Minutes of the Meeting of the Technical Board ============================================= May 23rd 2001, 9:30 - 12:00 Beam-pipe (J. Spengler): ------------------------ The status of the new beam-pipe is as follows: All segments are available and pressure tested except the first cylinder which is used to adjust the total length of the pipe. These segments were put together into three long sections. Some of the welding joints showed vacuum leaks afterwards. (Just after the meeting K. Ludwig reported that two sections passed the leak test). Segment 1 is being milled right now and will be finished in a few days. The RICH-ECAL section will be installed right after Withsun. This requires to move the complete detector by 1 m to introduce the pipe. Afterwards, all detector platforms will be surveyed and realigned. The magnet and PC sections will follow about two weeks later. Infrastructure (J. Spengler): ----------------------------- In order to clean up the magnet, all OTR and high-pt cables and gas pipes were taken out of the magnet and are now rerouted in the correct order. An enormous amount of garbage (magnetic and non-magnetic materials) have been found. The +x side is finished: the -x side will take at least one more week. The connections of the magnetic coils have been properly protected. Triggered by the problems we had with operating the ITR LV power supplies, a discussion with an expert from the Desy group MKK1 (electrical power) took place. The expert strongly suggested to install harmonic filters in the power distribution boxes installed within our detector (UV 1.12 - 7.12) to damp the higher frequencies. A large fraction of them is only present when HERA is operating, which might explain the fact that the problems observed during the run 2000 could not be reproduced by the manufacturer of the LV supplies (Wiener) nor by the ITR people during the shut-down. Target (J.S. for K. Ehret): --------------------------- Concerning the target mechanics, all parts are produced. The forks holding the target wires are just being cabled and prepared for installation. The new Lumi counter are assembled and tested at Dortmund. They will be mounted begin of June. TaCoS is essentially finished. The emergency handling and beam finding needs some more fine tuning. Klaus proposed the following wire arrangement: The default geometry will be round wires, 50 mu diameter. iI - W, iII - C foil, bI - Ti, bII - Pd, oI - Ti, oII - C foil, aI - Al 50*500 mu, a II - B 200 mu round. He gave up the C-nanotubes due to impurities. The B-wire has to be analyzed by the Bundesanstalt fuer Materialforschung. A lively discussion made clear that this arrangement has been rejected: What do we learn from a Boron wire which can be used in 1-wire mode only and which is very close to Carbon? To perform a measurement which can be published it's more important to minimize the systematic errors than to maximize the number of different materials. Why not a round Al-wire? Vertex (K.T. Knoepfle): ----------------------- Tasso summarized a discussion which he had with F. Willeke concerning the installation of the new RF-shielding with smaller ribbons (7 mm wide instead of 12.7 mm). Willeke was against the installation of the new version, because he expects a poorer shielding. In his mind our RF-shielding is anyhow marginal and he remembered well that we had problems when operating the 12.7 mm in the beginning. He would have agreed only in case the new shielding would be essential for the success of HERA-B. However, this we cannot prove. He agreed that we can install the new ribbons if there is an unscheduled break in Hera operation towards the end of 2002. Tasso reminded us that the present version was closed routinely to 15 mrad with a few tests down to 12 mrad. During the next weeks the VDS groups will try to establish how far we can close the ribbon in future operation. The repair of SL8 modules is going well. 6 double-sided detector modules for pot 103 are available and tested. The production of rate monitors is in progress. 15 wafers with Helix 3.1a chips have been delivered resulting in about 200 chips which will be given to the ITR group for MS10 and 13. The detector-fork assemblies for the 2002 modules is done and the bonding is progressing. Inner Tracker (Th. Hott): ------------------------- Concerning the non-trigger stations, MS11 and MS12 are reinstalled, MS01, MS03 and MS06 are finished. MS05 will not be ready before end of shut-down due to very late delivery of new plates. The placement of MS05 has not been decided. The proposal of J.S. to attach MS05 to the back-side (downstream) of MC4 is just being digested by the ITR experts. The repair work on MS10 and MS13 (trigger stations) started in April. 