1-VDC VERSION OF CMS DT VDC SYSTEM USER MANUAL
Contents
1. CERN gas group technical issues software work ended Gerd Fetchenhauer 16 3443 Daniel Teyssier 16 2680 cell phone 16 2680 CERN Office 70488 Aachen 49 241 80 27316 Alberto Benvenuti 16 3651 Marina Giunta 16 2355 Roberto Guida 16 2146 Jens Frangenheim at CERN 16 4583 71645 in Aachen 49 241 80 27265 cell phone 40 1577 1597265 10 4 Normal Operation during Running momeivacidata 2008111 0 vele_20081110_1202 txt wheels_supply_line E A I wheels_supply_line _fwheels_supply line Figure 4 1 The VDC standard user interface of the VDC readout software In normal continuous run conditions all HVs should be powered on and the software should take data Also after a power cut everything should be switched on automatically HV readout software Only after a power glitch it might be possible that you have to switch off on the VME crate because it crashes 11 Figure 4 2 The six valve to selected manually the gas input line of the VDC Open only one valve at the same time 4 1 Setting the gas source The gas source of the VDC can be chosen from six input lines see Fig L2 five analysis lines from the gas group analysis rack connected to the outlet of muon chambers analysis rack YBx and the gas supply line meaning the common gas supply for all wheels To change the gas source one has to e Open the gas valve for the corresponding source at the back of the VDC rack see2. is out of order You can try to recover it by pressing to its upper left side If it does not help the module needs to be replaces e If no data arrive at the discriminator check the LV supply for the devices VDC LV trigger unit with a multimeter Try to use another output channel for the corresponding SiPM upper part called trigger box of the trigger unit bottom of the VDC difficult to reach because the HV box is in front of it e If signal are indicated arriving at the discriminator check if the SiPM signals from the discriminator also arrive at the coincidence also red LEDs and if only the corresponding channels the first two ones unfortunately wrong labelled as ch7 and ch6 at the switch unit are on indicated by a green LED e For the anode signals you can also test the NIM to ECL converter by switching the another channel from 9 to 16 7 2 Detecting HV errors only for experts Please do this only with two people Do not work on the VDC when HV is on Keep attention when testing parts separately To distinguished between problems at the HV box the HV divider and the cathode Each of these parts can be tested separately by unplugging the corresponding connector from the HV box e Testing HV box Unplug the connector to the cathode and the HV divider from the HV box and ramp up the cathode voltage slowly up to 15kV Even at 15kV the current should be 0 during ramp ramp the current can be up to 1 pA due to the c
3. of the VDC is clean and that only the O ring seal is with high vacuum grease stored together with the spare parts Tighten the screw slowly and crosswise 7 3 Improving the anode rate only for experts If the signal rate decrease slowly probably an effect of outgasing of the used glue inside the chamber one can 24 1 Set a higher anode voltage but not more than 2 1kV and the current should be still 0 LA 2 Decrease the threshold for the anode at the discriminator normally 90mV Monitor the rate of anode rate and signal rate afterwards Clean the anode wire If the frontplate has to be removed from the VDC call the radioactive protection Gerald Dumont 16 4758 because if the frontplate is removed the shielding of the radioactive sources is limited Be very careful The anode wire has a diameter of only 25 um If the anode wire breaks the whole VDC will have to be replaced takes up to one week until a new VDC will be sent to CERN So do this only if there is a shutdown and the VDC cannot be used at the moment or if the anode behaviour is really very bad and the first and second action have failed To clean the anode wire Remove the front plate and clean the anode wire very carefully using a pincette a piece of absorbent cotton and alcohol Do the reinstallment of the front plate like for changing the backplate 8 Locate Software Errors 25
