MIMAC MIcro-tpc MAtrix of Chambers ( 3He + CF4) A Large TPC for non baryonic Dark Matter search Daniel Santos Laboratoire de Physique Subatomique et de Cosmologie Grenoble (CNRS/IN2P3-UJF-ENSPG) IDM08 – Stockholm, August 20th 2008 D. Santos

(Micro-tpc MAtrix of Chambers ) MIMAC: (Micro-tpc MAtrix of Chambers ) LPSC (Grenoble) : F. Mayet , D. Santos , A. Trichet Technical Coordination : O. Guillaudin - Electronics : G. Bosson, J-P. Richer - Gas detector : A. Pellisier, O. Zimmermann - Data Acquisition: O. Bourrion - Mechanical Structure : Ch. Fourel - Ion source : T. Lamy, P. Sole CEA-Saclay (Dapnia): I. Giomataris, P. Colas, A. Giganon, E. Ferrer, J. Pancin, J-P. Mols ILL (Grenoble) : B. Guerard, G. Manzin IRSN (Cadarache): L. Lebreton, A. Allaoua IDM08 – Stockholm, August 20th 2008 D. Santos

The MIMAC project Rejection of background events : Energy (ionization) A multi-chamber detector for Dark Matter Track-Energy measurements Matrix of chambers (correlation) µTPC : Micromegas technology 3He and CF4 gaz : s(A) dependancy Axial interaction High or low pressure regime Directionnal detector Rejection of background events : Energy (ionization) Track Direction (Cygnus) IDM08 – Stockholm, August 20th 2008 D. Santos

Why do we think we need a large TPC? Directionality (correlation with galactic halo) Axial interaction (3He, 19F) (complement of scalar (coherent) search ) Mass dependence cross section (modularity) Two different operating modes (pressure) Low energy threshold detection (< 300 eV) IDM08 – Stockholm, August 20th 2008 D. Santos

Directionality at low pressure (The ultimate signature to correlate to the galactic halo) Two different modes High pressure (1, 2 or 3 bars) to get WIMPs events !! Low pressure (~100 mbar) to get directionality Range of recoils (x 10 ) (1bar to 100 mbar ) Diffusion (x 2) Drift velocity (x 2) IDM08 – Stockholm, August 20th 2008 D. Santos

of non-baryonic dark matter 3He for axial detection of non-baryonic dark matter spin 1/2 nucleus  axial interaction sensitive to M (WIMP) > 6 GeV neutron capture signature: n + 3He  p + 3H + 764 keV very low sensivity to -rays the possibility to share in a “patchy” matrix with other gases to follow the A cross section function IDM08 – Stockholm, August 20th 2008 D. Santos

CF4 as a quencher and target Axial interaction (odd in proton) The volume needed to have the same number of nuclei that we have in 10 kg of 3He is the 20 m3 at 1 bar.  less volume for the same number of nuclei (at the same pressure) Discrimination electron- recoil by tracks even better than in 3He IDM08 – Stockholm, August 20th 2008 D. Santos

Spin contributions to the axial interaction Nucleus Z Odd nucleon J <Sp> <Sn> 3He 2 n 1/2 -0.05 0.49 19F 9 p 0.44 -0.11 27Al 13 5/2 0.34 0.03 129Xe 54 0.36 IDM08 – Stockholm, August 20th 2008 D. Santos

Cross section 3He- and event rate in MIMAC-He3 (10kg) Accelerator constrains Exclusion curve for background 10-3 kg-1jour-1 Neutralino mass (GeV/c2) IDM08 – Stockholm, August 20th 2008 D. Santos

Complementarity with scalar detection sSD and sSI not correlated E. Moulin et al, PLB 614 (2005)143 IDM08 – Stockholm, August 20th 2008 D. Santos

(Micro-tpc MAtrix of Chambers ) MIMAC: (Micro-tpc MAtrix of Chambers ) spatial temporal resolution energetic recoil track energy threshold ~ 200eV electron/recoil discrimination IDM08 – Stockholm, August 20th 2008 D. Santos

