Present: Stepan, Maurik, FX, Tim, Matt, John
Please send comments/correction to the whole EC email list.

We discussed several aspects of the advisability of moving the SVT in to 0.5mm.

Maurik presented a study of beam motion over the last week EC_meeting_2015_05_08.pdf. Beam motions at 2H02 have in general been small. A few have been outside the 300um limit, but would have been protected with chimes, which was only implemented on May 5. Beam motion may be associated with activity in other halls. No significant scaler increases were observed.

Stepan noted that halo counters will be added to FSD. All four downstream counters are or'd together.

Tim outline a calculation of local heating in the si if beam hits SVT Beam Accident Analysis.pdf. It is low enough that he thinks 0.5 mm operations are ok.

John reviewed where we stand in terms of quantity of data taken Moving SVT.pptx. We don't yet know if  the present trigger records A's with the same efficiency as that assumed in all Matt's reach calculations. Matt has learned that the data and MC for the present trigger conditions are in rough agreement wrt numbers of e+e- pairs.

We sampled opinions on when to move:

Takashi (relayed by Stepan)   stay at 1.5 mm
Stepan   stay at 1.5 mm until next Friday, move then for final running
Maurik  move to 0.5 in time to get a thorough check of these conditions, preferably soon
FX      get FSD working, the move to 0.5 mm soon
Tim   after appropriate interlocks, move cautiously toward 0.5 mm soon.
Matt  move to 0.5 soon
John move to 0.5 soon

Since we still need information on how many tridents our recorded triggers correspond to, and hope to get it in the next day or two, and since the machine is down until Sunday, we decided to continue the debate by email, hopefully adding some new information, with the goal of deciding something by the start of running on Sunday

John

 

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