DO - Galileo - University of Virginia
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1. or just the crate is a National Instruments NI NI PXI 1042 series chasis and the NI designed modules it houses The chasis itself is a Compact 3U rack mountable chasis that provides Universal AC a power overload breaker air temperature regulation and a removable modular power supply In most cases replacing a faulty component can take seconds Taken from National Instruments NI PXI 1042 Series User Manual and Specifications INSTRUMENTS NI PXI 1042 lt 10 KAJ oo0o00000 OO 1 Ol En ra e gt CON EJ Bo o offon o a l1 lO Fw lO 10 lO O gt i ae AE A 8 O 1 Backplane Connectors Located in Slots 1 8 6 System Controller Slot 2 On Off Standby Power Switch 7 Star Trigger Slot 3 Removable Feet 8 Peripheral Slots 4 Power LED 9 Filler Panel 5 Controller Expansion Slots 10 Chassis Model Figure 15 Front View of the PXI 1042 Chasis The chasis backplane supplies several busses to each slot First all modules share the 64 bit CompactPCI compatible PXI bus Second a Star Trigger Bus originates from Slot D and connects to the other six peripheral slots Third a Local Bus connects all seven peripheral slots in a daisy chain the left local bus signals on Slot are us2. 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 8 GETTING STARTED 26 8 3 1 Method 1 Using Finder If hep diskarray physics virginia edu is not already mounted mount it If you re not sure if it s mounted 1 Open Finder from the Dock 2 Press C 3 Look for hep diskarray physics virginia edu in the window presented Now you re ready to locate and copy the data 1 Navigate to hep diskarray physics virginia edu teststand gt VPT Stability Scanner data gt Taken with v3 0 Raw Data 2 Select VPT2181 dat through VPT2185 dat 3 Copy them to a convenient location on your hard drive 8 3 2 Method 2 Using wget Note The bash shell is assumed To mirror the most recent data for local viewing run wget m ftp teststand labview hep diskarray physics virginia edu teststand VPT Stability Scanner data Taken with v3 0 Raw Data VPT218 12345 dat If you don t want to copy the directory structure just drop the m option 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 9 PXI CRATE 27 9 PXI Crate 9 1 Logging into the PXI Crate RDP 9 1 1 Mac You ll need to download and install Microsoft s Remote Desktop Connection Client for Mac 1 Launch Remote Desktop Connection for Mac 2 In the Computer field enter the IP address 128 143 196 230 Press Connect 3 When prompted
3. A common type of RF connector for terminating coaxial cable Cables terminated at both ends by BNC connectors are colloquially called BNC cables BNC connectors are 50 2 terminators BNC stands for Bayonet Neill Concelman 5 DAQ An abbreviation for Data Acquisition DAQ refers to the process of capturing digital representations of physical processes By definition DAQ involves typically analog sensors circuitry to translate the analog signal into a digitizable form and an ADC Analog to Digital Converter Colloquially DAQ can also refer to the process of capturing those digital signals and recording them 18 FPGA Field Programmable Gate Array A Reconfigurable I O RIO device essentially a programmable integrated circuit IC It can be programmed through LabVIEW from the system controller only to provide real time signalling triggering or processing 3 19 LabVIEW Software development environment created by National Instruments for building and deploying programs called Virtual Instruments written in the visual programming langauge G 2 24 LED board LED pulser board designed and built by Mike Arenton Receives electrical triggers from the PXI Crate and sends optical pulses to the VPTs and PIN diodes 3 MOLEX Molex is a large supplier of electronic interconnects Molex connector is a vernacular term for the two piece interconnects manufactured by Molex 5 NI National Instruments 18 19
4. OS X or C Copy Windows 1 3 Links If this document is viewed as a PDF you ll be able to follow hyperlinks throughout the document These links have different styles depending on their destination EXAMPLE DESCRIPTION Google External link to URI hyperlink Manual pdf External link to local companion files 1 3 Links Internal link within the same document LabVIEW Internal link to glossary definition 108 109 110 111 112 113 114 115 116 2 OVERVIEW 3 2 Overview 2 1 Introduction The University of Virginia is part of the CMS experiment at CERN The CMS detector is a multistage general purpose detector The first inner stage of the detector is the electromagnetic calorimeter Ecal The central cavity of CMS is cylindrical with the beam coming in along its axis The walls of the cylinder are formed by the Ecal detectors The rounded walls are the barrel and at either end are the endcaps The detectors are made of two main components The masses that react with the beam products are dense inorganic PbWO lead tungstate scintillator crystals Behind those scintillators are the scintillation detectors In the barrel these detectors are avalanche photodiodes APDs In the endcap these detectors are Vacuum Photo Triodes VPTs Some of the main objectives of the CMS detector such as the discovery of the Higgs boson will be seen primarily in the Ecal If a light lt 140 GeV Higgs boson is discov
5. PXI Crate The National Instruments crate and contents including hardware modules and software to control the experiment and perform data acquisition DAQ 3 18 22 24 25 quench An abnormal termination of magnet operation caused by part of the superconducting material entering the normal resistive state A quench has not yet occured under HEP supervision A quench should not damage the magnet itself but it can induce kilo volt spikes and arcing and the rapid boil off of cryogens can cause asphyxiation 33 ReadyNAS See RNAS 19 rig Aluminum mounting brace attached to the supersolenoidal magnet housing the LED pulser boards VPT mounting enclosure and anode amplifier boards 3 RNAS ReadyNAS a specific NAS product produced by Netgear RNAS is a specific independent hardware module located in the HEP Computer Room FIXME 22 35 System Controller Generic term for the device that is housed in slot A of a National Instruments PXI chasis This is almost always an Embedded Computer 19 VI Virtual Instrument 20 VPT Vacuum Photo Triodes 9 VPT VI Literally Vacuum Photo triode Virtual Instruments Refers to the HEP software written in Lab VIEW for the National Instruments hardware Includes software and hardware logic 24 25
6. PxI 4071 PXI Digital Multimeter A software controlled Digital Multimeter 6 PXI 5154 Digitizer Oscilloscope A high frequency 2 GS s oscilloscope optimized for automated testing 7 PXI 2593 16 Channel Multiplexer A 16 channel high frequency switching multiplexer able to handle frequencies from DC to 500 MHz This switch receives the anode and PIN diode signals and routes 7 NATIONAL INSTRUMENTS 20 them to the oscilloscope FIXME All signals requiring measurement are routed from this multiplexer to either the DMM or the Oscilloscope FIXME Wouldn t it make more sense for this multiplexer to be adjacent to the 24 channel multiplexer so that they could communicate directly over the local bus 7 2 LabVIEW Host Main v3 2 vi Black Diagram on Stability Scanner Project lvpraj My Computer Stability Scanner Project Ivoroj My Computer Figure 17 LabVIEW Block Diagram of Host Main vi LabVIEW is a graphical programming environment used for developing programs called virtual instru ments or Virtual Instruments VIs which imitate physical instruments LabVIEW uses a visual program ming language called G for building virtual instruments G is a data flow driven language as opposed t
