118726538
Detecting Elastic pp Scattering by Radiative Photons in CMS at the LHC
Photon bremsstrahlung is studied for identifying elastic proton-proton interactions in the CMS experiment at the LHC. In addition to measurement of the elastic pp cross section (assuming that the elastic slope is known) the bremsstrahlung photons will allow evaluation of the total pp cross section, luminosity and alignment of the Zero Degree Calorimeters (ZDCs).
22084508
Status of zero degree calorimeter for CMS experiment
The Zero Degree Calorimeter (ZDC) is integral part of the CMS experiment, especially, for heavy ion studies. The design of the ZDC includes two independent calorimeter sections: an electromagnetic section and a hadronic section. Sampling calorimeters using tungsten and quartz fibers have been chosen for the energy measurements. An overview of the ZDC is presented along with a current status of calorimeter’s preparation for Day 1 of LHC.
6840080
What invariant one-particle multiplicity distributions and two-particle correlations are telling us about relativistic heavy-ion collisions
Many of you are vigorously searching for the quark-gluon plasma—a predicted new phase of nuclear matter where quarks roam almost freely throughout the medium instead of being confined to individual nucleons.1, 2 Such a plasma is believed to have existed in the first 10 μs of the universe during the big bang and could be produced in the laboratory during the little bang of a relativistic heavy-ion collision.
118432204
Particle spectra and HBT results from NA44
Recent results on baryon spectra and interferometry from NA44 are compared to RQMD and a hydrodynamical model. The importance of flow and rescattering on the rapidity and transverse mass distributions is discussed. The yields of protons and antiprotons are compared as a function of system, rapidity and multiplicity.
118972646
Reaction dynamics and multifragmentation in Fermi energy heavy ion reactions
The reaction systems, 64Zn + 58Ni, 64Zn + 92Mo, 64Zn + 197Au, at 26A, 35A and 47A MeV, have been studied both in experiments with a 4$\pi$ detector array, NIMROD, and with Antisymmetrized Molecular Dynamics model calculations employing effective interactions corresponding to soft and stiff equations of state (EOS). Direct experimental observables, such as multiplicity distributions, charge distributions, energy spectra and velocity spectra, have been compared in detail with those of the calculations and a reasonable agreement is obtained. The velocity distributions of $\alpha$ particles and fragments with Z >= 3 show distinct differences in calculations with the soft EOS and the stiff EOS. The velocity distributions of $\alpha$ particle and Intermediate Mass Fragments (IMF's) are best described by the stiff EOS. Neither of the above direct observables nor the strength of the elliptic flow are sensitive to changes in the in-medium nucleon-nucleon (NN) cross sections. A detailed analysis of the central collision events calculated with the stiff EOS revealed that multifragmentation with cold fragment emission is a common feature predicted for all reactions studied here. A possible multifragmentation scenario is presented; after the preequilibrium emission ceases in the composite system, cold light fragments are formed in a hotter gas of nucleons and stay cold until the composite system underdoes multifragmentation. For reaction with 197Au at 47A MeV a significant radial expansion takes place. For reactions with 58Ni and 92Mo at 47A MeV semi-transparency becomes prominent. The differing reaction dynamics drastically change the kinematic characteristics of emitted fragments. This scenario gives consistent explanations for many existing experimental results in the Fermi energy domain.
119203216
Performance of the combined zero degree calorimeter for CMS
The combined zero degree calorimeter (ZDC) is a combination of sampling quartz/tungsten electromagnetic and hadronic calorimeters. Two identical combined calorimeters are located in the LHC tunnel at CERN at the straight section ~140 m on each side of the CMS interaction vertex and between the two beam pipes. They will detect very forward |?| ? 8.5 photons and neutrons. ZDC information can be used for a variety of physics measurements as well as improving the collision centrality determination in heavy-ion collisions. Results are presented for ZDC performance studies with the CERN SPS H2 test beam.
