Buontempo, Salvatore

Declais, Yves

Votano, Lucia

CERN Document Server

CERN-SPSC-2006-27  SPSC-SR-013  October 2nd , 2006  1  OPERA Status Report                     Electronic detectors installation •  Target trackers and XPC/RPC of the 2 Super-modules are completed and have been used successfully during the run in August with the full DAQ system. We have worked out since to cure few problems with cabling and bad setting of sensors and more generally to improve the installation of the electronics and DAQ machines. We will resume for normal Data acquisition those detectors in the week starting on the 9th of October.  • HPT: we succeeded to include in the main DAQ the first doublet of the HPT of the first Super Module for the last days of the run in August and have been able to see correlated tracks with the other sub-detectors. The delay in the setting up of the HPT was due to the front end electronics (large delays for the chips delivery). We will install in the first week of October the remaining part of the front end electronics for the first spectrometer. Since the gas system is ready we will perform the first part of the commissioning with cosmic muons in waiting the beam. • VETO: the mechanical installation is going on and we expect to start the commissioning by the end of october. This is not a problem since we can use the target tracker plane downstream the filled walls as a veto. • Magnets: the 2 magnets have been successfully operated during the run in august. We are working out to solve few minor problems with one of the supply and to improve the slow control. CERN-SPSC-2006-27  SPSC-SR-013  October 2nd , 2006  2  2. Bricks production • Lead: the production is being commissioned at the site of Goslar with the final choice for the Pb (Pb/Ca non co-laminated). 2 transportation of Co-laminated lead were delivered to LNGS and rejected because of thickness out of specs. 3 transportations of useful lead have been already delivered at LNGS (~6 000 bricks). The mechanical shape of the lead plates is now within the specs, the washing protocol is being tuned for reducing the stickiness between plates when they are used in the BAM. • CS: all components are available, the refreshing protocol defined and the mass production started. Some work is going on for improving the reliability of the vacuum sealing of the emulsion doublet envelope. We have used 300 of those CS during the run in august for validating the track association between the target  tracker and the CS. The scanning is still going on but we have already found most of the muons from CNGS neutrino rock interactions tagged by the TT in the CS setup. This is an important milestone for defining the CS scanning strategy. • BAM: the entire system is now installed and commissioned at LNGS. The only missing part today is the automatic system for filling the drum with bricks (the filling is done by hand actually). This part will be installed in the beginning of October. The installation and the commissioning have been demanding for a lot of work taking into account the situation in the underground laboratory (access, power cut !) and the amount of tuning for taking into account the final parameters of the lead plates and the real emulsions. Last week ( week 39) 124 bricks have been produced  with the BAM in light (and so not useful for physics) for the final tuning of the BMS and 29 with the BAM in dark. So we can consider that the BAM is ready for starting the mass production and we hope to reach the nominal speed after one month. • BMS: the 2 systems are fully commissioned and the associated services ready in the Hall C. The final tuning with the real  bricks will last one week and so the filling of the detector could start during the week 41 (October 9th). 3. Brick filling schedule and event rate           We have made an estimate (see table below)  of the filling rate with 2 hypothesis ( realistic and optimistic) and of the event rate in the bricks for also 2 hypothesis of the CNGS beam conditions:  • Minimal : 1.8 1013 protons/extraction and 65% efficiency for the accelerator complex  • maximal : 2.4 1013 protons/extraction and 100% efficiency  CERN-SPSC-2006-27  SPSC-SR-013  October 2nd , 2006  3   We used an SPS super cycle of 39.6 sec (extended flat top for fix target) with 3 embedded CNGS cycles.  Nb of bricks installed conservative optimistic October 16th  750 1500 October 23rd  1500 4000 October 30th  2500 6500 November 11th  4000 9000 Number of events 4 ÷ 9 10 ÷ 21  4. Motivations for the new run    This run is important for completing the commissioning of the CNGS beam and the OPERA experiment:  CNGS beam : all the components of the CNGS neutrino beam have been successfully operated during the run in August. On the accelerator side there is still some tuning needed in order to define stable running conditions at the nominal high intensity : 4.8 1013 ppp . So a run at the maximum intensity will validate the performance of the CNGS for the following years. In addition we need to validate that the improvements applied to the accelerator data base and the timing system are effective.  