1. Micromegas TPC Part II : experiments
CCAST
Micromegas TPC Part II : experiments
P. Colas, Saclay
Lectures at the TPC school,
Tsinghua University, Beijing,
January 7-11, 2008
January 10, 2008
Micromegas TPC

2. OUTLINE PART I – operation and properties TPC, drift and amplification
Micromegas principle of operation
Micromegas properties
Gain stability and uniformity, optimal gap
Energy resolution
Electron collection efficiency and transparency
Ion feedback suppression
Micromegas manufacturing
meshes and pillars
InGrid
“bulk” technology
Resistive anode Micromegas
Digital TPC
January 10, 2008
Micromegas TPC

3. OUTLINE PART II – Micromegas experiments The COMPASS experiment
The CAST experiment
The KABES beam spectrometer
The T2K ND-280 TPC
The Large Prototype for the ILC
Micromegas neutron detectors
TPCs for Dark Matter search and neutrino studies
January 10, 2008
Micromegas TPC

4. COMPASS MIP detection for measuring the nucleon spin structure
High particle flow : 105 kHz/cm2
Sparks give less than 1 per mil dead time
Space resolution < 70 mm with 350 mm strips
The largest Micromegas so far (40x40 cm2)
In operation at CERN since 2002
efficiency>97%
Going to hadrons and new non-magnetic cathodes in 2008 (with a new magnet)
January 10, 2008
Micromegas TPC

5. CAST X ray CERN Axion Solar Telescope
Solar Axion detection : con- version of solar axions in a LHC magnet -> observe low-energy X-rays
2D with overlayed crossed strips
In operation at CERN since 2003
Improvements in progress (energy resolution, shielding, new detector, golden cathode to avoid copper fluorescence, new optics)
axions
Transverse magnetic field (B)
X ray
detector L
January 10, 2008
Micromegas TPC

6. CAST Low threshold : 600 eV ! Low background (fluorescence) Ar
6.5 keV g X y
Low threshold : 600 eV !
Low background (fluorescence) Cu
escape Fe Ar
Low energy spectrum from Micromegas in CAST
January 10, 2008
Micromegas TPC

7. NA48/KABES Tdrift2 KAon BEam Spectrometer
Micromegas
Gap 50 μm
Tdrift1
Micromegas TPC for CP violation expt in operation at CERN from summer 2003 to end of Extension for K+ -> pnn project (25 micron gap)?
Time resolution: 0.6 ns
Tagged K track
Space resolution from drift time measurement: 70 μm
(T0)KABES- (T0)DCH Spectrometer (ns)
XStation 1 or 2 - XStation 3 (cm)
Tagging with reconstructed K±  ± +  -
January 10, 2008
Micromegas TPC

8. January 10, 2008
Micromegas TPC

9. Neutron detection Use a converter to extract alphas
Numerous applications: neutron tomography, neutron detection in hostile environments
January 10, 2008
Micromegas TPC

10. Numerous applications: neutron tomography, neutron detection in hostile environments
January 10, 2008
Micromegas TPC

11. January 10, 2008
Micromegas TPC

12. X-ray Radiography (Roentgen 1895) : see bones through skin and meat
Neutron Radiography : see gas (H2) through glass and metal
Very useful for rocket engine studies
January 10, 2008
Micromegas TPC

13. T2K : Tokai to Kamiokande
Long Base Line neutrino experiment with an intense beam (0.75MW)
Aiming at q13 , and “atmospheric oscillation” measurements.
2 detectors: far (SK) and near at 280 m from target
Off-axis beam
JPARC currently under construction  first beam 2009
January 10, 2008
Micromegas TPC

14. T2K Physics Goals
P(νμ→ νμ)≈1- cos4 θ13 sin2 2θ23 sin2 (1.27 Δm223 L/Eν)
 disappearance
Need flux and spectrum measurement at ND280 detector
5000 ev/year SK, 105 ev/year ND280
P(νμ→ νe)≈sin2 2θ13 sin2 (1.27 Δm213 L/Eν)
1-sin2(2θ23)
Δ(m23)2
Eν(MeV)
100 ev/5 years for sin2(2θ13)=0.1, BKG 15
Need νe contamination at ND280 and study of other backgrounds
January 10, 2008
Micromegas TPC

