Whither WIMPs: Direct Detection of SUSY Cold Dark Matter

Transcription

1 Whither WIMPs: Direct Detection of SUSY Cold Dark Matter One Tonne - Have we got what it takes? Report To NFAC Committee Jly 25,2002 Brown University, Department of Physics sefl information at Gaitskell

2 NaIAD UK DRIFT I CDMS II XENON Dark Matter Experiments (Worldwide) (Rnning/Active Collaboration) ZEPLIN I ZEPLIN III ZEPLIN II US CRESST II Edelweiss II France Canada IGEX Majorana(DM) Germany Orphes Switzerland ANAIS DAMA LIBRA Italy Japan Rosebd CsI Xenon Simple HDMS/Genino LiF XMASS(DM) Picasso Rssia Elegant V&VI Spain Coricino Taiwan US

3 Dark Matter Experiments - By Site Site Experiment Techniqe Target Stats Baksan (Rssia) IGEX Ionisation 3kg Ge Bern (Switzerland) ORPHEUS SSD 0.5kg Sn Bolby (UK) NaI NaIAD ZEPLIN I ZEPLIN II/III ZEPLIN-MAX DRIFT-I DRIFT-10 Scintillator Scintillator Scintillator Scintillator/Ionisation Scintillator/Ionisation TPC TPC 5kg NaI 50kg NaI 5kg Lxe 30kg/7kg Xe 1000kg Xe 0.2kg CS 2 2kg CS 2 Completed Constrction Planned Planned Canfranc (Spain) COSME IGEX ANAIS ROSEBUD Ionisation Ionisation Scintillator Thermal 0.2kg Ge 2.1kg Ge 107kg NaI Al 2 O 3,Ge,CaWO 4 Completed Constrction Frejs (France) Saclay-NaI EDELWEISS I EDELWEISS II Scintillation Thermal/Ionisation Thermal/Ionisation 10kg NaI 0.07kg Ge 1.3 kg Ge Completed Completed Gran Sasso (Italy) Hdlberg/Mscw HDMS Genis DAMA LIBRA Xenon CRESST-I CRESST-II CUORICINO CUORE Ionisation Ionisation Ionisation Scintillation Scintillation Scintillation Thermal Thermal/Scintillation Thermal Thermal 2.7kg Ge 0.2kg Ge 100kg Ge 100kg NaI 250kg NaI 6kg Xe 1kg Al 2 O 3 10kg CaWO 4 40kg TeO 2 760kg TeO 2 Completed Planned Constrction Constrction Constrction Planned Kamioke (Japan) XMAS Scintillator/Ionisation 3 kg Xe 1000 kg Xe Planned Otto-Cosmo (Japan) Elegants V Elegants VI LiF Scintillation Scintillation Thermal NaI CaF 2 LiF Rstrel (France) SIMPLE SDD Freon Stanford (USA) CDMS-1 Thermal/Ionisation 0.1kg Si, 1kg Ge Completed Sodan (USA) CDMS-II CryoArray Phonons/Ionisation 0.3ks Si, 0.75kg Ge 2 kg Si, 7 kg Ge kg Ge Constrction Constrction Planned??? (USA) XENON Scintillator/Ionisation 1000 kg Xe Planned Sdbry (Canada) PICASSO SDD 1g Freon

4 Talk Overview Cosmology & WIMPs in the Early Universe WIMPs in or own galaxy SUSY Framework DM Detection: History & Ftre Projections Highlight Selection of Crrent Detectors & Their Evoltion Site Reqirements & Backgronds Smmary

5 Netralino Coplings Annihilation (many channels) Spin Independent - Scalar q Scattering from Nclei (A ncleons) Spin Independent - Scalar q q Spin Dependent - Axial Vector Coherent s~a 2 -->dominates Spin Dependent - Axial Vector a.d.t. time

6 SUSY Calclations of s Broad Spectrm of Theorists Making WIMP Rate Predictions Using SUSY inspired frameworks, broad consistemcy in reslts Ellis, Ferstl, Olive; Baltz, Gondolo; Corsetti, Nath; Arnowitt, Nath; Mandic, Pierce, Gondolo, Mayama; Baer, Brhlik; Bednyakov, Klapdor- Kleingrothas, Kovalenko; Bottino Codes based on DarkSUSY and NetDriver See Ellis, Ferstl, Olive PLB 532 (2002) 318 and refs therein Predicted Range of Cross-Sections Large range of SUSY space still allowed, SUSY mass scale ncertainty feeds directly into s ncertainty UPPER LIMIT Unable to make models consistent with DAMA signal, nless constraints on Ω m >0.2 (<0.6) are relaxed. Lower abndance, raises allowed annihilation s LOWER LIMIT? Plots on dmtools web site Important experimentally! Sets maximm scale of discovery detector