OPERA detector : a. We need horizontal tracks in the detector for the commissioning of the electronic detectors, especially for the HPT of the spectrometer which was not ready for the run in August.  b. We obtained 0.07 1019 pot in August and the statistics is limited for the commissioning of the analysis software which cannot be tuned efficiently with down going muons. c. Even if the number of interactions in the bricks will be limited it will allow the commissioning of the full chain of the brick processing with real events in the real experimental conditions since we cannot use cosmic rays tracks which are outside the angular acceptance of the scanning system (0.4 radians) : o Brick finding o X ray  marks for the track matching from the CS to the brick  o Cosmic rays irradiation density for the accurate plate to plate alignment o Scanning and data analysis d. We can also extract some  bricks which are tagged as containing a beam punch through muon in order to check the CS to the brick track matching and the brick to brick connexion.  CERN-SPSC-2006-27  SPSC-SR-013  October 2nd , 2006  4  5. Augutst run : CNGS beam performance  The run started on August 21st and lasted for 8.5 days (excluding MD). We had beam during 121 hours (5 days) accumulating 7.6 1017 pot onto the CNGS target. The efficiency of the CERN accelerator complex was 65%  (taking into account losses of data in the accelerator data base : 10%).                                        		    	 	 	  	  !"#$    %& ' 	   	 %() * +  , 	 &- ' - . /012 - 0$2 - 0! $.  3""104"5 ".  3""10"" 	  CERN-SPSC-2006-27  SPSC-SR-013  October 2nd , 2006  5   The beam events have been extracted in using the GPS time of the extraction wrt the event time stamp generated with the local GPS system. The GPS clocks of the CERN and LNGS system have been inter-calibrated and the two clocks can track each other with a stability better than 100 nsec. It can be seen from the following plots that the synchronization at CERN, which was created in using the kicker trigger pulse, was not stable. The system will be improved in using the proton beam monitor.                                       		#50 msExt1 Ext2(  &,3 	6	  		#10 µs7  	8 , Time difference of the in-time events with respect to the closest spill vs timeTime (Unix date)102 µs16 µs2.8 µs CERN-SPSC-2006-27  SPSC-SR-013  October 2nd , 2006  6  6. OPERA performance The electronic detectors, Target Tracker and RPC, have been running at high efficiency: integrated over the beam time the data taking efficiency  was ~95%. We loose some data for an accidental shutdown of the local GPS and network. The main source of losses is related to electrical power supply breakdown. We have used the full DAQ system and this run gives the possibility to validate the event builder, the selection of beam events and the data transfer in a OpRoot format. We are also using these data for tuning the data analysis software: tracking, muon filter, momentum and sign measurement in using the RPC.  At the level of the sub-detector the trigger was set at the minimum bias conditions for keeping data in the sub-detector data base : o TT: 2 p.e. threshold at the pixel level and then a majority of 2 planes with a total of 4 p.e. within a ‘software’ gate of 200 nsec o RPC : majority of 3 or 2 planes within a gate of 500 nsec. Then, offline, the event builder collect all event segment in a time window of 1µsec. to buildup an event requesting a minimum number of hits and write the event in the main DAQ data base. Using the timing information from the accelerator data base it is easy to separate beam events from  cosmic rays events. We have extracted  319 events within a gate of 1 msec. wrt the CNGS spill and more than 20 hits. We are analyzing those events, as well as cosmic rays events and producing the corresponding simulated data. As a first look you can see in the following figure the angular distribution of the beam events in good agreement with the expected CNGS beam direction at LNGS:                        CERN-SPSC-2006-27  SPSC-SR-013  October 2nd , 2006  7   The angular distribution of the cosmic rays events is in a good agreement with the expected spectrum taking into account the shape of the mountain above the underground laboratory :    Example of muon bundles from cosmic rays :                        CERN-SPSC-2006-27  SPSC-SR-013  October 2nd , 2006  8   Examples of beam events:                             Muon from neutrino  interaction In the material in front of the detector CC interaction in the first magnet CC interaction in the target tracker 

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