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

2. 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 2004-2008)  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 build @ 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 Selection@Soudan + 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

3. 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 build @ 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 Selection@Soudan + 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

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

5. 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

6. 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)

7. SOLO - Majorana - 10 Sept 2003 Rick Gaitskell SOLO Gamma Backgrounds (1) Cavern Background  238 U / 232 Th / 40 K / 137 Cs 214 Bi 609.3 keV U chain 46.1% 137 Cs 661.7 keV 85.2% 40 K 1406.8 keV K 10.7% 208 Tl 2614.4 keV Th chain 10.7%

8. 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 609.3 keV Rn 46.1% 207 Bi 569 keV 85.2% 194 Au 1468.9 keV 6.4% 207 Bi 1063.7 keV 74.5% 194 Au 328.5 keV 61.0%

9. 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

10. 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 0-1000 keV

11. 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

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

13. 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

14. 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 10-1000 mBq) - rapid