7 SUSY Calclations/Experimental Inpt (2) Important Inpts from Existing Accelerator Constraints SUSY m WIMP >50 GeV & m h (Lightest Higgs) >114 GeV Higgs constraints UPPER limit (now doing K) / LEP(final) Mon BNL (Anomalos Magnetic Moment) data a µ =(g-2)/2, a µ (exp)-a µ (SM)=4.3 ±1.6 x 10-10, where a µ measred ±1.3 ppm, theory ± 0.6ppm Represents 1.6s away from Standard Model prediction (revised down from 2.6s when SM theoretical calclation fond to contain nmerical sign error) Provides strong LOWER LIMIT ON WIMP s for models with µ>0 (see next slide)

8 SUSY Calclations/Experimental Inpt (3) Possible Ftre Inflential Accelerator Data BNL - New annoncement coming Tesday data 2000 data (4 times existing set): expect an exp. error of ppm If new reslt for a µ (exp is same as previos will give 2.6s deviation from SM If new reslt is consistent (@1s) with 1999 reslt then deviation cold be in range 0-4s) (Novosebirsk e+e-) Providing experimental rather than theoretical SM inpts to theoretical calc Crent claim takes crrent 1.6s -> 2s effect Ftre analysis data Expect finish analysis ~end redced systematics vs 2000 since better freqency choices Experiement is becoming systematics dominated (little statistical improvement possible) Tevatron (starting to rn ) SUSY discovery less likely However, strong SUSY loop inflence in b->bµµ decay channel G~(tanb) 6 Signal possible if tanb>30 BBar/Belle (rnning) Not likely, CP focs

9 SUSY Calclations/Experimental Inpt (4) LHC (Rnning by 2008) Consider LHC as backstop for SUSY Sensitive to sqarks&glinos <2.5 TeV, m1/2~1 TeV, m0~1.5 TeV For discovery at LHC, chosen framework wold have to imply m WIMP <500 GeVs Wide Range of Models Possible with crrent constraints If µ>0 (if g-2 reslts holds p, favors lower m 1/2, m 0 and µ>0) then If µ<0 Spin-independent s SI has range 6x x10-10 pb Spin-dependent s SD has range x10-7 pb Possible cancellation in SI interaction s SI ~ 0 Rely on SD interaction >10-8 pb

10 Crrent Experiments & SUSY Theory Range Edelweiss (Jne 2002) ~0.25 event/kg/d ~1 event/kg/yr ~ 1 event/100 kg/yr

11 Homestake (87) Direct Detection: History & Ftre 90% CL Limit on Cross section for 60 GeV WIMP (scalar copling) Gaitskell (astroph ) Oroville (88) [m=20 GeV] ~1 event kg -1 day -1 H-M (94) Edelweiss (98) UKDMC (96) H berg-moscow (98), IGEX (00) [m=100 GeV] DAMA (98) DAMA (00) CDMS SUF (99) DAMA (96) Edelweiss (01) ZEPLIN I Xe (02) CDMS SUF (02) Edelweiss (02) NOW ZEPLIN I 6 kg Xe (T) Different Colors Indicate Different Technologies Ge NaI Cryodet Liq Xe (T) Target Signal Majorana Phase 1 (T) GENINO (T) 100 kg Ge Diode ~1 event 100 kg -1 yr -1 ~1 event kg -1 yr -1 CDMS Sodan (T) 7 kg Ge+Si Cryodet ZEPLIN II+III 10 kg Xe (T) GENIUS (T) 100 kg Ge Diode CryoArray (T) LHC XENON / ZEPLIN 1t Xe tonne Cryodet [m =?? GeV - if significantly better limit obtained at different mass] Not meant to be a complete list - see rjg

12 Resolving Interpretation of DAMA Signal Positive Annal Modlation Signal No other experiment <2004 able to check annal mod Except for DAMA pgrade 250 kg Improved light yield (NaI / PMT) Lower backgrond (factor ~ few) Wold like to see revised acqisition strategy Retain mltiple events as control grop Direct Calibration of signal bin stability (g sorces & LEDs) Assming Scalar WIMP s ~ A 2 Cryogenic Ge CDMS I - netron backgrond limiting, bt inconsistent with mod amp. Reqire ~factor 3 lower limit to exclde all of 99% CL region at 90% Edelweiss already looking inconsistent ann mod. In 2002 look for ~10 kg-day exposre and zero events to rle ot CDMS II - First Dark start end 2002 Assming? particle (Not SUSY) Reqire NaI target to remove ncertainties Anias(Spain) & NaAID(UK) programs aim to se plse shape discrimination to srpass necessary sensitivity (DAMA do not plan to se PSD)