15. Purpose of ND280
Measure the neutrino spectrum before oscillation.
Measure the intrinsic e beam contamination from  and kaon decays.
Measure the 0 production in Neutral Current with neutrino flux close to the one at SK.
Measure the exclusive cross-sections at the relevant energies (< 1Gev).
Measure nuclear effects that are relevant at these energies:
Proton and pion rescattering and charge exchange.
B = 0.2 T
January 10, 2008
Micromegas TPC

16. T2K
3 TPC stations
2.5 m y z x
2.5 m
Detector module
1 m
Started in December 2004, should take data end 2009
3 TPCs stations; each with 2 planes of detector modules
→ From the beginning, think wide operating ranges, flexible hardware
modular architecture, design staging
January 10, 2008
Micromegas TPC

17. Switched capacitor array
The T2K TPC
TCP/IP
PC Linux
6 DCCs
VME/PCI
backplane bus
Gigabit
Ethernet
DAQ control
Detector B A
Global trigger
Réseau
3 TPC
1 m
2,5 m
1 of 6 TPC planes
(12-modules)
Outside magnet
Inside magnet
1 of 6 Data
Concentrator
Card
12 duplex
Optical fibres
x 6
Front End Mezzanine
Card (FEM)
288 channel
Front End Card (FEC)
1728 pad Micromegas plane
Slow control
network
Optical fiber to/from DCC
Power bar
Low voltage
Power supply
1 of 72 modules
1 of 1728 Front-End ASIC “AFTER”
72 channel x 511 time buckets
Switched capacitor array
January 10, 2008
Micromegas TPC

18. AFTER SCA: 76x511 Cells Technology: AMS CMOS 0.35mm
Number of transistors: 400,000
Area: 7546mm x 7139 mm
Package: LQFP 160 pins; 30 x 30 x 1.4 mm pitch: 0.65 mm
Submission: 24 April 2006
Delivery: end of July 2006
Characterization: October 2006 – March 2007
SCA:
76x511 Cells
January 10, 2008
Micromegas TPC

19. Connectors to detector plane
ASIC
4 channel
ADC
Passive Components
Connectors to detector plane
288 channel FE card
Digital output
~25 cm
~12 cm
→ Foresee FEC PRR in ~Q and production in ~Q2-Q3 2008
January 10, 2008
Micromegas TPC

20. Front-End Mezzanine
→ Foresee FEM Production Readiness Review in ~Q and production in ~Q4 2008
January 10, 2008
Micromegas TPC

21. Detector Module Read-out Electronics
288-channel analog
Front-End Card (FEC)
1728-pad detector plane
80-pin connector
72-channel ASIC
Slow-control
Network - CANbus
Quad-channel ADC
digital Front-end
Mezzanine card (FEM)
FPGA
Fiber to
DCC
Optical Transceiver
Low voltage
power
84 modules in total
Data taking at CERN on Harp setup in Sept. 07
electronics was very stable during the 10-day period of data taking
January 10, 2008
Micromegas TPC

22. Production and Test Bench at CERN
University of Geneva, Barcelona
January 10, 2008
Micromegas TPC

23. Read-out board Coverlay lamination Detector developed cured tested
January 10, 2008
Micromegas TPC

24. January 10, 2008
Micromegas TPC

25. January 10, 2008
Micromegas TPC

26. Bulk detectors are now very stable. Gains up to 60000
But run at
Ar CF4 Isobutane 95:3:2
January 10, 2008
Micromegas TPC

27. 36x34 cm2 1728 pads Pad pitch 6.9x9 mm2 January 10, 2008
Micromegas TPC

28. 1 ‘spark’ (100 nA) per 10 hours without beam.
Gain about 800 !
1 ‘spark’ (100 nA) per 10 hours without beam.
January 10, 2008
Micromegas TPC

29. Cluster space point resolution in T2K
B=0.2T
Cluster space point resolution in T2K
2005
1-pad
clusters
< 700 1m
2-pad clusters
Improved space point  for
2-pad clusters
Larger fraction of > 1-pad
clusters (low-noise FEE)
Preliminary values of dE/dx
resolution for ~ 35cm long
tracks (E=160V/cm):
% B=0.2T
% B=0.4T
 should fulfill requested
resolutions of 10% for ~70cm
long tracks on both 1
GeV/c and dE/dx
B=0.2T
2007
< 600 1m
2-pad clusters
1-pad
clusters
January 10, 2008
Micromegas TPC

