11389899
Centrality dependence of K+ produced in Pb+Pb collisions at 158 GeV per nucleon
The NA52 collaboration searches for a discontinuous behaviour of charged kaons produced in Pb+Pb collisions at 158 A GeV as a function of the impact parameter, which could reveal a hadron to quark-gluon plasma (QGP) phase transition. The K+ yield is found to grow proportional to the number of participating ('wounded') nucleons N, above N=100. Previous NA52 data agree with the above finding and show a discontinuous behaviour in the kaon centrality dependence near N=100, marking the onset of strangeness enhancement -over e.g. p+A data at the same \sqrt{s}- in a chemically equilibrated phase.
14164208
A prototype liquid Argon Time Projection Chamber for the study of UV laser multi-photonic ionization
This paper describes the design, realization and operation of a prototype liquid Argon Time Projection Chamber (LAr TPC) detector dedicated to the development of a novel online monitoring and calibration system exploiting UV laser beams. In particular, the system is intended to measure the lifetime of the primary ionization in LAr, in turn related to the LAr purity level. This technique could be exploited by present and next generation large mass LAr TPCs for which monitoring of the performance and calibration play an important role. Results from the first measurements are presented together with some considerations and outlook.
124388402
Strangelet search and particle production studies in Pb + Pb collisions at 158-A-GeV/c at CERN SPS
We searched for long-lived strange quark matter particles, so-calledstrangelets, and studied particle and antiparticle production in Pb+Pb collisions at 158 GeV/c per nucleon at zero degree production angle. We give upper limits for the production of strangelets covering a mass to charge ratio up to 120 GeV/c 2 and lifetimest lab>1.2 μs and plot invariant differential production cross sections as a function of rapidity for a variety of particles.
123035541
The NA52 strangelet search
The NA52 experiment searches for long-lived charged strangelets in 158 A GeV c-1 Pb + Pb collisions at CERN SPS. The experiment is able to identify single particles coming from the collisions at pt = 0. We collected 1013 Pb + Pb interactions looking for negatively charged strangelets and 3 × 1011 Pb + Pb interactions for positively charged ones. No evidence for the production of strangelets has been observed. We present here resulting experimental differential and total upper production limits.
119238918
A beam monitor detector based on doped silica and optical fibres
A beam monitor detector prototype based on doped silica fibres coupled to optical fibres has been designed, constructed and tested, mainly for accelerators used in medical applications. Scintillation light produced by Ce and Sb doped silica fibres moving across the beam has been measured, giving information on beam position, shape and intensity. Mostly based on commercial components, the detector is easy to install, to operate and no electronic components are located near the beam. Tests have been performed with a 2 MeV proton pulsed beam at an average current of 0.8 μA. The response characteristics of Sb doped silica fibres have been studied for the first time.
122225376
An investigation of the antinuclei and nuclei production mechanism in Pb + Pb collisions at 158 A GeV
We investigate the production mechanisms of p, d, t, 3He, 4He, 6Li, , and in Pb+Pb collisions at 158 A GeV measured near zero transverse momentum with the NA52 experiment at the CERN SPS. We find evidence that nuclei and antinuclei in Pb+Pb collisions are mainly produced via the coalescence mechanism out of a thermalized source of hadrons, at a time close to the thermal freeze-out of hadrons corresponding to a temperature of ~120 MeV.
117231264
Development of readout system for double-sided silicon strip modules
Y. Takubo ∗,a S. Gonzalez-Sevilla, c A. Clark, c M. Endo, b D. Ferrere, c K. Hanagaki, b Y. Ikegami, a S. Terada,a Y. Unno a and M. Weber c a High Energy Accelerator Research Organization (KEK) 1-1 Oho, Tsukuba, Ibaragi, Japan b Department of Physics, Osaka University 1-1 Machikaneyama Toyonaka Osaka, Japan c DPNC, University of Geneva 24, quai Ernest-Ansermet CH-1211 Geneva 4, Switzerland E-mail: yosuke.takubo@kek.jp
121921718
Hadronic response and e / pi separation with the H1 lead / fiber calorimeter
Hadronic response and electron identification performance of the new H1 lead-scintillating fibre calorimeter are investigated in the 1 to 7 GeV energy range using data taken at the CERN Proton Synchrotron. The energy response to minimum ionizing particles and interacting pions are studied and compared to Monte Carlo simulations. The measured energy of pions interacting either in the electromagnetic or in the hadronic section is found to scale linearly with the incident energy, providing an energy resolution σE ∼ 38% within a depth of one interaction length and σE ∼ 29% for a total depth of two interaction lengths. Several electron identification estimators are studied and combined as a function of energy and impact point. The probability for pions to be misidentified as electrons of any measured energy above 1 GeV ranges from 5% (for 2 GeV incident pions) to 0.4% (at 7 GeV) for an electron detection efficiency of 90%. The probability for pions of a given energy to be misidentified as electrons of the same energy falls to 0.25% at 7 GeV.
122383524
DIELECTRON SPECTROSCOPY IN COLD NUCLEAR MATTER
We report recent data on e+e- pair emission in proton nucleus collisions at energies slightly above the light vector meson production threshold. Invariant mass distributions for the p+Nb system at Ekin = 3.5 GeV/c2 show a clear ρ/ω signal and are compared to data from elementary p+p reactions. We observe a constant π0/ω yield ratio for both systems.
55821746
Trilepton final state from neutralino-chargino production in mSUGRA.
The direct production of neutralino-chargino pairs in the mSUGRA scenario with decays into pure trilepton final states has a significant cross section for low neutralino masses. The trilepton signature was studied with the full and fast CMS detector simulations. The 5 signal can be observed in the dilepton invariant mass distribution at the integrated luminosity of L 30 fb for GeV.
107061988
Design and assembly of double-sided silicon strip module prototypes for the ATLAS upgrade strip tracker
The LHC foresees a peak luminosity increase of up to ∼5×1034cm−2s−1 from ∼2022 with an integrated luminosity of ∼3000fb−1 before 2030. The current ATLAS Inner Detector will not stand the predicted radiation levels nor the expected large increase in the hit occupancy rates. A new inner tracker must therefore be designed, built and installed in a relatively short time-scale. The current layout assumes an all-silicon tracker with pixel detectors for the innermost layers and strip modules at higher radii. Major constraints are the requirements of radiation-hard sensors, efficient power distribution, minimum material budget, affordable cost, and fast and reliable production. This note reports on the design of double-sided silicon strip modules for the short-strip region of the upgraded ATLAS inner tracker. The different components of the module are described. The thermal performance is discussed. The assembly sequence of first module prototypes is explained in detail.