Minutes of the FMD workshop,  11- September-2001, CERN.

By Jens Jørgen Gaardhøje, NBI.

 

Agenda for the FMD meeting

Tuesday, September 11, 2001 at CERN. 9.00

ROOM (13-3-005)

 

1.    Approval of agenda and minutes of last meeting

2.    Integration. L. Leistam                                                    (09.10-09.25)

3.    FMD design overview. JJG                                                                   (09.25-09.50)

4.    Si-FMD Background simulations. A. Maievskaia                      (09.50-10.15)

5.    Si-FMD FE and RO electronics. B.S.Nielsen                       (10.15-10.40)

 

Coffee break

 

6.    Si Prototype. A. Angelis/NN                                              (11.00-11.25)

7.    T0 status. V.Grigoriev/ H. Trzaska                         (11.25-11.50)

8.    V0 status J.Y.Grossiord/L. Montano                        (11.50-12.15)

9.    PMD news. Y. Viyogi (?)                                                  (12.15-12.30)

10.  Summary-Conclusions-Actions,

       Formation of TDR writing group.                      JJG+all                               (12.30-13.00)

11.  AOB

 

 

 

Minutes:

 

Present: 

AM, MG,OK,MV,AP,YPV,TK,VG,AK,EK,AA,GHC,BSN,LL,CF,WHT,FG,HB,LMM,JS,JJG.

 

  1. The minutes from the previous meeting in May  (29-05-2001) were approved without comments.

 

  1. JJG presented the current design overview of the FMD. The geometry was discussed. The 3.5 cm inner radius was felt to be too restrictive. An inner envelope for the Si-FMD was agreed upon with the beam-pipe people. Accordingly, the details of the Si-ring geometry must be fine tuned again. The placement of Si1,2 and 3 was agreed upon at the few cm level. The pseudorapidity coverage will be around –5.4 to –1.6 on the left side and 1.6 to 3 on the right side. New results from BRAHMS/RHIC at 200GeV show a total of approx. 5000 charged particles at that energy. Scaling of the pseudorapidity density distributions to the LHC range suggests that the coverage of the Si-FMD is adequate to cover the non-fragmentation region. The segmentation of the Si system was discussed again. It appears desirable to increase the segmentation of the inner rings to 256 strips (see also item 4). This will be explored. The Si-FMD design is now sufficiently settled that specifications can be listed and first industrial bids should be sought in the next few months.

 

  1. LL showed the latest design of the beam pipe. The integration team will continue to try to reduce the amount of material associated with the pipe system. A model is being built for the ITS, FMD, muon absorber region. In a subsequent meeting a collision between ITS support structures and the Si-FMD was recognized. Also a massive steel cooling water manifold for the ITS in the acceptance of the FMD detectors was identified. To avoid such problems a coordination group consisting of Ch. Gregory (CERN),  Børge Svane N. (FMD) and Flavio Tosello  (ITS) was formed later in the week. The manifold is now removed from the acceptance and the ITS and beam pipe mounting frames are being revisited. 

 

  1. AM showed the latest simulations of the background. The latest ALIROOT version is used. The density of particles per detector strip (128 strips) in the inner rings closest to the IP reach 12 part/strip. This may be too high and it will be considered to double the segmentation. Background levels are approx. 40-50% in Si1-2 outer rings, approx 20-30% in Si1-2 inner rings and 200-300% in Si3.  Specific sources of background can be identified and should be minimized. F. ex. A ring at about –240cm from the IP. At  the present time there is still no precise description of the material in front of the FMD detectors from the ITS (Cables, cooling etc. ) This must be included in the near future. On the other hand the FMD mounting structures and services must also be included in the simulations. NBI will start realistic designs of Si-frame structures. INR will start studying the mounting of the T0 detectors.

 

  1. BSN discussed the electronics. The Si-FMD will not provide a LVL 0 trigger. The usefulness of a LVL 1 trigger participation is marginal. It was decided not to push this unless an elegant and simple technical solution arises. The FE electronics choices are narrowing down to the VIKING chips of IDEAS Norway. A possible increase in the segmentation to 256 strips was discussed. Perhaps the segmentation of the outer rings could also be increased at low cost and small increased complexity. In that case it might be advantageous to double  the PHI segmentation by subdividing sensors (wafers) electrically into two halves as for the inner ruing sensors. This is important for flow studies. Services to Si detectors will be defined ASAP after further consultation with IDEAS.

 

  1. Nothing particular to report on this item. The participation of the Athens groups in the design of the backend (BE) RO electronics and DAQ system was discussed. An interest was declared to participate more actively in this, still undefined, part of the system. In particular systematic work is required to investigate the interfacing with the overall ALICE DAQ and RO system and define a solution.

 

  1. The financing of the T0 is now assured by the Finnish group. MOU’s will be updated accordingly. The T0 will be built jointly by Jyvæskyla and MEPHI. It was decided to purchase two tubes from Hamamatsu and two Russian tubes and move on to realistic beam tests of timing resolution. The trigger and RO scheme for the T0 detectors was discussed. It was stressed that each PM must be read out with E, T into ADC’s and TDC’s for off line analysis (slewing corrections etc.). On line vertex and timing information is important. A new trigger and RO scheme must be established before the next meeting to demonstrate the required functionality and to assess the cost and complexity.

 

  1. No particular news. The urgent need for a RO and trigger scheme from VO was stressed.

 

  1. No particular news.

 

  1. JJG stressed the need to move on to the TRD level. This is also desired by ALICE.  A discussion ensued regarding the need for beam tests etc. for a TRD and regarding the format. It was agreed that a pre-TRD should be written even without extensive prototyping information available. Time scale is Xmas. A decision on when to publish must be taken later. In any case a succinct document summarizing the many design considerations made in the last year is needed urgently. It was decided that a TRD includes the Si-FMD, T0 and V0 as these detector share trigger and physics capabilities. JJG was empowered to produce a draft list of chapters and suggest a writing group. Fine tuning and adjustment can take place by email.

  

  1.  FMD group members are strongly encouraged to submit their transparencies in electronic form to Borge Svane N. (borge@nbi.dk) to be placed on the FMD home page.

 

PS: These recommendation were subsequently presented by JJG at the Technical Board. The decisions were endorsed.