30. Micromegas Panels for Large Prototype
Resistive anode from the start
-> resistive “bulk”
Use of T2K electronics
Several solutions for the resistive layer and the mesh under study
January 10, 2008
Micromegas TPC

31. AFTER-chip based readout
The most compact at present: 72 channels
Very flexible : 10 to 100 MHz sampling, shaping: peaking time from 90 to 800 ns, can be switched off, zero suppression.
Production decided last October 12. Will take place in Q ( channels for T2K, for LC-TPC LP)
January 10, 2008
Micromegas TPC

32. MICROMEGAS + RESIST. FOIL PANEL
24 rows x 72 pads HV
Resistive layer grounding
Av. Pad pitch
3.2 x 7 mm
January 10, 2008
Micromegas TPC

33. connector side
Detector side
January 10, 2008
Micromegas TPC

34. TimePix multi-chip panel
Daisy-chained chips to be equipped with InGrids
TimePix multi-chip panel
2x4 matrix
SiProt+Ingrid
1 MUROS
Pad ~ 2,8 x 6, 8 mm²
January 10, 2008
Micromegas TPC

35. ATLAS muon chambers for SLHC
average single count rates for L=1034 cm-2s-1
January 10, 2008
Micromegas TPC

36. ATLAS Micromegas R&D Collaboration
Evaluate possible use of micromegas for ATLAS muon chamber upgrade programme
EoI submitted in February 2007 to ATLAS Upgrade Office
Proposal submitted in June 2007
Expect approval by ATLAS EB in the near future
15 participating Institutes so far; with growing interest ...
Regular weekly meetings at CERN since February
TWiki page
January 10, 2008
Micromegas TPC

37. Goals
Phase I: Build and evaluate small prototype(s) based on micromegas technology to
get familiar with technology
demonstrate required performance
Decide on
Operating parameters (gas, gas gain, HV, etc...)
Readout pattern & electronics
Phase II: Develop techniques for the construction of large-size detectors (1m x 2m)
January 10, 2008
Micromegas TPC

38. The mesh(es) Mesh–readout electrode distance: 128 µm Prototype 1 (P1)
Homogeneous stainless steel mesh
325 lines/inch = 78 µm pitch
wire diameter: 20–25 µm
Prototype 2 (P2)
Unidirectional stainless steel/plastic mesh
200 lines/inch = 127 µm pitch
wire diameter: 40–45 µm
January 10, 2008
Micromegas TPC

39. Prototype assembling Al frame on both sides Cathode mounting
Assembled chamber
4/24/17 39
January 10, 2008
Micromegas TPC

40. Dark matter search More neutrino physics
Look for recoiling nuclei (few 100 keV)
Directionality : see the ‘wind of wimps’ : 24h-modulation of the direction
Many projects, many of them use Micromegas
Negative ion TPC : take an attaching gas (CS2, CH3NO3), drift negative ions, they are stripped in the amplification region. Very slow drift, but very low diffusion
More neutrino physics
Neutrinoless double-beta decay in 136Xe
January 10, 2008
Micromegas TPC

41. CONCLUSION
Micromegas is a very versatile detector suited to detection of charged particles, neutrons, photons, with high rate, high resolution (E,t,x), low rad. length, large surfaces, low cost, easy operation, robustness, good aging properties, etc…
Matter for this talk principally comes from:
IEEE/MPGD workshops, San Diego, October 29, 2006 and Honolulu, October 28, 2007, CERN, September 11, 2008
3rd Symposium on Large TPCs for Low Energy Rare Events, Paris, December 11-12, 2006
Recent work in Aachen, DESY, KEK, CERN, Carleton, Saclay…
January 10, 2008
Micromegas TPC

42. THANKS
To all colleagues from whom I stole transparencies or plots: I. Giomataris, B. Peyaud, T. Lux, E. Mazzucato, M. Zito, D. Calvet, J. Wotschak, R. de Oliveira, S. Andriamonje, M. Dixit, M. Riallot, A. Delbart, D. Attié, M. Chefdeville, S. Biagi, J. Martoff
For the animations : Gilles Barouch, Dan Burke, D. Attié
Questions/remarks:
January 10, 2008
Micromegas TPC

43. Information RD51 workshop April 16-18 in Amsterdam
IEEE/NSS in Dresden October 19-25
Large TPCs for Low Energy Rare Events (Paris, December 18-19)
January 10, 2008
Micromegas TPC