7. constant However checking daily will reveal if a fill was done improperly or if a quench occured 1 Locate the cryogen lab notebook near the cryogen gauges 2 Record the current date and time in the notebook Read the liquid nitrogen gauge which is always on Record the measurement in the notebook To begin taking a liquid helium measurement press the green power button to turn on the gauge oe A oe Wait several seconds then press the black MAN button to take a measurement The Sample light will light up 6 Wait until the Sample light goes out then read the measurement from the LCD display It s a percentage 7 Record the LHe measurement in the notebook 8 Press the green power button to turn off the LHe gauge x DO NOT leave the liquid helium gauge powered on It will unnecessarily heat the cryogens and cause them to boil off more rapidly 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 13 MAINTAINENCE 34 13 3 Filling LN2 Cryogen Y DO consider filling Monday and Friday and always well before reaching 10 capacity l 2 O 0 N Q A 10 11 Measure and log the cryogen levels as in 13 2 Climb up the ladder and unscrew the wingnut from the c clamp at the base of the black ventilation tower Remove the c clamp ventilation tower and the o ring beneath the tower Cli
8. 4 THE RIG 10 4 3 Vacuum Photo triodes The electromagic calorimeter Ecal is composed of scintillators and scintillator detectors The scintilators are transparent PbWO crystals These crystals are relatively weak scintillators producing only 50 photons per MeV K W Bell et al As such to reach the energy resolutions needed by CMS the photodetectors must have a built in gain mechanism with low noise production In the barrel of CMS Avalance Photo Diodes APDs are used However in endcap where radiation levels much higher Vacuum Photo Triodes VPTs are used Figure 7 Photograph of Vacuum Photo Triode A Vacuum Photo Triode VPT is a specific electronic light sensor with a built in photo electron multi plier effect Like a photodiode it exploits the photoelectric effect to liberate electrons with incoming photons As photons strike the photocathode electrons are ejected The photocathode has effectively infinite current to replenish its electrons In addition to the energy from the incident photon the electrons are imparted with an additional 1400 eV of potential energy from the high voltage applied to the anode and dynode Cathode Anode Dynode OV 800 V 600 V Figure 8 VPT Electron Action The emitted photoelectron falls towards the anode and may miss the anode mesh and collide with the dynode causing secondary electron emissions which will fall back towards the anode If the initial photoelectron hits the anode m
9. 4 Starting Data Acquisition 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 9 PXI CRATE 28 9 7 Resuming Data Acquisition Follow this procedure if you wish to resume recording data to the same files after an interruption 1 2 9 8 If necessary log into the PXI crate as in 9 1 Locate one of the data files and open it in a text editor Copy the first column of the last line This is the time offset to resume at If necessary start LabVIEW 89 2 open project VPT Stability 9 3 and or open Host Main vi On the top row of the Host Main vi front panel is a text input box labeled Test Start Time Offset Click to edit the contents and paste the time offset from step 2 Press the Run Once button When prompted enter the original VPT numbers and the rest of the information as before Shutting Down The Crate software Follow this procedure if you wish to shut down the PXI Crate to later reboot it l 2 3 4 9 9 If necessary log into the PXI crate as in 9 1 Logging into the PXI Crate RDP If necessary shut down DAQ as in 9 5 Stopping Data Acquisition Close LabVIEW FIxmE menu commands do not save VIs FIXME Click the start button and navigate to Start gt Logout then choose Power Off when prompted Powering On Hardware Locate the power button on the lower left hand side of the front of the PXI Crate Next to the bu
10. methods to set the voltage except that you press I set instead of V set and the keys 7 8 or 9 instead of 4 5 or 6 1 Press I set Enter a numeric value with the keypad then press Enter 2 Press I set Then use the t arrow keys to select a channel Adjust the voltage with the knob 3 Press the 7 8 or 9 key to select channel 1 2 or 3 Then enter a numerical value on the keypad Then press Enter 10 4 System Set System Set is a menu available from the Menu button One of the things it allows you to do is set channels for series or parallel operation Supply two should have Out Serial Set set to 1 3 For serial use Ch1 should be connected to Ch3 and Ch1 and Ch3 should connect to the load Ch 2 3 serial operation is not permitted 11 HIGH VOLTAGE SUPPLY 30 11 High Voltage Supply All high voltage supply directions are carried out with the small LCD display and keyboard attached to the large red CAEN Nuclear SY1527LC rack mounted system 11 1 Verifying Cable Configuration Inspect the back of the high voltage unit The module inserted in the middle marked 12 CH POS near the bottom in blue should have ten cables connected to channels 0 through 9 Verify the layout by reading the cable labels and comparing them with Table 5 p 30 Table 5 High Voltage Group 01 Channel Cable Label Channel Name Voltage Current HV Anode 1 VPT1 Anode 800 00 V 20 00 pA HV Dynode 1 VPT1 Dynode 600 00 V 20 00 pA HV Anode 2
11. use the username administrator and password UVAVPT If desired you can make local Mac hard drives and printers available to the PXI Crate while you re logged in by editing the connection File Edit a Connection 9 1 2 Linux You ll need to download and install rdesktop for accessing Windows Termainal Services Rdesktop is available through the package management systems of most distributions such as Debian Ubuntu and Redhat A Gnome frontend to rdesktop is also available called grdesktop These directions assume rdesktop 1 FIXME 9 2 Launching LabVIEW 9 3 Opening Project VPT Stability 9 4 Starting Data Acquisition 1 Open the VPT Stability project as in 89 3 2 Open the Host Main vi VI from the project file viewer 3 Press the Run Once button You will be prompted for information e VPT 1 5 reference numbers e Angle in field degrees e Min wait time seconds e Load on off time hours 9 5 Stopping Data Acquisition 1 If necessary log into the PXI crate as in 89 1 Logging into the PXI Crate RDP 2 Locate the Host Main vi window listed under the Window menu of any LabVIEW window The front panel is preferable but not necessary 3 Hit the 9 Stop button 9 6 Restarting Data Acquisition Follow this procedure if you were taking data and wish to start over with the same VPTs 1 If desired copy the old data files to a safe location 2 Delete the original data files 3 Begin following 9
12. 219 220 221 222 223 224 225 226 227 228 229 230 4 THE RIG 9 4 The Rig The rig is a mounting system attached to the superconducting magnet It includes mounts for the VPTs themselves in addition to the LED pulser boards and the Stephenson amplifiers The current rig was assembled during the 2009 2010 school year by Michael Balazs Brian Francis and Benjamin H BH Kent Associate Machine Shop Foreman It features a number of improvements over the previous rig It can accomodate up to five 5 VPTs at once up from two It also has a notched lever on the rear to rotate the VPTs from 25 gt 25 up from 0 gt 23 Figure 6 VPT Angle Adjustment Lever The LED boards are now mounted inside the field near the VPTs clearing a large amount of floorspace that was used for an articulating arm that protruded out of the field and limited the angle of rotation available for the VPTs A new housing has been constructed for the LED boards VPTs and Stephenson amplifiers 4 1 Amplifier Board rixur The Vacuum Photo Triodess VPTs are connected directly to a high speed low noise charge amplifier At the heart of the amplifier circuit is a National Semiconductor CLC428 datasheet which is the Stephenson pre amp chip Fixme Talk to Mike Having trouble following paper trail 4 2 LED Pulser Boards rixur FIXME The LEDs in use are probably 5mm LED RL5 B5515 David Phillips et al
