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Starting with run 301753824 we have two problems:

1/
We do not see any signal in the high energy diode in tower 4, layer X1, column 4, + side. From Eric Siskind: "Whether the failure is within the diode itself or in the GCFE electronics chain (HE preamp or slow shaper) is currently unknown". You can read the whole thread here:

https://www-glast.stanford.edu/protected/mail/datamon/4835.html

2/ While problem 1/ affects all (high energy) events in that channel, GCR events (4-range and zero-suppressed events) tickle FSW bug 1156:

https://jira.slac.stanford.edu/browse/FSW-1156

This means that about 10 events per run will fail in the decompression. Because of the way the Halfpipe works we lose the complete datagram for each of these events. Since a datagram contains about 110 events we are currently losing about 1100 events per run. This corresponds to about 2.5 seconds of data for each 90 minute run.

The FSW group have a fix for bug 1156 and will upload a new build asap.

Note that currently there is no failure mode in CalRecon so events from this channel is not treated in any special way. NRL is working on this.

It should also be noted that the problem was caught immediately by two separate parts of the Data monitoring. The automatic alarms caught both the missing datagrams and the missing signal from the diode. These runs are marked as 'GOOD' by the DQM shifter, but with a comment attached to them. Obviously we will have to live with the missing diode signal from now on.

Some of you will not have failed to notice the irony that it's GCR events tickling FSW bug 1156 (hint: SSC-258)

anders

What has failed?

Some text As soon as we understand exactly what has failed in this GCFE, I'll type something here.

Consequences of this failure

On 27 Jul 2010 (Day 208), at 2:15 PM EDT, J. Eric Grove wrote:

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status of h/w

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