CERN/LHCC 93-27

LHCC 5

19 May, 1993

LARGE HADRON COLLIDER COMMITTEE

Minutes of the fifth meeting held on Tuesday, Wednesday and Thursday, 6-8 April 1993

OPEN SESSION :

J. Schukraft presented a Letter of Intent for a dedicated heavy ion experiment ALICE (LHCC 93-16 / I 4).

G. Brianti briefly presented the results of recent measurements on the new magnet model. Quench results are encouraging.

CLOSED SESSION :

Present: J.V. Allaby*, J.J. Aubert (Chairman), G. Brianti*, R.J. Cashmore, L. Di Lella, P.J. Dornan, P. Duinker, K. Einsweiler, F. Eisele, J. Ellis, E. Fernandez, L. Foa, H. J. Hilke* (replacing J.V.Allaby) W. Hoogland, E. Iarocci*, P.G. Innocenti, K. Kajantie, V. Khovansky, C. Llewellyn Smith, G.W. London, L. Maiani, G. Mikenberg, K. Potter, K. Pretzl, C. Rubbia*, K. Schubert, D.M. Sendall (Secretary), D.O. Williams, S. Yamada

*) Part time

(F. Dydak and P. Jenni were present for point 4. K. Eggert, H. Hofer, R. Orava and S.C.C. Ting were present for point 6. R. Bellazzini, M. Della Negra, G.Hall and T. Virdee were present for point 8).

1. The minutes of the fourth LHCC meeting (LHCC 93-2 / LHCC 4) were approved without amendment.

The Chairman reminded the committee of the terms of reference as set out in letters from the Director General to the Chairman and the committee members, and in guidelines to the spokesmen of the Letters of Intent.

2. PRELIMINARY DISCUSSION OF HEAVY ION PRESENTATION

The committee held a preliminary discussion of the ALICE Letter of Intent. In the course of this a number of questions were raised, which the referees will discuss with the collaboration. A first report from the referees will be presented at the 8-9 June meeting. The committee decided to ask the CORE group to review the costs of this Letter of Intent.

3. REPORT ON TOP PHYSICS

L. Di Lella gave a report on the potential for top quark physics at LHC. High rates can be expected even at initial lower luminosities. Top physics is best studied in the absence of pile-up, at luminosities of 10**33cm-2s-1 or less. An important asset in reducing background will be b-tagging. It should be possible to measure the top mass to ~+/-2 GeV after 10**3 to 10**4 pb-1. Good sensitivity to exotic top decays is expected. The physics potential should not be seriously reduced by staging the detectors.

4. PRESENTATIONS BY THE ATLAS COLLABORATION

F. Dydak announced that the collaboration had decided in favour of the all air-core option for the magnet. The arguments in favour of this option were superior momentum resolution, low cut-off in pT, and stand-alone performance.

F. Dydak presented the scenarios for ATLAS staging / downgrading

(LHCC 93-21 / I-2 Add.1).

P. Jenni presented a status report on the ATLAS inner detector (LHCC 93-24). Based on physics requirements at both high and initial lower luminosities, the functionality of the inner detector has been critically reviewed. Work continues on design and optimisation.

P. Jenni presented a report on liquid krypton in the ATLAS calorimeter. ATLAS maintains the liquid argon technology as the baseline electromagnetic calorimetry for LHC startup. However, further studies are being pursued to evaluate the implications of a design which would optimise a possible later upgrade to liquid krypton

5. REFEREES' REPORT

F. Eisele presented the views of the ATLAS referees on the staging scenarios.

6. PRESENTATIONS BY THE L3P COLLABORATION

After a brief introduction by S.C.C. Ting, H. Hofer presented proposals for L3P staging (LHCC 93-23 / I-3 Add.6 and LHCC 93-30 / I-3 Add.6 rev.).

R. Orava presented a report on the Helsinki workshop on solenoid detectors at the LHC.

7. REFEREES' REPORT

R. Cashmore presented the views of the L3P referees on the staging proposals.

8. PRESENTATIONS BY THE CMS COLLABORATION

M. Della Negra presented the proposals for CMS staging (LHCC 93-22 / I-1 Add.1).

9. REFEREES' REPORT

L. Foa presented the views of the CMS referees on the staging proposals.

10. MAGNET ADVISORY GROUP

P. Lazeyras presented the report of the Group (LHCC 93-17). He recalled the terms of reference, composition and working methods of the group. The main conclusions were as follows. The construction of all the magnets appears to be feasible, and they should be capable of safe and reliable operation. All the difficulties are well identified at the present stage of the conceptual design. However, all these projects, particularly the superconducting ones, present major technical challenges in view of their scale and advanced nature. They represent substantial extrapolation of technology compared with existing magnets.

