TG 11 overview / Material screening Hardy Simgen MPI fr Kernphysik for Task Group 11 Outline News on hardware: -spectrometers Gas counting systems and radon monitor New results: Radon emanation measurements Talk by Grzegorz Zuzel Radon behaviour in liquid nitrogen Talk by Krzysztof Pelczar -ray screening results Other news News on hardware: LNGS GeMPI 3 + GeMPI 4 Both detectors suffer a 207 Bi contamination from within the cryostat GeMPI 4 cryostat was opened and thouroughly etched in July 07 October 07: 207 Bi 10x lower, but still present News on hardware: LNGS GeMPI 3 + GeMPI 4 Nov 07: FET failure in GeMPI 4 (UPS problem?) has to be repaired Future plans: GeMPI will be brought to MPIK for dismounting, electropolishing & replacing parts March / April 08 Refurbish Ge-diodes at Canberra Mounting MPIK June / July 08 ? News on hardware: LNGS GATOR New ultra-low background, 2.2 kg (100 % relative efficiency) HPGe- spectrometer at LNGS End of 2007: FET broken Exchanged at Canberra Supposed to be back at Gran Sasso in these days News on hardware: MPIK Low-Level Laboratory (LLL) Renovation of LLL completed end of 2007 News on hardware: MPIK Ge-spectrometers DAQ system re-started Muon-veto gas counters not yet running: Gas supply system missing ( this week) Corrado/Bruno: OK Dario: LN 2 cooling system broken: Detector was warm for months Cryostat had to be removed from the shield for fixing News on hardware: MPIK Adam Recently refurbished borehole detector Veto counters to be checked News on hardware: MPIK Gas counting system Entering in the GERDA construction phase: Need for 222 Rn counting system at LNGS to check cryostat, cryogenic infrastructure, lock, Proposal: Re-use of GNO counting system Very low background Convenient location (in hall A) Requires gas handling and proportional counter filling line at Gran Sasso. System almost ready After test at MPIK shipping to LNGS in summer News on hardware: LAr purification column for LArGe Modification of support system and temperature sensors Ready in April 08 News on hardware: Radon monitor Expected to be ready in May 08. Not yet any experience with Ar. -ray screening results: Recently investigated samples LabSample descriptionUsed forMass [g] LNGS PMT basesLArGe setup1522 VM 2000 with glue LArGe setup / water tank 1233 Baksan HV feedthrough SuhnerLArGe setup211 Signal feedthrough 50-SuhnerLArGe setup320 IRMM Big capacitors 8200 pFLArGe setup105 Small capacitors 4700 pFLArGe setup31 Resistors 470 kLArGe setup49 Steel cable Detector string suspension 2290 Steel platesTransport chain12383 Copper screwsMatrix mounting1062 -ray screening results: Electronics components Sample specific activity [Bq/kg] 228 Th 228 Ra 238 U 226 Ra 40 K HV feedthrough Suhner 0.23 0.4 Signal feed- through 50-Suhner 0.04 0.2 Big capacitors 8200 pF 1.0 0.2 Small capacitors 4700 pF 0.9 0.2 Resistors 470 k 0.20 0.1 -ray screening results: Suspension system Sample specific activity [mBq/kg] 228 Th 226 Ra 40 K 60 Co 137 Cs Steel plates 0.6 0.3 < 1 Steel cable before cleaning 13.4 92.8 0.6 Steel cable after cleaning 1,2) 2.1 1.5