Wenxin Wang

Wenxin Wang

(D. Attié, P. Colas, E. Delagnes, Yuanning Gao, Bitao Hu, Bo Li, Yulan Li, M. Riallot, Xiaodong Zhang)

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”

Self-Introduction Self-Introduction

Lyon, 09/04/2010 W. Wang - FCPPL workshop 1

1.2×0.4m2 Micromegas prototype

Micromegas Digital HCAL

I.I. ILC-TPCILC-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)

II.II. Fast Neutron Imaging Micromegas DetectorFast Neutron Imaging Micromegas Detector

OutlineOutline


I.I. ILC-TPCILC-TPC

1.1 Micromegas ILC-1.1 Micromegas ILC-

TPCTPC


4

• metallic micromesh (typical pitch 50μm)

• sustained by 50-100 μm pillars

• Spatial resolution ((<100<100μμmm)

• Time resolution (few nsfew ns)

• High-rate capability

• Good robustness

Amplification gap ~50-100 µm ~50 kV/cm

cathode

Drift gap~0.3 kV/cm

MicromegasMicromegas

Lyon, 09/04/2010 W. Wang - FCPPL workshop

Y. Giomataris, Ph. Rebourgeard, JP Robert and G. Charpak,

NIM A 376 (1996) 29

Edrift / Eamplif ~ 1/200

MICROMEsh GAseous Structure

5

E

Ionizing Particle

electrons are separated from ions

electrons diffuse and drift due to the E-field

Localization in time and position

B

x

y

A magnetic field reduces electron diffusion

Micromegas TPC : the amplification is made by Micromegas

Micromegas TPC: Time Projection ChamberMicromegas TPC: Time Projection Chamber


t• Ionization energy loss(dE/dx)• 3D track points reconstruction

Design for an ILD TPC in progress2x80 modules with 8000 pads each

6

ILC-TPC Large PrototypeILC-TPC Large Prototype


Goal: O(200) track points transverse resolution : 100 μm (2 m drift & 3.5 T magnet)

.

• 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

ILC-TPC Large PrototypeILC-TPC Large Prototype

W. Wang - FCPPL workshopLyon, 09/04/2010 7

ILDTPC

padspads

mesh

EB resistive foilgluepadspads

mesh

EB

Micromegas with Resistive AnodeMicromegas with Resistive Anode

Pad width limits MPGD TPC resolution

Direct signal readout technique A centroid calculation less precise

: pad width 0 : resolution at Z=0 without diffusionw


12~0

w

Charge dispersion technique with a resistive anode so that wide pads can be used for centroid determination

Resistive ink~3 MΩ/□

Resistive Kapton~5 MΩ/□

Standard

2 Resistive Kapton~3 MΩ/□

Micromegas Modules for TPCMicromegas Modules for TPC



• 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

T2K Electronics CharacteristicsT2K Electronics Characteristics

– frequency tunable from 1 to 100 MHz (most data at 25 MHz)

– 12 bit ADC (rms pedestals 4 to 6 channels)– pulser for calibration

10

NEW ELECTRONICS – FLAT ON THE BACK OF THE MODULE

11

T2K ElectronicsT2K Electronics


Goal : Fully equip 7 modules with more integrated electronics, still based on the T2K AFTER chip.

First prototype in June 2010Tests at fall 2010

Then production and characterization of 9 modules in 2011 at the CERN T2K clean room

Data Analysis ResultsData Analysis Results

12Lyon, 09/04/2010 W. Wang - FCPPL workshop

B=0 data : Drift velocity measurements

13

Vdrift = 7.698 +- 0.040 cm/µs at E=230 V/cm

(Magboltz : 7.583+-0.025(gas comp.))The difference is 1.5+-0.6 %



Drift Velocity in T2K gas compared to Magboltz simulations for - P=1035 hPa - T=19°C - 35 ppm H20

( T2K gas: Ar:CF4:iso=95:3:2)



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).

PRF(Pad Response Functions) fits, z ~ 5 cm15

B=1T data : comparison of resistive ink and Carbon-loaded Kapton




Position residuals xrow-xtrack


Z=5cm

Z=35cm

Z=50cm

MEAN RESIDUAL vs ROW number

• Z-independent distortions

• Distortions up to 50 microns for resistive paint

• Rms 7 microns for CLK film





0 : the resolution at Z=0Neff : the effective number of electrons

Resistive CLK:Resistive CLK:

0 =52.7 μm

18

eff

d

N

zC

22

0

Dependence of resolution with data taking conditions

19

Reso

lutio

n at

z=5

cm (µ

m)

Vmesh (V)



I.I. ILC-TPCILC-TPC

1.2 1.2 Tsinghua GEM-TPC (TU-TPC)Tsinghua GEM-TPC (TU-TPC)


Tsinghua GEM-TPC (TU-TPC)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

Tsinghua GEM-TPC ImprovementTsinghua GEM-TPC Improvement

Fi el d Cage Stri ps

Guard Ri ng*

GEM×3

ReadoutPads E

Dri f tel ectrode

Mi rror Stri ps*

Fi el d Cage Stri ps

Mi rror Stri ps*

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


II.II. Fast NeutronFast Neutron Imaging Micromegas DetectorImaging Micromegas Detector



Fast Neutron Imaging Micromegas DetectorFast Neutron Imaging Micromegas Detector

24

Scheme of the gadolinium foil (100 μm) etching and image obtained with the Micromegas detector.

The typical conversion reactions:

H(n,n)p 10B(n,α)7Li 6Li(n,α)t

α n → t p

F. Jeanneau et al. IEEE Transactions on Nuclear Science, vol. 53, issue 2, pp. 595-600



Readout electronics using AFTER-based electronics (made by Saclay)

25



PCB design for fast neutron detector( six T2K front end cards ~2000 pixels 1.5mm )

• 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.



27

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.

ConclusionsConclusions


Wenxin Wang

Documents

Transcript of Wenxin Wang