120705876
Presentation of search results: the CLs technique
I describe a framework for the presentation of search results which is motivated by frequentist statistics. The most well-known use of this framework is for the combined search for the Higgs boson at LEP. A toy neutrino oscillations experiment is used to illustrate the rich information available in the framework for exclusion and discovery. I argue that the so-called CLs technique for setting limits is appropriate for determining exclusion intervals while the determination of confidence intervals advocated by Feldman and Cousins' method is more appropriate for treating established signals, i.e. going beyond discovery to measurement. (From the workshop 'Advanced Statistical Techniques in Particle Physics', 18–22 March 2002)
123487894
The small angle tile calorimeter in the DELPHI experiment
Abstract The Small angle TIle Calorimeter (STIC) provides calorimetric coverage in the very forward region of the DELPHI experiment at the CERN LEP collider. The structure of the calorimeters, built with a so-called “shashlik” technique, gives a perfectly hermetic calorimeter and still allows for the insertion of tracking detectors within the sampling structure to measure the direction of the showering particle. A charged-particle veto system, composed of two scintillator layers, makes it possible to trigger on single photon events and provides e–γ separation. Results are presented from the extensive studies of these detectors in the CERN testbeams prior of installation and of the detector performance at LEP.
54787897
Performance of an ARC–enabled computing grid for ATLAS/LHC physics analysis and Monte Carlo production under realistic conditions
A significant amount of the computing resources available to the ATLAS experiment at the LHC are connected via the ARC grid middleware. ATLAS ARC-enabled resources, which consist of both major computing centers at the Tier-1 level and lesser, local clusters at Tier-2 and 3 level, have shown excellent performance running heavy Monte Carlo (MC) production for the experiment. However, with the imminent arrival of LHC physics data, it is imperative that the deployed grid middlewares also can handle data access patterns caused by user-defined physics analysis. These user-defined jobs can have radically different demands than systematic, centrally controlled MC production. We report on the performance of the ARC middleware, as deployed for ATLAS, for realistic situations with concurrent MC production and physics analysis running on the same resources. Data access patterns for ATLAS MC and physics analysis grid jobs will be shown, together with the performance of various possible storage and file staging models.
119941628
Prospects for the Standard Model Higgs Boson Search in the LEP 2000 Run
35536172
In-orbit performance of the EPIC-MOS detectors on XMM-Newton
XMM-Newton was launched into space on a highly eccentric 48 hour orbit on December 10th 1999. XMM-Newton is now in its fifth year of operation and has been an outstanding success, observing the Cosmos with imaging, spectroscopy and timing capabilities in the X-ray and optical wavebands. The EPIC-MOS CCD X-ray detectors comprise two out of three of the focal plane instruments on XMM-Newton. In this paper we discuss key aspects of the current status and performance history of the charge transfer ineffiency (CTI), energy resolution and spectral redistribution function (rmf) of EPIC-MOS in its fifth year of operation.
110699804
The small angle tile calorimeter project in DELPHI
The new Small Angle TIIe Calorimeter (STIC) covers the forward regions in DELPHI. The main motivation for its construction was to achieve a systematic error of 0.1% on the luminosity determination. This detector consists of a “shashlik” type calorimeter, equipped with two planes of silicon pad detectors placed respectively after 4 and 7.4 radiation lengths. A veto counter, composed of two scintillator planes, covers the front of the calorimeter to allow ϱ − γ separation and to provide a neutral energy trigger. The physics motivations for this project, results from extensive testbeam measurements and the performance during the 1994 LEP run are reported here.
121010683
PARTICLE PRODUCTION BY 10-30 Bev PROTONS INCIDENT ON Al AND Be
The production of p-bar, mesons ( pi /sup s), and mesons (K/sup s) by the interaction of protons on Al and Be targets is studied at energies of 10, 20, and 30 Bev. The production ratios and momenta of these particles are measured at angles of 4.75, 9, 13, and 20 deg . (T.F.H.)
120981188
LARGE-ANGLE PION--PROTON ELASTIC SCATTERING AT HIGH ENERGIES.
123035937
The design and performance of the FNAL high-energy polarized beam facility
We describe a new polarized-proton and -antiproton beam with 185-GeV/c momentum in the Fermilab MP beam line which is currently operational. The design uses the parity-conserving decay of lambda and antilambda hyperons to produce polarized protons and antiprotons, respectively. A beam-transport system minimizes depolarization effects and uses a set of 12 dipole magnets that rotate the beam-particle spin direction. A beam-tagging system determines the momentum and polarization of individual beam particles, allowing a selection of particles in definite intervals at momentum and polarization. We measured polarization of the beam by using two types of polarimeters, which verified the determination of polarization by a beam-particle tagging system. Two of these processes are the inverse-Primakoff effect and the Coulomb-nuclear interference (CNI) in elastic proton-proton scattering. Another experiment measured the {pi}{sup 0} production asymmetry of large-x{sub F} values; this process may now be used as an on-line beam polarimeter. 9 refs., 9 figs.
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.
122023821
Measurement of the double-spin asymmetry ALL for inclusive multi-γ pair production with 200 GeV/c polarized proton beam and polarized proton target
The invariant double-differential cross section, E1E2d6 delta/dp(1)3dp(2)3, and the double-spin asymmetry, A(LL), for inclusive multi-gamma pair production in which gamma-rays came from neutral mesons were measured with a 200 GeV/c longitudinally-polarized proton beam and a longitudinally-polarized proton target. Most of the multi-gamma pairs comes from two-jet type events which are sensitive to partonic interaction. The A(LL) values were found to be consistent with zero. The invariant double-differential cross section for inclusive pi0pi0 production was also measured. These measured cross sections are consistent with LUND Monte Carlo simulations. Using the LUND Monte Carlo simulation package with the Carlitz-Kaur model of spin dependent distribution functions of valence quarks, the A(LL) values have been compared with theoretical predictions of gluon polarization, DELTAG/G. The results put restrictions on the size of DELTAG/G in the region of 0.05 less-than-or-similar-to x less-than-or-similar-to 0.35.