ATLAS

Abstract:

The optical fibres that will be used in SLHC detectors will be exposed to high doses and low temperatures in the inner detectors. A number of single-Mode (sM) and Multi-Mode (MM) fibres have been tested for radiation hardness by exposure beyond a full SLHC dose to 500 kGy(Si) in the -25 °C operating temperatures expected in the upgraded inner detectors. From these measurements conservative estimates of the level of Radiation Induced Absorption (RIA) have been calculated for these fibres in realistic paths through an upgraded inner detector. Two SM fibres have been found whose total calculated RIAs were much lower than the budgeted 1 dB, despite the high dose rates used in the experiment. The RIAs for the DrakaElite Super RadHard Single-Mode Fiber and Fibre X were calculated to be 0.142 and 0.064 dB respectively. Another SM and a MM fibre showed high levels of RIA during the experiment, however they cannot be ruled out as candidate fibres due the the high dose rate of 27 kGy(Si)/hr used. © 2010 IOP Publishing Ltd and SISSA.

Abstract:

Scintillation properties of PbWO4 and PbMoO4 have been studied as potential cryogenic scintillators for rare event searches. The light output and decay kinetics of PbWO4 and PbMoO4 crystals for excitation with ²⁴¹Am α particles were examined over the temperature range 7300 K. The α/γ ratio was measured with a PbMoO4 crystal scintillator for 5.3 MeV α particles, and the ability to distinguish between signals induced by α particles and γ quanta by pulse shape discrimination was assessed for the PbMoO4 crystal scintillator at 77 K. The energy dependence of the quenching factor for oxygen, molybdenum, tungsten and lead ions at low energy was calculated using a semi-empirical approach with data from the α particle measurements. The study demonstrates the good potential of these scintillators for cryogenic dark matter search and double beta decay experiments. © 2010 Elsevier B.V. All rights reserved.

Abstract:

A search for new heavy particles manifested as resonances in two-jet final states is presented. The data were produced in 7 TeV proton-proton collisions by the LHC and correspond to an integrated luminosity of 315nb^-1 collected by the ATLAS detector. No resonances were observed. Upper limits were set on the product of cross section and signal acceptance for excited-quark (q^*) production as a function of q^* mass. These exclude at the 95% C.L. the q^* mass interval 0.30*<1.26TeV, extending the reach of previous experiments. © 2010 CERN, for the ATLAS Collaboration.