The PHENIX Experiment at RHIC is planning a series of major upgrades that will enable a comprehensive measurement of jets in relativistic heavy ion collisions, provide enhanced physics capabilities ...for studying nucleon-nucleus and polarized proton collisions, and allow a detailed study of electron-nucleus collisions at the Electron Ion Collider at Brookhaven (eRHIC). The first of these upgrades, sPHENIX, will be based on the former BaBar magnet and will include a hadronic calorimeter and new electromagnetic calorimeter that will cover ±1.1 units in pseudorapidity and 2π in azimuth in the central region, resulting in a factor of 6 increase in acceptance over the present PHENIX detector. The electromagnetic calorimeter will be a tungsten scintillating fiber design with a radiation length ~ 7 mm and a Moliere radius ~ 2 cm. It will have a total depth of ~ 18 radiation lengths and an energy resolution ~ 15%/ E. The hadronic calorimeter will consist of steel plates with scintillating tiles in between that are read out with wavelength shifting fibers, It will have a total depth of ~ 5 interaction lengths and an energy resolution 100%/ E. Both calorimeters will use silicon photomultipliers as the readout sensor. Detailed design studies and Monte Carlo simulations for both calorimeters have been carried out and prototype detectors have been constructed and tested in a test beam at Fermilab in February 2014. This contribution describes these design studies for the sPHENIX experiment and its future upgrade plans at RHIC.
The Relativistic Heavy Ion Collider (BNL) collides heavy nuclei and creates a strongly coupled medium at unprecedented density and temperature. Characteristic event structures may be efficiently ...selected with calorimeters, which can provide triggers on high-pT particles, "jets" of particles, or large transverse energy, along with precision measurements of the structures. The importance of calorimeters in studies of ultrarelativistic heavy-ion collisions was first recognized by W.Willis 1. The key requirements are photon identification and measurements, and high resolving power to handle extreme occupancies common to this kind of interactions. We present a fully developed and beam tested concept of the W-Si sampling calorimeter built to this specifications. Novel features of this design are concepts of silicon micromodules, use of microconnectors for the silicon alignment purposes and passive signal summation to form readout towers. A prototype calorimeter was built in collaboration between BNL and a number of University groups from USA, Russia, Korea, Finland and Czech Republic and exposed to particle beams at CERN PS and SPS.
The PHENIX (Nucl. Instr. and Meth. A 499 (2003)) detector at the Relativistic Heavy Ion Collider, BNL is designed to perform a broad study of A–A, p–A and p–p collisions to investigate nuclear matter ...under extreme conditions. The charged particle identification is currently provided for kaons and pions to a momentum of 2.4
GeV/
c and protons to 5
GeV/
c. These limits would be greatly extended by the now under construction Aerogel Threshold Cherenkov detector (refractive index
n=1.012).
A major upgrade is being planned for the PHENIX experiment that will have greatly enhanced physics capabilities to measure jets in relativistic heavy ion collisions at RHIC, as well as in polarized ...proton interactions, and eventually electron ion collisions at an Electron Ion Collider. This upgrade, sPHENIX, will include two new calorimeter systems. One will be a hadronic calorimeter, which will be the first hadronic calorimeter ever used in an experiment at RHIC, and another will be a new compact electromagnetic calorimeter. Both calorimeters will cover a region of ±1.1 in pseudorapidity and 2π in phi. The hadron calorimeter will be based on scintillator plates interspersed between steel absorber plates and read out with wavelength shifting fibers. The electromagnetic calorimeter will be an accordion design that will utilize scintillating fibers embedded in a matrix consisting of tungsten plates, tungsten powder and epoxy. The readout for both calorimeters will use silicon photomultipliers. The overall design of these two calorimeter systems is described along with the R&D efforts currently being pursued to develop them along with their readout.
The Si Mini-Pad sensor is an essential component of the MPC-EX preshower detector. This detector will be integrated into the PHENIX experiment at Brookhaven National Laboratory’s Relativistic Heavy ...Ion Collider. We describe the development of the surface pattern and the fabrication process of the Si Mini-Pad sensor and present a test by the low energy γ irradiation that is sensitive to the surface design.
The PHENIX MPC-EX is an W/Si pre-shower detector operating at small angles with respect to the beam in the Relativistic Heavy Ion Collider (RHIC). The Si Mini-Pad sensors are the active element of ...the detector. The expected hadron flux to the Si Mini-Pad sensors will generate significant non-ionizing energy loss in the sensors, which may damage the crystalline structure of the sensor’s bulk material. We investigated the nature of the hadron flux to the Si Mini-Pad sensors through a full simulation and determined its effect on the sensor’s characteristics based on a beam test. The investigation showed key issues in designing a preshower detector using silicon sensors and operating under a large neutron fluence and offered valuable information on the operation of the MPC-EX detector.
The PHENIX collaboration presents first measurements of low-momentum (0.4<p_{T}<3 GeV/c) direct-photon yields from Au+Au collisions at sqrts_{NN}=39 and 62.4 GeV. For both beam energies the ...direct-photon yields are substantially enhanced with respect to expectations from prompt processes, similar to the yields observed in Au+Au collisions at sqrts_{NN}=200. Analyzing the photon yield as a function of the experimental observable dN_{ch}/dη reveals that the low-momentum (>1 GeV/c) direct-photon yield dN_{γ}^{dir}/dη is a smooth function of dN_{ch}/dη and can be well described as proportional to (dN_{ch}/dη)^{α} with α≈1.25. This scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and the Large Hadron Collider, for centrality selected samples, as well as for different A+A collision systems. At a given beam energy, the scaling also holds for high p_{T} (>5 GeV/c), but when results from different collision energies are compared, an additional sqrts_{NN}-dependent multiplicative factor is needed to describe the integrated-direct-photon yield.
The PHENIX detector at RHIC has been designed to study hadronic and leptonic signatures of the Quark Gluon Plasma in heavy ion collisions and spin dependent structure functions in polarized proton ...collisions. The baseline detector measures muons in two muon spectrometers located forward and backward of mid-rapidity, and measures hadrons, electrons, and photons in two central spectrometer arms, each of which covers 90/spl deg/ in azimuth and 0.35 units of rapidity. Further progress requires extending rapidity coverage for hadronic and electromagnetic signatures by upgrading the functionality of the PHENIX muon spectrometers to include photon and jet measurement capabilities. Tungsten calorimeters with silicon pixel readout and fine transverse and longitudinal segmentation are proposed to attain this goal. The use of such a design provides the highest density and finest granularity possible in a calorimeter.
Extensive experimental data from high-energy nucleus-nucleus collisions were recorded using the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). The comprehensive set of measurements ...from the first three years of RHIC operation includes charged particle multiplicities, transverse energy, yield ratios and spectra of identified hadrons in a wide range of transverse momenta (
p
T
), elliptic flow, two-particle correlations, nonstatistical fluctuations, and suppression of particle production at high
p
T
. The results are examined with an emphasis on implications for the formation of a new state of dense matter. We find that the state of matter created at RHIC cannot be described in terms of ordinary color neutral hadrons.
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