1. Large TPCs for HEP ILC-TPC & Fast Neutron detector
Wenxin Wang
(D. Attié, P. Colas, E. Delagnes, Yuanning Gao, Bitao Hu, Bo Li, Yulan Li, M. Riallot, Xiaodong Zhang)

2. Self-Introduction Came from Lanzhou University
PhD thesis in Orsay University
Work in RD51 (advisor P. Colas)
“Study of large Micromegas detectors for calorimetry and muon detection”
1.2×0.4m2 Micromegas prototype
Micromegas Digital HCAL
Lyon, 09/04/2010
W. Wang - FCPPL workshop

3. Outline ILC-TPC 1.2 Tsinghua GEM-TPC improvement (TU-TPC)
1.1 Micromegas ILC-TPC:
ILC-TPC Large Prototype
Bulk Micromegas with resistive anodes
T2K electronics
Data analysis results
1.2 Tsinghua GEM-TPC improvement (TU-TPC)
Fast Neutron Imaging Micromegas Detector
Lyon, 09/04/2010
W. Wang - FCPPL workshop

4. ILC-TPC 1.1 Micromegas ILC-TPC
Lyon, 09/04/2010
W. Wang - FCPPL workshop

5. Micromegas Edrift / Eamplif ~ 1/200
Y. Giomataris,
Ph. Rebourgeard,
JP Robert
and G. Charpak,
NIM A 376 (1996) 29
MICROMEsh GAseous Structure
Edrift / Eamplif ~ 1/200
cathode
Drift gap
~0.3 kV/cm
metallic micromesh (typical pitch 50μm)
sustained by μm pillars
Spatial resolution (<100μm)
Time resolution (few ns)
High-rate capability
Good robustness
Amplification gap
~ µm ~50 kV/cm
Lyon, 09/04/2010
W. Wang - FCPPL workshop

6. Micromegas TPC: Time Projection Chamber
Ionization energy loss(dE/dx)
3D track points reconstruction t
electrons diffuse and drift due to the E-field
Ionizing Particle
electrons are separated from ions E B
A magnetic field reduces electron diffusion y x
Micromegas TPC : the amplification is made by Micromegas
Localization in time and position
Lyon, 09/04/2010
W. Wang - FCPPL workshop

7. ILC-TPC Large Prototype
Design for an ILD TPC in progress
2x80 modules with 8000 pads each
Goal:
O(200) track points
transverse resolution : 100 μm
(2 m drift & 3.5 T magnet) .
Lyon, 09/04/2010
W. Wang - FCPPL workshop

8. ILC-TPC Large Prototype
Built by the collaboration
Financed by EUDET
Located at DESY: 5 GeV e- beam
Sharing:
- magnet : KEK, Japan
- field cage : DESY, Germany
- Cosmic trigger : Saclay, France
- endplate : Cornell, USA
Testing:
- Micromegas : Saclay, France,
Carleton/Montreal, Canada
- GEM : Saga, Japan,
Tsinghua, China
- TimePix pixel : F, D, NL
TPC
ILD
Lyon, 09/04/2010
W. Wang - FCPPL workshop

9. Micromegas with Resistive Anode
Pad width limits MPGD TPC resolution
: pad width
0 : resolution at Z=0 without diffusion
pads
mesh E B
resistive foil
glue
pads
mesh E B
Charge dispersion technique with a resistive anode so that wide pads can be used for centroid determination
Direct signal readout technique
A centroid calculation less precise
Lyon, 09/04/2010
W. Wang - FCPPL workshop

10. Micromegas Modules for TPC
Resistive ink
~3 MΩ/□
Resistive Kapton
~5 MΩ/□
Standard
2 Resistive Kapton
Lyon, 09/04/2010
W. Wang - FCPPL workshop

11. T2K Electronics Characteristics
AFTER-based electronics (72 channels/chip) from T2K experiment:
low-noise (700 e-) pre-amplifier-shaper
100 ns to 2 μs tunable peaking time
Zero Suppression capability
full wave sampling by SCA
Bulk Micromegas detector: 1726 (24x72) pads of ~3x7 mm²
frequency tunable from 1 to 100 MHz (most data at 25 MHz)
12 bit ADC (rms pedestals 4 to 6 channels)
pulser for calibration
Lyon, 09/04/2010
W. Wang - FCPPL workshop

12. T2K Electronics NEW ELECTRONICS – FLAT ON THE BACK OF THE MODULE
Goal : Fully equip 7 modules with more integrated electronics, still based on the T2K AFTER chip.
First prototype in June 2010
Tests at fall 2010
Then production and characterization of 9 modules in 2011 at the CERN T2K clean room
Lyon, 09/04/2010
W. Wang - FCPPL workshop

