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.
120752441
Observation of the UV scintillation light from high energy electron showers in liquid xenon
The UV scintillation light in liquid xenon has been observed using silicon drift photodiodes. Measurements were carried out in a rectangular light cell of dimentions 7.4 × 7.4 × 60 cm3 using 5 GeV electrons. The photodiodes and the preamplifiers were immersed in the liquid. A high quantum efficiency for 175 nm UV light has been measured. The scintillation light yield is found to be (1.5 ± 0.6) × 104 photons per MeV of energy deposited in liquid xenon. A light attenuation lenght of ≈ 40 cm has been measured.
94093096
UV quantum efficiencies of organic fluors
The need for, and benefits of using, wavelength shifters with certain dark matter scintillator detectors is discussed. The dependence of conversion efficiency on thickness and incident wavelength is extensively investigated for evaporated coatings of p-terphenyl and tetraphenyl butadiene, and for plastic waveshifters based upon p-terphenyl. For the latter the effect of varying the p-terphenyl concentration is studied and some factors which must be considered when developing them for use in the UV are also discussed.
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.
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.
121404010
The performance of prototype vacuum phototriodes in the first full sized supercrystal array for the CMS ECAL endcaps
The performance of prototype vacuum phototriodes is presented from the first full sized supercrystal array for the CMS ECAL endcaps. The array was exposed to high-energy electrons and tested in magnetic fields of up to 3 T, in the CERN North area, in July and August 1999. The mean VPT electron yield, normalised to a naked crystal light yield of 8 photoelectrons/MeV into an HPMT, was found to be 25 electrons/MeV at 3 T for devices from Research Institute Electron, 35 electrons/MeV for devices from Hamamatsu and 18/23 electrons/MeV from Electron Tubes.
126252051
Understanding and calibrating the DS-ECal for T2K's ND280
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.
121516515
The T2K experiment and downstream electromagnetic calorimeter
T2K (Tokai to Kamioka) is a 295km long-baseline experiment in Japan, which is due to start taking commissioning data late in 2009. It is designed to measure muon-neutrino oscillations to other flavours. This will enable the measurement of some of the components of the MNSP mixing matrix. One of the UK's main contributions is the construction of an Electromagnetic Calorimeter (ECal) for the near detector, ND280, situated 280m downstream from the neutrino production target. This poster focuses on the Downstream ECal. Construction of this key module is due to begin in October 2007. It is then to be packaged and shipped to CERN in Spring 2009 for calibration tests and it is the aim that it will be installed in Tokai later in 2009. Lancaster University is responsible for the construction of the DS-ECal.
25386498
Simulations of the Temperature Dependence of the Charge Transfer Inefficiency in a High-Speed CCD
Results of detailed simulations of the charge transfer inefficiency of a prototype serial readout CCD chip are reported. The effect of radiation damage on the chip operating in a particle detector at high frequency at a future accelerator is studied, specifically the creation of 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 former level but not for the latter. Optimum operation is predicted to be at about 250 K where the effects of the traps is minimal; this being approximately independent of readout frequency in the range 7-50 MHz. This work has been carried out within the Linear Collider Flavour Identification (LCFI) collaboration in the context of the International Linear Collider (ILC) project.