1. TPC R3 B R3B – TPC Philippe Legou Krakow, February 2010 2nd
CEA Saclay - France B
TPC R3
© Ph. LEGOU & F.G. NIZERY

2. 2- Principle of detection 3- Construction of the detector:
Outline
1- Motivation
2- Principle of detection
3- Construction of the detector:
- the detector
- the front-end electronics
4- Results

3. R3B - TPC in few words … . What is it?
R3B for : Reaction studies with Radioactive Relativistic Beams)
What is it?
▪ a multi track Time Projection Chamber detector for
protons to beam heavy ions.
Why ?
to measure precisely kinematics characteristics of
particles with minimum amount of material in the beam.
Who ? (for instance)
 several teams of CEA Saclay : SPhN, SIS, SEDI
 Cracovie (university and Nuclear Physics institute)
 IN2P3 CNRS CPPM
 Bratislava (Nuclear Physics Institute)
Where ?
 at GSI, just after GLAD magnet.
When ?
end of 2015 ?

4. R3B hall in the FAIR facility
Still to build
FAIR
GSI
Cave C
R3B

5. the Mesh Micromegas : MICROMEsh GASeous
Close-up of a mesh
On behalf of Rui de Oliveira at CERN
the Mesh
Two way of making a mesh for a Micromegas design
A Kapton foil streched and glued on a
Frame, and the frame is screwed on the PCB
A « bulk » which can be seen as
Other layers of the PCB
Improvements are possible (other gap)
Ready to use solution
Mounting operation is required
No improvements + difficult to repair

6. Micromegas used in TPC mode
Micromegas : MICROMEsh GAS
detector
TPC: Time Projection Chamber
Cathode
Gas
Ionization electrons
Electrical field
Mesh
100 µm
Spacers
Mother board with strips
Beam

7. Bulk Micromegas ▪ Large area and robustness
▪ Easy implementation
▪Low cost
▪Industrial process
Bulk Micromegas obtained by lamination of a woven grid on an anode with a photo-imageable film
« Bulk » : construction process
Low material detectors

8. Choice of the amplification gap
electron
Ion tail
Small gap fast signals
12.5 m Micromegas has been tested for NA48-3
Ion collection time are <5 ns
No Ballistic deficit

9. a 100 µm mesh bulk detector No frame anymore ! Mesh 10×10 cm2
100mm kapton
+5mm Cu

10. R3B – TPC test setup in cave C October 2008 & March 2009
Six detectors along the beam between scintillators for the DACQ trigger
Beam direction

11. + + a TracKer 48 channels Mother board Width of strips : 835 µm
Very fast Preamp
Space between 2 strips : 65 µm
Or 7 channels of 5mm with
150 µm between 2 strips.

12. Front-end module : FAMMAS (ph.Legou)
( Fast Amplifier Module for Micromegas ApplicationS)
In few figures …
Power supply : + 5V -5V
Consumption  50 mW
Input: positive or negative
Size: 22 x 20 x 5 mm
weight : 4g
Noise: 600 µV rms
Rise time : < 1ns

13. Characterization of the front-end in the lab
Very good uniformity of the noise
on the 48 channels front-end cards
on each tracker detector

14. CEA - FAMMAS Front-end module
FAMMAS vs commercial Module
Minicircuits
1GHz ZFL-1000LN
CEA - FAMMAS Front-end module
Amplitude
width
Amplitude
width
3.07ns F4 F2 F4
2.57ns F2
Fall time
90% - 10%
Rise time
10% - 90%
Fall time
90% - 10%
Rise time
10% - 90%
2.16ns F1 F1
1.11ns
1.08ns F6
0.8ns F6

15. Characterization of the detector
Both detectors have the same gain
in the area of the operating point.

16. Test on a 100 µm gap detector at CERN
Test conditions :  visualisation at about 30 meters coaxial cable.
 Gaz : COMPASS.
 Beam.
Mesh Voltage : 350 V
Mesh Voltage : 370 V

17. Test on a 100 µm gap detector at CERN
No crosstalk between
neighbour channels
Test conditions :  visualisation at about 30 meters coaxial cable.
 Gaz : COMPASS.
 Beam.
Mesh Voltage : 340 V
Mesh Voltage : 340 V

18. Tests on a 100 µm gap Bulk detector at GSI
… 2008, october 19th.
Test conditions :  visualisation at about 30 meters coaxial cable.
 Gaz : P10
 Beam.
Mesh Voltage : 380 V
Drift Voltage : 2000V

19. Resistive micromegas detectors
By adding a resistive foil (2MΩ/□ ) on the strips we can spread the charge on several strips.
M. Dixit et al.
(Carleton U. – Ottawa)
Micromegas mesh
Resistive foil
Glue
Pads

20. Signals on resistive Bulk detectors Pics from the scope of two
neigbourg strips

21. Response of three neighbour strips seen by the ADC

22. Tests on a resistive 100 µm gap Bulk detector at GSI
March 2009 in Cave C.
Classical detectors
The charge is more spread
on resistive detectors
« classic 835 µ »
« resistive 835 µ »
« resistive 5 mm »

23. The « One meter » detector test - station
One meter station
@ saclay in « lab #534 »
The elctrical
field cage
Electric field cage
To provide an uniform
fieldIn the whole convertion
gap
≈2m
Aim of this detector :
to test the real drift
distance

24. R3B – TPC @ GSI End Cap Gas enclosure Detection boxes 1,6 m ≈ 8 m

25. R3B TPC … the just after GALD magnet and the Helium tank… .
GLAD magnet
≈4 m

26. Tracks seen by all the chambers
C 835 µm
C 835 µm
R 835 µm
R 5 mm
R 5 mm
C 835 µm

27. Pads response function of the pads
classical 835 µm 
 resistive 835 µm 
resistive 5 mm

28. - the transfert properties of the magnet.
Taking into account :
- the transfert properties of the magnet.
- the multiple scattering from the target point
to the detector.
We need a position reconstruction in the TPC of
200 µm RMS