13. 27 1 2 2 Advisories For commands that should be entered literally into a terminal a bold mono spaced font is used For options the user should supply a brief description of the option is surrounded in angle brackets For software application names and operating systems a sans serif font is used The maker of a component is typeset this way The make manufacturer and model number of a component are type set this way The model number of a component is typeset this way A AVOID hazards pointed out by the warning signs Y DO read positive recommendations in boxes like this x DO NOT ignore negative recommendations without consulting with the experiment maintainer 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 1 PREAMBLE 2 1 2 3 Symbols Used For brevity and consistency a number of standard symbols are used to represent keyboard keys These conventions were largely adopted from Mac OS X Table 1 Keyboard Symbols SYMBOL NAME ALSO KNOWN As Shift Control Option Alt Command Windows Key Delete Right Delete Left Escape Return Enter Left NN Up Right Down Tab gt D lel gt 1 ttCAJN se Four of these keys are modifiers 38 X These keys do nothing on their own except for 8 which toggles the Start Menu in Windows and have to be combined with another character This is denoted by joining two keys such as C Copy
14. 282044 e ea da BEE e e o eee a ea 27 9 3 Opening Project VPT Stability o an ee 27 94 Starting Data Acquisition osc oso ssaa errau ee 2 9 5 Stopping Data Acquisition ooo 27 9 6 Restarting Data Acquisition 0 2 ee 27 9 7 Resuming Data Acquisition 1 0 ee 28 9 8 Shutting Down The Crate software ooa a 28 9 9 Powering On Hardware ee 28 9 10 Powering Down Hardware 28 oN Du 10 Low Voltage Supply 29 101 Panel Controls sie a add fH wa Ae BOR die ek Boe eo ee ek A ew GE a 29 10 2 Setting Voltage om me s da a EEE a HERE Dee ee BS 29 10 3 wetting Current vega ca E Pee e PERE ee ee ee fae eee ew 4 29 10 4 System S t cea it eee pbk dda bee eee eld a waa eee OED ES HS 29 11 High Voltage Supply 30 11 1 Verifying Cable Configuration aoaaa 30 11 2 Verifying the Voltage Settings 0000000000000 0000 30 11 3 Killing the High Voltage 2 me o o 30 11 4 Ramping Down the High Voltage e 30 11 5 Ramping Up the High Voltage 0000002000000 0000 31 11 6 Turning Off the High Voltage System e 31 11 7 Turning On the High Voltage System en 31 12 Vaccum Photo triodes VPTs 32 IXTI CleaninhE ica a A a wl AAA AAA oe ed 32 12 2 Mounting VPIS esee swa aadi adada eee ee edana ea ee ee di 32 13 Maintainence 33 18 1 Schedule sa teaa aae 224 WE OY MAS A a REDE SORTASE SG e GAE e O a 33 13 2 Measuring Cryogen Levels aa a a 3
15. 3 13 3 Filling LN2 Cryogen 5 44464 46 65 4 se PEE ene eben daed as dea 34 13 4 Ordering LN2 Cryogen wa a aaiae d a b ee 34 13 5 Filling LHe Oryoge ea sa eee eee eR a AAA ee A 34 13 6 Ordering LHe Cryogen 1 1 odena aaan aa a A 34 List of Figures ANAK WN EH Schematic View of CMS Electromagnetic Calorimeter 00000 3 Rig Connections 4 4404 bh a ea ae SS OE De eae Pee eee ee 4 Signal Pathan Teststand 2 340403 4 4 done y a BE ee Ba ee de da amp 5 Distribution Box for Cathode Signal to Terminal Block o oo o 5 Top down external view of Superconducting Solenoidal Magnet aooaa a 7 VPT Angle Adjustment Lever ee 9 Photograph of Vacuum Photo Triode o 10 VPT Electr n Action seconds oda a eee es 10 VPT Electron Potential Well qualitative o o o o 11 VPT Pulse Shapes iaa aaa a ER EA ds aaa a Pe as 11 VPT Angle Repsponse Example 12 VPT Long Term Eflect uri goes a ra e a e e Y a 12 Front Panel of the SY1527LC System 2 2 14 BK Precision 9130 Front View 020000002000 02020222 16 Front View of the PXI 1042 Chasis 000000000002 2 ee 18 PXI Local Bus and Star Trigger Routing 00000020000 000 19 LabVIEW Block Diagram of Host Main vi 2 ee 20 LabVIEW default Icon and Connection Panels 2 0 000 000 0000 00000004 21 LabVIEW Arrangement Buttons 2l Kimtech Science Kimwipes e 32 List of
16. Operating Instructions for VPT Experiments at UVa s HEP Laboratory Written by John Christopher Jones Summer 2010 DRAFT Contents Contents i List of Figures ii List of Tables ii 1 Preamble 1 1 1 How This Document Was Written e 1 1 2 Conventions Used in This Text 2 2 2 ee 1 13 Links yedun arina a Mi Gee he he e a aa MY A ea a a eR ae E a 2 2 Overview 3 21 Tntrod ctiom sea s saaan hh e RR a Ge Bae eG A 3 2 2 Experimental Setup ss st koa 4k ke aa ad eS 3 I Equipment 6 3 Superconducting Solenoidal Magnet T 31 Cryogeen System a a e a a a a a a a a A a a a a wee G OS ee dc T g2 WALINBS s eca ee A ha AA A BOR AH 8 4 The Rig 9 4 1 Aimplitier Board PMB codi uae eo aa ee ee ee ee a as 9 4 2 LED Pulser Boards FIXME e s a oou c con a d oa a aea a a a a a pa a S aSa a a a a a a 9 4 3 Vacuum Photo triodes a 10 5 High Voltage Supply 14 6 Low Voltage Supply 16 7 National Instruments 18 Wak SP XIVCrAGG skea ae e wee PEGG RSE AA AA A Ra Bee eo 18 2 LabVIEW os saca tha db OO Rt ee Bae e RR a Bae ell Ge a 20 7 3 ReadyNAS RNAS 2 ee 22 II Operations Manual 23 8 Getting Started 24 8 1 Installing LabVIEW 2009 0 2 00002 ee 24 82 Installing the VPT Vis 2 2 6 54364 2 S445 e eee ee e da a 24 8 3 Getting the Latest Data e e 25 9 PXI Crate 27 9 1 Logging into the PXI Crate RDP 2 000000 eee ee 27 9 2 Launching LabVIEW 24 2
17. Switch PXI Crate FPGA Switch 4 4 4 S Low Voltage a Er High Voltage m LED Pulser Board T Ampt Sal 3 x Wry yh Ce n Yo yet j Conceptual node anode only Figure 2 Rig Connections 2 2 1 LED Branch The FPGA sends three TTL signals to a set of powered line driver chips 74LS241N and 74L8241PC which then drives the TTL signals over BNC cables to the powered LED board Each TTL signal corresponds to a single LED 4 2 LED Pulser Boards FIxME Load Signal is a simple simulated collider beam signal intended to represent photon activity during beam events Soak Signal is a faux load between beam events to maintain the VPT s response curve Reference Signal is a measurement pulse inserted between the load and soak pulses to measure the VPT s response characteristics Each of the three optical signals that the LED board emits are multiplexed muxed into five different optical fibers and terminate in light sealed boxes containing a VPT and a PIN diode The PIN diode s signal can be used to make adjustments do to variations in LED light output on a pulse by pulse basis The light from each fiber is projected onto the entirety of the VPT s photocathode So in total each VPT receives three fibers one from each LED and there are five PIN diodes one for each VPT acting as references for LED light output 2 2 2 VPT Branch A VPT 84 3 Vacuum Photo triodes is a single st
18. Tables 1 2 3 Keyboard Symbols s sea ne raa eae ey ype ea Bah Dae e a a aa Waele ee Ey a 2 CAEN Nuclear Components a ooa ee 15 DC Power Supply Channel Configuration 0 0 0 00000000000 0004 16 List of Tables 4 DC Voltage Requirements 5 High Voltage Group 01 iii 1 PREAMBLE 1 Preamble 1 1 How This Document Was Written This document was written in ATX and was compiled with X4I X 0 94 from MacT X 2009 for Unicode support The Lucida Grande font is used for sans serif typefaces available on Mac OS X Anonymous Pro is used for the monospaced font also available on Mac OS X A number of ATEX packages were used The document was typeset with the Memoir class Graphics are provided with the TikZ package The glossary was constructed with the glossaries package Tables make use of the booktabs and multirow packages Links are provided by the hyperref package Several other packages are loaded for symbol support amsmath textcomp ucs xunicode xltxtra 1 2 Conventions Used in This Text 1 2 1 Font Conventions The following conventions are used in this text EXAMPLE DESCRIPTION File Open For menu items a sans serif font is used with gt between the menu items keys For short key sequences that sould be pressed a sans serif font is used foo bar For directories filenames and paths a mono spaced font is used command o file ext file named field LabVIEW CAEN CAEN sy1527LC SY15
