1. Gaitskell DAMA + CDMS I & II “Whither WIMPs: SUSY CDM” Rick Gaitskell University College London, Physics & Astronomy source at http://www.hep.ucl.ac.uk/~gaitskel

2. CDMS Status / April 2001 Rick Gaitskell, UCL Ω (assumes h~0.7) Underlying scale from Mike Turner, Chicago Structure Formation washed out by relativistic particles SuperK  ~0.1 eV  ~0.01-0.001 eV CMB SNIa BBN Observation Ω CMB photons ~10 -5 Map Galaxy Clusters at few Mpc scale using: Gas Mass i) x-rays from gas ii) Mapping S-Z CBR decrement Galaxy Cluster Mass i) Galaxy Motion and Virial Th. ii) Hydrostatic Gas iii) Grav. Lensing CDM 010320.3.rjg All Success of CDM Cold Dark Matter Models in relating Homogeneity of CMB Cosmic Microwave Background with development of LSS Large Scale Structure Extrapolation flat universe at z≈1000 CDM only baryonic Large scale structure CMB 10 4 Mpc 1 Mpc ~50/50 @ 8 kpc in Milky Way number ≈ number of photons density mass 40 eV /c 2 =>  ≈1

3. CDMS Status / April 2001 Rick Gaitskell, UCL 1 bn yrs Cosmic Evolution (Animation) 14bn yrs 300,000 y5,000 y3 mins 1 ps Size~1 m Size~Solar Sys. Size~10 26 m Matter Dominates  m ~a -3 Radiation Dominates   ~a -4  Dominates   ~const

4. CDMS Status / April 2001 Rick Gaitskell, UCL WIMPs - a Candidate for Non-Baryonic CDM But, weakly interacting  may freeze out before total annihilation if  ann ~ n   ann v  i.e., if annihilation too slow to keep up with Hubble expansion Leaves a relic abundance:   h 2  10 -27 cm 3 s -1  ann v  fr if m  and  ann determined by electroweak physics, then   ~ 1 A WIMP  is like a massive neutrino: produced when T >> m  via annihilation through Z (+other channels). Annihilation/pair creation maintain thermal equilibrium. If interaction rates high enough, comoving density drops as exp(- m  /T) as T drops below m  : annihilation continues, production becomes suppressed.  freeze out

5. CDMS Status / April 2001 Rick Gaitskell, UCL Direct Detection of WIMPs WIMPs elastically scatter off nuclei in targets, producing nuclear recoils, with  n  related roughly by crossing to  A (~10 -38 cm 2 ) Because spin-independent interactions are coherent (  A 2 ) at low energy, they dominate for most models. Target material needs odd number of protons and/or neutrons to detect spin-dependent interactions. Energy spectrum & rate depend on Dark Matter Halo  Straw-man model: isothermal and spherical, Maxwell-Boltzmann velocity distribution  V 0 = 230 km/s, v esc = 650 km/s,  = 0.3 GeV / cm 3 Energy spectrum of recoils is featureless exponential with  E  ~ 50 keV, dependent on WIMP and target nucleus masses Event rate normalized by  n , and coherence- measuring form factor A 2 F 2 ( <1 event / kg / day)  H,h,Z  q q   q q q ~ I/Xe Ge Si Form Factors A 2 F 2

6. CDMS Status / April 2001 Rick Gaitskell, UCL WIMP Direct Searches Current Technologies: Ge Diode “Traditional” Reduce backgrounds — Heidelberg-Moscow (-> Genius) / IGEX “Cryogenic” Event by event background discrimination — Edelweiss / CRESST / Rosebud / CDMS Scintillator: NaI “Traditional” -> Xe “Discrimination” — DAMA (NaI), Boulby DMC (NaI->Liq Xe & Gas TPC [Ar/CS 2 ]) Superheated Droplets bi-state - selective sensitivity/high discrimination — Simple+Picasso Remarkable spread of technologies Varies the Systematic Errors, important for reinforcement of positive signals All techniques have equally aggressive projections for future performance — But different methods for improving sensitivity 010320.1.rjg