123332232
Hard exclusive measurements with a polarised target at HERMES
Hard exclusive measurements at HERMES provide access to the information framework of Generalised Parton Distributions. This framework has the potential to provide a thorough, phenomenological description of the nucleon and aspects of it can be constrained by recent measurements made at the HERMES experiment at DESY. Consideration of meson production allows access to some GPDs, whilst observables from the deeply virtual Compton scattering process can allow a constraint on model parameters which are directly connected to the total angular momentum contribution of up and down quarks to the nucleon's spin.
119217305
Overview of Deeply Virtual Compton Scattering at HERMES
Deeply Virtual Compton Scattering represents the best experimental channel through which to understand Generalised Parton Distributions. The HERMES experiment measured the most diverse set of DVCS results of any experiment; this talk discusses the most recent sets of DVCS results released by HERMES and the unique experimental conditions found at HERMES that facilitated the measurements. We also examine the various ways in which the HERMES experimental measurements are being used to constrain GPDs and how future experiments can learn from the HERMES program.
120484753
The front-end readout electronics for the P̄ANDA Focussing-Lightguide Disc DIRC
One of the key detectors of the upcoming ANDA experiment for particle identification will be the Focussing-Lightguide Disc DIRC, based on a novel detector technique. It will use a fused silica disc as a solid radiator to generate Cherenkov light by the passing of charged particles. These photons will be transported by total-internal-reflection to the rim, where LiF crystals will be used to perform dispersion corrections. Focussing lightguides will map propagation angles to spatial positions on the surface of photon detectors. Fast single photon detection devices will be used to measure azimuthal angles and spatial positions, which can be used to reconstruct kinematic properties of the passing particles. The expected average interaction rate of 20 MHz yields a photon detection rate of 1.3 MHz, as it is foreseen to use 128 MCP-PMT, each with 32 channels, for continuous readout. Moderate timing resolution of 300 ps improves signal from noise separation. The readout design requirements for the Focussing-Lightguide Disc DIRC will be introduced. The current candidate for implementation of the front-end readout electronic system will be described and several alternative readout scenarios will be discussed. Finally, a summary and an outlook for further developments and tests will be given.
113252484
Reconstruction methods — PANDA Focussing-Lightguide Disc DIRC
The Focussing-Lightguide Disc DIRC will provide crucial Particle Identification (PID) information for the PANDA experiment at FAIR, GSI. This detector presents a challenging environment for reconstruction due to the complexity of the expected hit patterns and the operating conditions of the PANDA experiment. A discussion of possible methods to reconstruct PID from this detector is given here. Reconstruction software is currently under development.
122525362
DVCS at HERMES: The Recoil Detector & Transverse Target Spin Asymmetries
The HERMES experiment is a large forward angle spectrometer located at the HERA accelerator ring at DESY, Hamburg. One of the most exciting topics studied at HERMES is Deeply Virtual Compton Scattering (DVCS) which is the simplest interaction that provides a gateway for access to Generalised Parton Distributions (GPDs). GPDs are a theoretical framework which can be used to calculate the total angular momentum of the quarks in the nucleon. As such, they provide one piece of the puzzle of nucleonic spin structure. In 2005, HERMES was upgraded in the target region with a Recoil Detector that allows it to make truly exclusive measurements of the DVCS interaction for the first time. The design and construction of the Recoil Detector is discussed herein, in addition to a complete analysis of the Transverse Target Spin Asymmetry (TTSA) in DVCS. Experimental facilities that enable measurement of this asymmetry are rare. The importance of the information on the TTSA from HERMES is made yet greater as the transversely polarised target that allows the asymmetry to be measured has been replaced by an unpolarised target. This was to allow the Recoil Detector to be installed. The final stage of this thesis shows a model-dependent method for constraining the angular momentum of the quarks in the nucleon and speculates as to the other pieces of the spin puzzle.