13. Data Analysis Results
Lyon, 09/04/2010
W. Wang - FCPPL workshop

14. B=0 data : Drift velocity measurements
Data Analysis Results
Drift Velocity in T2K gas compared to Magboltz simulations for
- P=1035 hPa
- T=19°C
ppm H20
( T2K gas: Ar:CF4:iso=95:3:2)
Vdrift = cm/µs at E=230 V/cm
(Magboltz : (gas comp.))
The difference is %
B=0 data : Drift velocity measurements
Lyon, 09/04/2010
W. Wang - FCPPL workshop

15. Data Analysis Results PRF : Pad Response Function
a measure of signal size as a function of track position
relative to the pad
using pulse shape information to optimize the PRF  
The PRF:
is not Gaussian.
can be characterized by its FWHM (z) & base Width (z).
Lyon, 09/04/2010
W. Wang - FCPPL workshop

16. PRF(Pad Response Functions) fits, z ~ 5 cm
Data Analysis Results
B=1T data : comparison of resistive ink and Carbon-loaded Kapton
PRF(Pad Response Functions) fits, z ~ 5 cm
Lyon, 09/04/2010
W. Wang - FCPPL workshop

17. Data Analysis Results Position residuals xrow-xtrack Lyon, 09/04/2010
W. Wang - FCPPL workshop

18. Data Analysis Results MEAN RESIDUAL vs ROW number
Z-independent distortions
Distortions up to 50 microns
for resistive paint
Rms 7 microns for CLK film
Z=5cm
Z=35cm
Z=50cm
Lyon, 09/04/2010
W. Wang - FCPPL workshop

19. Data Analysis Results 0 =52.7 μm 0 : the resolution at Z=0
Resistive CLK:
0 =52.7 μm
0 : the resolution at Z=0
Neff : the effective number of electrons
Lyon, 09/04/2010
W. Wang - FCPPL workshop

20. Dependence of resolution with data taking conditions
Data Analysis Results
Resolution at z=5cm (µm)
Vmesh (V)
Dependence of resolution with data taking conditions
Lyon, 09/04/2010
W. Wang - FCPPL workshop

21. 1.2 Tsinghua GEM-TPC (TU-TPC)
ILC-TPC
1.2 Tsinghua GEM-TPC (TU-TPC)
Lyon, 09/04/2010
W. Wang - FCPPL workshop

22. Tsinghua GEM-TPC (TU-TPC)
Small TU-TPC prototype (GEM-TPC)
Total: 99 strips
Pitch: 5 mm
Strip Width: 2 mm
Maximum drift length: 50cm
Readout detector: triple-GEM
Scheme of TU-TPC prototype
Lyon, 09/04/2010
W. Wang - FCPPL workshop

23. Tsinghua GEM-TPC Improvement
TU-TPC
Field cage: single-side strip
to mirror strip: done
Guard ring: adopted
DAQ: from Q, T separately,
to pulse sampling, delayed,
but coming soon
Space charge calculation
Lyon, 09/04/2010
W. Wang - FCPPL workshop

24. Imaging Micromegas Detector
Fast Neutron
Imaging Micromegas Detector
Lyon, 09/04/2010
W. Wang - FCPPL workshop

25. Fast Neutron Imaging Micromegas Detector
The typical conversion reactions:
H(n,n)p 10B(n,α)7Li 6Li(n,α)t α
n → t p
Scheme of the gadolinium foil (100 μm) etching and image obtained with the Micromegas detector.
F. Jeanneau et al. IEEE Transactions on Nuclear Science, vol. 53, issue 2, pp
Lyon, 09/04/2010
W. Wang - FCPPL workshop

26. Fast Neutron Imaging Micromegas Detector
Readout electronics using AFTER-based electronics (made by Saclay)
Lyon, 09/04/2010
W. Wang - FCPPL workshop

27. Fast Neutron Imaging Micromegas Detector
PCB design for fast neutron detector
( six T2K front end cards
~2000 pixels
1.5mm )
Lyon, 09/04/2010
W. Wang - FCPPL workshop

28. Fast Neutron Imaging Micromegas Detector
Present - August 2010: Design, construction, transportation and assembly of fast neutron detector;
September 2010: Date taking with fast neutron detector using a 14MeV neutron beam in Lanzhou University.
Lyon, 09/04/2010
W. Wang - FCPPL workshop

29. Fast Neutron Imaging Micromegas Detector:
Conclusions
Micromegas ILC-TPC:
Since December 2008 , 5 modules of Micromegas TPC have been measured and got good results. The concept is globally validated.
Next step well advanced : 7 modules to fully equip the present endplate.
Fast Neutron Imaging Micromegas Detector:
We have finished the basic design of fast neutron Micromegas detector and will take data in this year. All these make good preparation for research of neutron imaging.
Lyon, 09/04/2010
W. Wang - FCPPL workshop

30. Thank you for your attention
And
Thanks to all others for the texts and pictures I “borrowed”
Lyon, 09/04/2010
W. Wang - FCPPL workshop