7. CDMS Status / April 2001 Rick Gaitskell, UCL Direct Detection: History & Future Oroville (88) [m=20 GeV] Homestake (87) Heidelberg-Moscow (94) Heidelberg-Moscow (98) [m = ?? GeV - if significantly better limit obtained at different mass] DAMA (96) UKDMC (96) [m=100 GeV] DAMA (98/00) 90% CL Limit on Cross section for 60 GeV WIMP (scalar coupling) CDMS SUF (T) CDMS Soudan (T) 7 kg Ge+Si Cryodet GENINO (T) 100 kg Ge Diode GENIUS (T) 100 kg Ge Diode CryoArray (T) 0.1-1 tonne Cryodet ~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 010402.3.rjg Ge NaI Cryodet (T) Target Signal Liq Xe CDMS SUF (99) CDMS SUF (00) Edelweiss (98) Edelweiss (01)

8. CDMS Status / April 2001 Rick Gaitskell, UCL Gran Sasso National Laboratory (LNGS)

9. CDMS Status / April 2001 Rick Gaitskell, UCL NaI PMT Copper Lead Polyethelene DAMA - 100 kg NaI Experimental Apparatus Very elegant experimental setup - in place >1996 Low Activity NaI scintillator 9  9.7 kg NaI crystals, each viewed by 2 PMTs Located at Gran Sasso Underground Lab (3.8 kmwe) + Photon and Neutron shielding Two modes of Background discrimination  Pulse shape  Annual modulation: ~2% modulation amplitude POSITIVE SIGNAL

10. CDMS Status / April 2001 Rick Gaitskell, UCL Annual Modulation of Rate & Spectrum galactic center v0v0 Sun 230 km/s Earth 30 km/s (15 km/s in galactic plane) log dN/dErecoil Erecoil June Dec ~5% effect June Dec. WIMP Isothermal Halo (assume no co-rotation) v 0 ~ 230 km/s

11. CDMS Status / April 2001 Rick Gaitskell, UCL Modulation Animation in NaI 150 GeV WIMP 50 GeV WIMP 000904.4 rjg Background Sun moving through WIMP Halo Earth moving around Sun WIMPs - not to scale ! Threshold

12. CDMS Status / April 2001 Rick Gaitskell, UCL Annual Modulation Not distinguish between WIMP signal and Background directly From the amplitude of the modulation, we can calculate the underlying WIMP interaction rate ±2% Background June Dec WIMP Signal June Dec

13. CDMS Status / April 2001 Rick Gaitskell, UCL Modulation Amplitude There is clearly a modulation (4  - compared to null hypothesis) Final likelihood also uses B ijk > 0 mean over 2-6 keVee (22 – 66 keV recoil) DAMA 2000 paper Figure 2 DAMA 1 5,000 kg-day DAMA 2 15,000 kg-day DAMA 3 + 4 38,000 kg-day Minimum DAMA NaI/1-4 (3  ) Best fit to Ann Mod data alone Best fit to Ann Mod data alone Best Fit DAMA NaI/1-4 Best-fit WIMP model’s expected annual modulation does not appear to fit data; lowest point of 3  contour is much worse. Why? Additional constraint applied during max likelihood analysis: DC WIMP signal implied by AC signal must not exceed observed DC count rate  best-fit cross-section is decreased

14. CDMS Status / April 2001 Rick Gaitskell, UCL Lowest energy bin is most important when setting dark matter limit DAMA - Energy Spectra Bernabei et al. PLB450(1999)448 Data re-plotted by Gaitskell, CfPA Rate corresponding to best fit to Ann Mod data alone (  = 14.0 10 -42 cm 2 ) is shown as cyan - exceeds signal in 2-3 keV bin WIMP component assuming: (50 GeV,7.2x10 -42 cm 2 ) (50 GeV,14.0x10 -42 cm 2 ) Best fit to Ann Mod data alone CDMS 2000 limit (90% CL) Low Background in Det #8 constrains max  All Histograms already corrected for trigger / cut efficiencies

