2. Gaitskell “Whither WIMPs:” Direct Detection of SUSY Cold Dark Matter WORKING GROUP LEADERS: Rick Gaitskell (Brown University) & Dick Arnowitt (Texas A&M University) useful information at http://www.physics.umd.edu/ness02/ - follow working group link http://gaitskell.brown.edu/physics/NeSS2002/web_darkmatter/ One Tonne - Have we got what it takes? Has NUSEL got what we need?

3. NeSS Sept 2002 Rick Gaitskell Dark Matter Working Group Thanks to the working group Rick Gaitskell, Brown Dick Arnowitt, Texas A&M Elena Aprile, Columbia John Ellis, CERN Jonathan Feng, UC Irvine Gilles Gerbier, Saclay Alexander Kusenko, UCLA Jeff Martoff, Temple Richard Schnee, CWRU Nigel Smith, RAL

4. NeSS Sept 2002 Rick Gaitskell Andy Warhol - Pop Artist 1960’s - “Exactly” The pop artist Andy Warhol once approached me at a party and told me that he collected scientific journals, but he couldn't understand them. He drifted away, then came back and said, "Do you mind if I ask you a question?…Why does science take so long?" I said, "Mr. Warhol, when you do a picture of Marilyn Monroe, does it have to be exactly like her, as close to being her as you can make it?" He said, "Oh no." I said, "Well, in science it has to be exact, as EXACT as you can make it." He looked at me with sympathy and said, "Isn't that terrible?" Gerald M. Edelman Bright Air, Brilliant Fire (1992)

5. NeSS Sept 2002 Rick Gaitskell Dark Matter Experiments (Worldwide/affiliations) (Running/Active Collaboration) CsI ANAIS Rosebud UK NaIAD DRIFT I ZEPLIN II ZEPLIN III ZEPLIN I Picasso France Germany Italy DAMALIBRA Xenon CRESST II Edelweiss II Russia Switzerland US Majorana(DM) CDMS II XENON Simple Canada Taiwan Japan XMASS(DM) Elegant V&VI LiF Spain Orpheus IGEX HDMS/Genino Cuoricino US >20 Experiments currently operating underground Only 1 is located u/g in the US

6. NeSS Sept 2002 Rick Gaitskell Direct Detection: History & Future Oroville (88) [m = ?? GeV - if significantly better limit obtained at different mass] 90% CL Limit on Cross section for 60 GeV WIMP (scalar coupling) ~1 event kg -1 day -1 ~1 event kg -1 yr -1 ~1 event 100 kg -1 yr -1 LHC Not meant to be a complete list - see http://dmtools.berkeley.edu Different Colours Indicate Different Technologies NO W 020921.7.rjg [m=20 GeV] Homestake (87) H-M (94) H’berg-Moscow (98), IGEX (00) DAMA (96) UKDMC (96) [m=100 GeV] DAMA (98) DAMA (00) Gaitskell (astroph 0106200) CDMS SUF (99) CDMS SUF (02) Edelweiss (98) Edelweiss (01) ZEPLIN I Xe (02) Edelweiss (02) DRIFT II 1 kg CS 2 (T) ZEPLIN II+III 10 kg Xe (T) XENON / ZEPLIN 1t Xe (T) CDMS Soudan (T) 7 kg Ge+Si Cryodet Majorana Phase 1 (T) GENINO (T) 100 kg Ge Diode GENIUS (T) 100 kg Ge Diode CryoArray (T) 0.1-1 tonne Cryodet DRIFT III 100 kg CS 2 (T) Ge NaI Cryodet (T) Target Signal Liq Xe Gas CS 2

7. NeSS Sept 2002 Rick Gaitskell Some of Current (2001-) and Projected Experiments (2005-) Funding Profile - current experiments (investment in det R&D >10 yr)  Construction Capital 5-15M$ ; Operating 2-4M$/yr, Personnel FTE 15-40 Funding Profile - Projected Experiments (1 tonne)  Construction Capital 20-50+M$ ; Operating 4-8M$/yr, Personnel FTE 30-60 **** Not a complete list, experiments reported at meeting *** 500 kg 1000 kg

8. NeSS Sept 2002 Rick Gaitskell b to s  WIMP Dark Matter Physics Physics Motivation  Cosmology: Need for Non-Baryonic Dark Matter Ω unknown matter =0.27+/-0.04) [Turner]  Particle Physics: Naturally generates solution SUSY [Ellis] Non-Pointlike DM [Kusenko] Kaluza-Klein Extra Dimensions [Feng] Existing Direct Detection Experiments  Testing some models  As sensitivity improves - will continue to test more models Recent/current accelerator constraints shrinking SUSY bounds  Mainly constrained UPPER bound of cross-section  g-2 [BNL] can provide constraint on LOWER bound (for µ>0) if tentative disagreement is due to SUSY g-2 Relic Density Ellis, Ferstl, Olive hep-ph/0111064 SUSY - cMSSM Higgs

