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A new phase of matter in Oakland

Description: Recent results from the Relativistic Heavy Ion Collider (RHIC) and the phase diagram of matter at very high energies were the focal points of Quark Matter 2004, held January 10-17, 2004 in the Oakland, California convention center. About 700 participants, including 125 students, from 28 countries gathered for 5 days of plenary and parallel sessions. Besides the scientific discussions, participants enjoyed an afternoon of excursions; choices included visits to San Francisco, the Muir woods, and, of course, a chance to sample Napa Valley wines. There was also a day of introductory lectures for graduate students and a separate afternoon program for 50 local high school teachers. The ''Quark Matter'' conference series has evolved into the premier venue for relativistic heavy ion collisions, and QM2004 was no exception. The 44 plenary and 92 parallel session talks featured a veritable flood of data from STAR (Kai Schweda, LBNL), PHENIX (Tony Frawley, Florida State), PHOBOS (Peter Steinberg, BNL) and BRAHMS (Michael Murray, Kansas), at RHIC. This was accompanied by contributions from HERMES ( Pasquale DiNezza, Frascati) and HERA-B (Joakim Spengler, Heidelberg) and continuing analyses from NA-49 (Marek Gazdzicki, Frankfurt) and NA-57 (Giuseppe Bruno, Bari) at the CERN SPS. The theoretical contributions presented a broad range of models and calculations, from microscopic particle-by-particle simulations to hydrodynamic models that model the bulk behavior using an equation of state. A focus of much discussion was the question ''Have we found the Quark Gluon Plasma (QGP)?'' This search was the prime motivation to build RHIC. Although the RHIC experiments made no formal statement, most conference attendees seemed to feel that the answer was yes. No single measurement makes the case, but the variety of data featured at QM2004 seems most easily explained in the context of a QGP. Some of the signatures included the suppression of high ...
Date: March 18, 2004
Creator: Klein, Spencer & Nystrand, Joakim
Partner: UNT Libraries Government Documents Department

Deutron photodissociation in ultraperipheral relativistic heavyion on deutron collisions

Description: In ultraperipheral relativistic deuteron on heavy-ion collisions, a photon emitted from the heavy nucleus may dissociate the deuterium ion. We find deuterium breakup cross sections of 1.24 barns for deuterium-gold collisions at a center of mass energy of 200 GeV per nucleon, as studied at the Relativistic Heavy Ion Collider, and 2.35 barns for deuterium-lead collisions at a center of mass energy of 6.2 TeV, as proposed for the Large Hadron Collider. In the latter case, the cross section is as large as that of hadronic interactions. The estimated error is 5%. We discuss the use of this process as a luminosity monitor and a 'tag' for moderate impact parameter collisions.
Date: March 24, 2003
Creator: Klein, Spencer & Vogt, Ramona
Partner: UNT Libraries Government Documents Department

Muon Production in Relativistic Cosmic-Ray Interactions

Description: Cosmic-rays with energies up to 3x1020 eV have been observed. The nuclear composition of these cosmic rays is unknown but if the incident nuclei are protons then the corresponding center of mass energy is sqrt snn = 700 TeV. High energy muons can be used to probe the composition of these incident nuclei. The energy spectra of high-energy (> 1 TeV) cosmic ray induced muons have been measured with deep underground or under-ice detectors. These muons come from pion and kaon decays and from charm production in the atmosphere. Terrestrial experiments are most sensitive to far-forward muons so the production rates aresensitive to high-x partons in the incident nucleus and low-x partons in the nitrogen/oxygen targets. Muon measurements can complement the central-particle data collected at colliders.This paper will review muon production data and discuss some non-perturbative (soft) models that have been used to interpret the data. I will show measurements of TeV muon transverse momentum (pT) spectra in cosmic-ray air showers fromMACRO, and describe how the IceCube neutrino observatory and the proposed Km3Net detector will extend these measurements to a higher pT region where perturbative QCD should apply. With a 1 km2 surface area, the full IceCube detector should observe hundreds of muons/year with pT in the pQCD regime.
Date: July 27, 2009
Creator: Klein, Spencer
Partner: UNT Libraries Government Documents Department