19. VPT2 Anode 800 00 V 20 00 pA HV Dynode 2 VPT2 Dynode 600 00 V 20 00 pA HV Anode 3 VPT3 Anode 800 00 V 20 00 pA HV Dynode 3 VPT3 Dynode 600 00 V 20 00 pA HV Anode 4 VPT4 Anode 800 00 V 20 00 pA HV Dynode 4 VPT4 Dynode 600 00 V 20 00 pA HV Anode 5 VPT5 Anode 800 00 V 20 00 pA HV Dynode 5 VPT5 Dynode 600 00 V 20 00 pA OOBONDOBWNF CO Inspect the rig inside the superconducting solenoidal magnet When viewed from the rear which faces the exterior door the high voltage cables enter from the front opposite side and are attached to the VPT mounting rig on the left hand side Visually verify that the top five cables facing you are labeled HV Anode 1 through HV Anode 5 from top to bottom Verify from the front side that the top five cables facing you on the right hand side are labeled HV Dynode 1 through HV Dynode 5 11 2 Verifying the Voltage Settings From the front of the rack examine the color LCD monitor below the high voltage unit Verify that the voltage settings correspond to Table 5 p 30 11 3 Killing the High Voltage A AVOID killing the high voltage unless it s worth the risk of damaging the equipment 1 Turn the key to the off position Y DO ramp the voltage down before shutting the system down whenever possible See 11 4 Ramping 8 8 Down the High Voltage for ramp down instructions 11 4 Ramping Down the High Voltage FIXME Placeholder until detailed walkthrough can be practiced 1 Toggle group mod
20. age photomultiplier The VPT s photocathode dynode and anode accumulate charge as light impacts the photocathode with the most charge accumulating on the anode As photons strike the photocathode electrons are liberated A large potential of 600 V is driven from the photocathode to the dynode The current from the VPT s anode and cathode are ultimately routed 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 2 OVERVIEW 5 gt Multiple Cables 6 Oscilloscope gt Single Cable reference A System Controller Figure 3 Signal Path in Teststand to the PXI Crate s switches and then on to the crate s DMM or oscilloscope Before that they go through an amplification stage The VPT s anode is connected directly to a Stephenson amplifier 4 1 Amplifier Board Fixme which connects to the high frequency switch The PIN diode signal passes unmodified to that same 7 high frequency switch The cathode signal cables connect to a distribution box near the PXI Crate The dis tribution box then routes their signals to the terminal block on the O low frequency switch All of these signals leave the rig over BNC cables before terminating at or adjacent to the PXI Crate Figure 4 Distribution Box for Cathode Signal to Terminal Block A temperature and humidity monitor is moun
21. e from the Groups menu 2 Turn off any channel while group mode is enabled all grouped channels will ramp down together 11 HIGH VOLTAGE SUPPLY 31 11 5 Ramping Up the High Voltage FIXME Placeholder until detailed walkthrough can be practiced 1 Toggle group mode from the Groups menu 2 Turn on any channel while group mode is enabled all grouped channels will ramp up together 11 6 Turning Off the High Voltage System The system rarely needs to be entirely turned off Channel boards and power supplies may be hot swapped and channels only need to be ramped down before disconnecting cables However there is an additional safety factor in powering the entire system down before tampering with high voltage 1 Ramp down the voltage see 11 4 p 30 2 Turn the key to the off position 11 7 Turning On the High Voltage System To turn the high voltage on from a power off state 1 Turn the key to the local position 2 Ramp up the voltage see 11 5 p 31 Note In the future the key may need to be turned to remote Check with the experiment maintainer if there are additional cables connected to the front panel 12 VACCUM PHOTO TRIODES VPTS 32 12 Vaccum Photo triodes VPTs 12 1 Cleaning Only the photocathode face needs to be cleaned Fingerprints should be wiped away using disposable lens cloths A small green cardboard box of Kimwipes Delicate Task Wipers is usually located near the rig for easy access Kimwipe
22. ed for Star Trigger and the right local bus signals on Slot are not routed The Local Bus is 13 lines wide and can pass anything from high speed TTL to analog signals up to 42 V Fourth the Trigger Bus provides eight shared trigger lines to all eight slots Finally the chasis supplies a 10 MHz system reference clock signal PXI_CLK10 independently to each peripheral slot The clock signal is also accessible externally via rear mounted BNC connectors 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 7 NATIONAL INSTRUMENTS 19 Taken from National Instruments NI PXI 1042 Series User Manual and Specifications Star Triggers y Y l Local Bus Bus V7 Peripheral Slot 4 Peripheral Slot 8 System Controller Slot 1 Star Trigger Peripheral Slot 2 Peripheral Slot 7 __ PCI Arbitration and Clock Signals Figure 16 PXI Local Bus and Star Trigger Routing 7 1 2 Modules The chasis at HEP is configured with the following modules described in the following sections A PXI 8104 Embedded Computer A full featured embedded computer running Windows XP down graded from Windows Vista Business by default by NI This module ultimately controls all the other components in the crate It
23. er 2009 on the left hand side Insert the disc and install the package titled LabVIEWPro2009 mpkg You re done 8 2 Installing the VPT VIs Copy the most recent VPT VIs from the ReadyNAS to a convenient location Their remote location is ftp hep diskarray physics virginia edu teststand VPT Stability Scanner v3 0 5 VPTs All data is stored on the ReadyNAS see 7 3 and accessible via FTP Open an FTP connection to ftp hep diskarray physics virginia edu The teststand directory contains all of the data which is intended for use by the PXI Crate To install the latest version of the VPT Stability Scanner VIs download the directory teststand VPT Stability Scanner v3 0 5 VPTs If you re unfamiliar with FTP you may use any of the following methods 8 2 1 Method 1 Using Finder First connect to the server To do this for the first time 1 Select Finder from the Dock 2 Press 38K or select Go gt Connect to Server from the menubar 3 Enter the server address as ftp teststand labview hep diskarray physics virginia edu 4 optional Click the button to add it to your favorite servers 5 Press the Connect button If you ve added the server to your favorites and later eject the server you can reconnect by the following procedure 1 Select Finder from the Dock 2 Press 38K or select Go gt Connect to Server from the menubar 3 Select ftp teststand labview hep diskarray physics v
24. er Reading We are currently Summer 2010 studying their long term response behavior which has been shown to decay over time 2 2 Experimental Setup The experimental setup at UVa has two main sections The PXI Crate and the Rig The PXI Crate sends signals from its D Field Programmable Gate Array FPGA module to the rig s LED boards The boards send a photon pulse to VPTs housed inside a 3 8 T magnetic field and the VPT translates those photons into a charge on its anode The anode signal is amplified by a Stephenson amplifier and that amplified signal is sent back to the PXI Crate s G Switch The PXI Crate then processes and records the signals 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 2 OVERVIEW 4 Conceptually part of the rig a high voltage supply provides a 800 V and 600 V potential difference to the VPT s anode and dynode respectively A low voltage supply provides power to the LED pulser boards and the Stephenson amplifier Figure 2 is a conceptual view of the conduits between the components of the rig The Amp branch is a simplification Only the VPT anode connects to the amp which then connects to the T Switch The VPT cathode bypasses the amp and connects to the G Switch The PIN diode 2 2 2 VPT Branch part of the VPT node here also bypasses the Amp to connect to the 7
