Page History

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10:10
Module fully installed but powered off. Out sensor is ~177cm from the exit window.
Mike setting up electron gun; some tuning is needed on the beam line since last experiment ran at 60MeV instead of 120MeV.

Noise before beam:
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10:30
Beam E=119.3MeV, 50pC at gun, 10Hz
Start with 0 foils in order to search for the beam on the insertable phosphor screen.
The Phosphor screen is at ~75cm from exit window.
We use the measured voltage on the toroid located downstream of the spectrometer magnet: "ADC1".
At this point ADC1=0.06V which is ~40pC according to Mike.

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11:36
Everything looks ok for 1pC setting.

Baseline taken at 180V, after irradiating with 1 pC at 180V:
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Baseline taken at 180V, after irradiating with 1 pC at 250V:
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Baseline taken at 180V, after irradiating with 1 pC at 400V:
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Baseline taken at 180V, after irradiating with 1 pC at 450V:
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Baseline taken at 180V, after irradiating with 1 pC at 500V:
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12:00
At 10pC and 500V we observed a channel with x3 higher noise in the "weird" apv chip which looked like a pinhole candidate. However, after cycling the bias it went away.
We observe a previously unseen step in the noise from 30 to 35 ADC in the middle of both working APV25. This step was turning on over a couple of channels. Not sure what this is.

Baseline taken at 180V, after irradiating with 10 pC at 180V:
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Baseline taken at 180V, after irradiating with 10 pC at 350V:
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Baseline taken at 180V, after irradiating with 10 pC at 500V:
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12:15
Continue to 100pC and 180V.
Here we see a drastic change and what looks like many shorts has developed across the sensors. We don't see any case where the channel get a larger noise but they all go down to a level of about 20ADC.
The step in noise also become worse.

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