Photoproduction at RHIC and the LHC

Description: The strong electromagnetic fields carried by relativistic highly charged ions make heavy-ion colliders attractive places to study photonuclear interactions and two-photon interactions. At RHIC, three experiments have studied coherent photoproduction of {rho}{sup 0}, 4{pi}, J/{psi}, e{sup +}e{sup -} pairs, and e{sup +}e{sup -} pairs where the electron is bound to one of the incident nuclei. These results show that photoproduction studies are possible, and demonstrate some of the unique possibilities due to the symmetric final states and the ion targets. The LHC will reach photon-nucleon energies many times higher than at HERA; these collisions can be used to measure the gluon distributions in nuclei at very low Bjorken-x, where shadowing and gluon saturation may become important; LHC {gamma}{gamma} collisions may also be attractive places to search for some types of new physics. ATLAS, CMS and ALICE are all planning to study photoproduction. After introducing the principles of photoproduction at hadron colliders, I will review recent results from RHIC on meson and e{sup +}e{sup -} production, and then discuss prospects for studies at the LHC.
Date: October 6, 2008
Creator: Klein, Spencer
Partner: UNT Libraries Government Documents Department

Observation of Au + Au --> Au + Au + rho(0) and Au + Au --> Au* + Au* + rho(0) with STAR

Description: We report the first observation of the reactions Au + Au {yields} Au + Au + {rho}{sup 0} and Au + Au {yields} Au* + Au* + {rho}{sup 0} with the STAR detector. The {rho} are produced at small perpendicular momentum, as expected if they couple coherently to both nuclei. We discuss models of vector meson production and the correlation with nuclear breakup, and present a fundamental test of quantum mechanics that is possible with the system.
Date: March 10, 2001
Creator: Klein, Spencer & Collaboration, STAR
Partner: UNT Libraries Government Documents Department

Ultra-peripheral collisions with STAR at RHIC

Description: The strong electromagnetic fields of heavy nuclei can produce a wide variety of two-photon and photonuclear reactions at relativistic ion colliders. We present recent results from the STAR collaboration on these ''ultra-peripheral'' interactions, focusing on vector meson production and interferometry, and on e{sup +}e{sup -} pair production. The vector meson interferometry occurs because of the symmetric initial state: nucleus 1 can emit a photon which scatters from nucleus 2, emerging as a vector meson, or vice-versa. The two processes are indistinguishable, and so interfere, even though the production points are separated enough that the produced mesons decay before their wave functions can overlap, so the system can be used for interesting tests of quantum mechanics.
Date: October 22, 2003
Creator: Klein, Spencer & Collaboration, STAR
Partner: UNT Libraries Government Documents Department

Quantum interferometry in rho{sup 0} production in ultra-peripheral heavy ion collisions

Description: In {rho}{sup 0} photoproduction in ultra-peripheral heavy ion collisions, either ion can be the photon emitter or the target. The two possibilities are indistinguishable, and they should be able to interfere, reducing {rho}{sup 0} production at low transverse momentum, p{sub T} < {h_bar}/<b>, where <b> is the median impact parameter. The two {rho}{sup 0} production points are separated by <b> {approx} 18-46 fm, while the {rho}{sup 0} decay before travelling 1 fm. The two decay points are well separated in spacetime, so the decays proceed independently and any interference must involve the final state {pi}{sup +}{pi}{sup -}. This requires a non-local wave function.
Date: December 30, 2003
Creator: Klein, Spencer R. & Collaboration, STAR
Partner: UNT Libraries Government Documents Department

Heavy Nuclei, From RHIC to The Cosmos

Description: Ultra-relativistic heavy ion collisions produce a high-temperature, thermalized system that may mimic the conditions present shortly after the big bang. This writeup will given an overview of early results from the Relativistic Heavy Ion Collider (RHIC), and discuss what we have learned about hot, strongly interacting nuclear systems. The thermal and chemical composition of the system will be discussed, along with observables that are sensitive to the early evolution of the system. I will also discuss the implications of the RHIC results for cosmic ray air showers.
Date: November 1, 2002
Creator: Klein, Spencer R.
Partner: UNT Libraries Government Documents Department

Electrodynamics at the highest energies

Description: At very high energies, the bremsstrahlung and pair production cross sections exhibit complex behavior due to the material in which the interactions occur. The cross sections in dense media can be dramatically different than for isolated atoms. This writeup discusses these in-medium effects, emphasizing how the cross section has different energy and target density dependencies in different regimes. Data from SLAC experiment E-146 will be presented to confirm the energy and density scaling. Finally, QCD analogs of the electrodynamics effects will be discussed.
Date: June 17, 2002
Creator: Klein, Spencer R.
Partner: UNT Libraries Government Documents Department

Studying High pT muons in Cosmic-Ray Air Showers

Description: Most cosmic-ray air shower arrays have focused on detectingelectromagnetic shower particles and low energy muons. A few groups (mostnotably MACRO + EASTOP and SPASE + AMANDA) have studied the high energymuon component of showers. However, these experiments had small solidangles, and did not study muons far from the core. The IceTop + IceCubecombination, with its 1 km$^2$ muon detection area can study muons farfrom the shower core. IceCube can measure their energy loss ($dE/dx$),and hence their energy. With the energy, and the known distribution ofproduction heights, the transverse momentum ($p_T$) spectrum of high$p_T$ muons can be determined. The production of the semuons iscalculable in perturbative QCD, so the measured muon spectra can be usedto probe the composition of incident cosmic-rays.
Date: December 1, 2006
Creator: Klein, Spencer R.
Partner: UNT Libraries Government Documents Department