25. ered it will be from a H 2y decay Above 140 GeV and through 600 GeV the Higgs boson is predicted to decay into two Z bosons which further decay into four leptops such as electrons and muons Electrons and photons will be detected by the Ecal Taken from K W Bell et al Vacuum Phototriodes for the CMS Electromagnetic Calorimeter Endcap IEEE Transactions on Nuclear Science vol 51 no 5 pp 2284 2287 2004 3 5m Figure 1 Schematic View of CMS Electromagnetic Calorimeter As the beam comes in on axis the majority of the beam products are produced just off axis This means that the endcaps receive the highest radiation dosage and the detectors need to be especially hardened against neutron radiation The PbWO crystals scintillate in the visible spectrum near 420nm The faceplates of the VPTs are made of a radiation hard UV transmitting borosilicate glass Glass tends to darken when exposed to neutron radiation The glass used for the VPT faceplates is manufactured in small batches and is proven to have less than 10 transmission loss after a dose of 20kGy over a 48 hour period using a Co source prior to being accepted for use in VPT production The exact performance characteristics of VPTs under extended optical loads in strong magnetic fields are still being studied The University of Virginia has previously studied their performance under temperature variation and also under a non axial magnetic field 4 3 1 Furth
26. esh it may also cause secondary emissions which will impact the dynode and cause tertiary emissions to fall back to the dynode The electrons continue falling up and down the potential energy well causing secondary emissions until their kinetic energy at the anode is less than the work function and so get absorbed without secondary emissions This results in a rapid rise in output anode current 249 257 258 259 260 261 262 263 264 265 266 4 THE RIG 11 followed by a slower fall off This process is extremely fast returning to zero current from a pulse of 420 nm light in around 200 ns The 200 ns response time of VPTs makes them acceptable for use in CMS which operates at 40 MHz T 25ns The chance of beam products interacting with the same barrel crystal before complete recovery is small and the occasional overlapping event can be detected accounted for U x T Q gt A e E o Figure 9 VPT Electron Potential Well qualitative Taken from Christine Drown s PHY 393 Spring 2008 Paper Test Data gt THe Figure 10 VPT Pulse Shape When we test a VPT at HEP we send a pulse of light from a single source an LED down at least two different fibers One fiber illuminates the photocathode of the VPT while the other illuminates a standardized PIN diode We use the PIN diode s output as a reference for the light input to the VPT We can then calculate the gain or the amount of charge amplificatio
27. hosts an RDP server for remote login The maximum amount of RAM has been installed 2 GiB as two SO DIMMs of PC2 5300 1 GiB 128 MiBx64 CL 5 1 18inch max NI part number 779302 1024 It also features a Celeron M 440 1 86 GHz single core a 60 GB SATA hard drive and gigabit ethernet As it occupies the System Controller slot it is generally referred to as the system controller in NI literature For detailed information see the PXI 8104 User Manual The internal hard drive is only used for system and experiment software All experimental data is stored on the ReadyNAS D PXI 7851R FPGA Essentially a reprogrammable integrated circuit the FPGA controls all the real time trigger signals The module itself has a break out box connector and the break out box houses the connections to devices which receive external trigger signals Namely the LED pulser boards The break out box is an NI SCB 68 3 FIXME 24 Channel two wire Multiplexer Referred to as the switch Featuring a single large external port the switch connects any of the 24 two wire channels to the internal busses The switching mechanism is software controlled An NI TB 2605 multiplexing terminal block is currently mounted directly on it This switch receives the cathode current and humiter signals and routes them to the DMM FIXME This is either an PXI 2501 or PXI 2503 multiplexer 4 PxI 4119 DC Power Supply A software controlled DC power supply not currently in use 5
28. ill only allow you to complete connections between compatible types but it will automatically insert conversion components for you if possible New components may be dragged onto the block diagram from the Controls palette The exact behavior produced by a left click varies with the click s distance from an element For instance clicking adjacent to a wire splices a branching connection into the wire while clicking exactly on the wire allows you to select the wire itself The cursor will change to help you determine what will happen o gt iB gt gt Figure 19 LabVIEW Arrangement Buttons a a 1 Because editing with the mouse can be a bit tedious LabVIEW has a number of tools to automate a lot of large scale housekeeping on block diagrams Under the Edit menu you can automatically Remove Broken Wires and Clean Up Diagram In the toolbar of the block diagram you ll find menus to align distribute group layer and clean up selected components 7 2 2 Projects and VIs A collection of LabVIEW files and non LabVIEW files that you can use to create build speci fications and deploy or download files to targets Definition of project from Getting Started with Lab VIEW A project in LabVIEW is a somewhat informal collection of files which can aggregate dependencies and help build and deploy files to targets A project is not even necessary for most tasks in LabVIEW and VIs can be designed and run without crea
29. irginia edu from the favorites list 4 Press the Connect button 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 8 GETTING STARTED 25 Opening an FTP site in Finder works exactly like any regular folder in Finder If you like you can switch the view to Browser Mode by hitting the clear oblong oval in the far upper right hand corner of the window Navigate to teststand VPT Stability Scanner and drag v3 0 5 VPTs to a convenient location Note Do not attempt to view data on the remotely mounted server Copy the VIs and the data to your local hard drive before working on them It was discovered through trial and error that it s best to view the data on a machine separate from the one that is taking data Working non locally with data or VIs while an experiment is running may cause problems for you or the experiment 8 2 2 Method 2 Using wget If you have a unix like operating system Linux Mac OS X or use Cygwin on Windows and are comfortable on the command line wget is an excellent tool to use This method duplicates the directory structure of hep diskarray which can be very convenient for maintaining consistency between your local copy and the PXI Crate Open a terminal and cd to a directory where you d like to store your mirrored directories To
30. may also contain any number of additional VIs VIs referenced within another VI are called sub VIs for the sake of discussion but are otherwise the same as any other VI 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 7 NATIONAL INSTRUMENTS 21 Figure 18 LabVIEW default Icon and Connection Panels From the front panel a small icon is visible in the upper right hand corner of the window This is how the VI appears when placed in another VI If you right click this icon from the front panel only and select Show Connector and then a component on the front panel you ll reveal connection pins that you can assign to front panel components by clicking the pin and then a front panel component If you use this VI as a sub VI you ll be able to fill in front panel inputs and read front panel outputs from another VI by using the pin connections The block diagram will automatically be populated with the required components for the front panel and the pin connections you ve designated from the front panel Connections between block diagram components can be made by clicking on the small pin out location you wish to start from and the small pin in location on the destination A wire will be drawn from the source to the destination The style color thickness pattern will indicate its type LabVIEW w
