122305754
Elastic scattering and coherent single pion production in proton-helium interactions at 18.6 GeV/c
Abstract Proton-helium elastic scattering and coherent single-pion production have been studied at 18.6 GeV/ c in the four-momentum transfer region (−0.06, −0.17) GeV/ c 2 . The elastic t -distribution has a somewhat steeper slope than is predicted by the Glauber approximation. The invariant-mass distribution of the Nπ system agrees with the double Regge-pole model except at about 1.65 GeV/ c 2 where an enhancement presumably due to N ∗ resonances is seen. The model also predicts the correct magnitude of the slope for n π + α events. By using our cross sections at t ′ = −0.06 (GeV/ c ) 2 where the impulse approximation should be valid, the isospin-zero exchange elementary cross section for the n π + production is evaluated. The inelastic angular distributions are consistent with several spinparity states contributing at all Nπ masses.
118121131
USE OF THE 3.5-MRAD BEAM FOR ELECTRONS.
121757543
Measurement of single spin asymmetry for direct photon production in pp collisions at 200 GeV/c
The single spin asymmetry for inclusive direct-photon production has been measured using a polarized proton beam of 200 GeV/c with an unpolarized proton target at −0.15 < xf < 0.15 and 2.5 < pt < 3.1 GeV/c at Fermilab. The data on the cross section for pp → γX at 2.5 < pt < 3.8 GeV/c are also provided. The measurement was done using lead-glass calorimeters and photon detectors which surrounded the fiducial area of the calorimeters. Background rejection has been done using these surrounding photon detectors. The cross section obtained is consistent with the results of previous measurements assuming a nuclear dependence of A1.0. The single spin asymmetry, AN, for the direct-photon production is consistent with zero within experimental uncertainty.
123662576
Observation of a likely example of the decay of a charmed particle produced in a high energy neutrino interaction
Abstract In a study of neutrino interactions occurring in nuclear emulsion, an event has been found that is most readily interpreted as the decay of a charmed particle with lifetime a few times 10 −13 s.
120981188
LARGE-ANGLE PION--PROTON ELASTIC SCATTERING AT HIGH ENERGIES.
124689502
A POSSIBLE SPECTROMETER FOR ACCOMPLISHING A SECONDARY BEAM SURVEY AT NAL.
108962738
Performance of the new high precision luminosity monitor of DELPHI
The STIC calorimeter was installed in the DELPHI detector in 1994. The main goal is to measure the luminosity with an accuracy better than 0.1%. The calorimeter was built using the “Shashlik” technique. The light is collected by wavelength shifting fibers and readout by phototetrodes that can operate inside the magnetic field. The detector performance during the 1994–1995 data taking is presented. The different contributions to the systematic error on the luminosity measurement are discussed.
111306611
Prototype design, construction and test of a Pb/scintillator sampling calorimeter with wavelength shifter fiber optic readout
A prototype for the new DELPHI luminosity monitor has been built and tested. The scope of this prototype is to measure the response of the proposed calorimeter in the region which is most critical for the luminosity measurement, i.e., at the inner edge of the acceptance. The aim of the new luminosity monitor is to measure the LEP (Large Electron Position Collider) luminosity with per mill systematic uncertainty. This requires experimental biases at the level of 50 mu m or less in the definition of the fiducial volume. The technique used ensures good energy resolution and high spatial uniformity. With the prototype, better than 2% uniformity in response and an energy resolution of 3% at 45 GeV have been achieved. >
110034857
The DELPHI small angle tile calorimeter
The small angle tile Calorimeter (STIC) provides calorimetric coverage in the very forward region for the DELPHI experiment at the CERN LEP collider. A veto system composed of two scintillator layers allows one to trigger on single photon events and provides e-/spl gamma/ separation. We present here some results of extensive measurements performed on part of the calorimeter and the veto system in the CERN test beams prior to installation and report on the performance achieved during the 1994 LEP run. >
110552488
Complete distributed computing environment for a HEP experiment: experience with ARC-connected infrastructure for ATLAS
Computing and storage resources connected by the Nordugrid ARC middleware in the Nordic countries, Switzerland and Slovenia are a part of the ATLAS computing Grid. This infrastructure is being commissioned with the ongoing ATLAS Monte Carlo simulation production in preparation for the commencement of data taking in 2008. The unique non-intrusive architecture of ARC, its straightforward interplay with the ATLAS Production System via the Dulcinea executor, and its performance during the commissioning exercise is described. ARC support for flexible and powerful end-user analysis within the GANGA distributed analysis framework is also shown. Whereas the storage solution for this Grid was earlier based on a large, distributed collection of GridFTP-servers, the ATLAS computing design includes a structured SRM-based system with a limited number of storage endpoints. The characteristics, integration and performance of the old and new storage solutions are presented. Although the hardware resources in this Grid are quite modest, it has provided more than double the agreed contribution to the ATLAS production with an efficiency above 95% during long periods of stable operation.
121337614
Absolute in situ energy calibration of luminosity calorimeters in the DELPHI experiment at LEP
Abstract Methods to perform the absolute energy calibration of DELPHI's Small Angle Tagger luminosity calorimeters at LEP are presented and compared. The input was small angle Bhabha scattering events. A significant nonlinearity in the response of the calorimeters was observed. The conjugate gradient method was applied to solve the least squares problem. This method is particularly useful for least squares problems which are large, ill-behaved or even singular, and for cases with a sparse coefficient matrix.