification in high energy particle collision applications. Typically, the most challenging regime is at high pseudorapidity (forward) where particle identification must perform well at high laboratory momenta. For the upcoming electron ion collider (EIC), the physics goals require hadron (π, K, p) identification up to ~50 GeV/c. In this region Cerenkov ring-imaging (RICH) is the most viable solution. The speed of light in a radiator medium is inversely proportional to the refractive index. Hence, for particle identification (PID) reaching out to high momenta a small index of refraction is required. Unfortunately, the lowest indices of refraction also result in the lowest light yield ([(dNγ)/dx] ∝ sin2(θC)) driving up the radiator length and thereby the overall detector cost. In this paper we report on a successful test of a compact RICH detector (1 meter radiator) capable of delivering in excess of 10 photoelectrons per ring with a low index radiator gas (CF4). The detector concept is a natural extension of the PHENIX hadron-blind detector (HBD) achieved by adding focusing capability at low wavelength and adequate gain for high efficiency detection of single-electron induced avalanches. Our results indicate that this technology is indeed a viable choice in the forward direction of the EIC. The setup and results are described within.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