critRHIC: The RHIC Low Energy Program

Recent experimental and theoretical developments have motivated interest in a more detailed exploration of heavy ion collisions in the range sqrt(sNN)=5-15 GeV. In contrast to interactions at the full RHIC energy of sqrt(sNN)=200 GeV, such collisions result in systems characterized by much higher baryon chemical potential, muB. Extensions of lattice QCD calculations to non-zero values of muB suggest that a critical point may exist in this region of the QCD phase diagram. Discovery of the critical point or, equivalently, determining the location where the phase transition from partonic to hadronic matter switches from a smooth crossover to 1st order would establish a major landmark in the phase diagram. Initial studies of Pb+Pb collisions in this energy range have revealed several unexpected features in the data. In response to these results, it has been suggested that the existing RHIC accelerator and experiments can be used to further the investigation of this important physics topic. This proceeding briefly summarizes the theoretical and experimental situation with particular emphasis on the conclusions from a RIKEN BNL workshop held in March of 2006.Comment: 8 pages, 2 figures, Conference Proceeding from Strangeness in Quark Matter 2006, accepted for publication in J. Phys. G; Added final journal reference and fixed typo in Ref

Low cost solar energy collection system

A fixed, linear, ground-based primary reflector having an extended, curved sawtooth contoured surface covered with a metallized polymeric reflecting material, reflected solar energy to a movably supported collector that was kept at the concentrated line focus of the reflector primary. Efficient utilization leading to high temperatures from the reflected solar energy was obtained by cylindrical shaped secondary reflectors that directed off-angle energy to the absorber pipe

Interferometry signatures for QCD first-order phase transition in heavy ion collisions at GSI-FAIR energies

Using the technique of quantum transport of the interfering pair we examine the Hanbury-Brown-Twiss (HBT) interferometry signatures for the particle-emitting sources of pions and kaons produced in the heavy ion collisions at GSI-FAIR energies. The evolution of the sources is described by relativistic hydrodynamics with the system equation of state of the first-order phase transition from quark-gluon plasma (QGP) to hadronic matter. We use quantum probability amplitudes in a path-integral formalism to calculate the two-particle correlation functions, where the effects of particle decay and multiple scattering are taken into consideration. We find that the HBT radii of kaons are smaller than those of pions for the same initial conditions. Both the HBT radii of pions and kaons increase with the system initial energy density. The HBT lifetimes of the pion and kaon sources are sensitive to the initial energy density. They are significantly prolonged when the initial energy density is tuned to the phase boundary between the QGP and mixed phase. This prolongations of the HBT lifetimes of pions and kaons may likely be observed in the heavy ion collisions with an incident energy in the GSI-FAIR energy range.Comment: 16 pages, 4 figure

Is Strangeness still interesting at RHIC ?

With the advent of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL), Heavy Ion Physics will enter a new energy regime. The question is whether the signatures proposed for the discovery of a phase transition from hadronic matter to a Quark Gluon Plasma (QGP), that were established on the basis of collisions at the BEVALAC, the AGS, and the SPS, respectively, are still useful and detectable at these high incident energies. In the past two decades, measurements related to strangeness formation in the collision were advocated as potential signatures and were tested in numerous fixed target experiments at the AGS and the SPS. In this article I will review the capabilities of the RHIC detectors to measure various aspects of strangeness, and I will try to answer the question whether the information content of those measurements is comparable to the one at lower energies.Comment: 12 pages, 7 figures, Invited Talk at the IV International Conference on Strangeness in Quark Matter, Padova (Italy), July 20-24, 199

Antihyperon-Production in Relativistic Heavy Ion Collision

Recently it has been shown that the observed antiproton yield in heavy-ion collisions at CERN-SpS energies can be understood by multi-pionic interactions which enforce local chemical equilibrium of the antiprotons with the nucleons and pions. Here we show that antihyperons are driven towards local chemical equilibrium with pions, nucleons and kaons on a timescale of less than 3 fm/c when applying a similar argument for the antihyperons by considering the inverse channel of annihilation reactions anti-Y + p to pions + kaons. These multi-mesonic reactions easily explain the antihyperon yields at CERN-SpS energies as advertised in pure thermal, hadronic models without the need of a quark gluon plasma phase. In addition, the argument also applies for AGS energies.Comment: 4 pages using RevTeX, 1 eps figur

System-size dependence of the pion freeze-out volume as a potential signature for the phase transition to a Quark Gluon Plasma

Hanburry-Brown-Twiss (HBT) correlation functions and radii of negatively charged pions from C+C, Si+Si, Cu+Cu, and In+In at lower RHIC/SPS energies are calculated with the UrQMD transport model and the CRAB analyzing program. We find a minimum in the excitation function of the pion freeze-out volume at low transverse momenta and around $E_{lab}\sim 20-30A$GeV which can be related to the transition from hadronic to string matter (which might be interpreted as a pre-cursor of the QGP). The existence of the minimum is explained by the competition of two mechanisms of the particle production, resonance decays and string formation/fragmentation.Comment: 12 pages, 4 fig

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 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.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 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