1. DHCAL and MICROMEGAS at LAPP
Catherine Adloff Franck Cadoux Sébastien Cap
Cyril Drancourt
Ambroise Espagilière Raphael Gallet Claude Girard Nicolas Geffroy
Richard Hermel Kostas Karakostas (invité) Yannis Karyotakis
Inocencio Monteiro Fabrice Peltier Julie Prast
24 Jan 2008
DHCAL Meeting

2. MicroMegas Prototypes
PCB and bulk from CERN (Rui de Oliveira)
325 LPI mesh
spacers : 120 m heigh m diameter
pads : 0.98x0.98 cm2, 200m between pads
The chamber
95% Argon, 5% Isobutane
conversion volume (3mm)
a top in Stainless Steel with a cupper drift cathode
The pad readout : analogue
Gassiplex board : 6 gassiplex chips - 96 channels Electronics card built for CAST by DAPNIA (P. Colas, Philippe Abbon)
VME sequencer and ADC from CAEN
CENTAURE acquisition (SUBATECH, Nantes, D.Roy)
DHCAL Meeting
24 Jan 2008

3. MicroMegas Studies X-ray studies (5.9 keV) Cosmics Gain
Response versus Vmesh
Response versus Vdrift
Gas flow dependencies
Time stability
HV supply dependencies
Cosmics
MIP value measurement
First glance on X-talk
DHCAL Meeting
24 Jan 2008

4. all pads : 96 entries for each trigger
X-ray Results
55Fe source (5.9 keV  228e in drift volume)
Trigger on mesh : preamp (T output) + fast ampli
Vmesh = 420 V
Vdrift = 470 V
Emesh = 35 kV/cm
Edrift = 167 V/cm
Entries
ADC Counts
all pads : 96 entries for each trigger
escape peak
A. Espargilière
pedestal
@ 20 ADC
X-ray keV
Gassiplex Readout :
Peak = 680 ADC cnts
= 996 mV
 277 fC
 Gain 7600
FWHM = 25.5%
T2K(same techno) :
FWHM = 26%
DHCAL Meeting
24 Jan 2008

5. X-ray Results (K. Karakostas)
Vmesh = 390 V
Vdrift = 440 V
Emesh = 32.5 kV/cm
Edrift = 167 V/cm
T1 Optimisation for Gassiplex readout
Mean (ADC Counts)
Pad signal :
Gassiplex readout
K. Karakostas
T1 (ns)
Charge = 820(1500mV)/1024/3.6(mV/fC) = 334 fC
DHCAL Meeting
24 Jan 2008

6. X-ray Results expected exponential behaviour Response versus Vmesh
K. Karakostas
Vdrift = Vmesh + 70 V
Edrift = 233 V/cm
expected exponential behaviour
DHCAL Meeting
24 Jan 2008

7. X-ray Results Saturates for Flow > 0.20 l/h  7 volume/h
Response versus Vdrift and Gas flow dependencies
K. Karakostas
Vmesh = 395 V
Emesh = 33 kV/cm
Edrift = V/cm
Saturates for Flow > 0.20 l/h  7 volume/h
Gain  when Drift field 
DHCAL Meeting
24 Jan 2008

8. X-ray Results Gain  when Atmospheric Pressure  Time Stability
K. Karakostas
Gain  when Atmospheric Pressure 
DHCAL Meeting
24 Jan 2008

9. X-ray Results Slope = - 4.9 ADC/mbar = 2 fC/mbar
Time Stability
Slope = ADC/mbar
= 2 fC/mbar
K. Karakostas
Gain  when Atmospheric Pressure 
DHCAL Meeting
24 Jan 2008

10. X-ray Results HV supply dependencies
Vmesh = 390 V
Vdrift = 450 V
Emesh = 32.5 kV/cm
Edrift = 200 V/cm
HV supply dependencies
old and not reliable HV supply
No significant difference between HV supplies
DHCAL Meeting
24 Jan 2008

11. Cosmics Trigger on 3 scintillators coincidence
Mesh Signal :
Preamp (E output)
+ shaper (gain=25)
Charge  210(mV)/25/0.312(mV/fC) = 27 fC
DHCAL Meeting
24 Jan 2008

12. Cosmics Gassiplex Readout Charge  80(1500mV)/1024/3.6(mV/fC) = 32 fC
Chamber mapping (geographic occupancy)
Pad with highest signal
Nb of Events
Mean (Pedestal) = 21
Sigma(Pedestal) = 1.4
muon selection :
ADC(Pad with highest signal) > 40
reflects scintillators geometry
ADC Counts
Charge  80(1500mV)/1024/3.6(mV/fC) = 32 fC
Gain  6900
DHCAL Meeting
24 Jan 2008

13. Cosmics Dominant Crosstalk?
After muon selection : distance between pad with highest signal (muon pad) and pad with 2nd highest signal (second pad)
Normalised Number of Events (%)
PCB routing along X
(same Y than muon pad)
20% of the events with a muon
have the second highest signal
close to the muon pad
Dominant Crosstalk?
DHCAL Meeting
24 Jan 2008

14. Future X-ray, source, TB Mini analogue calorimeter prototype
pad homogeneity (cosmics, TB)
prototypes disparity
X-talk
different gas mixture
efficiency (cosmics, TB)
Mini analogue calorimeter prototype
3 MicroMegas 6cmx16cm
2 MicroMegas 12cmx32cm
DHCAL Meeting
24 Jan 2008