15. CDMS Status / April 2001 Rick Gaitskell, UCL CDMS Status Cryogenic Dark Matter Search - Results from CDMS-I  Results from CDMS I (Stanford) & comparison with DAMA positive result  See also Edelweiss (Frejus Tunnel) CDMS II  Installing Buildings & Fridge at Soudan Mine, Minnesota (2050 mwe)  “First Dark” This Winter Future of SUSY Dark Matter Experiments  SUSY Reach Predictions for LSP s on quarks - lower limit apparent for calculations using mSUGRA Framework & Naturalness  Future of Experiments

16. CDMS Status / April 2001 Rick Gaitskell, UCL CDMS Nuclear Recoil Discrimination - Event by Event Nuclear recoils arise from  WIMPs  Neutrons Electron Recoils arise from  photons  electrons  alphas (Typical Background) Ionization yield  ionization/recoil energy strongly dependent on type of recoil Recoil energy  Phonons give full recoil energy Neutrons (external source) Gammas (external source) Trigger Threshold NOT A SIMULATION! 1334 gamma events, 616 neutron events 1 / 2 year’s background >> 1 / 2 year’s signal !! 010402.3.rjg

17. CDMS Status / April 2001 Rick Gaitskell, UCL Ge BLIP Ionization & Phonon Detectors Four 165 g Ge detectors, for total mass of 0.66 kg during 1999 Run Calorimetric measurement of total energy ENERGY Resolution  = Ionisation 220 eV, Phonons 250 eV Inner Ionization Electrode Outer Ionization Electrode Passive Ge shielding (NTD Phonon Sensors on underside) Tower WiringWiring heat sinkingheat sinking holds cold FETs for amplifiersholds cold FETs for amplifiers BLIP

18. CDMS Status / April 2001 Rick Gaitskell, UCL Current CDMS Site : Stanford Shielded, low-background environment Shallow site: 17 mwe rock  Hadronic component down by >1000  Muon flux down by ~5 Active scintillator muon veto  >99.9% efficient  Reject ~100 “internal” neutrons / kg /day produced by muons within shield Expect residual neutron background ~2 / kg / day produced outside shield; measured with  Si detectors (Ge for WIMPs)  Multiple-scatters Active Muon Veto Detectors Inner Pb shield Polyethylene Pb Shield 10.6 m earth

19. CDMS Status / April 2001 Rick Gaitskell, UCL 4 x BLIP Tower Schematic (1999 Run) 1999 Run (net 10.6 kg-days) Low-radioactivity Cu and Ge housing Self-shielding through close packing  Spacing 3 mm vertically Ge shielding BLIP 4 BLIP 3 BLIP 5 BLIP 6 60 mm Outer Ionization Electrodes less shielded from electrons (surface events) imperfect ionization yield (electrode break)

20. CDMS Status / April 2001 Rick Gaitskell, UCL 1999 Run Ge BLIP Data Set Combined all single- scatters NR candidates Entire 96 live days operation Ge BLIPs = 10.6 kg-days  Gamma and electron bands well separated from NR band NR candidates are truly NR’s  See a total of 13 events > 10 keV  ~ 1.2 events/kg/day NR Band asymmetric (-3 ,+1.28  )= 90% efficient Expect 40 events for scalar WIMP  given by the DAMA Ann Mod Signal 001008.2.rjg Gammas Surface Betas Nuclear Recoils

21. CDMS Status / April 2001 Rick Gaitskell, UCL Anatomy of Penetrating Neutron Event (ii) 330 MeV neutron from rock (iii)Pb nucleus shattered 9 n (T 0.1-50 MeV) 9 g (E 0.1-2.5 MeV) (vi)Following ~12 scatters in Cu/poly neutron (now T~100 keV) (vi) scatters in two Ge detectors (Er~5 keV), and then (vii) ultimately captures on H in poly. (v)Higher energy (30 MeV) neutron traverses poly m.f.p ~ 100 cm (i) ~100 GeV µ interacts in rock of tunnel generating neutron (iv)Lower energy neutrons moderate in polyethylene m.f.p ~ 3 cm@1 MeV