4. 1 VDC VERSION OF CMs DT VDC SYSTEM USER MANUAL CMS DT group status 2008 12 03 Contents sl 4 2 1 Online remote 4 2 2 In the gas roo ecting Switching the rrors in the reado error tem only for exper 11 12 12 13 13 15 15 17 19 19 19 20 20 20 21 23 23 23 24 25 1 Overview 1 1 Location The interim version of CMS DT Drift velocity monitoring system consisting of a single VDC VelocityDriftChamber is located in the gas room at USC55 at the position shown in Fig The chamber and its ancillary electronics are inside a single rack housing from top to bottom the VDC and its trigger a NIM crate a VME crate a SY127 mainframe and a standalone 80 V power supply PSP1803 at the back of the rack 1 2 Operation scheme As a interim version of the final 6 VDC system at the current system only the drift velocity of the gas from a single source can be measured A al 1 VATED e Distribution u E n SSS SS SS SS Figure 1 1 Floor plan of USC55 gas room including the position of the two racks with the VDC system from https edms cern ch file 684147 3 CMS_Racks_UX doc 2 Safety 2 1 General safety rules safety in the gas room Note Keep the CERN safety rules in mind You are not allowed to work alone in a room You need a second close to you working person That means you need a second person which is also in underg
5. Fig All other valves must be closed e Set this gas source in the VDC software see Fig LT by choosing the gas source from the drop down menu at set input line and confirm the selection by clicking on set for next runs e In the case a output line of the gas group analysis rack has been selected the corresponding muon chamber ID is got automatically from DCS 4 2 Additional things to be checked The normal operator following things should be done checked 12 4 2 1 Online remote e Check the vgrif values and the E field values in the DCS system on pcemscr18 cern ch They should be at 55 0 1 0 umns resp 224 0 1 0 Vmm e If the values are not inside this range especially if 1 is displayed for vaript which is indicating an error login to the VDC PC DTGAS VDC 01 CMS cern ch as user vdc from inside the CMS network e Change directory to home vdc data current_date e Open the current data file VCD_analysis_date txt or the corresponding root file VCD analysis_date txt root and check voltages currents and rates Uanode 1900 50 V Ucathode 15000 50 V U PM1 2280 10 V U PM2 2130 10 V U SiPMs 70 60 0 20 V R local trigger 32 5 Hz R anode 28 15 Hz R signal 25 10 Hz If the voltage currents or trigger rate are not in those regions call an expert If the anode and signal rate is too low c
6. apacitor inside the HV box If the power supply trips replace the HV box and if necessary also the corresponding cable by spare parts from the corresponding barrack upstairs e HV divider Connect only the HV divider to the HV Box and ramp it up the cathode voltage to max 5kV Because if the cathode is not powered the voltage difference between the cathode and the first layer of field shaping tubes is to large the voltage divider cannot be tested at higher voltages in this configuration The current at 5kV 23 should be less than 9 LA To test the voltage divider at higher voltages remove it from the chamber and test it on a non conductible surface If the voltage divider seems to be damaged or you do not want to test 1t replace it by a spare voltage divider from the barrack upstairs Keep attention to the cable at the frontside of the HV divider to ground It is fragile VDC backplate Connect only the VDC backplate cathode to the HV Box and ramp it up the cathode voltage to max 5kV same reason than for the voltage divider The current at 5kV should be 0 A If the backplate has to be removed from the VDC for replacing or further testing call the radioactive protection Gerald Dumont 16 4758 because if the backplate is removed the shielding of the radioactive sources is limited During replacing the backplate by a spare VDC backplate from the corresponding barrack upstairs make sure that the backplate and the backside
