LARGE HADRON COLLIDER COMMITTEE
Minutes of the fiftieth meeting held on
Wednesday and Thursday, 31 January - 1 February 2001
Present: R. Cashmore, D. Cassel, J. Dainton, M. Delfino*, J.
Engelen (Chairman), A. Ereditato, L.R. Evans*,
G. Goggi, J.-J. Gomez-Cadenas, M. Hauschild, U. Heinz*, P. Lebrun*, J. Lee-Franzini, B. Löhr, M. Mangano,
J. May*, J. Nash, J. Panman, K. Potter, P. Roudeau, P. Sharp*, K. Tokushuku, E. Tsesmelis (Secretary), G. Zech.
The minutes of the forty-ninth LHCC meeting (LHCC 2000-051/LHCC 49) were approved with the following modification: in point 8 (report from the CMS referees) the last sentence should be replaced by: `A decision is needed as soon as possible and a further report will be made at the January 2001 meeting of the LHCCí.
The referees also reported on the instigation by ATLAS of a technical committee with the mandate to monitor the production phase of the experiment. This new body will be called the ATLAS activity Systems Status Overviews (ASSO) committee.
The development of the photon detector for the RICH remains a critical item that requires milestones leading to the choice between the Pixel HPD and Multi Anode PMT options. A recent LHCb review concluded that the development of the Pixel HPD should proceed but with a revised schedule and that the Multi Anode PMT should remain as a back-up until the work on the Pixel HPD is completed. The LHCC requests to be informed of progress towards the final decision, which is scheduled for October 2001.
Furthermore, the referees noted that the Calorimeter TDR does not contain enough information on the support system and integration and that the Collaboration should provide more details on these issues as the engineering design develops. The LHCC also recommends that LHCb should perform beam tests with some modules incorporating the final electronics, establish procedures for (inter-) calibration and monitoring and follow the established practice of conducting independent reviews of the engineering designs.
The referees also reviewed the status of the various sub-systems. The design of the beam pipe is being re-optimised to reduce the backgrounds from secondaries produced in the stainless steel bellows and flanges. This effort will lead to the re-optimsation of the tracking system but will result in the delay in the submission of the Outer Tracker TDR and possibly to that for the Inner Tracker. Also, the final design of the T2 to T6 stations of the Outer Tracker depends on the beam pipe design and that for the T11 station needs further optimisation as it currently exhibits high occupancy. The proposal is to delay the submission of the Outer Tracker TDR to September 2001, namely to coincide with the Inner Tracker TDR submission date. The delay in submission is thought not to be critical. The referees will make a further review of the beam pipe, Inner Tracker and Outer Tracker at the next meeting of the LHCC.
Moreover, the design of the interface between the VELO and the beam pipe has advanced. Further studies are planned to optimise this region and to evaluate the risk to the vacuum system of the beam pipe, and hence to the operation of the LHC machine.
The referees reported that CMS is finalizing their new set of milestones. In view of the upcoming Resource Review Boards in April, the LHCC has asked CMS to present to the LHCCís next Closed Session in March details of the experimentís plan for detector completion, installation and commissioning.
The referees also reviewed various sub-systems. Good progress was reported on the development of the alignment system. The purpose of this system is to measure relative deviations from their nominal position for all active elements of the central Tracker, to transfer the coordinates of the Tracker as a rigid body to the Muon detector via the Link system and to have a compatible survey and assembly scheme.
The referees also reported on the RPC noise. The RPC trigger was designed assuming that the single hit rate will be dominated by neutrons. However, test beam results show that the RPC noise is much higher than the neutron rate, resulting in an unacceptably high trigger rate. Three ways of curing the problem are being investigated and have been reported to a recent workshop on this issue: reduction of the RPC noise by surface coating with linseed oil, doubling the data transmission bandwidth by replacing the links, and tuning the trigger by optimizing the rate and using additional RPC planes for coincidence As RPC production for the LHC experiments has already started, the LHCC considers the matter to be urgent and has asked for a report from the recent Pisa workshop on RPCs together with reports from the LHC experiments at the Committeeís next Closed Session.
The referees also reported on their preliminary reactions to the Technical Design Report for the Level-1 Trigger. The trigger is the start of the physics event selection process and will make a decision to retain an event for further consideration every 25 ns. The CMS Level-1 Trigger is based on the identification of muons, electrons, photons, jets and missing transverse energy and will operate in both proton and heavy-ion running. Following further questions and discussions, the referees will make a full report at the next meeting of the LHCC.
In view of this, the referee recommends that the R&D project be continued in 2001 with the aim of reaching the above objectives. A status report is expected to be submitted to the LHCC at the end of 2001. The Committee agrees to the continuation of the project on this basis.
In view of this, the former has been replaced with the LHC Electronics Coordinating Committee (LECC). The mandate of the LECC is to identify and implement common solutions for the electronics of the LHC experiments, review and recommend support for LHC electronics, facilitate the design, fabrication, testing, commissioning and maintenance of electronics for the LHC and to organize the annual LHC Electronics Workshop.
ACES has been replaced with the EP Electronics Advisory Board (EAB). Its role is to act as an advisory committee to the electronics general support and services in the Research Sector. Moreover, it is to give guidelines for electronics service activities in the Research Sector, including the EP Electronics Pool, within the framework of the CERN financial and purchasing rules.
M. Hauschild also reported on the increasing number of users at the PS Complex. Although the situation appears to be manageable until 2003, there seems to be uncertainty about providing the beam intensities requested by the various users beyond this date. In view of this, studies are underway at the PS Booster to run the machine with a shorter cycle.
Since the approval of the Technical Proposal in 1997, the ALICE Collaboration has made very significant progress towards the realisation of an experimental set-up ready to record heavy-ion collisions at the LHC in 2006. In particular, most of the detector technologies to be used, together with the associated electronics, have successfully gone through the R&D phase. The design and tests of the front-end electronics have in general been successfully completed.
The conclusions and concerns of the LHCC are given below. They will allow the Committee to follow-up outstanding issues and to monitor future progress of this project in upcoming sessions of the LHCC prior to the next ALICE Comprehensive Review.