15 Helix 3.1a wafers are now at GMA to produce new PCBs. The boards for MS13+ are available. All problems with the z-bonding have been solved which means that the production for MS13+ can start now. Thomas is convinced that 3 out of 4 PC stations will be reinstalled before mid of July. The TC stations (MS14 + 15) will be installed until end of 2001. Till end of June, the software of the gas system will be optimized, all LV power supplies are back from repair/upgrade, an improved slow control (concerning Helix programming and HV error recovery) will be available by end of June. The installation of trigger electronics is planned for June and July. Outer Tracker (U. Uwer): ------------------------ Uli reported on the repair status of the OTR. All PC+, PC1-, PC4- and both TC1 chambers are finished. MC3 and MC4+ are ready and reinstalled, MC3 and MC4- are being repaired right now. It is planned to reinstall them during the shut-down. The assembly of TC2- just started. The repair/exchange of all ASD8 boards is ongoing, thresholds could be reduced by 100 mV with respect to hall 5 tests (linkboards are not yet connected). PC+ and TC1+ are finished. However, the debugging takes too long and they are behind schedule. If they do not speed up, PC2- and PC3- will not be tested before we have to close our experiment. 30 (out of 106) trigger link boards were modified and passed the test procedure. The standard TDC extenders arrived last week and recabeling of PC1+ TDCs has started. Most likely they will not be able to recable all trigger layers during the shut-down. Inner high-pt (R. Mizuk): ------------------------- Roman reported that all ASD-8 cards were tested in Zeuthen. About 100 bad channels were repaired. DACs to adjust the optical transceivers were installed in the FED crates. He expects a delay with the production of the shielding boxes because their technician didn't arrive yet at Hamburg due to visa problems. Outer high-pt (A. Schwartz): ---------------------------- Alan apologized that he is not able to come. He provided the following summary: History: In April we fully shielded PT1+ in the magnet and instrumented it with 18 ASD-8 cards in the central region (+- 50 mrad). We cabled the cards and confirmed that there were no oscillations down to ASD-8 thresholds of (at least) 0.8 V. This value corresponds to an input charge of 3 fC, which subsequently corresponds to a shaper signal of about 40 mV. Shaper signals observed from cosmic rays and a Ruthenium source have sizes typically in the range 100-200 mV, which is one reason why we believe this ASD-8 threshold satisfactory. (We also have beam test data supporting this.) The noise observed on the shaper pin had V_rms of only 6-8 mV, which corresponds to an ASD-8 threshold well below 0.8 V. (Caveat: some of these numbers correspond to an ASD-8 voltage of 3.0 V while we now run at 2.5 V; thus these will be re-measured). Progress: In May we fully shielded PT1-, 75% shielded PT3-, and 50% shielded PT3+. Both PT3 chambers were dismounted from the MC8 chambers and mounted (temporarily) on the PT2 rails. Plans: (a) instrument PT1- with 18 ASD-8 cards in central region (b) complete shielding of PT3+ (c) complete shielding of PT3- (d) add 26 more ASD-8 cards to PT1+, fully instrumenting this chamber (e) install PT3- rail, move PT3- chamber from PT2- rail to this one, and move PT2- chamber from Hall 5 onto PT2- rail (in magnet). (f) shield/instrument PT2-. RICH (S. Korpar): ----------------- Samo came in very late because he had to attend the alignment meeting. He was too shy to make the sleepy chairman aware of his presence. However, his beautiful transparency has been added to the pdf-file. The work on the photon detector is carried out as scheduled. The system hard- ware was tested, some new PM's were mounted. A complete read-out test is planned for June. The missing gas-expert is a still unresolved problem. TRD (): ------- ECAL (S. Shuvalov, M. Bruschi): ------------------------------- Sergey expects to finalize the mounting of inner bases till the meeting in Copenhagen. The radiation damage of the innermost modules has to be measured before the installation of the Al beampipe. Marco reported that all ADC boards were modified and reinstalled. Tests of the read-out chain have started and should be finalized till June 8th. After this, he plans to work with the pretrigger electronics (reducing bit error rate, commission Brems. recovery logic). The