Detecting low energy recoils with Micromegas Giomataris Ioannis, DAPNIA-Saclay Principle, performance Low threshold results Axion-WIMP search, polarimetry Large gaseous TPC Conclusions
1 40 kv/cm 1 kv/cm MICROMEGAS Y.Giomataris, Ph. Rebourgeard, J.P Robert and G. Charpak NIM A376 (1996) 29 HV1 Conversion 3 mm e - Amplification 100 µm Micromesh Strips E 2 E HV2 Particle Drift electrode Drift plane Small amplification gap Fast signals Good time and space resolution Micromesh micromesh Anode strips Or any other readout structure Insulator strip Pillar
1000000 100000 10000 A great motivation Virtue of the small gap 300Volts He + 6% Isobutane 350 Volts 400 Volts 450 Volts E 1 E 1 > E 2 Gain 1000 E 2 100 10 1 0.001 0.01 0.1 1 Gap(mm) Optimum gap : 30-100 microns pd Ref: Y. Giomataris, NIM A419, p239 (1998) V Optimal liquide gap < 10 µm Stable gain and relative immunity to flatness defects or temperature and pressure variation Good energy resolution
Good energy resolution A. Delbart, R. de Oliveira, J. Derre, Y. Giomataris, F. Jeanneau, Y. Papadopoulos, P. Rebourgeard Nucl.Instrum.Meth.A461:84-87,2001
Background shape at low energy with CAST Micromegas detector Raw data Trigger rate < 1 Hz 3x10-5 kev -1 cm -2 s -1 filtered data Cu peak Raw data Single electrons dark count:about 1Hz/m 2 background flat down to 100 ev 3x10-5 kev -1 cm -2 s -1 filtered data
Polarimetry: : Big step forward Micromegas readout by silicon pixels CERN-NIKHEF-Saclay-Twente MEDIPIX + Micromegas tested TIMEPIX is under development 5.9 kev photoelectron in Argon 500 µm Cosmic muon Argon provides higher efficiency x10
High precision detector for X-ray Polarimetery with Time Projection Chambers Photoelectric polarimetery with a pixelized micropattern gas detector Highly sensitive technique first demonstrated by Bellazzini et al (2001) and K. Black, K. Jahoda, P. Deines-Jones et al., NASA MPGD Gas pixel detector polarimeter concept Track images Modulation
Limits of the pixelized detector technique Electron diffusion in the drift region creates a tradeoff between quantum efficiency, modulation Polarimeter at higher energy : 50 kev-1 MeV Compton scattering > 1 MeV pair production Polarimeter figure-of-merit vs energy Need of high accuracy - high granularity detector
WIMP directional TPCs DRIFT PROJECT N. Spooner et al. MIMAC-He3 MIcro-tpc Matrix of Chambers of He3 A new 3 He detector for non-baryonic dark matter search Details in D. Santos presentation
How to get it bigger: T2K TPC In HARP TPC T2K 12 m2 of Micromegas read-out will be built in the next 2 years
How to get much bigger The spherical detector D=1.3 m V=1 m 3 Spherical vessel made of Cu (6 mm thick) P up to 5 bar possible (up to 1.5 tested up to now) Vacuum tight: ~10-6 mbar (outgassing: ~10-9 mbar/s) In Xe gas : 29 Kgr at p=5 bar 145 Kgr at p=20 bar
Spherical TPC with spherical proportional counter read-out Micromegas read-out is in test e - 5.9 kev 55 Fe signal Very low electronic noise: low threshold Good fit to theoretical curve including avalanche induction and electronics E=A/R 2 20 µs E One read-out channel!!! signal HV
How to get simple and cheap Supernova counter Neutrino-nucleus coherent elastic scattering σ N 2 E 2, D. Z. Freedman, Phys. Rev.D,9(1389)1974 Supernova neutrino detection with a 4 m spherical detector Y. Giomataris, J. D. Vergados, Phys.Lett.B634:23-29,2006 For E ν = 10 MeV σ N 2 E 2 2.5x10-39 cm 2, T max = 1.500 kev For E ν = 25 MeV σ 1.5x10-38 cm 2, T max = 9 kev Expected signal : 100 events (Xenon at p=10 bar) per galactic explosion Idea : A European or world wide network of several (tenths or hundreds) of such dedicated Supernova detectors robust, low cost, simple (one channel) To be managed by an international scientific consortium and operated by students ν e - ν e ν µ,τ 0.1 1 10 s
Long term program I. Giomataris, J. Vergados, Nucl.Instrum.Meth.A530:330-358,2004, High Voltage S. Aune et al., Conf.Proc.785:110-118,2005 Shield Large Spherical TPC 10 m radius 200 MCi tritium source in the center Neutrinos oscillate inside detector volume L 23 =13 m Objectives Measure θ 13 (systematic free) E 10m Tritium Source Drift Gaseous Volume Neutrino magnetic moment studies << 10-12 µ B Measurement of the Weinberg angle at low energy Challenge : detect electron recoils down to T=100 ev (Tmax=1.27 ev) Low background level (to be measured and subtracted) Measure the radial depth of the interaction
Symposium ON LARGE TPC FOR LOW ENERGY RARE EVENT DETECTION December 11-12, Paris Low energy neutrino physics, WIMP-axion search, axion search, double-beta decay With gaseous and noble liquid TPCs New read-out technologies