7. ation e g 10min one data file is generated with the name vde_yyyyMMmm txt For each day a directory named by the date for these raw data files is generated The raw data format are UFT 8 text files containing six data types e global header e header global block values block values e TDC channel association e TDC data Analysis of raw data files At the end of each run the last written raw data files is analyzed by the C program VDC_ver08 Three files are generated 1 Histogram file VDC_rootfile yyyyMMdd_hhmm root Containing histograms including drift time spectra and other evaluations of the TDC data 2 Analysis file VDC_analysis _yyyyMMdd_hhmm txt Containing all evaluated data from raw data files including the drift velocity These file has text format and the content is organized in blocks 3 Summary file VDC_summary_yyyyMMdd_hhmm txt Containing one block the Sum mary block from the analysis file The content of this summary block is displayed inside the LabView program The content of the summary file is read by the dip server and transmitted to the DCS 19 The time yyyyMMdd_hhmm inside the filenames is given by the start time of the first mea surement of the day first file in the directory The program VDC_ver08 is reading the filenames of the raw data files inside the current directory and compares them with the names of the files that have already been analyzed using the filenames
8. firm by Each function has to be chose for the corresponding channel which has to be selected before Example 1 Switching on ch 13 F 0 13 F 10 Example 2 Setting voltage at channel 13 to 14000 V F 0 4 13 4 F 1 14000 Example 3 Setting voltage at channel 13 to 12000 V in case channel has already been selected F 1 14000 Example 4 View current at channel 13 to 12000 V in case channel has already been selected F 7 PM trigger Check the PM voltage settings set voltage VO current limit 10 and the values voltage current at the CAEN N470 module see Fig B I ch0 PM1 Up 2280 V lp 2000 pA 1950 pA typ chi PM2 Up 2130 V Ip 2000 pA 1710 uA typ and switch the channels ch 0 and ch 1 on SiPM trigger Check the SiPM voltage settings at the PSP1803 see Fig at the backside of the rack U 70 60 V Use the menu button to change between normal and fine voltage set The current of both SiPMs should be around 4uA so that is far below the resolution of the PSP1803 Switch the voltage on 15 16 e PM trigger should not be the case Check the PM voltage settings set voltage VO current limit 10 and the values voltage current at the CAEN N470 module see Fig EI ch0 PM1 Uo 2280 V To 2000 pA 1950 LA typ ch1 PM2 Uo 2130 V Ip 2000 pA 1710 pA typ and switch the channels ch 0 and ch 1 on e Check the VDC cathode voltage se
9. heck the gas flow in the DCS At the moment the remote control voltage current readout of the SiPMs is disabled 4 2 2 In the gas room e Make sure that the set input line is entered correctly in the readout software e Make sure that the gas flow is around 5L h by adjusting the flow meter a rotameter at the rear side of the VDC rack e Make sure that there is a normal gas supply while adjusting the flow because otherwise if you adjust the gas flow at low supply pressure there will be a huge flow through the VDC when the pressure goes back to its normal value If there is no gas flow check also if the gas valve at the gas outlet of the VDC is open If it is not possible to establish a correct gas flow inform Roberto Giuda e Check the rates at the counter module on the right in the NIM crate Fig 1 in detail they should be Anode Between 3kHz and 6k Hz a too low rate indicates a stop of the gas flow a hight high rates maybe cause by a too high anode voltage Otherwise there is another error like an error at the preamplifier inside the VDC In this case inform an expert PM1 SiPM1 90 Hz to 150 Hz 2kHz to 8 kHz PM2 SiPM2 50 Hz to 90 Hz 2kHz to 8kHz If the rate is not in this region check the voltage s for the Si PMs If the voltage is set correctly and the rate is still not in this region inform an expert shifter Si PM1 Si PM2 trigger rate 28 Hz to 38 Hz PM system 20 Hz to 50 Hz SiPM system e Enter one c
10. inator channels which are connected to the output of the trigger system you want to use to the inputs of the switch unit Switch on the voltage for the PM system power on the N470 channels by hand for the SiPM system switch on the PSP1808 the rest is done by remote control nn Select the trigger system in the VDC software Select file vi properties protection and chose unlock Now Select the new trigger type 2 scintillator 2 PMS or 2 SiPMs Hamamatsu in the right of the expert setting Type in also the voltages for the SiPM s PMs at individual voltage settings set U SiPMx Note In the software everything is labeled with SiPM PM1 2280 V PM2 2130 V SiPM1 SiPM2 70 60 V After that mark the corresponding fields and chose edit make selected value default After that nn 2 lock the vi again and save the vi Check if the rate are OK 21 22 7 Locate Hardware Errors 7 1 Detecting errors in the readout system Follow the flow of the signal starting target made diagram will be insert e At the discriminator If at any of the three input channels anode SiPM1 2 no red LED Is blinking switch the cable from the device to the input of another discriminator channel If the LED of this channel now is blinking the discriminator channel is out of order and you should do a recabling to the the working discriminator channel In no LEDs of the discriminator are on the module as a whole
