The effects of radiation damage in silicon photomultipliers (SiPMs) from gamma rays have been measured and compared with the damage produced by neutrons. Several types of multipixel photon counters ...from Hamamatsu were exposed to gamma rays and neutrons at the Solid State Gamma Ray Irradiation Facility (SSGRIF) at the Brookhaven National Laboratory and the Institute for Nuclear Research (Atomki) in Debrecen, Hungary. The gamma ray exposures ranged from 1 krad to 1 Mrad and the neutron exposures ranged from 10 8 to 10 12 n/cm 2 . The main effect of gamma ray damage is an increase in the noise and leakage current in the irradiated devices, similar to what is seen from neutron damage, but the level of damage is considerably less at comparable high levels of exposure. In addition, the damage from gamma rays saturates after a few hundred krad, while the damage from neutrons shows no sign of saturation, suggestive of different damage mechanisms in the two cases. The change in optical absorption in the window material of the SiPMs due to radiation was also measured. This paper was carried out in order to evaluate the use of SiPMs for particle physics applications with moderate levels of radiation exposures.
The super Pioneering High Energy Nuclear Interaction eXperiment (sPHENIX) at the Relativistic Heavy Ion Collider will perform high-precision measurements of jets and heavy flavor observables for a ...wide selection of nuclear collision systems, elucidating the microscopic nature of strongly interacting matter ranging from nucleons to the strongly coupled quark-gluon plasma. A prototype of the sPHENIX calorimeter system was tested at the Fermilab Test Beam Facility as experiment T-1044 in the spring of 2016. The electromagnetic calorimeter (EMCal) prototype is composed of scintillating fibers embedded in a mixture of tungsten powder and epoxy. The hadronic calorimeter (HCal) prototype is composed of tilted steel plates alternating with the plastic scintillator. Results of the test beam reveal the energy resolution for electrons in the EMCal is <inline-formula> <tex-math notation="LaTeX">2.8\%\oplus 15.5\%/\sqrt {E} </tex-math></inline-formula> and the energy resolution for hadrons in the combined EMCal plus HCal system is <inline-formula> <tex-math notation="LaTeX">13.5\%\oplus 64.9\%/\sqrt {E} </tex-math></inline-formula>. These results demonstrate that the performance of the proposed calorimeter system satisfies the sPHENIX specifications.
sPHENIX is a new experiment under construction for the Relativistic Heavy Ion Collider at Brookhaven National Laboratory which will study the quark-gluon plasma to further the understanding of ...quantum chromodynamics (QCP) matter and interactions. A prototype of the sPHENIX electromagnetic calorimeter (EMCal) was tested at the Fermilab Test Beam Facility in Spring 2018 as experiment T-1044. The EMCal prototype corresponds to a solid angle of <inline-formula> <tex-math notation="LaTeX">\Delta \eta \times \Delta \phi = 0.2 \times 0.2 </tex-math></inline-formula> centered at pseudo-rapidity <inline-formula> <tex-math notation="LaTeX">\eta = 1 </tex-math></inline-formula>. The prototype consists of scintillating fibers embedded in a mix of tungsten powder and epoxy. The fibers project back approximately to the center of the sPHENIX detector, giving 2-D projectivity. The energy response of the EMCal prototype was studied as a function of position and input energy. The energy resolution of the EMCal prototype was obtained after applying a position-dependent energy correction and a beam profile correction. Two separate position-dependent corrections were considered. The EMCal energy resolution was found to be <inline-formula> <tex-math notation="LaTeX">\sigma (E)/\langle E\rangle = 3.5(0.1) \oplus 13.3(0.2)/\sqrt {E} </tex-math></inline-formula> based on the hodoscope position-dependent correction, and <inline-formula> <tex-math notation="LaTeX">\sigma (E)/\langle E\rangle = 3.0(0.1) \oplus 15.4(0.3)/\sqrt {E} </tex-math></inline-formula> based on the cluster position-dependent correction. These energy resolution results meet the requirements of the sPHENIX physics program.
