LPC meeting summary 29-06-2016 - final

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Minutes and Summary

Main purpose of the meeting: Discussing the date and the contents of the second high β* development session.


It has been decided that the second high β* development day will take place on Sunday the 31st of July. This will be directly after the MD1 which will take place from Tuesday the 25th to Saturday the 30th of July. (The MD teams kindly agreed to shift the MD1 block by one day on a request from the LPC after the meeting, and the 2.5km experts agreed to work on Sunday where all experts could be present. This allows to place the 2.5km development session directly after the MD1, which is believed to be optimal in terms of efficiency.)

Activities during the session

The first two fills will be dedicated to machine studies. It is followed by a fill dedicated to background measurements in ALFA and TOTEM.

First Fill

This fill will be done with non colliding probes. It will be dedicated to confirm the coupling corrections found in the previous session in the second part of the desqueeze from 500m to 2.5km (the desqueeze to 500m is already fully commissioned and the beams will be brought to 500m β* in one go). The second part of the de-squeeze will be done slowly with intermediate measurements. The resulting corrections will be implemented in automatic functions for the subsequent fill.

Second Fill

The de-squeeze to 2.5km will be done using the functions obtained in the first fill. This fill will be used to validate the corrections and automated functions found in the first fill. Also this fill will be done with non-colliding probes since a good tune measurement is needed for the verification.

Third Fill

This fill will be dedicated to various measurements in TOTEM and ALFA. Both experiments request at least one colliding "nominal" bunch. The total intensity during the 2.5km fills is limited to 3 nominal bunches (approx. 3x1011). In the final physics fill this intensity will be probably divided equally among the 4 or 5 bunches, depending on what is believed to give the highest physics lumi. Jörg emphasized that the transverse damper will not yet been set up during this session and it is not clear that low emittance bunches will not cause any problems. Using bunches similar to the once foreseen to be used during the physics run would allow to identify potential problems already now.