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Micromegas µTPC for direct Dark Matter search with MIMAC

Micromegas µTPC for direct Dark Matter search with MIMAC. Frédéric Mayet, C. Grignon, O. Guillaudin, C. Koumeir, D. Santos Laboratoire de Physique Subatomique et de Cosmologie Grenoble – Université Joseph Fourier - CNRS/IN2P3. The MIMAC project.

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Micromegas µTPC for direct Dark Matter search with MIMAC

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  1. Micromegas µTPC for direct Dark Matter search with MIMAC Frédéric Mayet, C. Grignon, O. Guillaudin, C. Koumeir, D. Santos Laboratoire de Physique Subatomique et de Cosmologie Grenoble – Université Joseph Fourier - CNRS/IN2P3

  2. The MIMAC project Challenge : discriminate WIMP signal from background • MIMAC : A multi-chamber detector for Dark Matter • µTPC : Micromegas technology • 3He and CF4 gaz : s(A) dependancy • Rejection of background events : • Energy (ionization) • Track • Direction (Cygnus), 2nd step of MIMAC • Directionnal detector : need to work at High and low pressure regime F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  3. MIMAC Collaboration LPSC (Grenoble) : D. Santos, F. Mayet, C. Grignon, C. Koumeir Technical coordinator : O. Guillaudin Team : O. Bourrion, G. Bosson, J-P. Richer, Ch. Fourel, T. Lamy, P. Sole, J.P. Scordilis, J. Angot CEA-IRFU (Saclay): I. Giomataris, P. Colas, J. Pancin IRSN (Cadarache) : A. Allaoua, L. Lebreton F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  4. Spin contributions to the axial interaction Spin dependent Interaction(complentarity) Interaction with n (He) or p (F) Low mass targetLow energy recoils First phase : focus on low energy Helium ions Erecoil < 6 keV F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  5. A micromegas µTPC for Dark Matter • spatial • High timeresolution • energy • recoil track projection • energy threshold ~ 1 keV • electron/recoil discrimination Next talk by Olivier Guillaudin First step : low Energy measurement Next step : track measurement Collaboration : CEA Saclay (I. Giomataris, P. Colas et al.) F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  6. MIMAC : µTPC chamber Real size prototype for Track measurement cathod Drift space : 15 cm GEMs (or Micromegas) +pixellized anod (x,y) F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  7. Energy measurement: Quenching factor c • Recoil energy is shared among : • Scintillation • Heat • ionization c Ionization Quenching factor • Helium Quenching factor is predicted by Lindhard theory • … but need to be measured ! • Key point for Dark Matterto compute recoil energy F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  8. QF measurement: Lindhard prediction for He 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) Start with 4He… F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  9. QF measurement: experimental set-up ECR source • Low energy ion source • 1 to 50 keV • Developped @LPSC He ions 1 µm hole Micromegas µTPC F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  10. QF measurement: calibration 1,486 keV X ray (Al) 5,97 keV X ray (Fe) X a F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  11. QF measurement: low energy ions 1,5 keV 4He 50 keV 4He • Ionization energy : 400 eV ! • Energy Resolution (s/E) : 34% • Ionization energy : 35,5 keV • Energy Resolution (s/E) : 2% 4He from 1 keV to 50 keV F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  12. Quenching factor @ 700 mbars Range of interest for Dark Matter QF measurement: results 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 To be done :Q(3He) D. Santos et al. 2008, arXiv:0810.1137 F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  13. QF measurement: versus pressure Quenching factor from 350 to 1300 mbars • Helium quenching factor • depends sligthly on Pressure • Ionization should not depend on Pressure • Scintillation ? • Increases with increasing P D. Santos et al. 2008, arXiv:0810.1137 F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  14. Lindhard : pure 4He Part of energy given to electrons QF measurement: versus Lindhard & SRIM Scintillation ? • SRIM : simulation of 4He • in 95% 4He + 5% C4H10 D (SRIM-DATA) May be assigned to scintillation Need to measure He scintillation… F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008 D. Santos et al. 2008, arXiv:0810.1137

  15. 3He recoils electrons SRIM 6 0,6 Range (mm) Range (mm) Energy (keV) Energy (keV) Tracks : Range vs Energy Electron track is 10 times longer than 3He track (of the same energy) Going further (directionnality) requires 3D tracks … F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  16. 100V/cm 100V/cm Tracks : Simulation of 3D track reconstruction SIMULATION t=0 ns Scan the anod every 25 ns t=25 ns sDiff = 200 mm √L(cm) vdiff = 26 mm/ns t=50 ns 3D track is reconstructed from 25 ns scan of the (x,y) anod L, q and f C. Grignon et al. 2009 (to appear) F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  17. DL Df Dq s = 300 mm s = 2.6 deg s = 3.7 deg Tracks : expected performance SIMULATION C. Grignon et al. 2009 (to appear) Simulation shows that 3D reconstruction can be achieved with good resolutions Proof of principle… F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  18. Tracks : Very first track reconstructed in MiMac Obtained this week… Track after DAQ 3D reconstructed Track DATA • Alpha from Radon contaminent • To be done for low energy recoils • Obtained with GEMs • To be done with Micromegas F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  19. MIMAC : track measurements Spring 2009 @ IRSN Cadarache • Amande facility : • Neutron field with energies down to a few keV • Team : L. Lebreton, A. Allaoua et al. F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  20. MIMAC : conclusion and work ahead • He Quenching factor has been measured at various pressures • Key point for a gazeous Dark Matter detector • Sub-keV threshold has been reached • First track observed in lab. and simulated reconstruction is ok. Next step : First measurement of low-energy tracks in Helium Project underway with IRSN Cadarache F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  21. Discrimination electron/recoil • Discrimination e/recoil may be done on the shape of the track • Rejection increases with pressure E. Moulin (Ph.D. th.,2005) a/b a/b a/b F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  22. Micromegas µTPC : resolution • Energy resolution of Micromegas µTPC has been measured down to 1 keV • We have shown that : • It does not depend on pressure • It does not affect Dark Matter (number of events expected) even at low energy • F. Mayet et al. 2008 (to appear) Energy measurement of recoils with a 4He Micromegas µTPC : fully studied for our purpose (resolution & quenching) F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  23. Axial Cross section 3He- E. Moulin et al, PLB 614 (2005)143 • 0.02< Ωh2<0.15 • Accelerator constrains Exclusion curve for background 10-2 day-1 Event rate in MIMAC (10kg He) Neutralino mass (GeV/c2) F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  24. Axial vs Scalar direct detection E. Moulin et al, PLB 614 (2005)143 Red points : may be visible in MIMAC • Axial and scalar interactions • not correlated • Needs to develop both strategies F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  25. Time collection = f(pressure) F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  26. a/b ratio vs. Time collection E. Moulin (Ph.D. th.,2005) F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

  27. Drift velocity vs. Pressure F. Mayet - 4th Symposium on large TPCs for low energy rare events detection - Paris - Dec. 2008

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