1. Studies on TH2 chamber Michele, Maria, Givi, Joerg
Weekly MicroMegas Meeting 12/3/2013
MicroMegas Weekly Meeting 2013/03/12

2. MicroMegas Weekly Meeting 2013/03/12
Overview
TH2 chamber Vs Txx chambers
TH2 studies with X-ray
Cosmic stand for 10x10 cm chambers
TH2-Txx comparison with cosmic
HV scan on TH2 chamber with FR4 frame
HV scan on T3 chamber with Alu frame
MicroMegas Weekly Meeting 2013/03/12

3. MicroMegas Weekly Meeting 2013/03/12
TH2 chamber Vs Txxx chamber
TH2 Chamber
T3 Chamber
RO Strips with screen printing deposition technique
~60 µm
~15/20 µm
MicroMegas Weekly Meeting 2013/03/12

4. MicroMegas Weekly Meeting 2013/03/12
Setup X-ray Gun
In order to evaluate the TH2 chamber gain w.r.t. the others, a HV scan under X-ray irradiation has been performed
Electron current of the gun: ~1 mA
Monitor detector current from HV power supply
Chambers tested: TH2, T3, T8, Z1
MicroMegas Weekly Meeting 2013/03/12

5. MicroMegas Weekly Meeting 2013/03/12
Current Measurement (X-Ray)
From the HV scan with X-ray gun, it is evident that the TH2 chamber has about 10 Volts of shift w.r.t. the T3-T8 chambers.
A few microns difference in height of the amplification region is enough to explain this difference
MicroMegas Weekly Meeting 2013/03/12

6. MicroMegas Weekly Meeting 2013/03/12
Setup – Mini Cosmic Stand
Scintillator 1
TH2 Chamber
T3 Chamber
T7 Chamber
4 cm Lead
Scintillator 2
MicroMegas Weekly Meeting 2013/03/12

7. MicroMegas Weekly Meeting 2013/03/12
Setup – Mini Cosmic Stand
HV scan to evaluate Cluster charge response of TH2 w.r.t. T3/T7 chambers
HV scan replacing Aluminium frame with plastic frame on TH2 chamber
HV scan replacing Aluminium frame with plastic frame on T3 chamber
T7 Chamber used as reference
MicroMegas Weekly Meeting 2013/03/12

8. MicroMegas Weekly Meeting 2013/03/12
MicroMegas chamber with plastic (FR4) frame
The idea is to monitor the chamber response using different frames.
The metallic frame is close to the R.O. Strips and act like a capacitance and reduce the induced signal.
FR4 frame
Alu frame
MicroMegas Weekly Meeting 2013/03/12

9. HV scan TH2-T3-T7 Alu frame
As for the HV scan with X-ray gun also in this case a systematic shift of the cluster charge distribution of TH2 w.r.t. T3-T7 is clear evident
MicroMegas Weekly Meeting 2013/03/12

10. HV scan TH2-T3-T7 Alu frame
T3-T7 500 V
TH2 510 V
T3-T7 510 V
TH2 520 V
T7 520 V
TH2 530 V
T3-T7 530 V
TH2 540 V
T3-T7 540 V
TH2 550 V
Cluster Charge distributions of T3-T7 are well reproduced by TH2 applying 10 Volt more, as expected from calibration with X-ray
MicroMegas Weekly Meeting 2013/03/12

11. T3-TH2 HV with Alu or FR4 frame
Any difference in cluster charge response are shown from T3 and TH2 using aluminum or FR4 frame.
MicroMegas Weekly Meeting 2013/03/12

12. MicroMegas Weekly Meeting 2013/03/12
Maximum Probably Value
of Cluster Charge Distributions
The M.P.V. from the Cluster Charge distribution is extracted with Landau function for each step and chamber.
No difference for T3 and TH2 chambers are found using FR4 or Aluminium frame.
T7 chamber as been used as reference and to normalize the result taking in to account also the variation of the environmental conditions.
MicroMegas Weekly Meeting 2013/03/12

13. MicroMegas Weekly Meeting 2013/03/12
Conclusions
New small (10x10 cm) MM chamber (TH2), with different thickness of insulating layer between copper and resistive strips have been built and tested.
Comparison of the chamber gain, under X-ray flux, with standard TXXX chambers has been performed.
The operating point of TH2 seems to shifted of 10 Volts w.r.t. the TXXX chambers
New small cosmic telescope, for systematic studies on 10x10 cm chambers, is now available in the gas lab.
HV scan performed with cosmic on TH2 and T3-T7 chambers confirm the shift on operating point found with the X-ray scan ( This kind of shift can be simply explained with few microns of difference of the amplification region )
Cluster charge response seems to be independent from the frame (alu or FR4) adopted to close the small chambers
MicroMegas Weekly Meeting 2013/03/12