Gaitskell SOLO SOudan LOw Background Counting Facility Rick Gaitskell Brown University, Department of Physics see information at (Password for internal part of Web Site is same as Majorana web site) v8

SOLO - Majorana - 10 Sept 2003 Rick Gaitskell Summary: Purpose & Timetable (DOE) Low Background Gamma Screening Facility  Majorana Double Beta Decay Screening Program/Materials selection required during construction Parent Proposal will be submitted before Feb 2004 (Screening )  CDMS II New screening in the event of significant excess of gamma counts over CDMS I — Awaiting first accurate look at CDMS II b/g in Sept 2003 Allow improvement of b/g Monte Carlos in CDMS II, and projections for CDMS III  XENON PMT / Photo-detector backgrounds, Chamber Material / Teflon + other construction material screening Opportunity to Soudan  Two HP Ge detectors (taken from previous DBD Experiments) “TWIN 2124” 1.05 kg + “Diode M” 0.5 kg looking at two independent (8”) 3  Shield 10 tonne 14” thick Pb shield DOE Run (210Pb 50 Bq/kg) 225 kg 2” thick German “Ancient” Pb (210Pb 50 mBq/kg) Radon Purge + Loading Timetable 2003 Feb-Mar Site + Initial shield assembly + HP Ge detector commissioning 2003 Apr-Jun Radon purge + DAQ development + Pb shield contamination identification & removal 2003 Aug 1%remaining inner Pb shield leaks removal 2003 Sept-Oct Ready for sample counting

SOLO - Majorana - 10 Sept 2003 Rick Gaitskell Summary: Purpose & Timetable Low Background Gamma Screening Facility  Majorana Double Beta Decay Ready to prepare screening list  CDMS II New screening in the event of significant excess of gamma counts over CDMS I — Awaiting first accurate look at CDMS II b/g in Sept-Dec 2003 Allow improvement of b/g Monte Carlos in CDMS II, and projections for CDMS III  XENON Immediate demand if other programs permit PMT / Photo-detector backgrounds, Chamber Material / Teflon + other construction material screening We have exploited opportunity to Soudan  Two HP Ge detectors (taken from previous DBD Experiments) “TWIN 2124” 1.05 kg + “Diode M” 0.5 kg looking at two independent (8”) 3  Shield 10 tonne 14” thick Pb shield DOE Run (210Pb 50 Bq/kg) 225 kg 2” thick German “Ancient” Pb (210Pb 50 mBq/kg) Radon Shield (Double layer thick 100 um mylar) + Purge (2 liq liters/day) No load lock at present (we will need to add one to reduce delay due to mine 200 Bq/m 3 Rn) History 2003 Feb-Mar Site + Initial shield assembly + HP Ge detector commissioning 2003 Apr-Jun Radon purge + DAQ development + Pb shield contamination identification & removal 2003 Aug 1%remaining inner Pb shield leaks removal 2003 Sept-Oct Ready for sample counting

SOLO - Majorana - 10 Sept 2003 Rick Gaitskell SOLO Soudan SOLO is located where MINOS emulsion target was to be located CDMS MINOS Completed shield (40”) 3 with white Rn shield

SOLO - Majorana - 10 Sept 2003 Rick Gaitskell SOLO Construction 12” - 16” Pb Doe Run Shield ( 210 Pb 50 Bq/kg) 2” inner liner of German Pb (150 year old Pb) ( 210 Pb 50 mBq/kg) Radon Seal and N 2 Purge Two separate chambers for counting Access port to 2 chambers, each (8”) 3 Pb Shield (half completed) Ancient Pb liner 2 High Purity Ge Detectors

SOLO - Majorana - 10 Sept 2003 Rick Gaitskell SOLO - Commissioning & Operation Brown Group  Mike Attisha (Grad)  John-Paul Thompson (Grad)  Rick Gaitskell Plus…  Jim Reeves (Tech, PNL)  Jerry Meier (Phys, Soudan/UMinn) Thanks also  Harry Miley (Majorana Spokesmen, PNL), Ron Brodzinski (PNL), Craig Aalseth (PNL), Richard Arthur (DAQ Software, PNL)  Jim Beaty & Bruce Lavin (Tech, Soudan), Dave Sarenen (Networks, Soudan)

SOLO - Majorana - 10 Sept 2003 Rick Gaitskell SOLO Gamma Backgrounds (1) Cavern Background  238 U / 232 Th / 40 K / 137 Cs 214 Bi keV U chain 46.1% 137 Cs keV 85.2% 40 K keV K 10.7% 208 Tl keV Th chain 10.7%