22. CDMS Status / April 2001 Rick Gaitskell, UCL Neutron Multiple Scatters Observe 4 neutron multiple scatters in 10-100 keV multiple events  3 neighbors, 1 non-neighbor Calibration indicates negligible contamination by electron multiples Ionization Yield B6 Ionization Yield B4 photons neutron neutrons Ionization Yield B5,6 Ionization Yield B4,5 surface electrons photons Neighbor interactio n B4 B3 B5 B6 Non- Neighbor interaction Neighbors Non-Neighbors

23. CDMS Status / April 2001 Rick Gaitskell, UCL Muon-Coincident & Calibration Neutrons Agreement between MC and data is good - no free parameters  (i) Simulate neutrons generated in Pb/Cu shielding by muons  (ii) Simulate neutrons from Am/Be source on top of Pb shield (poly out) Singles/multiples ratios & shape in MC match data well ~15% syst much smaller than statistical fluctuation in final result

24. CDMS Status / April 2001 Rick Gaitskell, UCL Consistency of Neutron Interpretation with MC Predicted ratios of numbers of events set by Monte Carlo simulations Ge multiples and Si singles imply large expected neutron background with large statistical uncertainty Likelihood-ratio test indicates we should expect worse agreement 6% of the time Energy spectra consistent with expectations for neutrons (also with WIMPs) Nuclear Recoil Events 4 13 16 1 3.4  Data w/ 68% confidence interval Prediction based on Ge mult, Si Predictions based on most likely  +

25. CDMS Status / April 2001 Rick Gaitskell, UCL mean over 2-6 keVee (22 – 66 keV recoil) DAMA 2000 paper Figure 2 DAMA 1 5,000 kg-day DAMA 2 15,000 kg-day DAMA 3 + 4 38,000 kg-day New CDMS Limit CDMS 2000 (90% CL) CDMS Limit (Published PRL 17June2000) incompatible with DAMA (4  ) annual modulation signal at 99.98% Minimum DAMA NaI/1-4 (3  ) Best fit to Ann Mod data alone Best fit to Ann Mod data alone Best Fit DAMA NaI/1-4 DAMA 1996 (90% CL)

26. CDMS Status / April 2001 Rick Gaitskell, UCL Considerable Debate in the US Press...

27. CDMS Status / April 2001 Rick Gaitskell, UCL Compatibility of CDMS and DAMA CDMS results incompatible with DAMA Figure 2 data (left) at > 99.98% CL Estimate full DAMA likelihood function:  Two experiments are incompatible at 99.8% CL  Ignore multiple scatters: 96.8% CL CDMS data Best simultaneous fit to CDMS and DAMA predicts too little annual modulation in DAMA, too many events in CDMS predicte d spectru m DAMA 2000 paper Figure 2

28. CDMS Status / April 2001 Rick Gaitskell, UCL Combined Likelihood CDMS limit & DAMA signal Expected sensitivity for CDMS with multiples subtraction (when exposure would see 1 multiple rather than 4, and 16 singles rather than 13) raises N WIMPs by 50%: ≤ 12 (90% CL) Combined likelihoods based on CDMS calculated fit to ann. mod. & an inferred likelihood for data when constraint of 2-3 keV bin included (DAMA actual likelihood function not yet made available) N WIMPs is number of WIMPs in 10.6 kg-days Ge in CDMS run (E r >10 keV) 001008.4.rjg

29. CDMS Status / April 2001 Rick Gaitskell, UCL Edelweiss (French Group): Frejus (Modane) Tunnel Close pack shielding Charge contact has outer veto ring ~50% volume NTD Ge Thermistor Nuclear Recoil Band Latest results (Nov-Dec 2000) from 1 of 3 x 320g Cryogenic Ge detectors ionisation+phonons (NTD) similar to CDMS  No events after 3.1 kg-days fiducial 25-100 keVr  rejection > 99.9% Deep site (3.5 kmwe) - no high energy neutrons from muons expected Expect ~8 events >25 keV for DAMA Ann Mod.