31. mb down and slowly turn the blue valve connected by pipe to the magnet Allow the LN2 to flow slowly at first to cool the valve and piping then open the valve all the way A constant plume of white vapour will shoot from the valve where the ventilation tower was removed Return to the LN2 gauge and monitor the fill It takes 10 min on average to fill 25 Dust frost off the ventillation tower valve every 5 10 min or so Once the gauge reaches 100 return to the LN2 dewar and shut off the blue valve Climb up the ladder and thoroughly clean the tower valve Replace the o ring ventillation tower and re attach the c clamp Firmly tighten the wingnut on the c clamp by hand Return to the cryogen gauges and record the 100 LN2 level as in 13 2 x DO NOT forget to replace the o ring Failing to replace the o ring is the easiest mistake to make during an LN2 fill and will cause LN2 to boil off more rapidly J DO move the empty dewar through the computer room and out the doors to the concrete patio 13 4 Ordering LN2 Cryogen FIXME Chris in the stock room in the Beams building handles orders 13 5 Filling LHe Cryogen Y DO fill between 20 30 capacity to use an entire LHe dewar FIXME Placeholder for practiced fill v DO move the empty dewar through the computer room and out the doors to the concrete patio 13 6 Ordering LHe Cryogen Mike HEP handles orders Takes 2 3 weeks GLOSSARY 35 Glossary BNC
32. mirror only the latest running VPT VI software run wget m ftp teststand labview hep diskarray physics virginia edu teststand VPT Stability Scanner v3 0 5 VPTs This will copy the VIs vi in the following directory structure to your working directory hep diskarray physics virginia edu teststand VPT Stability Scanner v3 0 5 VPTs C FPGA Bitfiles vi If you don t want to copy the directory structure and just want the VIs themselves cd to your own directory and run a command like the following to copy the desired files directly without the directory structure above wget ftp teststand labview hep diskarray physics virginia edu teststand VPT Stability Scanner v3 0 5 VPTs vi 8 3 Getting the Latest Data The location of the latest data is always subject to change All data is usually located in a data directory under the particular experiment s main directory on the RNAS such as teststand VPT Stability Scanner Check with the current experiment maintainer for the latest location For demonstration purposes we ll assume the latest data is located on the RNAS in the following files teststand VPT Stability Scanner data Taken with v3 0 Raw Data VPT2181 dat VPT2182 dat VPT2183 dat VPT2814 dat VPT2185 dat 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552
33. n the VPT provides VPTs have a number of interesting characteristics that need to be studied One of the reasons VPTs were chosen is that they continue to function in strong non axial magnetic fields due to their single stage photomultiplier design However they still exhibit varibility in their response within non axial magnetic fields The field in CMS is not entirely uniform between the beam axis and the outer edges of the endcap Therefore the relative gain of each VPT is affected by the direction of the magnetic field which varies continuously depending on how far from the beam axis the VPT is placed VPTs also demonstrate a burn in effect which can sometimes be quite pronounced The amplification VP s produce degrades over time so that the same pulsed photocurrent will result in less output days later The effect is not permanent however The self correcting behavior of VPTs was being studied at UVA in 2009 when an electrical failure of the old NIM crate damaged several instruments and interrupted the experiment 4 3 1 Further Reading e D C Imrie Long Term Behaviour Of Three Prototype Vacuum Phototriodes Operated With High Photocurrents January 2000 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 4 THE RIG VPTs 16280 16270 16271 Response ADC counts Charge pC Angle deg Figure 11 VPT Angle Repsp
34. o a procedural like C or functional language like LISP or Haskell rixme rephrase In LabVIEW program execution is determined by the availability of data to the components inside a VI As such LabVIEW s programs are inherently parallel meaning that different parts of the program can run simultaneously To get started with LabVIEW right away read the manual Getting Started with LabVIEW This manual is also available from within the LabVIEW 2009 Getting Started dialog when the application is launched in the right hand pane under Help For historical background on LabVIEW see the Wikipedia entry The remainder of this section is a conceptual crash course in LabVIEW For hands on practice FIXME 7 2 1 Block Diagram and Front Panel A Virtual Instrument VI is a program in LabVIEW for which LabVIEW provides a visual programming interface Every VI has a front panel which is a visual representation of its inputs and outputs and a block diagram which is a functional diagram of how to process its inputs and to produce its outputs The actual programming of a VI takes place in the block diagram However you generally start creating the VI from the front panel much like how you generally start writing a function with its interface or signature A VI may be made of atomic logic units like numbers arithmetic and control structures like loops and conditional branches It will contain any widgets you created on the front panel It
35. onse Example Angle 15 Photo Cathode Current 10 nA Anode PIN Corrected Field 3 8 T T VPT 16523 m VPT 16541 240 220 200 Pp 00 o Pp a o 120 L f 0 100 200 300 400 500 600 700 800 Time hour Figure 12 VPT Long Term Effect 12 4 THE RIG 13 e M N Achasov et al Compact Vacuum Phototriodes for operation in strong magnetic field 26 February 2001 e K W Bell et al Vacuum Phototriodes for the CMS Electromagnetic Calorimeter Endcap October 2004 e P Adzic et al Intercalibration of the barrel electromagnetic calorimeter of the CMS experiment at start up October 2008 At UVA e C Drown Properties of Vacuum Photo Triodes in a 4T Magnetic Field Spring 2008 e D G Phillips II et al A Measurement of the Temperature Stability of Vacuum Phototriodes for the CMS ECAL e J C Jones Long Term VPT Response of Vacuum Photo Triodes Fall 2008 5 HIGH VOLTAGE SUPPLY 14 5 High Voltage Supply Our high voltage supply is made by CAEN CAEN is one of the main companies responsible for the design and manufacturing of components in ATLAS CMS ALICE and LHCb To date CAEN has supplied the LHC with 6138 units The modular CAEN high voltage supply replaced an aging power supply in 2009 Our high voltage modules are housed in an 8U high 19 inch wide CAEN sY1527LC Universal Multichannel Power Supply System which acts as a chasis and system controller for the various installed module
36. ot set up A key on the primary power supply front bottom right module may be set to Off Local or Remote Off completely powers down the rig and immediately kills any voltage supply channels without ramping down the voltage Local powers on the system and provides local control via the LCD and keyboard Remote sets the system to allow a remote power on using NIM RS232 or ethernet 5 HIGH VOLTAGE SUPPLY 15 Model Number Location Description SY1527LC Chasis Modular power supply chasis A1531 Front Primary chasis power supply A1532 Front Auxillary chasis power supply A1833D Rear Positive high voltage supply A1833N Rear Negative high voltage supply Table 2 CAEN Nuclear Components x DO NOT power down the system by turning the key on the primary power supply without first initiating a software controlled ramp down Y DO power down the rig by first setting all of the channels to ramp down and then turning off the system with the key For detailed information on the SY1527 system see the CAEN SY1527 User Manual At present only the positive HV channel board is used to supply 800 V and 600V to the five VPT anodes and dynodes respectively These ten cables run across the floor to the magnet and connect to the rig For further operating instructions see 11 High Voltage Supply 6 LOW VOLTAGE SUPPLY 16 6 Low Voltage Supply 334 Most of the pieces of equipment in the rig have low voltage and current requirements For our exte
