122130577
Status on PWO crystals from Bogoroditsk after one year of preproduction for CMS–ECAL
Abstract In September 1998, the CMS electromagnetic calorimeter entered into its construction phase. Since that time, more than 2000 crystals have been produced by Bogoroditsk Techno-Chemical Plant (BTCP) in Russia and analysed at CERN. An overview about mechanical and optical properties as well as radiation hardness characteristics of these crystals will be presented.
120972438
Liquid xenon as a dark matter detector. Prospects for nuclear recoil discrimination by photon timing
Abstract Two mechanisms lead to liquid xenon scintillatlon, and are excited differently by incident electrons and by heavy charged nuclei. This could be used to discriminate nuclear recoil events from radioactive background in a search for hypothetical Galactic dark matter particles. To achieve low energy threshold a likelihood analysis is proposed using the time intervals between detected photons. Results are presented of Monte Carlo simulations, showing the background rejection achievable as a function of the number of detected photons. Some comments are included on background discrimination by simultaneous measurement of scintillation and ionization signals.
119930862
A study of the monitoring of radiation damage to CMS ECAL crystals, performed at X5-GIF
The ratio R, defined as the fractional decrease in the beam signal divided by the fractional decrease in the light monitoring signal, was measured at the GIF-X5 facility for a set of 20 ECAL barrel crystals. The dependence of R on the wavelength of the injected monitoring light and its path length in the crystals was studied. Measurements of the inter-crystal variation in R are presented for 10 pre-production crystals. Results on the dependence of signal loss on the irradiation profile are given. The use of lead filters, placed between a 137Cs source and a crystal, to reproduce different longitudinal irradiation profiles has been tested.
124663512
Energy Resolution of a Prototype Lead Tungstate Crystal Matrix with Vacuum Phototriode Readout for the CMS Endcap Electromagnetic Calorimeter
Data obtained in June 1998 from a 3x3 array of PbWO4 in the H4 testbeam indicate that an energy resolution better than 0.5% at 100GeV can be obtained from a matrix of PbWO4 endcap crystals with vacuum phototriode readout. These data are the first obtained for ECAL endcap shaped crystals and used crystals 220mm long with 24.7x24.7mm 2 front face. Tests with a full sized super-crystal, a 5x5 array of fullsized crystals (28.6x28.6mm 2 front face), will be performed in summer 1999.
17593732
Standard Model Higgs Search in the Four Jet Channel at LEP
The Standard Model Higgs boson was searched for at LEP, by the four collaborations in the year 2000, at centre-of-mass energies from 200-209GeV. An excess of events, potentially compatible with the production of a Higgs boson of mass ~115GeV was observed, largely in the four-jet channel. The search in this channel is discussed in this letter.
14010060
Initial Tests on First Full-size ECAL Endcap Crystals
At the end of last year the first full size ECAL endcap crystals were delivered to CERN.Thirty in number, they were produced to the final geometrical specifications; 220mm long with a rear square face of 30mm and a front square face of 28.6mm. All were delivered polished. The visual inspection , dimension, transmission, light yield and light yield uniformity tests carried out since are discussed , with particular emphasis on the light yield uniformity. The results are very encouraging. suggesting that the endcap crystals will not need uniformisation.
115380373
NOvA: Present and Future
NOvA is a next generation neutrino oscillation experiment designed to search for muon neutrino to electron neutrino oscillations by comparing electron neutrino event rates in a Near Detector at Fermilab with the rates observed in a large Far Detector at Ash River, Minnesota, 810 km from Fermilab. The detectors are totally active, segmented, liquid scintillator detectors and are located 14 mrad off the NuMI beam axis. The Far Detector has begun construction and will begin taking data in early 2013. The experiment aims to measure the neutrino mixing angle theta_13 and will push the search for electron neutrino appearance beyond the current limits by more than an order of magnitude. For non-zero theta_13, it is possible for NOvA to observe CP violation in neutrinos and establish the neutrino mass hierarchy. The NOvA prototype near detector on the surface (NDOS) began running at Fermilab in November and registered its first neutrinos from the NuMI beam in December 2010. An overview and current status of the experiment will be presented.
17032836
Radiation Hardness of CCD Vertex Detectors for the ILC
Results of detailed simulations of the charge transfer inefficiency of a prototype CCD chip are reported. The effect of radiation damage in a particle detector operating at a future accelerator is studied by examining two electron trap levels, 0.17 eV and 0.44 eV below the bottom of the conduction band. Good agreement is found between simulations using the ISE-TCAD DESSIS program and an analytical model for the 0.17 eV level. Optimum operation is predicted to be at about 250 K where the effects of the traps is minimal which is approximately independent of readout frequency. This work has been carried out within the Linear Collider Flavour Identification (LCFI) collaboration in the context of the International Linear Collider (ILC) project.