1. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Daniel Santos & Emmanuel Moulin Laboratoire de Physique Subatomique et de Cosmologie Grenoble MIMAC-He3 MIcro-tpc Matrix of Chambers of He3 A new 3 He detector for non-baryonic dark matter search

2. D. Santos Large TPC Workshop – LPNHE 21/12/2004 MIMAC-He3: (MIcro-tpc MAtrix of Chambers of Helium 3) LPSC (Grenoble) : O. Bourrion, G. Bosson, V. Comparat, G.Duhamel, J. Genevey, R. Guglielmini, O. Guillaudin, T. Lamy, E. Moulin, J.A. Pinston, D. Santos, P. Sortais, Ch. Vescovi. Dapnia-Saclay: S. Aune, I. Giomataris CPPM (Marseille): J. Bustó CdF (Paris): Ph. Gorodetzky, P. Salin ILL (Grenoble): B. Guerard, G. Manzin, P. Van Esch

3. D. Santos Large TPC Workshop – LPNHE 21/12/2004 3 He for axial detection of non-baryonic dark matter  spin 1/2 nucleus  axial interaction with  high signal/noise ratio : energy range ~ (~1 – 5) keV  sensitive to M (WIMP) > 5 GeV  neutron capture signature: n + 3 He  p + 1 H + 764 keV  very low sensivity to  -rays  no intrinsic X-rays

4. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Recoil energy range for a 3 He detector 4.8 keV 117.8 keV  It must be convoluted by the QF(E) ! 194.1 keV Energy threshold for 3 He detector: 500eV-1keV

5. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Lindhard theory (1) Energy transfer to: - electrons - atomic recoils Electronic vs. nuclear stopping cross-sections in reduced units (  ) :

6. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Lindhard theory (2) for particle energy > 100 eV Ionization ratio R: where k = 0.133 Z 2/3 A -1/2  = 11.5  E(keV)  Z -7/3  g(  ) semi-empirical function

7. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Ionization quenching factor measurements for Ge Figure adapted from NIMA507,643,2003

8. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Ionization ratio based on Lindhard theory

9. D. Santos Large TPC Workshop – LPNHE 21/12/2004 MIMAC-He3: (MIcroTPC MAtrix of Cells of He 3) spatial High temporal resolution energetic  recoil track projection  energy threshold < 1 keV  electron/recoil discrimination

10. D. Santos Large TPC Workshop – LPNHE 21/12/2004

11. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Distribution of energy depositions from 6.4 keV X-rays Argon escape peak (operating gas: Ar/isobutane 95/5) X-ray detection threshold: 0.6 keV CAST collaboration

12. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Pixels (anode) in CAST Pitch: 350 μm

13. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Range of recoils (He3) vs. Recoil Energy (SRIM-2003)

14. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Diffusion & Charge collection D~ 200μm √ L[cm] => D~800 μm => 30 pixels ( L ~15 cm and pixels~250 μm ) He => 41 eV/ pair (e-ion) => 25 pairs/keV With a gain G~3000 => 75000 e-/keV over 30 pixels => threshold ~ 2500e- “gassiplex” does the job…but we’ll try to do better !

15. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Drift velocity vs. Pressure

16. D. Santos Large TPC Workshop – LPNHE 21/12/2004 a/b ratio simulation (Geant 4) a: major axis b: minor axis of the trajectory projection Isotropically emitted at 10 cm of the anode E. Moulin (LPSC)

17. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Discrimination Electronic/Nuclear recoils

18. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Recoil Source : 3 He 2+ in the keV range

19. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Recoil energy distribution after a polypropilene foil of 0.44μg/cm2 for acceleration energies of 45 and 50 keV

20. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Two-elastic interactions distance in He3 (2 atm) for a 8 keV neutron

21. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Elastic-capture distance distribution in He3(2 atm) for a 8 keV neutron

22. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Axial cross section 3 He-  and rate in 10 kg 3 He detector M  6 GeV    0.3 Exclusion curve for 0.01 day -1 background

23. D. Santos Large TPC Workshop – LPNHE 21/12/2004 CDMS 2004 Edelweiss 2003 Complementarity with scalar detection Rate  0.01 day -1 Rate < 0.01 day -1

24. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Conclusion MIMAC-He3 prototype under construction: GEM and Micomegas will be tested 3 He source for QF measurements under construction New electronics design in progress QF measurement by May 2005 !! Installation of the prototype at LSBB (Rustrel) by November 2005 with the first version of the “new” electronics

25. D. Santos Large TPC Workshop – LPNHE 21/12/2004 The lightest neutralino  lowest mass linear superposition of superpartners of the gauge and higgs bosons: ~ ~ ~ ~ ~  = a 1 B + a 2 W 3 + a 3 H 1 + a 4 H 2  neutral, colorless, only weak interaction  stable with R-parity conservation  non-relativistic at decoupling  CDM  relic density can be compatible with cosmological observations

26. D. Santos Large TPC Workshop – LPNHE 21/12/2004 in universal models: M 1, M 2 gaugino mass unification at M GUT  standard relation at EW scale (after RGE): M 1 = 5/3 tan 2  W  0.5 M 2 -   M 1,M 2 : m  ~ M 1 neutralino and chargino m  ± ~ M 2 mass matrix: -   M 1,M 2 : m  ~  m  ± ~  LEP2 constraint on  ± mass: m  ± > 103 GeV  M 2,   103 GeV  m   50 GeV Light neutralinos ? (1)

27. D. Santos Large TPC Workshop – LPNHE 21/12/2004 in non-universal models: masses M 1, M 2 non unified at M GUT M 1  M 2 /2 at EW scale  LEP2 constraint not valid on neutralino mass M 1 = R M 2, R free parameter (constraint at EW scale relaxed) constraint on the neutralino mass in non-universal models: m   6 GeV A. Bottino et al, PRD69:037302,2004 G. Belanger et al, JHEP0403:012,2004 … Light neutralinos ? (2)

28. D. Santos Large TPC Workshop – LPNHE 21/12/2004 SUSY model and parameter scan Large scan of in phenomenological SUSY space: gaugino mass parameter : M 2 (100,1000) GeV higgsino mass parameter :  (100,1000) GeV common scalar mass : m 0 (100,1000) GeV pseudo scalar higgs mass : M A (100,1000) GeV higgs vev ratio : tan  (5,50) trilinear couplings : A t,b = 0 gaugino non-universality: 0.01  R  0.5 all parameters defined at EW scale (DarkSUSY)

29. D. Santos Large TPC Workshop – LPNHE 21/12/2004 3 He-  cross-section SI cross-section :  SI ( A X)   SI (p)×A 4 SD cross-section :  SD ( A X)   SD (p)×A 2 For 3 He :  SD   SI  only  SD considered For A X nucleus:  ( 3 He)  m r 2 (J+1)/J (a p +a n ) 2 with 3 He spin content: =-0.05 =0.49  scattering on the unpaired neutron

30. D. Santos Large TPC Workshop – LPNHE 21/12/2004 SUSY model constraints Indirect limits: Anomalous magnetic moment of the muon :-25 <  a  x10 10 < 69 Branching ratio of b  s+  : 2.04 < BR(b  s+  )x10 4 < 4.42 Accelerator constraints: h mass > 91.6 GeV   mass > 73 GeV Cosmological constraint : relic density:   < 0.3 Lower bound on the neutralino mass : m  > 6 GeV

31. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Gamma Background estimation (preliminary)

32. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Projection of electron (6 keV) tracks orthogonal to the anode

33. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Cu escape Fe escape Ar Low energy spectrum from Micromegas in CAST

34. D. Santos Large TPC Workshop – LPNHE 21/12/2004 x-y image of 6.4 KeV X-ray beam in MicroMegas chamber (log scale for density) x, y projections

35. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Projected exclusion curve for 3 He detector Background = 0.01 day -1 Energy threshold = 1 keV CRESST Saphire ELEGANT V NaI UKDMC NaI NAIAD projection

36. D. Santos Large TPC Workshop – LPNHE 21/12/2004 Projected exclusion curve for scalar detectors 2003 Edelweiss and CDMS projections