Range vs. Energy 3He recoils Electrons IDM08 – Stockholm, August 20th 2008 D. Santos

a/b ratio = f (pressure) L~10 cm IDM08 – Stockholm, August 20th 2008 D. Santos

Time collection = f(pressure) IDM08 – Stockholm, August 20th 2008 D. Santos

He => 41 eV/ pair (e-ion) => 25 pairs/keV 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- IDM08 – Stockholm, August 20th 2008 D. Santos

ASIC MIMAC 16 « pixel » channels + mixer & shaper [energy] + double serialiser Process BiCMOS-SiGe 0.35mm Mixer & Shaper [2 gains] « pixel » channel [x 16] serialiser @ 400MHz [x 2] IDM08 – Stockholm, August 20th 2008 D. Santos

Quenching factor calculation (Lindhard theory) F. Mayet (2006) IDM08 – Stockholm, August 20th 2008 D. Santos

Lindhard prediction for Helium From J. Lindhard (1963) Lewin & Smith (1996) parametrization Fraction given to nuclei Quenching factor High Q value for Helium Fraction given to electrons Need to be measured Recoil energy Q(3He) slightly greater than Q(4He) IDM08 – Stockholm, August 20th 2008 D. Santos

Quenching factor measurement ECR source Low energy ion source 1 to 50 keV Developped @LPSC He ions Micromegas µTPC IDM08 – Stockholm, August 20th 2008 D. Santos

MIMAC : µTPC chamber Real size prototype cathod Drift space : 15 cm Micromegas +pixellized anod (x,y) IDM08 – Stockholm, August 20th 2008 D. Santos

MIMAC : energy measurements Recoil energy is shared among : Scintillation Heat ionization c Ionization Quenching factor Helium Quenching factor is predicted by Lindhard theory … but has not yet been measured ! Key point for Dark Matter to get the recoil energy IDM08 – Stockholm, August 20th 2008 D. Santos

QF measurement : calibration 1,486 keV X ray (Al) 5,97 keV X ray (Fe) X a IDM08 – Stockholm, August 20th 2008 D. Santos

Ionization (4He (50 keV)) IDM08 – Stockholm, August 20th 2008 D. Santos

Detection of 4He (recoils) of 1.5 keV !! ( 95% 4He + 5% iso) at 700mbars IDM08 – Stockholm, August 20th 2008 D. Santos

4He (1.25 keV) !!! IDM08 – Stockholm, August 20th 2008 D. Santos

Quenching factor @ 700 mbars QF measurement !! Quenching factor @ 700 mbars Range of interest for Dark Matter Measurement of 4He in 95% 4He + 5% C4H10 Threshold :300 eV (ioni.) or 1 keV (recoil) The response of this 4He detector is fully understood from 1 to 50 keV Dark Matter range : covered IDM08 – Stockholm, August 20th 2008 D. Santos

Quenching factor from 350 to 1300 mbars D. Santos et al. 2008 (to appear) IDM08 – Stockholm, August 20th 2008 D. Santos

QF measurement vs Lindhard & SRIM Scintillation SRIM : simulation of 4He in 95% 4He + 5% C4H10 IDM08 – Stockholm, August 20th 2008 D. Santos

MIMAC : track measurements July 2008 @ IRSN Cadarache Amande facility : Neutron field with energies down to a few keV IDM08 – Stockholm, August 20th 2008 D. Santos

Two-elastic interactions distance in He3 (2 atm) for a 8 keV neutron IDM08 – Stockholm, August 20th 2008 D. Santos

Elastic-capture distance distribution in He3(2 atm) for a 8 keV neutron IDM08 – Stockholm, August 20th 2008 D. Santos

4He (6 keV) in 4He (100mbar) range ~ 4mm IDM08 – Stockholm, August 20th 2008 D. Santos

Diffusion of primary electrons IDM08 – Stockholm, August 20th 2008 D. Santos

Drift velocity vs. Pressure IDM08 – Stockholm, August 20th 2008 D. Santos