analog interface of the energy inhibit card is working okay now; the tests of the Sharc interface started, the protocol seems to work according to spec's. Concerning the installation and commissioning no plans are available. Up to now, no manpower was assigned to this task. Marco plans to discuss the next steps with the target group. MUON (Y. Zaitsev, P. Buchholz): ------------------------------- Yuri reported that 6 pad chambers of MU3- had to be removed due to noise problems. They will be reinstalled during the next days. Concerning MU4-, all chambers have been mounted except the 6 pad chambers which will be equipped with modified electronics. For MU1 and MU2 frames the power distribution boxes have to be fixed to a place which is easily accessible during running. This work is planned for the first weeks of June. MU2 pixel chamber is being repaired right now. After a detailed test of the gas system with nitrogen they plan HV tests requiring the "running" gas mixture. The availability of CF4 should be checked. Peter described the modifications of the front-end electronics. 6 pad chambers will be equipped with the L3 preamp, using different grounding schemes and different types of cables. More details including photos of the modified chambers can be found in the pdf-file. First Level Trigger (I. Riu): ----------------------------- Starting with the hardware situation, Imma reported that all OTR TFUs are in operation. The modification of OTR linkboards is going on well. However, the cabling and test of these boards is time critical. When analyzing their tests, they found a small shift in x (2 - 3 mm) between the generated track position and the one found by the FLT. The influence of a modified coincidence matrix was studied with a MC simulation of a perfect OTR. They expect the influence of masking rather small. a) Standard matrix: coincidence in all three view (two stereo layers + 0 deg.) b) "Mannheim" matrix: coincidence in two out of three views c) "modified" matrix: if a) is not fulfilled, ask for both stereo layers. However, a technical realization of this matrix was not found up to now. The FLT rates are as follows: 5 MHz, pt=1 GeV/c a) 9 kHz, b) 33 kHz, c) 16 kHz and 10 MHz, pt=1 GeV/c a) 23 kHz, b) 90 kHz, c) 45 kHz. Good progress was achieved with the test vector test. Latency plots were shown (see pdf-file) and they plan to extend the test to the Muon system, which will take about four more weeks. Second Level Trigger (P. Kreuzer): ---------------------------------- Peter discussed the upgrades of various SLT algorithms. OTR drift time is now used to update the track parameters in REFIT. Residuals in PC1 go down from ~1,6 mm to ~0,7 mm. An improved version of L2SILI is ten times faster than the old one and has a better track resolution. The suppression seems to be worse which needs further studies. The effect of different SLT scenarios (use of OTR drift-time, upgraded L2SILI and L2MAGNET code, use of ITR hits) was tested by Teresa using hard selected J/Y --> mu mu data and a similar MC sample. Most of the improvements give a ~20% reduction in backgound at a signal efficiency of about 98%. Adding the ITR hits results in 24% additional events in MC and a 16% loss of triggered data (expect 0%). This loss is not understood up to now. The SLT group has to take over the SLT-Muon tracking, because V. Eiges will not be around over the summer. This additional task leads to a rather tight SLT schedule. Nevertheless Peter is confident that they can make it. Fourth Level Trigger + DAQ (J. Hernandez): ------------------------------------------ Jose reported both on 4LT and DAQ items, because Vladimir is on holidays. Right now, the DAQ group is working on the online histogram display and on the software for the standalone run. A successful test of the upgraded system took place using 20 SLT nodes. It is planned to get rid of Lynx2.3 running on hb-vme01 - 20. The users are asked to recompile their code with Lynx2.5. The old Lynx2.3 home directories are still accessible under 2.5. Whoever wants to run under Lynx2.3 is asked to contact Klaus Ehret. The upgrade of the online computing (described in previous minutes) takes place end of May. No DAQ or 4LT services will be available for a few days. The reprocessing rate was improved from 17 Hz to 30 Hz by introducing a multi- threading scheme for the event distribution. hb-delfi1 is used for staging and event distribution to the various 4LT nodes. Right now, some selected runs are reprocesses to test the three different pattern recognition programs. Date of next meeting: June 19th 2001