123630749
Jet energy correction with charged particle tracks in CMS
Abstract.The performance of a jet-energy-correction algorithm using reconstructed charged particle tracks is presented. The jet energy correction allows the jet energy scale to be restored and improves the energy resolution for jets with energies up to 120 GeV. For low energy jets (20 GeV) it improves the resolution by a factor 1.7 with respect to uncorrected jets. For 100 GeV jets the resolution improves by 15%. The deviation from unity of the ratio of the reconstructed to the generator jet transverse energies decreases by a factor two for low-$\rm E_{\rm T}$ jets ($\rm E_{\rm T} < 30$ GeV). For high-$\rm E_{\rm T}$ jets, this ratio amounts to $1.00\pm0.04$.
120049072
The resistive plate chambers for CMS and their simulation
In this paper some results obtained by the CMS Resistive Plate Chamber collaboration during its five years long period of research and development are reported. The importance of the simulation in the design of the Resistive Plate Chambers for CMS is stressed.
115001576
Single event effect measurements on the resistive plate chambers front-end chips for the CMS experiment
123170336
NEUTRON-INDUCED SINGLE EVENT UPSET ON THE RPC FRONT-END CHIPS FOR THE CMS EXPERIMENT
Neutrons from a reactor and from a cyclotron have been used to characterise the CMS Resistive Plate Chambers (RPCs) front-end chip to neutron-induced damaging events. Single Event Upset (SEU) cross-sections have been measured up to for different chip thresholds. Tests at a reactor were done with an integrated fast () neutron fluence of and a thermal neutron fluence of . High-energy neutrons from a cyclotron were used up to a fluence of . Data indicate the existence of a chip SEU sensitivity already at thermal energy and a saturated SEU cross-section from 3 to . Values of the SEU cross-sections from the thermal run well agree with those obtained by another CMS group that uses the same technology ( BiCMOS) though with different architecture. Cross-sections obtained with fast neutrons (from to about ) are consistently higher by one order of magnitude compared to the thermal one. The average time between consecutive SEU events in each chip of the CMS barrel RPCs can be estimated to be 1 h.
56416813
Aging study for Resistive Plate Chambers of the CMS Muon Trigger Detector
A long-term aging test of a Resistive Plate Chamber (RPC) was carried out with an intense gamma source. The detector was operated in avalanche mode and had the bakelite surface treated with linseed oil. After the irradiation the estimated dose, charge and fluence were approximately equal to the expected values after 10 years of operation in the CMS barrel region. During and after the irradiation, the RPC performance was monitored with cosmic muons and showed no relevant aging effects. Moreover, no variation of the bakelite resistance was observed.
15045293
The bakelite for the RPCs of the experiment CMS
Results from aging tests on the bakelite used for the CMS RPCs are presented. Samples of melaminic bakelite were exposed to a heavy gamma and neutron radiation. Data on the bulk resistivity were collected while accumulating gamma and neutron doses and particles fluence up to values well beyond those expected in 10 years of RPCs operation in the barrel region of CMS. The test with gamma radiation was performed at the CERN Gamma Irradiation Facility (GIF) with a 20 Ci 137Cs source. A total absorbed dose of 5 Gy was accumulated during an irradiation period of about one month. The test with both neutron and gamma radiation was held at the Triga Mark II 250 kW reactor located in Pavia. A total of 80 h of exposure were accumulated integrating a neutron and gamma dose of about 80 Gy and a fast neutron fluence of some . Experimental data on dose rate in both the test facilities have been compared to simulation output and show a good agreement.
118028873
Results on Lambda and Xi production in Pb-Pb collisions at 160 GeV/c per nucleon from the NA57 experiment
The NA57 experiment has been designed to study the onset of enhanced production of strange baryons and anti-baryons in Pb-Pb collisions with respect to p-Be collisions. This enhancement is considered a sensitive signature for a phase transition to a new state of matter -- the Quark Gluon Plasma (QGP). In this paper, we report results on Lambda and Xi hyperon production in central Pb-Pb collisions at 160 GeV/c per nucleon beam momentum.
118167912
Studio della produzione di particelle strane e della dinamica di espansione in collisioni nucleari ultra-relativistiche all'SPS
This is my Ph.D thesis on hyperon production, HBT correlation between negative pions and blast-wave analysis of m_t spectra in Pb-Pb collisions at SPS.
117970185
Search for pentaquarks in WA97 experiment at CERN
The WA97 experiment at CERN has collected data aiming to study strangeness production in heavy ion collisions at 158 A GeV/c; p‐Be data were also taken as reference data. Here we show some results of an analysis of these p‐Be data in order to check for evidence of a recently claimed pentaquark state.
15825535
Blast-wave analysis of strange particle mT spectra in Pb–Pb collisions at the SPS
The transverse mass spectra of high statistics, high purity samples of $K^{0}_{S}, \Lambda, \Xi and \Omega$ particles produced in Pb–Pb collisions at SPS energy have been studied in the framework of the blast-wave model. The dependence of the freezeout parameters on particle species and event centrality is discussed. Results at 40 A GeV/c are presented here for the first time
15830879
Centrality dependence of the expansion dynamics in Pb Pb collisions at 158-A-GeV/c
Two-particle correlation functions of negatively charged hadrons from Pb-Pb collisions at 158?GeV?c-1/nucleon have been measured by the WA97 experiment at the CERN SPS. A Coulomb correction procedure that assumes an expanding source has been implemented. Within the framework of an expanding thermalized source model the size and dynamical state of the collision fireball at freeze-out have been reconstructed as a function of the centrality of the collision. Less central collisions exhibit a different dynamics than central ones: both transverse and longitudinal expansion velocities are slower, the expansion duration is shorter and the system freezes out, showing smaller dimensions and higher temperature.