11. ng the voltages and current of all devices using the vis in home VDC_software Labview_software hv VDC_readout TDC e TDC_set_parameters vi initialization of the TDC setting the opcodes and control their setting e TDC_readout vi reads the TDC data from the TDC buffer e TDC_data vi sorting the TDC_data achieved from TDC_readout vi VDC_readout scripting vis and data files reading containing the VDC software parameters VDC_readout data_write vis write the several data block to the output files 20 6 6 Changing the trigger system Please call Gerd Fetchenhauer 16 3443 or Daniel Teyssier 16 2680 to assist you If you want to change from one trigger system PM or SiPM based to the other one Switch off the voltage to the trigger system you want to remove Remove the current trigger system mechanical form the VDC For the PM system you have to remove three of the four screws The remaining screw must be in one the screws in the back which are fixing the holder to the plate in the rack Than you can turn the PM system For the SiPM system remove the four screws which are fixing the trigger unit via its scintillator plate to the VDC and remove the trigger unit from the VDC Place the new trigger unit to the chamber Change the cabling In principle all cables and connectors should be marked so that you should see what to do Although in detail Change the cable input to the switch unit Connect the output of the two discrim
12. omment which will be inserted into the data file of the current run section comment Optionally the comment can also be included into the files of subsequent runs until the user changes this setting Note that the first 32 characters of the comment will also appear in the summary list which displays one line per run 13 14 5 Switching On Off 5 1 Switching the System ON In case the whole system is OFF one has to Make sure the desired gas to be measured is flowing at 5 L h through the VDC rotameter at rear side of VDC rack Switch ON the NIM crate PM trigger system Make sure that the HV ENABLE lever at the CAEN N470 module see Fig is in ON position HV ON lights Switch ON the SY127 at the bottom mainframe turn the key to the right Make sure that the HV ENABLE lever is in ON position HV ON lights Switch ON the VME crate Switch ON the PC and the monitor the system logs in automatically In case of not using the voltage remote control you have to power up each channel at the Sy127 and N470 PM trigger PSP1803 SiPM trigger manually I case you are not firm in using this old generation of CAEN power supplies The manual is printed directly on the front plate of the Sy127 device Select a function by F followed by the number of the function and confirm by and than for corresponding functions enter the value you want to set and con
13. round as long as you are in underground and you must have contact to his person in intervals of at maximum 30 min The main risk in the gas room is a lost of oxygen So leave the door open as long you are in the room And make sure that the second person will come to the gas room if he or she has no contact with you One way to guarantee this is to place some kind alarm clock near to the second person which will give some kind of an alarm if it is not disabled before 30 min have elapsed this job could be done by the count down function of a cell phone 2 2 Safety related to using the VDC racks Caution Radioactive sources 2 9 Sr sources 10 MBq each and high voltages are present Read the VDC Sr safety manual in the rack also under EDMS ID 887629 Do not plug HV cables or remove any parts of the chamber Do not change current limits for the HV supplies Otherwise over currents cannot be detected probably Do not set voltages above 2 1kV for the anode 2 3kV for the photo multipliers and 70V for the silicon photomultipliers SiPMs NOTE It is forbidden to remove the radioactive source from the chamber or to remove its lead cover It is not required to wear a dosimeter during operating the VDC system 3 Contact Persons permanently at CERN mostly in Aachen radioactive sources gas system storage of spare parts project supervisor DCS system storage of spare parts Aachen responsible other experts