Prerequisites for their success include R&D work on stability, modelling, conductors, impregnation procedures and properties of materials. This must be well planned and adequately resourced, and is estimated to take about 2 years.

Good contacts with industry will be essential as the designs progress. Technical and financial monitoring, funding and responsibilities will need to be defined at an early stage. Present cost estimates should be regarded with caution, and reviewed in the light of R&D results. Refrigeration should be studied with a view to global optimisation. A realistic risk assessment can only be made at a later stage, when more complete design and R&D results are available, and production steps and quality control are understood.

Further details on each of the magnet systems considered are to be found in the report.

The committee accepted the report as a basis for its further discussion, and the Chairman thanked the group for its efforts.

11. COST REVIEW GROUP

F. Brasse presented the first report of the CORE group (LHCC 93-18). All the collaborations have made very detailed investigations, especially since submitting the Letters of Intent, and have been able to make rather realistic estimates. The group has looked for areas of uncertainty, important inconsistencies, or underestimates. In this spirit, comparisons have been made between the cost estimates of the three collaborations, as well as with other experiments and with industrial prices. CORE has identified a number of areas of concern, and corrected some costs to be on the safer side.

CORE has looked at costs of calorimeters, trackers, muon detectors, data acquisition and triggering, offline computing, infrastructure and laboratory manpower requirements. The updated estimates are a good basis for further detailed studies at the stage of preparing technical proposals.

F. Brasse also presented the reaction of CORE to the staging scenarios. As in the case of the Letters of Intent, CORE has corrected some costs to be on the safer side.

The committee accepted the report as a basis for its further discussion, and the Chairman thanked the group for its efforts.

12. REFEREES' REPORTS

L. Di Lella and J. Ellis summarised the work of the physics performance referees, with some comments on the effects of the staging proposals. It was noted that for all three detectors there would be a loss of H -> gamma gamma at low luminosity running.

F. Eisele summarised the work of the ATLAS referees, with tentative general conclusions.

L. Foa summarised the work of the CMS referees, with tentative general conclusions.

R. Cashmore summarised the work of the L3P referees, with tentative general conclusions.

The referees had made a comparative study of various aspects of the detectors across the three Letters of Intent. P.J. Dornan reported on tracking, F. Eisele on calorimetry, and P. Duinker on muon detectors.

13. DISCUSSIONS

The committee had extensive discussions on each of the three Letters of Intent in the light of the referees' reports. As a result of these discussions, the committee agreed on preliminary recommendations to be sent to the Director General for consideration by the Research Board. A copy of these recommendations is attached to the minutes.

14. TIMETABLE AND FUTURE MEETINGS

A tentative agenda for the B physics workshop on 11-12 May was discussed. Further details will be circulated shortly. It was agreed that there will be a closed session on 12 May after the workshop. However, there will be no continuation of the closed session on 13 May, a date which had been held in reserve.

15. DATES FOR 1993 MEETINGS

11-12 May (B physics workshop and closed session)

8-9 June

31 August - 1 September

16-17 November

The LHCC received the following documents:

o Min Chen (MIT): L3H, a muon-electron-photon detector for LHC heavy ion physics (LHCC 93-15)

o The ALICE Collaboration: Letter of intent for A Large Ion Collider Experiment (LHCC 93-16 / I 4)

o LHCC magnet advisory group: A report on the magnets proposed for LHC experiments (LHCC 93-17)

o LHCC cost review group: First report of the cost review group CORE to the LHCC (LHCC 93-18)

o The ATLAS Collaboration: Staging / down-grading of ATLAS (LHCC 93-21 / I 2 Add. 1)

o The CMS Collaboration: Staging of the CMS detector (LHCC 93-22 / I 1 Add. 1)

o The L3P Collaboration: Report to the LHCC on the staging of L3P (LHCC 93-23 / I 2 Add. 6)

o The ATLAS Collaboration: The ATLAS inner detector (LHCC 93-24)

o The ATLAS Collaboration: Liquid Krypton in the ATLAS calorimeter (LHCC 93-25)

o The CMS Collaboration: Reducing the magnetic field in CMS (LHCC 93-28)

o The L3P Collaboration: Report to the LHCC on the staging of L3P (LHCC 93-30 / I 2 Add. 6 Rev.)

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MS, 21 July 1993