Santos D

Slide1: 

Daniel Santos & Emmanuel Moulin Laboratoire de Physique Subatomique et de Cosmologie Grenoble MIMAC-He3 MIcro-tpc Matrix of Chambers of He3 A new 3He detector for non-baryonic dark matter search

Slide2: 

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

Slide3: 

3He 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 + 3He  p + 1H + 764 keV very low sensivity to -rays no intrinsic X-rays

Slide4: 

Recoil energy range for a 3He detector 4.8 keV 117.8 keV  It must be convoluted by the QF(E) ! 194.1 keV Energy threshold for 3He detector: 500eV-1keV

Slide5: 

Lindhard theory (1) Energy transfer to: - electrons - atomic recoils Electronic vs. nuclear stopping cross-sections in reduced units (e,r) :

Slide6: 

Lindhard theory (2) for particle energy > 100 eV Ionization ratio R: where k = 0.133 Z2/3A-1/2 e = 11.5 E(keV) Z-7/3 g(e) semi-empirical function

Slide7: 

Ionization quenching factor measurements for Ge Figure adapted from NIMA507,643,2003

Slide8: 

Ionization ratio based on Lindhard theory

Slide9: 

MIMAC-He3: (MIcroTPC MAtrix of Cells of He 3) spatial High temporal resolution energetic recoil track projection energy threshold < 1 keV electron/recoil discrimination

Slide11: 

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

Slide12: 

Pixels (anode) in CAST Pitch: 350 μm

Range of recoils (He3) vs. Recoil Energy(SRIM-2003): 

Range of recoils (He3) vs. Recoil Energy (SRIM-2003)

Diffusion & Charge collectionD~ 200μm √ L[cm] => D~800 μm => 30 pixels( L ~15 cm and pixels~250 μm ): 

Diffusion & Charge collection D~ 200μm √ L[cm] => D~800 μm => 30 pixels ( L ~15 cm and pixels~250 μm )

Slide15: 

Drift velocity vs. Pressure

Slide16: 

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)

Slide17: 

Discrimination Electronic/Nuclear recoils

Slide18: 

Recoil Source : 3He2+ in the keV range

Recoil energy distribution after a polypropilene foil of 0.44μg/cm2for acceleration energies of 45 and 50 keV: 

Recoil energy distribution after a polypropilene foil of 0.44μg/cm2 for acceleration energies of 45 and 50 keV

Slide20: 

Two-elastic interactions distance in He3 (2 atm) for a 8 keV neutron

Slide21: 

Elastic-capture distance distribution in He3(2 atm) for a 8 keV neutron

Slide22: 

Axial cross section 3He- and rate in 10 kg 3He detector M  6 GeV   0.3 Exclusion curve for 0.01 day-1 background

Slide23: 

Complementarity with scalar detection Rate  0.01 day-1 Rate < 0.01 day-1

Conclusion: 

Conclusion MIMAC-He3 prototype under construction: GEM and Micomegas will be tested 3He 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

Slide25: 

The lightest neutralino lowest mass linear superposition of superpartners of the gauge and higgs bosons: ~ ~ ~ ~ ~ = a1B + a2W3 + a3H1 + a4H2 neutral, colorless, only weak interaction stable with R-parity conservation non-relativistic at decoupling  CDM relic density can be compatible with cosmological observations

Slide26: 

in universal models: M1 , M2 gaugino mass unification at MGUT  standard relation at EW scale (after RGE): M1 = 5/3 tan2 W  0.5 M2 -   M1,M2 : m ~ M1 neutralino and chargino m± ~ M2 mass matrix: -   M1,M2 : m ~  m± ~  LEP2 constraint on ± mass: m± > 103 GeV  M2,  103 GeV  m  50 GeV Light neutralinos ? (1)

Slide27: 

in non-universal models: masses M1 , M2 non unified at MGUT M1  M2/2 at EW scale  LEP2 constraint not valid on neutralino mass M1 = R M2 , 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)

Slide28: 

SUSY model and parameter scan Large scan of in phenomenological SUSY space: gaugino mass parameter : M2 (100,1000) GeV higgsino mass parameter :  (100,1000) GeV common scalar mass : m0 (100,1000) GeV pseudo scalar higgs mass : MA (100,1000) GeV higgs vev ratio : tan  (5,50) trilinear couplings : At,b = 0 gaugino non-universality: 0.01  R  0.5 all parameters defined at EW scale (DarkSUSY)

Slide29: 

3He- cross-section SI cross-section : SI(AX)  SI(p)×A4 SD cross-section : SD(AX)  SD(p)×A2 For 3He : SD  SI  only SD considered For AX nucleus: (3He)  mr2 (J+1)/J (ap<Sp>+an<Sn>)2 with 3He spin content: <Sp>=-0.05 <Sn>=0.49  scattering on the unpaired neutron

Slide30: 

SUSY model constraints Indirect limits: Anomalous magnetic moment of the muon :-25 < ax1010 < 69 Branching ratio of bs+: 2.04 < BR(bs+)x104 < 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

Gamma Background estimation(preliminary): 

Gamma Background estimation (preliminary)

Projection of electron (6 keV) tracks orthogonal to the anode: 

Projection of electron (6 keV) tracks orthogonal to the anode

Slide33: 

Cu escape Fe Fe escape Ar Low energy spectrum from Micromegas in CAST

Slide34: 

x-y image of 6.4 KeV X-ray beam in MicroMegas chamber (log scale for density) x, y projections

Slide35: 

Projected exclusion curve for 3He detector Background = 0.01 day-1 Energy threshold = 1 keV

Slide36: 

Projected exclusion curve for scalar detectors 2003 Edelweiss and CDMS projections