Recent Results from RHIC&Some Lessons for Cosmic-RayPhysicists

Description: The Relativistic Heavy Ion Collider (RHIC) studies nuclear matter under a variety of conditions. Cold nuclear matter is probed with deuteron-gold collisions, while hot nuclear matter (possibly a quark-gluon plasma (QGP)) is created in heavy-ion collisions. The distribution of spin in polarized nucleons is measured with polarized proton collisions, and photoproduction is studied using the photons that accompany heavy nuclei. The deuteron-gold data shows less forward particle production than would be expected from a superposition of pp collisions, as expected due to saturation/shadowing. Particle production in AA collisions is well described by a model of an expanding fireball in thermal equilibrium. Strong hydrodynamic flow and jet quenching shows that the produced matter interacts very strongly. These phenomena are consistent with new non-perturbative interactions near the transition temperature to the QGP. This report discusses these results, and their implications for cosmic-ray physicists.
Date: October 1, 2006
Creator: Klein, Spencer R.
Partner: UNT Libraries Government Documents Department

First Results from IceCube

Description: IceCube is a 1 km{sup 3} neutrino observatory being built to study neutrino production in active galactic nuclei, gamma-ray bursts, supernova remnants, and a host of other astrophysical sources. High-energy neutrinos may signal the sources of ultra-high energy cosmic rays. IceCube will also study many particle-physics topics: searches for WIMP annihilation in the Earth or the Sun, and for signatures of supersymmetry in neutrino interactions, studies of neutrino properties, including searches for extra dimensions, and searches for exotica such as magnetic monopoles or Q-balls. IceCube will also study the cosmic-ray composition. In January, 2005, 60 digital optical modules (DOMs) were deployed in the South Polar ice at depths ranging from 1450 to 2450 meters, and 8 ice-tanks, each containing 2 DOMs were deployed as part of a surface air-shower array. All 76 DOMs are collecting high-quality data. After discussing the IceCube physics program and hardware, I will present some initial results with the first DOMs.
Date: January 12, 2006
Creator: Klein, Spencer R.
Partner: UNT Libraries Government Documents Department

Coherent rho 0 photoproduction in bulk matter at high energies

Description: The momentum transfer {Delta}k required for a photon to scatter from a target and emerge as a {rho}{sup 0} decreases as the photon energy k rises. For k > 3 x 10{sup 14} eV, {Delta}k is small enough that the interaction cannot be localized to a single nucleus. At still higher energies, photons may coherently scatter elastically from bulk matter and emerge as a {rho}{sup 0}, in a manner akin to kaon regeneration. Constructive interference from the different nuclei coherently raises the cross section and the interaction probability rises linearly with energy. At energies above 10{sup 23} eV, coherent conversion is the dominant process; photons interact predominantly as {rho}{sup 0}. We compute the coherent scattering probabilities in slabs of lead, water and rock, and discuss the implications of the increased hadronic interaction probabilities for photons on ultra-high energy shower development.
Date: January 9, 2009
Creator: Couderc, Elsa & Klein, Spencer
Partner: UNT Libraries Government Documents Department

Determination of the Atmospheric Neutrino Flux and Searches for New Physics with AMANDA-II

Description: The AMANDA-II detector, operating since 2000 in the deep ice at the geographic South Pole, has accumulated a large sample of atmospheric muon neutrinos in the 100 GeV to 10 TeV energy range. The zenith angle and energy distribution of these events can be used to search for various phenomenological signatures of quantum gravity in the neutrino sector, such as violation of Lorentz invariance (VLI) or quantum decoherence (QD). Analyzing a set of 5511 candidate neutrino events collected during 1387 days of livetime from 2000 to 2006, we find no evidence for such effects and set upper limits on VLI and QD parameters using a maximum likelihood method. Given the absence of evidence for new flavor-changing physics, we use the same methodology to determine the conventional atmospheric muon neutrino flux above 100 GeV.
Date: June 2, 2009
Creator: Collaboration, IceCube; Klein, Spencer & Collaboration, IceCube
Partner: UNT Libraries Government Documents Department

