10-30-08 GEM HRRL Photon Runs

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The Goal today is to observe the GEM detector output when hit with MeV photons

14 MeV photons

We are sending 14 MeV phtoton through a 4" thick brick wall collimator. A 4" Al brick in front of the HRRL exit port is used as a FC.


FC: 223B2 NaI: 223B5 Acc Gate: 223B8 GEMtrig: 223B3

Vdrift= 3700 Volt

VGem=3400 IGem=815 microA


The scope trace below shows output when electron beam current is 9 mA.

10-30-08 14MeV9mAHRRL GEM strip8.png

The scope trace below shows output when electron beam current is 18 mA.

10-30-08 18mAHRRL GEM strip8.png

The scope trace below shows output when electron beam current is 36 mA.

10-30-08 14MeV36mAHRRL GEM strip8.png

The scope trace below shows output when electron beam current is 55 mA.

10-30-08 14MeV55mAHRRL GEM strip8.png


Now Max Gain on GEM

Vdrift= 3800 Volt

VGem=3500 IGem=841 microA

The scope trace below shows output when electron beam current is 9 mA.

10-30-08 14MeV9mAHRRL GEM strip8 Vd3800.png

The scope trace below shows output when electron beam current is 4 mA.

10-30-08 14MeV4mAHRRL GEM strip8 Vd3800.png

10 MeV photons

The scope trace below shows output when electron beam current is 20 mA.

10-30-08 10MeV20mAHRRL GEM strip8 Vd3800.png

Peak amplitude is same but rate is much lower