30. CDMS Status / April 2001 Rick Gaitskell, UCL CDMS: Summary (I) and New Experiment (II) CDMS I probing Supersymmetry region  Results for scalar-interacting (  ~A 2 ) WIMPs (CDMS: 10.6 kg-day Ge) & Edelweiss (3.1 kg-day Ge) are incompatible with DAMA(58,000 kg-day NaI) signal at high confidence  PRL published / PRD to follow  Will release additional analysis: 40% increase exposure (larger fiducial volume)  Signal due to external neutron background from muons in rock CDMS II (99-05)  Construction underway at Soudan mine, Northern Minnesota (Deep 2050 mwe)  “First Dark” this Winter  CDMS detectors have the potential for tremendous additional reach: 100 times lower than current limits ~1 event / kg / year R. Abusaidi et al., Phys. Rev. Lett. 84, 5699 (17June2000) astro-ph/0002471 PRD in preparation + Thesis Golwala 010403.4.rjg http://cdms.berkeley.edu

31. CDMS Status / April 2001 Rick Gaitskell, UCL Si ZIP Ionization & Phonon Detectors ZIP: At end of fabrication steps involving µm photolithography at Stanford Nanofabrication Facility Advanced athermal phonon detection technology  Superconducting thin films of W/Al 4 K 0.6 K 0.06 K 0.02 K

32. CDMS Status / April 2001 Rick Gaitskell, UCL CDMS Ge & Si Fast Phonon & New Electrode Detectors Al/W Grid 60% Area Coverage 37 - 5 mm Squares 888 X 1 µm tungsten TES in parallel Aluminum Collector Fins 8 Traps

33. CDMS Status / April 2001 Rick Gaitskell, UCL collimator X y Px = (C + D - A - B)/(A+B+C+D) Delay plot xyZIP: Position Sensitivity

34. CDMS Status / April 2001 Rick Gaitskell, UCL 1 per minute in 4 m 2 shield CDMS II: Site Depths & Muon Flux Depth (mwe) Muon Flux (m -2 s -1 ) Stanford Underground Site SUF->Soudan Muon Flux Falls by ~10 4.5 MC predict residual punch-through neutron signal 10 -4 events/keV/kg/day 500 Hz muons in 4 m 2 shield

35. CDMS Status / April 2001 Rick Gaitskell, UCL Already demonstrated discrimination to < 10 event / kg / year  >99.9% rejection of photons >10 keV (~0.5 events/keV/kg/day)  >99% rejection of surface-electrons >15 keV (~0.05 events/keV/kg/day) Identical Icebox, but no internal lead/poly, so fits seven Towers each with three Ge & three Si ZIP detectors  Total mass of Ge = 7 X 3 X 0.25 kg > 5 kg  Total mass of Si = 7 X 3 X 0.10 kg > 2 kg CDMS II Detector Deployment

36. CDMS Status / April 2001 Rick Gaitskell, UCL Neutralino Couplings Annihilation (many channels)  Spin Independent - Scalar  Spin Dependent - Axial Vector Scattering from Nuclei (A nucleons)  Spin Independent - Scalar  Spin Dependent - Axial Vector time a.d.t. Coherent  ~A 2 -->dominates

37. CDMS Status / April 2001 Rick Gaitskell, UCL Current SUSY Theory ~ 1 event/100 kg/yr CDMS (Feb 2000) ~1 event/kg/d CryoArray 1 tonne event by event discrim. ~1 event/kg/yr http://dmtools.berkeley.edu http://dmtools.in2p3.fr DAMA Edelweiss (Jan 2001)

38. CDMS Status / April 2001 Rick Gaitskell, UCL Current Experimental & Theoretical Regions http://dmtools.berkeley.edu DAMA Ann Mod CDMS I Edelweiss DAMA(96) Heidelberg-Moscow/IGEX Ellis et al. Gondolo… (g-2) Mandic et al

