Summary notes of the LCU meeting on 26/01/2010

Present:  CA, OB, HB, RC, OD, SF, MG, WH, BH, JJ, EL, YL, JM, AR, FS, RT, GV, SW

Report from meetings

• General information -> MG
  As decided a while ago when it was not sure how much progress we would have with beams, the Chamonix workshop this year does not include beam commissioning. This was instead discussed in the LHC beam commissioning workshop in Evian last week. Slides are available from indico. There are several follow up items which concern us. Measuring and correcting the beta beating has top priority, such that the rest of the operation in 2010 can profit from this. There is also follow up on possible sources of the beta-beating, like the MQWA in IR3/7 and Q2 in IR2/8.
  MG reminds about requests for summer students - the deadline for requests is next week.
  MG also reminds that travel requests should always be made in time, well before the trip. The paper document with the details of the trip should be filled as well as the EDH to record the absence. Both steps are essential for insurance reasons.
  There was an information meeting on the BTE-desktop support. We are all supposed to know about this service which handles any computer (desktop and laptop) related purchase in our department, as well as other hardware. Requests should first be discussed with our group representative, HB. For information, see the BTE desktop support page. One of points clarified during the presentation was the responsibility of BTE desktop support and IT helpdesk: while the first is supposed to help with local hardware (laptop, desktop etc.) and related software, the latter deals with issues related to central machines. It was suggested to inform BTE support also in case of issues for IT helpdesk. The web site provides a number of forms to be used for the various types of interventions.
• LBS-LPC -> HB
  There has been an extended joint LBS-LPC meeting with about 50 participants from the machine and the experiments on Monday 18th January 2010, discussing the experimental conditions of the recent LHC run and implications for the future. The experiments showed luminosity and beam spot information. Slides are on indico. The machine aspects and experiments / machine communication via DIP, LHC VISTAR pages etc will be further followed up in the LBS. The next LBS meeting is planned for February 8, after the LPC meeting.
• FZ -> LMC
  FZ reported from the last LMC meetings. Details can be found in the minutes.

Trip report from Fermilab Workshop -> FS (slides)

RA and FS went two days to Fermilab to discuss the possible use of the TEVATRON for machine studies before the final shutdown end of 2011. Proposals from FNAL (to improve the understanding of the machine before shutdown), BNL (e-lens), CERN (test that are not considered suitable for the LHC).
A number of ideas have already been collected. Further ideas are encouraged.
It will be probably not possible to ask for hardware changes in view of these tests.
The planning will proceed in further iterations.
A revised list of proposals should be prepared by April and Fermilab will officialy submit these proposals by July 2010.

The complete set of information can be found at the Workshop site.

News on the LHC online model and data analysis -> CA (slides)

CA reported about applications of the online model in the recent LHC run.
One application was to calculate coupling correction knobs.
CA also used the online model to study the effects of the measured alignment errors. This, however, should be combined with the use of measured closed orbit.
CA also presented the analysis of the data taken during aperture measurements in the LHC. The main aim is to quantify the available aperture and compare with the nominal estimates. Furthermore, one aims at evaluating a measured n1, which is crucial for the collimation setting up. The aperture in the LHC was measured systematically with circulating beams, by means of 7-8 sigma bump amplitude at injection, and then increased until losses were observed. Various phases were scanned in order to provide the minimum aperture over the whole ring (H/V and Beam 1/2). Data analysis is still in progress. It is planned to perform in future also measurements of the off-momentum aperture.

Latest revisions of nominal 7 TeV IR8 optics -> EL (slides)

EL reported that the settings of the crossing and separation bumps for the nominal squeeze of IR8 are referring to 5 TeV. This led to a revision of the parameters in view of translating everything to 7 TeV and simplifying the sequence of changes. In addition, the observed limitation of the MCBX to 350 A was folded into the new bumps. The proposal consists of keeping the separation constant to 2 mm from injection to the first point of the squeeze and it is then reduced to 0.5 mm. Similarly, the crossing angle is kept constant to 170 murad up to the end of pre-squeeze and it is then increased to 235 murad and kept constant during the squeeze. The transition between the end of pre-squeeze and the beginning of the squeeze is not at all smooth and could induce some problems. It is worth mentioning that the number of MCBX used is now 4 in order to decrease the strength/magnet and remain within the limit found during the hardware commissionig.
SF proposes to simplify further the operation by keeping the separation constant to 2 mm from injection to squeeze (down to 2 m of beta*). In order to fulfill the initial assumption that half of the strength of the MCBX was devoted to misalignment correction, a different sharing between the strength for the crossing/separation bump that the one presented should be used. Another iteration will be made.

AOB

None

Last update: 26-January-10

MG & HB

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