SOLO - Majorana - 10 Sept 2003 Rick Gaitskell SOLO Gamma Backgrounds (2) Cavern Background  238 U / 232 Th / 40 K / 137 Cs Initial Pb Shield Construction  222 Rn (gas) -> 214 Pb -> 214 Bi -> Eliminated with clean N 2 purge  207 Bi & 194 Hg/Au A few “Unusual” Pb bricks from Fermilab (>>10 MeV protons on Pb) 214 Bi keV Rn 46.1% 207 Bi 569 keV 85.2% 194 Au keV 6.4% 207 Bi keV 74.5% 194 Au keV 61.0%

SOLO - Majorana - 10 Sept 2003 Rick Gaitskell TP Brick Contamination 207 Bi & 194 Hg/Au  Rare isotopes Production (>>10 MeV protons on Pb)  A few “Unusual” Pb bricks from Fermilab

SOLO - Majorana - 10 Sept 2003 Rick Gaitskell SOLO Gamma Backgrounds (3) Cavern Background  238 U / 232 Th / 40 K / 137 Cs Initial Pb Shield Construction  222 Rn (gas) -> 214 Pb -> 214 Bi -> Eliminated with clean N 2 purge  207 Bi & 194 Hg/Au A few “Unusual” Pb bricks from Fermilab (>>10 MeV protons on Pb) With improved Pb Shield (40 kg-days)  No statistically significant lines >100 keV  Remaining bremsstrahlung leakage from outer Pb 210 Pb -> 210 Bi -> 210 Bi Q  =1161 keV 210 Bi Brem keV

SOLO - Majorana - 10 Sept 2003 Rick Gaitskell SOLO Gamma Backgrounds (4) Cavern Background  238 U / 232 Th / 40 K / 137 Cs Initial Pb Shield Construction  222 Rn (gas) -> 214 Pb -> 214 Bi -> Eliminated with clean N 2 purge  207 Bi & 194 Hg/Au A few “Unusual” Pb bricks from Fermilab (>>10 MeV protons on Pb) Improved Pb Shield (40 kg-days)  No statistically significant lines >100 keV  Remaining bremsstrahlung leakage from outer Pb 210 Pb -> 210 Bi -> 210 Bi Q  =1161 keV Compared to original Homestake DBD (148 kg-days)  Identical b/g >1200 keV Based on >1200 keV expect final spectrum to match DBD

SOLO - Majorana - 10 Sept 2003 Rick Gaitskell Bremsstrahlung Leakage Brem Monte Carlo (not normalised) TWIN 1.05 kg HP Ge

SOLO - Majorana - 10 Sept 2003 Rick Gaitskell SOLO Conclusions (DOE) SOudon LOw Background Counting Facility  >1200 keV have achieved b/g levels of earlier DBD experiments  <1200 keV dominated by residual bremsstrahlung from outer Pb Final iteration sealing 1% leak of brem around inner Pb shield PB from Collar Sept 2003 expect to be ready to start counting samples  World Class Facility Sensitivity (if brem reduced by x0.1) comparable to World best Expect to be able to screen to U 50 ppt/ Th 50 ppt/ K 50 ppb (refine MC simulation) Very few systems - limited availability (Oroville LBL / Gran Sasso)  Majorana / CDMSII / XENON Dark Matter experiments will directly benefit Great opportunity exploited  Detectors & Shield & DAQ borrowed from old DBD assemblies (PNL)  Labor from CDMSII grads + few $k of technical support  Useful training experience for graduates on low background (modest) scale experiment

SOLO - Majorana - 10 Sept 2003 Rick Gaitskell SOLO Conclusions SOudon LOw Background Counting Facility  >1200 keV have achieved b/g levels of earlier DBD experiments  <1200 keV dominated by residual bremsstrahlung from outer Pb Final iteration sealing 1% leak of brem around inner Pb shield — We have started collecting new data after replacing Pb - waiting for Rn level to fall to negligible Pb from Collar has been substitutes in top layer - awaiting results Sensitivity  Perform Monte Carlos to assess  Collecting b/g data from LNGS and Frejus Facilities to compare Hardware  NEED Load Lock for samples - improve turn around  DAQ revision to handle two detectors (TWIN & Diode-M) - considering full pulse dig system Counting Program  All spectra available (in simple byte format KDE) at SOLO web site  Majorana Pb from Chicago - Ready to go into chamber Need to discuss next tasks  CDMS II B/G will be known soon - if worse than expected - possible screening starts Dec 2003  XENON PMT measurements (Typically mBq) - rapid