37. rconducting magnets have a number of significant advantages over ferromagnetic solenoids Operat ing at high currents they can be relatively compact compared with their ferromagnetic cousins Of practical benefit in the lab their interior where the field direction and magnitude is nearly uniform can be empty and externally accessible as in our lab Ferromagnetic solenoids must house a ferromagnetic yoke along their axis to achieve the field strengths of supersolenoids When wired in persistent mode a supersolenoid requires no additional electrical power and may remain at full strength while disconnected from a power source indefinitely While in persistent mode a supersolenoid s field is more stable than a ferromagnetic solenoid which is practically advantageous when measurements must be taken over extended periods 3 1 Cryogen System Maintenance of the superconductor s cryogen system is detailed in 13 Maintainence The cryogens boil off and need to be monitored regularly as detailed in 13 2 Measuring Cryogen Levels 3 1 1 Liquid Nitrogen The liquid nitrogen boils off at a rate of 10 per day when it is nearly full The rate increases somewhat as the tank approaches empty It s generally good policy to keep the LN2 level as high as possible filling on Mondays and Fridays in case a fill must be missed for some reason The liquid nitrogen is usually delivered in 240 L dewars such as the Taylor Wharton XL 65 dewar For filling instr
38. rnal 335 power supply we use two BK Precision 9130 Triple Output Programmable DC Power Supplies 336 Taken from BK Precision 9130 Manual Figure 14 BK Precision 9130 Front View The BK Precision 9130 Triple Output Programmable DC Power Supply has three independent outputs 337 providing 0 30 V amp 0 3 A on two channels and 0 5 V amp 0 3 A on a third It can be remotely controlled over 338 USB or RS232 It is also rack mountable at 2 Ux U 339 Supply Channel Voltage Current Distributed to 1 1 12 0 V 0 665 A LCD Monitor Power 1 2 12 0 V 0 082 A LED Pulser Board Power Humiditer Power 1 3 5 0 V 0 045 A LED Pulser Board Voltage Bias Trigger s Pulse Gen erator Chip Power 2 1 10 0 V 0 421 A Supply 2 is wired in series to provide a 5 V supply 2 2 0 0 V OFF relative to the ground shared by the Stephenson 2 3 Series CH1 3 Amp and FPGA rather than a floating ground Table 3 DC Power Supply Channel Configuration For detailed information on the external power supplies see the BK Precision 9130 Manual 340 Table 3 lists the voltage each channel is set to and what it is currently connected to Table 4 lists the 341 cables which require low voltage supplies and where they re currently connected 342 The FPGA is capable of meeting the voltage and current requirements for the LED boards and directly 343 connecting them would also allow the LED bias to be controlled directly by the FPGA That would permit 344 us to cont
39. rol the photocurrent automatically They were removed from the FPGA while tracking down a 345 source of signal noise and may be safely re attached to the FPGA at a later date 346 The Trigger Pulse Generator Chip is a pair of a 74LS241N and 74LS241PC line drivers chips designed 347 to be able to drive signals over BNC cables The trigger signals run from the FPGA to the generator chips 348 and then on to the LED boards themselves The FPGA isn t capable of driving the BNC cables directly 349 6 LOW VOLTAGE SUPPLY Cable Name Cable Pair Voltage Supply blue LED Bias 5V Supply 1 Ch 3 i green LED Bias 5V Supply 1 Ch 3 DRL Volinas orange LED Bias 5V Supply 1 Ch 3 brown LED Power 12V Supply 1 Ch 2 Stephenson Amp 5V to earth ground Supply 2 blue Trigger Pulse Gen 5V Supply 1 Ch 3 Local Power brown Not used 12V Supply 1 Ch 2 Humiditer green Power 12V Supply 1 Ch 2 LCD Panel red amp black Power 12V Supply 1 Ch 1 Table 4 DC Voltage Requirements 17 7 NATIONAL INSTRUMENTS 18 7 National Instruments 7 1 PXI Crate The National Instruments PXI Crate is a programmable experimental test stand capable of automating many aspects of an experiment It can be configured to control the experiment perform advanced analog and digital signalling and sampling control power supplies perform DAQ process and export data and more 7 1 1 NI PXI 1042 Chasis What we refer to as the PXI Crate
40. s Essuie tout pour t ches d licates Pa os para tareas delicadas Figure 20 Kimtech Science Kimwipes 12 2 Mounting VPTs Each VPT has three cables connected to the anode tan white dynode blue and cathode gold yellow The cathode is sometimes labeled with the letter K from the Russian spelling The dynode and cathode colors can be remembered with the euphemistic mnemonic as KY dB 714 715 716 13 MAINTAINENCE 33 13 Maintainence 13 1 Schedule This section lists tasks which must be done regularly to maintain the experimental equipment or ongoing experiments The following vocabulary is used in this section DAILY Once per day at any time unless otherwise specified SEMI DAILY Every other day BIWEEKLY Twice a week or every 3 4 days MONTHLY Once per month AS NEEDED As often as necessary frequency determined by another maintenance step 13 1 1 Under All Conditions The following tasks must be carried out whether or not an experiment is currently under way DAILY Measure cryogen levels AS NEEDED Fill LN2 cryogen AS NEEDED Fill LHe cryogen MONTHLY Measure magnetic field strength 13 1 2 Experiment VPT Stability The following tasks are only required during VPT Stability experiments DAILY Verify DAQ is still running BIWEEKLY Examine data for experimental errors 13 2 Measuring Cryogen Levels Cryogen levels should be checked daily Under normal conditions the cryogen evaporation rate is virtually
41. s The sY1527 system has four main sections On the front are the CPU and Front Panel section and the Power Supply section On the rear are the Board Section and the Fan Unit The Lc designation means low cost and refers to lack of a built in LCD screen compact switch alphanumeric keyboard and I O Control section Taken from CAEN SY1527 User Manual Figure 2 3 CAEN Nuclear O gt dy E Interface Bus fo 2 o Figure 13 Front Panel of the SY1527LC System The Power Supply Section houses up to four power supply units which provide power to the whole system We use one optional power supply in addition to the primary power supply The Board Section houses up to 16 Channel Boards We use two standard HV boards which distribute high voltage to the experimental rig However the system is capable of housing other types of boards including low voltage and generic I O boards We do not use CAEN LV boards for our needs they are cost prohibitive The system may be controlled either locally or remotely A small 7 7 inch color LCD and a standard PS 2 keyboard are attached to the system for local control The system can be remotely controlled over RS232 serial or ethernet Over ethernet the system can be logged into via telnet CAEN has also developed a C language library CAEN HV Wrapper for remotely monitoring and controlling system parameters over TCP IP Currently remote control is n