39. CDMS Status / April 2001 Rick Gaitskell, UCL Direct Detection: History & Future Oroville (88) [m=20 GeV] Homestake (87) Heidelberg-Moscow (94) Heidelberg-Moscow (98) [m = ?? GeV - if significantly better limit obtained at different mass] DAMA (96) UKDMC (96) [m=100 GeV] DAMA (98/00) 90% CL Limit on Cross section for 60 GeV WIMP (scalar coupling) CDMS SUF (T) CDMS Soudan (T) 7 kg Ge+Si Cryodet GENINO (T) 100 kg Ge Diode GENIUS (T) 100 kg Ge Diode CryoArray (T) 0.1-1 tonne Cryodet ~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 010402.3.rjg Ge NaI Cryodet (T) Target Signal Liq Xe CDMS SUF (99) CDMS SUF (00) Edelweiss (98) Edelweiss (01)

40. CDMS Status / April 2001 Rick Gaitskell, UCL WIMP SUSY Dark Matter Conclusion Cosmology: Need for Non-Baryonic Dark Matter (Ω~0.2-0.3) Current Direct Detection Experiments  Testing some SUSY models, very close to top of region of broad agreement Accelerator constraints shrinking bounds (more to come …)  DAMA 4  positive signal, is being/will be tested (need to rule out systematics) in 2001/2 by CDMS and Edelweiss (both look incompatible at present for  ~A 2 ) Boulby (UK) ~50 kg NaI (Pulse Shape Discrimination) in 2001/2 DAMA 250 kg upgrade (Ann Mod / Low backgrounds / Higher Light Yield) Axial Vector (Spin Dependent) Quark-WIMP Couplings?

41. CDMS Status / April 2001 Rick Gaitskell, UCL Spin Dependent Interpretation of DAMA Ann Mod Signal (Ullio, Kamionkowski, Vogel: hep- ph/ 0010036) Preceding analysis and comparison of (mass,cross- section) limits for NaI, Ge and Si targets assumed scalar coupling of WIMPs  SUSY couplings at this level dominated by coherent cross section   ~A 2 I (A=127), Ge (A=72), Si (A=28) However if we consider axial vector (spin dependent) scattering  Comparison of Na and I (both mono-isotopic odd-p) and Ge/Si target (8% 73 Ge, 5% 29 Si both odd-n) must be model-dependent  DAMA interaction rates well above current SUSY (axial coupling) predictions (~50x) Spin Dependent (axial-vector) WIMPs in DAMA  If  proton dominates the failure to observe neutrinos from sun puts model independent constraint >30x Original DAMA Xe direct detection limit also constrains m W <20 GeV  So require  neutron >>  proton (by 10 4 ) This avoids sun detection limit This is well outside any existing theoretical models

42. CDMS Status / April 2001 Rick Gaitskell, UCL WIMP SUSY Dark Matter Conclusion Cosmology: Need for Non-Baryonic Dark Matter (Ω~0.2-0.3) Current Direct Detection Experiments  Testing some SUSY models, very close to top of region of broad agreement Accelerator constraints shrinking bounds (more to come …)  DAMA 4  positive signal, is being/will be tested (need to rule out systematics) in 2001/2 by CDMS and Edelweiss (both look incompatible at present for  ~A 2 ) Boulby (UK) ~50 kg NaI (Pulse Shape Discrimination) in 2001/2 DAMA 250 kg upgrade (Ann Mod / Low backgrounds / Higher Light Yield) Axial Vector (Spin Dependent) Quark-WIMP Couplings? Future Experiments  Cryogenic experiments Detectors -> necessary performance 1 event /detector (~250 g) /year  Liquid Xe (Boulby) await new performance data  Gas TPC (Boulby) 1 m 3 -> 20 m 3 Subsequent Generation -> 1 event /100 kg/year  ~10 -46 cm 2 )  ~6 years: just in time for TeV / LHC SUSY signal