14. stored in the summary file The new data is put into the existing files Plots After each run and the finishing of the VDC_ver08 program output file plotter program analysis_reader is run It takes the analysis files and plots the values and stored them in the root file VDC_analysis_yyyyMMdd_hhmm txt root The kinds of the plots can be set by the file Scrip dat inside the directory of the output file plotter 6 3 Output file merger To view the data of more than one day inside one plot use the program Outputfile_merger It needs two parameters the start date yyyyMMdd and the end date of the period you want to plot For both dates the corresponding directories must be present It created a file VDC_ analysis_startdate_to_enddate txt Run outputfile reader by outputfile reader VDC_analy sis_startdate_to_enddate txt and you will rechieve a root file outputfile reader VDC analysis startdate_to_enddate txt root containing the plots 6 4 LabView program structure The outer structure of the LabView program consist of two kinds of while loops One kind is use to run measurements and the other one to detect user interactions fast The most important loop is the loop for the data taking During stopped measurement the problem shall stay in this look and should not enter the inside if case 6 5 Sub Vis In home VDC_software Labview_software vdc VDC_readout HV setting controlling readi
15. t PSP1803 at the backside of the rack and than switch off the device e Power down the cathode voltage at the front panel of the SY127 mainframe ch 13 e Power down the anode voltage at the front panel of the SY127 mainframe ch 16 e Switch OFF the NIM crate e Switch OFF the VME crate e At the SY127 mainframe switch HV ENABLE down HV ENABLE lever is in OFF position HV ON does not light e Switch OFF the SY127 mainframe Turn the key to the left e Stop the gas flow at the rotameter 17 reitet Pd Sr PRE IR Pa We oa ee et Ny lie Al use to adjust 0 e P we gt voltage voltage SiPMs ye PSP 1803 ESH l PHYSIK INST THAACHEN E el w use to select make sure Vcore fine 4 that LED is on Figure 5 2 The PSP1803 module used as power supply for SiPM based trigger system 18 6 Expert Settings 6 1 Directories data home vde data yyyymmdd yyyymmdd date of measurements LabView programs vis home VDC_software LabView_software VDC readout programs home VDC software LabView _software vdc VDC readout HV steering home VDC software LabView software hv dim server DCS system home vdc linux VDC analysis software home VDC software VDC_ver08 output file plotter home VDC software Outputfile_ reader output file merger home VDC software Outputfile merger backup home backup 6 2 Data flow Raw data files For each run dur
16. tting at the front panel of the SY127 mainframe see Fig BI on channel 13 In normal condition it should be set to 15kV otherwise the current value is indicated somewhere at the racks Switch ON the VDC cathode voltage at the front panel of the SY127 mainframe select channel 13 and switch it on Icathode 28 pA to 35 pA e Check the VDC anode voltage setting at the front panel of the SY127 mainframe on channel 16 It should be set to 1850 V Switch ON the anode voltage Ianode OMA to 1 pA a Counter ii a rates for i E anode Mg Si PMs trigger WES or z gt gt E coincidence a 3 a 2 3 Yn Na pez on off s switch Figure 5 1 The VDC rack and the modules to be operated 5 2 Switching the system OFF Stop the readout click on stop button and or switch of the high voltage at the software Shut down the PC Switch OFF the PC using the switch at its power supply and the monitor also at the backside In case of not using the voltage remote control you have to power down each channel at the Sy127 and N470 PM trigger PSP1803 SiPM trigger manually e PM trigger Power down PM voltages at the CAEN N470 module at C1 and wait until less than 20 V is measured for both channels switch HV ENABLE down Never switch of the NIM crate or switch the HV ENABLE lever to disable when the HV for any of the PMs is on The PM could be destroyed e SiPM trigger Switch off the voltage a
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