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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
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(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
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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
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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
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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
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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 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
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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
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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
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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
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Complementarity with scalar detection
sSD and sSI not correlated E. Moulin et al, PLB 614 (2005)143 IDM08 – Stockholm, August 20th 2008 D. Santos
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(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
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Range vs. Energy 3He recoils Electrons
IDM08 – Stockholm, August 20th 2008 D. Santos
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a/b ratio = f (pressure) L~10 cm
IDM08 – Stockholm, August 20th 2008 D. Santos
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Time collection = f(pressure)
IDM08 – Stockholm, August 20th 2008 D. Santos
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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 => e-/keV over 30 pixels => threshold ~ 2500e- IDM08 – Stockholm, August 20th 2008 D. Santos
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ASIC MIMAC 16 « pixel » channels + mixer & shaper [energy] + double serialiser
Process BiCMOS-SiGe 0.35mm Mixer & Shaper [2 gains] « pixel » channel [x 16] 400MHz [x 2] IDM08 – Stockholm, August 20th 2008 D. Santos
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Quenching factor calculation (Lindhard theory)
F. Mayet (2006) IDM08 – Stockholm, August 20th 2008 D. Santos
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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
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Quenching factor measurement
ECR source Low energy ion source 1 to 50 keV He ions Micromegas µTPC IDM08 – Stockholm, August 20th 2008 D. Santos
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MIMAC : µTPC chamber Real size prototype cathod Drift space : 15 cm
Micromegas +pixellized anod (x,y) IDM08 – Stockholm, August 20th 2008 D. Santos
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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
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QF measurement : calibration
1,486 keV X ray (Al) 5,97 keV X ray (Fe) X a IDM08 – Stockholm, August 20th 2008 D. Santos
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Ionization (4He (50 keV)) IDM08 – Stockholm, August 20th 2008
D. Santos
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Detection of 4He (recoils) of 1.5 keV !! ( 95% 4He + 5% iso) at 700mbars
IDM08 – Stockholm, August 20th 2008 D. Santos
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4He (1.25 keV) !!! IDM08 – Stockholm, August 20th 2008 D. Santos
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Quenching factor @ 700 mbars
QF measurement !! Quenching 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
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Quenching factor from 350 to 1300 mbars
D. Santos et al (to appear) IDM08 – Stockholm, August 20th 2008 D. Santos
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QF measurement vs Lindhard & SRIM
Scintillation SRIM : simulation of 4He in 95% 4He + 5% C4H10 IDM08 – Stockholm, August 20th 2008 D. Santos
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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
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Two-elastic interactions distance in He3 (2 atm) for a 8 keV neutron
IDM08 – Stockholm, August 20th 2008 D. Santos
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Elastic-capture distance distribution in He3(2 atm) for a 8 keV neutron
IDM08 – Stockholm, August 20th 2008 D. Santos
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4He (6 keV) in 4He (100mbar) range ~ 4mm
IDM08 – Stockholm, August 20th 2008 D. Santos
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Diffusion of primary electrons
IDM08 – Stockholm, August 20th 2008 D. Santos
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Drift velocity vs. Pressure
IDM08 – Stockholm, August 20th 2008 D. Santos
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