42. s peripheral hardware such as the FPGA DMM oscilloscope or switches These components need to be programmed and tested from LabVIEW on the PXI Crate itself as in 9 1 Logging into the PXI Crate RDP The RNAS is configured for FTP access For FTP directions see 8 2 Installing the VPT VIs and 8 3 Getting the Latest Data x DO NOT upload VIs without first making sure that LabVIEW on the crate has closed those VIs x DO NOT directly edit VIs or use viewing or processing VIs to view or edit data directly from the RNAS if you have chosen to mount the remote filesystem You may corrupt LabVIEW state on the crate or your own computer or cause availability or timing errors in ongoing experiments Y DO make a local copy of any VI or data you wish to use You may safely copy data files while they are being written to Part Il Operations Manual 8 GETTING STARTED 24 8 Getting Started 8 1 Installing LabVIEW 2009 You will need access to LabVIEW to start and stop experiments to view data and to export data As of Summer 2010 you ll need LabVIEW 2009 The National Instruments site licensed installation discs are located in the HEP building in a small square black CD sized zipper pouch with a blue spine The pouch s spine is labeled National Instruments Academic Site License 2009 Software for Classrooms Labs ES Research 8 1 1 Mac Locate the white DVD labeled NI LabVIEW 2009 This disc also bears the label Third Quart
43. t to keep the context help fixed on it Usually the best way to find out how to do something new is to find an example The example search engine can be found in LabVIEW by navigating to Help gt Find Examples One of the directories listed under Browse tab is called Fundamentals which will show you how to deal with the basics such as basic data types control structures and file I O Going through most of the examples in this directory will help you become familiar with the visual vocabulary of LabVIEW The official National Instruments forums are also a useful source of information In addition the UVa Site License includes a support contract For help FIXME 7 3 ReadyNAS RNAS The ReadyNAS RNAS is a ready made NAS solution NAS is an acronym for Network Attached Storage a file level as opposed to block level remote storage system The NetGEAR ReadyNAS NV acts as a network filesystem for the PXI Crate in addition to the crate s native filesystem on its local SATA hard drive The RNAS is backed up daily by Brian Wright Much of your interaction with the crate will happen indirectly via the RNAS You ll usually want to edit VIs locally and then upload them to the RNAS when its time to update the experiment s software VIs are usually programmed to log their data to the RNAS so you ll retreive the latest data from the RNAS as well The main exception to this is any VI which requires access to the crate
44. ted next to the rig and a single cat5 cable carries power to 175 176 177 178 179 180 181 182 it and returns its readings to the O low frequency switch via the distribution box It connects via MOLEX 183 connector next to the cathode signal BNC connectors 184 Part I Equipment 3 SUPERCONDUCTING SOLENOIDAL MAGNET 7 3 Superconducting Solenoidal Magnet Figure 5 Top down external view of Superconducting Solenoidal Magnet The laboratory at HEP houses a Type I superconducting solenoidal supersolenoid electromagnet wired for persistent operation Lacking the flux resistive characteristics of Type II superconductors a Type I superconducting electromagnet is able to maintain a constant field over the course of years rather than the weeks to months of a higher temperature Type II supersolenoid However like all known Type I super conductors its critical temperature lies just north of 4K necessitating that it be cooled with liquid helium LHe Similar to other small LHe cryogen systems the supersolenoid uses a three chamber system The outer chamber is under partial vaccum to insulate the interior chambers from ambient temperature The middle chamber is filled with liquid nitrogen to cool the interior chambers to a maximum of 78K The innermost chamber which houses the superconducting solenoid is filled with liquid helium Liquid helium comes into direct contact with the supersolenoid Supe
45. ting a project This is a little different from a lot of development suites which use projects to define the development environment VIs run in the proprietary LabVIEW runtime environment which handles things like execution compilation and dependency resolution You need to use a project if you need to build and deploy a file to a target such as an FPGA or some other statically programmed instrument Other than that projects have little to do with the programming and running of VIs 7 2 3 Documentation There are a number of useful sources of documentation for LabVIEW One of the most useful tools is the Context Help found under Help Show Context Help This will reveal a palette window that will give you information about whatever component you hover the mouse over For instance when hovering over a wire it will tell you the data type the wire caries If you hover over 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 7 NATIONAL INSTRUMENTS 22 a component on the block diagram it will tell you what that component does what its connections are and which are optional You can also get detailed help on anything you can get context help on by clicking the question mark on the lower edge of the context help window Select the componen
46. tton is an LED light If the light near the button is lit the crate is already powered on If it is not lit press the power button 9 10 Powering Down Hardware 1 2 3 First perform a software shutdown as in 9 8 Shutting Down The Crate software Check if the power LED is still lit It is located on the lower left hand side of the front of the PXI Crate near the power button If still powered press the power button once 10 LOW VOLTAGE SUPPLY 29 10 Low Voltage Supply For operating instructions including troubleshooting reference the BK Precision 9130 User Manual or the BK Precision Model 9130 product page 10 1 Panel Controls The On Off key controls the output state on off of all three channels simultaneously To control the output state of an individual channel use the number keys 1 3 Use the 1 3 keys to set the output state of channels 1 3 Similarly use 4 6 keys to set the voltage and 7 9 keys to set the current for each channel 10 2 Setting Voltage There are three different methods to set the voltage 1 Press V set Enter a numeric value with the keypad then press Enter 2 Press V set Then use the t arrow keys to select a channel Adjust the voltage with the knob 3 Press the 4 5 or 6 key to select channel 1 2 or 3 Then enter a numerical value on the keypad Then press Enter 10 3 Setting Current There are three different methods to set the current They are identical to the
47. uctions see 13 3 Filling LN2 Cryogen 3 1 2 Liquid Helium The liquid helium boils off at a rate of 10 per week One full 250L liquid helium dewar will fill the magnet s tank from 20 to around 95 For filling instructions see 13 5 Filling LHe Cryogen 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 3 SUPERCONDUCTING SOLENOIDAL MAGNET 8 3 2 Warnings A AVOID proximity to the magnet if you carry medical equipment including remote monitors and pace makers A AVOID contact with the outer casing while the high voltage is active The central cavity of the magnet houses high voltage equipment Although the outer casing of the magnet should not carry an electric potential improper grounding wiring or cable failure may occur The high voltage to this equipment should be powered down before touching the outer casing of the magnet or the rig A AVOID bringing magnetic materials near the magnet The strength of the magnetic field grows inversely to the cube of distance that is much faster than intuition may suggest Screwdrivers metallic watches and even metal glasses have been known to be pulled off of individuals passing by the magnet Remember to remove your wallet before approaching the 10000 gauss line near the magnet because it will erase your credit cards
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