15 August 2001
LARGE HADRON COLLIDER COMMITTEE
Minutes of the fifty-third meeting held on
Wednesday and Thursday, 4-5 July 2001
1.LHCb Vertex Locator Technical Design Report: T. Ruf, J. van den BrandCLOSED SESSION:
2.LHCb Muon System Technical Design Report: B. Schmidt, G. Carboni
The Research Director for Collider Programmes reported on issues being currently considered to appraise the status of the LHC programme. The completion plans and the resources required to realise the experiments will be discussed at the next Resource Review Boards (RRBs) in October. As part of the regular reports from the LHCC to the RRBs, which provide a summary of the principal deliberations of the Committee, the LHCC is asked to provide an evaluation of the soundness and feasibility of these plans. Moreover, the LHCC `COREí group will appraise the costs required to complete the experiments. In addition, the RRBs are evaluating the required funds to cover the maintenance and operation of the LHC experiments. The LHC computing resources will be addressed in the context of the LHC Computing Grid Project. Together with the principal contracts for the LHC Machine, this information will be presented subsequently to the CERN Council, thus providing an evaluation of the whole LHC programme.
The referees also reported on the interest of US groups to participate in the ALICE programme. The groups intend to submit a proposal to the Department of Energy for funding in view of this participation, emphasizing the uniqueness of the LHC heavy-ion programme. The proposal will be based on building an additional electromagnetic calorimeter to further the study of high-PT probes and jet quenching.
The referees also presented a progress report on the Time-of-Flight detector. The Committee noted the impressive R&D results on the detector strip performance and on the prototype of the front-end amplifier card. However, a number of issues concerning both the detector and electronics must still go through the R&D phase. An issue which needs urgent resolution is the choice between discrete front-end electronics versus ASIC. The decision would be taken by ALICE in the coming weeks and will be communicated to the LHCC. The Committee encourages ALICE to make a single choice as the baseline and to proceed with that, leaving the other option as a back-up. Due to the delays in completing the R&D phase, ALICE requests that the Addendum Technical Design Report be submitted later than originally agreed, namely in March 2002. The LHCC considers that the submission would now come late and encourages ALICE to advance it as much as possible.
The VELO consists of a series of silicon stations placed along the beam direction at a radial distance from the beam that is smaller than the aperture required by the LHC during injection and must therefore be retractable. The detector must provide precise measurements of track coordinates close to the interaction region to be used to reconstruct production and decay vertices of beauty- and charm- hadrons, to provide an accurate measurement of their decay lifetimes, and to measure the impact parameter of particles used to tag their flavour. The VELO measurements are also a vital input to the second level trigger, which enriches the b-decay content of the data.
The Muon System consists of five stations using RPCs in the regions where the expected rate is relatively low and MWPCs for all other regions except for the innermost part of the first station where the expected rates will be highest. In this latter part a detector technology has still to be selected. Various technologies such as asymmetric MWPCs or triple-GEM detectors are under investigation. The Muon System will provide the muon triggering and offline muon reconstruction, fundamental requirements of the LHCb experiment since muons are present in the final states of many CP-sensitive B decays.
Following further questions and discussions, the referees will make a full report on both of these Technical Design Reports at the next meeting of the LHCC.
A formal project structure will be put in place to ensure the achievement of the required functionality and performance of the overall system. The LHCC underlines that the composition of the project structure should be in the full interest of the LHC programme, with the experiments being intimately involved.
The LHCC considers that this plan, which includes the required additional resources both at CERN and in the Member States and Non Member States, is reasonable and endorses it as the next step forward in proceeding with the LHC Computing.
The design and tests of the front-end electronics have in general been successfully completed, although in some cases the transfer of these designs into radiation-hard technologies has not yet been achieved. Back-up solutions have, however, been identified and are being implemented.
It is realistic to expect ATLAS to install an initial working detector for the first collisions of the LHC pilot run starting in April 2006 and for the physics run starting in August 2006, although detector installation can be foreseen beyond this date.
However, the LHCC considers that the ATLAS plan to have commissioned an initial working detector for first collisions in April 2006 is challenging, as a number of systems no longer have any contingency in the schedule, originally included as a safety margin for their installation. The schedules of the Barrel Toroid Magnet, the TRT End-cap A, the LAr EM Barrel, the LAr End-cap A, and the Muon Drift Tube chambers are considered to be critical. The LHCC observes that additional resources, both in terms of money and manpower, would aid in accelerating the current ATLAS schedule, thereby allowing a timely completion of the initial detector in 2006.
A detailed scenario to complete the initial working detector by August 2006 is being worked out by ATLAS and will be submitted to the LHCC at the end of October. The ATLAS Collaboration must develop such a detailed scenario, which should in particular address the critical schedule issues above.
Detector elements not installed by August 2006 will be staged. The staging plan consists of deferring installation of some components of the Inner Detector, the Calorimetry, the Muon Instrumentation, the High-level Trigger and DAQ and the radiation shielding. Their installation in a shutdown of a few months in 2007 after the completion of the first physics run, while requiring additional resources, would complete the ATLAS detector as described in the approved Technical Design Reports.
The LHCC considers that a completed initial working detector, in time for the first physics run in August 2006, should allow the experiment to address satisfactorily the physics searches for Higgs and SUSY at the 10 fb-1 luminosity level. The proposed staging scenarios of the detector have a minimal impact on the searches at a luminosity of order 1033 cm-2 s-1. The staged components would, however, need to be installed for the higher luminosity running.
The second of the LHCC Comprehensive Reviews of ATLAS took place on 2-3 July 2001. The LHCC referees addressed the following areas: Inner Detector, Calorimetery, Muon Spectrometer, Trigger/DAQ/DCS, Physics Studies, Computing, and the topics of Management, Technical Coordination, Integration, Schedules and Costs.
The principle conclusions and concerns of the LHCC are summarized 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 ATLAS Comprehensive Review.
Provisional Dates for 2002:
3- 4 July
2- 3 October
The LHCC received the following documents