13 Key Points: Detectors, their environment & location Probable that we are witnessing the peak of worldwide diversity in DM Crrent WIMP detection limit ~0.25 events/kg/day (no WIMP-like events seen in ~10 kg-days exposre) Expect Rapid Progress in (based on assessment of crrent programs that are rnning, or in constrction) Will be achieving large exposres with Zero Backgrond Eqivalent for ~100 kg-days Reqired scale may prohibit some new technology entering arena, nless spported by large engineering effort Challenges for next stage

14 Key Points: Detectors, their environment & location (2) Greatest Challenges Constrction & Operation of Detector Arrays Undergrond Many of experiments experiencing delays All Grops wold benefit greatly from infrastrctre/spport of Undergrond Lab Knowledgeable Technical/Engineering Assistance Achieving Detector Discrimination Performance (free systematics) (Demanding Backgrond Discrimination >>99%) Improvements needed in Screening Facilities Redce Internal Radioactivity Crrent scale of typical collaboration has difficlty meeting all screening reqirements Experiments >2005 clearly demand access to systems beyond simple HPGe screening Srface/low energy radioactivity screening (Providing Inpt to NUSL -> Screen Fac Initiative) Fabrication of some (internal) constrction materials ndergrond Still being stdied by grops

15 Key Points: Detectors, their environment & location (3) Backgronds External Radioactivity Shielding Most dedicated (discriminating) WIMP experiments will se traditional shield This is not seen as a difficlty in larger experiments Pb for g s Poly (H) to moderate external (a,n) netrons (<10 MeV) from rock High Energy Netrons from mons in rock are a concern (see next slide)

16 Key Points: Detectors, their environment & location (3) Site Depth Reqirement Shallow ~1700 mwe (1 mons/m 2 /minte) will be satisfactory for compact (non-gas) targets Satisfactory for cosmogenic activation Mons passing throgh detector array can be vetoed by simple mon veto (>99% being achieved) Mons otside mon veto will generate high energy netrons ( MeV) that cannot be moderated directly sing poly A nmber of shielding strategies being developed, bt they all involve traditional technology Additional cost of thick active shield will not dominate total cost - consenss Withot thick shield, HE netrons events occr jst below CDMS II level (1 event/100 kg/day) Collaborations wold like to develop Monte Carlos of fll experiments to ensre that goal of backgrond <1 event/100 kg/year can be met Intermediate ~3800 mwe (Factor ~50x redction in mons/he netrons) Redced thick shielding cost Additional comfort factor, general consenss that 1 tonne experiments can fnction comfortably wrt to HE netrons from mons Depth may be necessary for gas target given mch large srface area to shield Deep ~6000 mwe (Frther factor ~50x redction in mon/he netrons) Not crrently on the road map - consenss overkill

17 High Energy (E>10 MeV) Netrons from Mons Netron prodction ~ Mon Flx With slight modification for hardening of mon spectrm mean(e m )~ Depth 0.47 Sodan Site * Not excavated (Mltiple levels given in ft) Relative Mon Flx Relative Netron Flx >10 MeV WIPP (2130 ft) x 65 x 45 Sodan x 30 x 25 Kamioke x 12 x 11 Bolby x 4 x 4 Gran Sasso Frejs, Homestake (4860 ft) x 1 x 1 Mont Blanc x 6-1 x 6-1 Sdbry x 25-1 x 25-1 Homestake (8200 ft) x 50-1 x 50-1 Aglietta et.al. Nove Cimento 12, N4, page 467

18 Key Points: Detectors, their environment & location (4) Technologies have/are crossing over Detectors: DBD decay Solar Netrino Netrino Magnetic Moment Searches Low backgrond techniqes/screening facilities: Pt in place strctre for mlti-ser

19 Inter-Collaboration / Synergies: Dark Matter Dark Matter has new concerns, beyond those of Crrent Low Backgrond Experiments kev Srface Contamination This will reqire New Screening Strategies Stdies/proposals nderway in US (-> NUSL) Los Alamos / Princeton List Created at Aspen Jne 2002 DM Workshop New Sorces of Backgrond Not jst U / Th / K What are the phenomenologies?.. plate-ot rates, materials preferences etc Low Backgrond Materials Selection Database from previos and live experiments e.g. Jst starting a database at Los Alamos (Tom Bowles), attached to NUSL Monte Carlos Low Backgrond Modeling NUSLib / BolbyLib / GranSassoLib? GEANT4 - able to track down to 250 ev

