Studies on TH2 chamber Michele, Maria, - PowerPoint Presentation

Slide1

Studies on TH2 chamber

Michele, Maria,

Givi, JoergWeekly MicroMegas Meeting 12/3/2013

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MicroMegas Weekly Meeting 2013/03/12

Overview

TH2 chamber Vs

Txx chambersTH2 studies with X-rayCosmic stand for 10x10 cm chambersTH2-Txx comparison with cosmic

HV scan on TH2 chamber with FR4 frame

HV scan on T3 chamber with

Alu

frame

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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

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MicroMegas Weekly Meeting 2013/03/12

Setup X-ray Gun

Electron current of the gun: ~1 mA

Monitor detector current from HV power supplyChambers tested: TH2, T3, T8, Z1

In order to evaluate the TH2 chamber gain

w.r.t

. the others, a HV scan under X-ray irradiation has been performed

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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

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MicroMegas Weekly Meeting 2013/03/12

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MicroMegas Weekly Meeting 2013/03/12

Setup – Mini Cosmic Stand

Scintillator

1

Scintillator

2

4 cm Lead

T7 Chamber

T3 Chamber

TH2 Chamber

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MicroMegas

Weekly Meeting 2013/03/12Setup – 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 chamber with plastic (FR4) frame

FR4 frame

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MicroMegas Weekly Meeting 2013/03/12

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.

Alu

frame

HV scan TH2-T3-T7 Alu

frameMicroMegas Weekly Meeting 2013/03/12

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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

500 V

510 V

520 V

530 V

540 V

550 V

HV scan TH2-T3-T7 Alu

frameMicroMegas Weekly Meeting 2013/03/12

10Cluster Charge distributions of T3-T7 are well reproduced by TH2 applying 10 Volt more, as expected from calibration with X-ray

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

T3-TH2 HV with Alu or FR4 frame

MicroMegas Weekly Meeting 2013/03/12

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Any difference in cluster charge response are shown from T3 and TH2 using aluminum or FR4 frame.

Maximum Probably Value

of Cluster Charge Distributions12

MicroMegas Weekly Meeting 2013/03/12

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.

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 chambersNew 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

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MicroMegas Weekly Meeting 2013/03/12