9. NeSS Sept 2002 Rick Gaitskell Greatest Experimental Challenges Construction & Operation of Detector Arrays Underground  Many of experiments experiencing “delays” associated with construction/operation “Project Risk”  All Groups would benefit greatly from infrastructure/support of Underground Lab Knowledgeable Technical/Engineering Assistance Achieving Detector Discrimination Performance (free of systematics)  Demanding Background Discrimination >>99%) Improvements needed in Screening Facilities  Dark Matter has new concerns, beyond those of Current Low Background Experiments 0-100 keV & Surface Contamination  To reduce internal radioactivity Experiments >2005 clearly demand access to systems beyond simple HPGe screening — 10 -12 g/g U/Th Surface/low energy radioactivity screening (Providing Input to NUSL -> Screen Fac Initiative) — 1 m -2 day -1  Scale of “intermediate” collaboration has difficulty meeting all screening requirements Fabrication of some target/construction materials underground  Ge crystal growth / Electroformed Cu Purification / Isotopic enrichment of target materials (e.g. Xe)

10. NeSS Sept 2002 Rick Gaitskell Dark Matter Depth Requirements Site Depth Requirement  Dominated by need to reduce high energy neutrons (50-600 MeV), generated by muons, that cannot be moderated directly using poly  Shallow ~1700 mwe (1 muons/m 2 /minute) Just satisfactory for 10 kg scale experiments (  ~10 -8 pb) 1 tonne experiments would require large additional active shield (>1 m thick) — >99% veto Risk associated with systematic misidentification  Intermediate ~3800 mwe Factor ~50x reduction in muons/HE neutrons compared to shallow Additional comfort factor, general consensus that 1 tonne experiments can function comfortably wrt to HE neutrons from muons (  ~10 -10 pb) Depth may be necessary for gas target given much large surface area to shield Satisfactory for cosmogenic activation Muons passing through detector array can be vetoed by simple muon veto (>99% being achieved)  Deep ~6000 mwe (Further factor ~50x reduction in muon/HE neutrons) Does not appear to be necessary for 1 tonne (  ~10 -10 pb), but eliminates any risk, and will allow next-next generation

11. NeSS Sept 2002 Rick Gaitskell WIMP SUSY Dark Matter Conclusion Planned Projects for sensitivity -> 1 event /100 kg/year  ~10 -46 cm 2 )  Target masses of 1 tonne  Data from existing round of detectors will be used to inform design Support of Underground Laboratory will be vital for their successful construction and operation  “Intermediate Scale Experiments  Significant extra burden bringing full resource requirements to hole in ground Next Generation 2005-: complementary TeV / LHC SUSY signal If signal is discovered then range of large detectors can be used to do WIMP astronomy and study SUSY / Dark Matter physics  Different target materials - study coupling / kinematics on different nuclei  Directional Detectors - WIMP Velocity distribution  SUSY Parameters that can’t be determined in accelerators (R-Parity)  Tests models of particle generation in Big Bang

12. NeSS Sept 2002 Rick Gaitskell Working Group Mission Statement The working groups will review the important science, survey existing experiments, outline an agenda and proposed time line for future work, and discuss how the research effort should be balanced among the world's different geographic regions. Each of the working groups will produce an executive summary that will be presented at the concluding session of the workshop and will be incorporated into the final workshop report (produced under the direction of the International Organizing Committee). The working groups will also be responsible for producing a summary of their discussions, with links to appropriate papers and documents. Review the important science worldwide  Survey existing experiments and investment (facilities and people) to date  Summarize potential discovery and break-through opportunities the investment has created Future (Keep the above discussions in the worldwide perspective)  Outline an agenda and proposed timeline for future work  Identify resources required  Estimate size of present community and required growth  Identify detector development required Produce an executive summary to be incorporated in the final workshop report to be produced under the direction of the International Organizing Committee  Present the executive summary at the concluding session of the workshop  Produce a summary of the working group discussions, with links to appropriate papers and documents

13. NeSS Sept 2002 Rick Gaitskell Experimental Questionnaire (1) What scientific question does the experiment address and what is its importance?  Assume it will be WIMP Dark Matter, but you could mention other major applications (2) What is the improvement over the performance of existing facilities?  Spin Independent and Spin Dependent Cross- section projected milestones are a good way to summarise this. For experiment with directionally sensitivity, as well as discrimination quote sensitivity reach in each mode. You may have other suggestions for measuring performance? (3) How does the physics reach compare with other proposals?  Don't need to answer this, since previous question allows direct comparison of experiments, unless you have additional insight... (4) What development is required?  Possible areas to comment on include  Detectors - Discrimination Target Performance  Target Radioactive Contamination in Detector elements - Production  What is the background goal in the active region?  What new background assay and contamination reduction techniques required?  New shielding configurations? (5) When will the experiment be ready, and what is the detector mass?  Should include expected milestones for staged experiment.) (6) What modes will it be sensitive to and what are the backgrounds?  Answer if not answered for questions above (7) What depth is needed?  Can express as a range of depths/options (8) What are the background radiation requirements?  Answered above (9) What are the space requirements?  General numbers fine, modest in most cases? (10) How might the experiment interfere with others in the lab? What are possible synergies with other experiments.  Do you have any concerns/synergies? (11) What is the estimated cost?  Broad numbers would be useful, detailed costing may not be known.)