20 Collaboration / Synergies: Dark Matter (2) Ftre Alignment with Demands of/soltions from other experiments e.g. pp solar netrino, DBD experiments Read-ot Technologies Gas Readot Schemes MWPC / GEMs / MicroMegas Photo Detectors Cryogenic Detectors Field spported a diverse range of technologies Will it create difficlties when the necessary reintegration occrs for larger experiments? Proto-collaborations of collaborations forming. Individal DM Experiments Benefit from Progress of Other DM Experiments c.f. John Nash

21 Collaboration / Synergies: Dark Matter (3) Spport from International Laboratories Intermediate Scale Experiments Not capable of bringing fll resorce reqirements to hole in grond Probable that those labs providing best spport will benefit as will the experiments drawn to best labs

22 WIMP SUSY Dark Matter Conclsion (1) Cosmology: Need for Non-Baryonic Dark Matter (Ω~ ) Crrent Direct Detection Experiments Testing some SUSY models As sensitivity improves - will contine to test more models Recent/crrent accelerator constraints shrinking bonds Mainly constrained UPPER bond of cross-section g-2 can provide constraint on LOWER bond (for µ>0) if it remains statistically significant DAMA 4s positive signal, is being/will be tested (need to rle ot systematics) in 2002 by CDMS and Edelweiss (both look incompatible at present for s~a 2 ) Anais(Spain) ~50 kg NaI (Plse Shape Discrimination) in 2003/4 DAMA 250 kg pgrade (Ann Mod / Low backgronds / Higher Light Yield) Axial Vector (Spin Dependent) Qark-WIMP Coplings?.

23 WIMP SUSY Dark Matter Conclsion (2) Experimental Stats Cryogenic experiments (reporting reslts) Systematics increasingly well nderstood and dealt with (matring technology) able to zero signal contamination - Edelweiss 2002 (+ CDMS II detectors when moved to Sodan 2003 based on shallow site tests 80 kg-days) + Others Scale p to ~10 kg targets in 2003/4 Liqid Xe ZEP I 3 kg fid. single phase crrently rnning ndergrond (Bolby) ZEP II & III ~7 kg 2-phase (gas & liqid) being constrcted - deploy 2003 Performance data of prototypes sed to assess ZEPLIN MAX~100 kg design XMASS rnning 3 kg 2-phase ndergrond (Kamioke) XENON (fnded) start prototype 7 kg -> design 100 kg modle Some, or all, of these grops may collaborate on next phase Gas TPC (Bolby) 1 m 3 (/g in 2001) -> 20 m 3 (next phase 2004) Awaiting data from /g rnning Target mass is a challenge: 1 m 3 ~ 30 g Ge eqiv. / Axis data difficlt to fake HPGe Main focs is DBD, bt strong dark matter search component Pls a nmber of other experiments rnning ndergrond

24 WIMP SUSY Dark Matter Conclsion (3) Sbseqent Generations: Stdying Designs for sensitivity -> 1 event /100 kg/year s~10-46 cm 2 ) Data from existing rond of detectors will be sed to inform design Target masses of 1 tonne Spport of Undergrond Laboratory will be vital for their sccessfl contrction and operation <2008: jst in time to scoop TeV / LHC SUSY signal >2008: If signal is discovered then range of large detectors (different target materials) can be sed to stdy SUSY / Dark Matter physics

25 WIMP SUSY Dark Matter Conclsion Cosmology: Need for Non-Baryonic Dark Matter (Ω~ ) Crrent Direct Detection Experiments Testing some SUSY models, very close to top of region of broad agreement DAMA 4s positive signal, is being/will be tested (need to rle ot systematics) Ftre Experiments Cryogenic experiments Systematics increasingly well nderstood and dealt with (matring technology) Liqid Xe (Bolby) First reslts from ZEPLIN I Await deployment and performance data from ZEPLIN II+III ZEP I 3 kg fid. single phase crrently rnning ndergrond (Backgronds) ZEP II & III ~7 kg fid. gas & liqid phase discrimination (How good will discrimination be?) Gas TPC (Bolby) 1 m 3 (/g in 2001) -> 20 m 3 (next phase 2004) Sbseqent Generation: Move toward -> 1 event /100 kg/year s~10-46 cm 2 ) WIMP detectors: Target masses of 100 kg - 1 tonne (ZEPLIN / XENON / CryoArray) ~6 years: jst in time to scoop TeV / LHC SUSY signal