sPHENIX is a major upgrade to the PHENIX detector enabling high-rate, large acceptance measurements of upsilons, direct photons and fully reconstructed jets in p-p, p-A and A-A collisions at the ...Relativistic Heavy Ion Collider (RHIC). These detailed measurements will probe the Quark Gluon Plasma near its transition temperature, in a region of strongest coupling. The sPHENIX detector consists of hadronic and electromagnetic calorimetry, and charged particle tracking in conjunction with the recently acquired 1.5 tesla BaBar super-conducting solenoid. The sPHENIX acceptance of 2π in azimuth and |η| < 1.1 in pseudo-rapidity provides a factor of six improvement over the present PHENIX central spectrometer. Beyond being an excellent RHIC detector, sPHENIX provides an outstanding foundation for a detector focused on the physics of a possible future electron-ion collider at RHIC (eRHIC). In this talk we will discuss the physics potential of the sPHENIX detector, the design and technology choices for the sPHENIX calorimeters, and the conceptual design of a day-one detector for eRHIC.
Air-fluorescence detectors such as the High Resolution Fly's Eye (HiRes) detector are very sensitive to upward-going, Earth-skimming ultra-high-energy electron-neutrino-induced showers. This is due ...to the relatively large interaction cross sections of these high-energy neutrinos and to the Landau- Pomeranchuk-Migdal (LPM) effect. The LPM effect causes a significant decrease in the cross sections for bremsstrahlung and pair production, allowing charged-current electron-neutrino-induced showers occurring deep in the Earth's crust to be detectable as they exit the Earth into the atmosphere. A search for upward-going neutrino-induced showers in the HiRes-II monocular data set has yielded a null result. From an LPM calculation of the energy spectrum of charged particles as a function of primary energy and depth for electron-induced showers in rock, we calculate the shape of the resulting profile of these showers in air. We describe a full detector Monte Carlo simulation to determine the detector response to upward-going electron- neutrino-induced cascades and present an upper limit on the flux of electron neutrinos.
Experimental studies of the collisions of heavy nuclei at relativistic energies have established the properties of the quark–gluon plasma (QGP), a state of hot, dense nuclear matter in which quarks ...and gluons are not bound into hadrons1–4. In this state, matter behaves as a nearly inviscid fluid5 that efficiently translates initial spatial anisotropies into correlated momentum anisotropies among the particles produced, creating a common velocity field pattern known as collective flow. In recent years, comparable momentum anisotropies have been measured in small-system proton–proton (p+p) and proton–nucleus (p+A) collisions, despite expectations that the volume and lifetime of the medium produced would be too small to form a QGP. Here we report on the observation of elliptic and triangular flow patterns of charged particles produced in proton–gold (p+Au), deuteron–gold (d+Au) and helium–gold (3He+Au) collisions at a nucleon–nucleon centre-of-mass energy \\sqrt {s_{{\mathrm{NN}}}\ = 200 GeV. The unique combination of three distinct initial geometries and two flow patterns provides unprecedented model discrimination. Hydrodynamical models, which include the formation of a short-lived QGP droplet, provide the best simultaneous description of these measurements.
Recently, multiparticle-correlation measurements of relativistic p/d/^{3}He+Au, p+Pb, and even p+p collisions show surprising collective signatures. Here, we present beam-energy-scan measurements of ...two-, four-, and six-particle angular correlations in d+Au collisions at sqrts_{NN}=200, 62.4, 39, and 19.6 GeV. We also present measurements of two- and four-particle angular correlations in p+Au collisions at sqrts_{NN}=200 GeV. We find the four-particle cumulant to be real valued for d+Au collisions at all four energies. We also find that the four-particle cumulant in p+Au has the opposite sign as that in d+Au. Further, we find that the six-particle cumulant agrees with the four-particle cumulant in d+Au collisions at 200 GeV, indicating that nonflow effects are subdominant. These observations provide strong evidence that the correlations originate from the initial geometric configuration, which is then translated into the momentum distribution for all particles, commonly referred to as collectivity.
The average mass composition of cosmic rays with primary energies between 10(17) and 10(18) eV has been studied using a hybrid detector consisting of the High Resolution Fly's Eye (HiRes) prototype ...and the MIA muon array. Measurements have been made of the change in the depth of shower maximum and the muon density as a function of energy. The results show that the composition is changing from a heavy to lighter mix as the energy increases.
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