Detection of Atmospheric Muon Neutrinoswith the IceCube 9-String Detector

Description: The IceCube neutrino detector is a cubic kilometer TeV to PeV neutrino detector under construction at the geographic South Pole. The dominant population of neutrinos detected in IceCube is due to meson decay in cosmic-ray air showers. These atmospheric neutrinos are relatively well understood and serve as a calibration and verification tool for the new detector. In 2006, the detector was approximately 10% completed, and we report on data acquired from the detector in this configuration. We observe an atmospheric neutrino signal consistent with expectations, demonstrating that the IceCube detector is capable of identifying neutrino events. In the first 137.4 days of livetime, 234 neutrino candidates were selected with an expectation of 211 {+-} 76.1(syst.) {+-} 14.5(stat.) events from atmospheric neutrinos.
Date: May 12, 2007
Creator: Collaboration, IceCube; Klein, Spencer & Achterberg, A.
Partner: UNT Libraries Government Documents Department

FIRST NEUTRINO POINT-SOURCE RESULTS FROM THE 22-STRING ICECUBE DETECTOR

Description: We present new results of searches for neutrino point sources in the northern sky, using data recorded in 2007-08 with 22 strings of the IceCube detector (approximately one-fourth of the planned total) and 275.7 days of livetime. The final sample of 5114 neutrino candidate events agrees well with the expected background of atmospheric muon neutrinos and a small component of atmospheric muons. No evidence of a point source is found, with the most significant excess of events in the sky at 2.2 {sigma} after accounting for all trials. The average upper limit over the northern sky for point sources of muon-neutrinos with E{sup -2} spectrum is E{sup 2} {Phi}{sub {nu}{sub {mu}}} < 1.4 x 10{sup -1} TeV cm{sup -2}s{sup -1}, in the energy range from 3 TeV to 3 PeV, improving the previous best average upper limit by the AMANDA-II detector by a factor of two.
Date: May 14, 2009
Creator: Collaboration, IceCube & Klein, Spencer
Partner: UNT Libraries Government Documents Department

Supersymmetric and Kaluza-Klein Particles Multiple Scattering in the Earth

Description: Neutrino telescopes with cubic kilometer volume have the potential to discover new particles. Among them are next to lightest supersymmetric (NLSPs) and next to lightest Kaluza-Klein (NLKPs) particles. Two NLSPs or NLKPs will transverse the detector simultaneously producing parallel charged tracks. The track separation inside the detector can be a few hundred meters. As these particles might propagate a few thousand kilometers before reaching the detector, multiple scattering could enhance the pair separation at the detector. We find that the multiple scattering will alter the separation distribution enough to increase the number of NLKP pairs separated by more than 100 meters (a reasonable experimental cut) by up to 46% depending on the NLKP mass. Vertical upcoming NLSPs will have their separation increased by 24% due to multiple scattering.
Date: May 19, 2009
Creator: Albuquerque, Ivone & Klein, Spencer
Partner: UNT Libraries Government Documents Department

IceCube: A Cubic Kilometer Radiation Detector

Description: IceCube is a 1 km{sup 3} neutrino detector now being built at the Amudsen-Scott South Pole Station. It consists of 4800 Digital Optical Modules (DOMs) which detect Cherenkov radiation from the charged particles produced in neutrino interactions. IceCube will observe astrophysical neutrinos with energies above about 100 GeV. IceCube will be able to separate {nu}{sub {mu}}, {nu}{sub t}, and {nu}{sub {tau}} interactions because of their different topologies. IceCube construction is currently 50% complete.
Date: June 1, 2008
Creator: Collaboration, IceCube; Klein, Spencer R & Klein, S.R.
Partner: UNT Libraries Government Documents Department

Measurement of sound speed vs. depth in South Pole ice: pressure waves and shear waves

Description: We have measured the speed of both pressure waves and shear waves as a function of depth between 80 and 500 m depth in South Pole ice with better than 1% precision. The measurements were made using the South Pole Acoustic Test Setup (SPATS), an array of transmitters and sensors deployed in the ice at the South Pole in order to measure the acoustic properties relevant to acoustic detection of astrophysical neutrinos. The transmitters and sensors use piezoceramics operating at {approx}5-25 kHz. Between 200 m and 500 m depth, the measured profile is consistent with zero variation of the sound speed with depth, resulting in zero refraction, for both pressure and shear waves. We also performed a complementary study featuring an explosive signal propagating vertically from 50 to 2250 m depth, from which we determined a value for the pressure wave speed consistent with that determined for shallower depths, higher frequencies, and horizontal propagation with the SPATS sensors. The sound speed profile presented here can be used to achieve good acoustic source position and emission time reconstruction in general, and neutrino direction and energy reconstruction in particular. The reconstructed quantities could also help separate neutrino signals from background.
Date: June 4, 2009
Creator: Collaboration, IceCube & Klein, Spencer
Partner: UNT Libraries Government Documents Department