123939194
Antinuclei production in heavy ion collisions at CERN SPS
Abstract Besides the dedicated search for strangelets NA52 measures light (anti)particle and (anti)nuclei production over a wide range of rapidity. Compared to previous runs the statistics has been increased in the 1998 run by more than one order of magnitude for negatively charged objects at different spectrometer rigidities. At a rigidity of −20 GeV/ c we measured 10 6 p , 10 3 d and one 3 He without any centrality requirements. These preliminary results together with previous measurements near central rapidity are discussed in the framework of a thermodynamical and a coalescence model.
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.
109891378
The DØ silicon micro-strip tracker
The D0 silicon micro-strip tracker (SMT) is part of the D0 upgrade for the Tevatron RunII at Fermilab. The detector has been running successfully since the start of the RunII physics data taking. The tracking and vertexing performance match the expectation from Monte-Carlo studies. An additional inner layer (Layer0) of silicon sensors at R = 1.6cm will be installed in 2005.
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.
118548096
Measurement of the two-photon absorption cross-section of liquid argon with a time projection chamber
This paper reports on laser-induced multiphoton ionization at 266?nm of liquid argon in a time projection chamber (LAr TPC) detector. The electron signal produced by the laser beam is a formidable tool for the calibration and monitoring of next-generation large-mass LAr TPCs. The detector that we designed and tested allowed us to measure the two-photon absorption cross-section of LAr with unprecedented accuracy and precision: ?ex=(1.24?0.10stat?0.30syst)?10? 56?cm4?s? 1.
121444397
New results from NA52 on particle production in Pb+Pb collisions at 158 GeV per nucleon
Abstract We present new results on the centrality and rapidity dependence and on azimuthal anisotropies of particle production in Pb+Pb collisions at 158 GeV per nucleon.
119401854
Charge transfer and charge broadening of GEM structures in high magnetic fields
Abstract We report on the measurements of charge transfer in Gas Electron Multipliers (GEM) structures in high magnetic fields. These were performed in the framework of the R&D work for a Time Projection Chamber at a future Linear Collider. A small test chamber has been installed in the aperture of a superconducting magnet with the GEM structures mounted perpendicular to the B -field direction. The charge transfer is derived from the electrical currents monitored during irradiation with an 55 Fe source. No significant loss of primary ionisation charge is observed, and an improved ion feedback suppression is achieved for high magnetic fields. Additionally, the width of the charge cloud released by individual 55 Fe photons is measured using a finely segmented strip readout after the triple GEM structure. Charge widths between 0.3 and 0.5 mm RMS are observed, which originate from the charge broadening inside the GEM amplification. This charge broadening is only partly suppressed at high magnetic fields.
118621343
Validation of Kalman Filter alignment algorithm with cosmic-ray data using a CMS silicon strip tracker endcap
A Kalman Filter alignment algorithm has been applied to cosmic-ray data. We discuss the alignment algorithm and an experiment-independent implementation including outlier rejection and treatment of weakly determined parameters. Using this implementation, the algorithm has been applied to data recorded with one CMS silicon tracker endcap. Results are compared to both photogrammetry measurements and data obtained from a dedicated hardware alignment system, and good agreement is observed.
119968279
A Study of Radon Background in the XENON100 Experiment
The XENON100 Dark Matter experiment has recently published first results from an analysis of 11.2 live days of data, setting an upper limit on the spin‐independent WIMP‐nucleon elastic scattering cross section of 3.4×10−44 cm2 at 55 GeV/c2 and 90% confidence level. This article focuses on one specific background component of the XENON100 detector by presenting two independent methods of measuring the 222Rn concentration during operation phase. A first estimate of radon activity is derived for the 11.2 days analysis, proving the feasibility of on‐line radon monitoring. Remaining systematic uncertainties are discussed.
119399268
Measurement of Boson Self Couplings at LEP and Search for Anomalies
With center of mass energies up to 209 GeV of LEP II, massive W and Z bosons can be produced in pairs and jointly with photons. This allows to study boson-boson couplings. Since the W and Z bosons are unstable and decay into fermions, two- and four-fermion final states, accompanied possibly by photons, play an important role for these measurements. The couplings of the W to other bosons have been measured to be g1Z = 0.990+0.023-0.024, kappa_gamma = 0.896+0.058-0.056, and lambda_gamma = -0.023 +0.025 -0.023. They are in agreement with the Standard Model expectation of g1Z = 1, kappa_gamma = 1, and lambda_gamma = 0. No sign for couplings of three neutral bosons, parametrized by the couplings f_i^V and h_i^V, and for anomalous couplings of four gauge bosons, parametrized by a_0, a_n and a_c has been found.
119932741
Electroweak radiative corrections to e+ e- -> t anti-t H
We have calculated the complete electroweak O(alpha) radiative corrections to the Higgs-boson production process e+ e- -> t anti-t H in the electroweak Standard Model. Initial-state radiation beyond O(alpha) is included in the structure-function approach. The calculation of the corrections is briefly described, and numerical results are presented for the total cross section. Both the photonic and the genuine weak corrections reach the order of about 10% or even more and show a non-trivial dependence on the Higgs-boson mass and on the scattering energy. We compare our results with two previous calculations that obtained differing results at high energies.