View source for 10-30-08 GEM HRRL Photon Runs

=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.

[[Image:10-30-08_14MeV9mAHRRL_GEM_strip8.png | 200 px]]

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

[[Image:10-30-08_18mAHRRL_GEM_strip8.png | 200 px]]

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

[[Image:10-30-08_14MeV36mAHRRL_GEM_strip8.png | 200 px]]

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

[[Image:10-30-08_14MeV55mAHRRL_GEM_strip8.png | 200 px]]


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.

[[Image:10-30-08_14MeV9mAHRRL_GEM_strip8_Vd3800.png | 200 px]]

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

[[Image:10-30-08_14MeV4mAHRRL_GEM_strip8_Vd3800.png | 200 px]]

=10 MeV photons=

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

[[Image:10-30-08_10MeV20mAHRRL_GEM_strip8_Vd3800.png | 200 px]]

Peak amplitude is same but rate is much lower