From: VAXLNF::VAXLNF::VAXLNF::MRGATE::"C=DE::A=d400-gw::P=desy::O=vxdesy::S=wagnera" 23-MAR-1995 12:19:51.48 To: VAXLNF::SCIC CC: Subj: From: NAME: Albrecht Wagner FUNC: vxdesy To: FUNC: CERN NAME: calvetti CC: NAME: SCIC , NAME: feliciello , DD.RFC-822=davier(a)lalcls.in2p3.fr@P=internet@A=red@C=fr RFC-822-Headers: MIME-version: 1.0 Content-type: text/plain; charset="us-ascii" Content-transfer-encoding: 7BIT Dear Alessandro, please forward to Prof. Bressani: Summary of a meeting between the FINUDA Collaboration and the referees ---------------------------------------------------------------------- M. Calvetti and A. Wagner ------------------------- On March 20, 1995 M. Calvetti and A. Wagner met in Torino with members of the FINUDA collaboration. Before the meeting the two referees were provided with a number of documents as specific response to the questions raised during the last meeting of the Scientific Committee of LNF. In the meeting at Torino members of the collaboration presented the most recent status of FINUDA. . Bressani: Overview of the status of the experiment F. L. Fabbri: Magnet and installation schedule D. Cambiaghi: The mechanical structure (clepsydra) A. Zenoni: Simulation and reconstruction programs These presentations were accompanied by extensive discussions with the referees. Before entering into a detailed discussion of the answers to the questions of the committee we would like to make some general observations about the status of FINUDA: 1) The collaboration has made considerable progress in the detailed design of FINUDA and has provided a number of indepth answers to the questions raised by the scientific committee. 2) The regrettable delay which has occurred in the installation of DAFNE provides FINUDA with more room for the (modified) installation. 3) Recent first estimates of the machine induced background have revealed a potential source of serious concern, both for the trigger rates and the pattern recognition. These studies must be pursued vigorously under the most realistic conditions to assess the true scope of the problem. Furthermore, the referees would like to see a more robust trigger with additional redundancy and possibilities to determine its efficiency experimentally (the present trigger relies most heavily on a pulsehight cut in the inner TOF counters which are most vulnerable to machine induced background). 4) Also the most recent tests of the hybrid photomultipliers do not yet prove that these devices provide the performance (signal/noise ratio, time resolution etc.) necessary for the read out of TOFINO. The FINUDA group is strongly urged to also study alternative methods of read out, such as mesh photomultipliers. 5) The FINUDA needs in all areas (detector construction, Monte Carlo studies, etc.) to continue to maintain the present effort in order to meet the very ambitious time scale. As requested by the Committee, the collaboration has provided written reports on the following issues and furthermore presented additional information at the meeting: - Test beam results on the LMDC's and straw tubes, and their consequences for the final design of the chambers The test beam results on the LMDC's as reported at the Vienna Wire Chamber Conference show the expected performance which agrees with the assumptions of the Monte Carlo Simulation. The straw tubes were studied with different gas mixtures. Although the resolution for the preferred, non flammable gas is somewhat worse than assumed in the MC, this does not influence the overall momentum resolution which is mainly limited by multiple scattering. - Status of and test results of the HPM's: see above - Engineering design of the detector including support structures and installation procedures of all subdetectors, and the support, installation and alignment of machine elements inside the detector; Much progress has been made in this area, including a detailed stress analysis, mounting schemes for the different subsystems, installation plans, thus providing a credible basis for a more detailed mechanical design. However, much work remains to be done in this area on a very short time scale. - Service lines, cable routing, and helium-bag design: Here the question of the layout of the helium-bag between the two outer LMDCs remains a region of concern. This has to be studied in more detail, probably by using a model. - Monte Carlo simulation of the performance of this more realistic detector configuration: The present knowledge about the most realistic detector configuration including support structures and detectors has been included in the MC situation. The simulation has in fact been used to maximize the acceptance of the detector. Estimation of the machine-induced background and a simulation of its impact on trigger and pattern recognition: see abov - Status of the electronics development and possible delivery schedule: A schedule was submitted in writing, but not discussed. - Discussion of the physics related to the choice of targets, target construction with a view to minimizing target exchange operations: The collaboration plans to work during the fist year simultaneously with targets made from C, Li and Al and does not plan to change targets during this time. In addition a detailed mechanical study is being performed about the access to the target in beam position. The choice of target materials was not discussed at the meeting. - Definitions of milestones for 1995 and 1996: A flow chart for the construction and assembly of FINUDA was submitted in writing, but not discussed due to lack of time. The referees think that the delivery of the magnet is on the critical path and that therefore a continuous and close contact with Ansaldo is vital for assuring the timely completion of the FINUDA magnet. This summarizes the results of the meeting. The referees agree in their general assessment of the status, although the detailed wording of the above text is the responsibility of AW. Albrecht Wagner Director of Research DESY -F- Notkestr. 85 D 22603 Hamburg Tel 49 40 8998 3000 Fax 49 40 8994 4304 e-mail: wagnera @ desy.de