labg report 1
DESCRIPTION
LABG Report 1TRANSCRIPT
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LabG Report 1
*In this Report, I begin presenting the main ideas told to us by Howard Budd about the main hardware components relevant for the DAQ at the MINERvA Detector.
Antonio ZB, Feb 19 to 27
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What we saw at LabG● We were presented the FEBs, the daisy-chain connections, the
button on the FEB to reset them if any problem arises, we were told about the CRIM (which supplies timing) and also about the CRATE controller & the CROC (More details will be presented below in this report).
● Some relevant numbers: At the Test-Beam: ~45 FEBs and ~500 in the MINERvA Detector. A chain consists of ~6-11 FEBs. There is 1 CRATE for the Test-Beam and 2 for the MINERvA-Detector.
● We saw the inner part of a PMT, the 64 clean-fibbers which transmit light to a specific part inside the PMT which converts this into electric-charge (a high voltage there, according to Howard ~O(100 volts)). Here there is a phototube which acts as an amplifier based on the photoelectric effect.
● The Charge is stored by the TripT-chips. The digitalization of this charge is performed at the FEBs.
● We were explained by Gianina about the most common damages these fibbers can experience and how we can detect it by seeing the reflection of light from the damaged part.
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● The “nearline” has basic information coming from the detector.
● We will be able to Reset or Change a FBE is there is any problem (most of the time the problem resides in 1 single FEB). It's relevant for us to be able to detect a failure among the FEBs in usage. But we cannot replace PMTs, there is specific personnel designed to perform this work.
● Then Howard presented us a program, a file he used and told us that in the case at hand (when the FEBs were not connected to any PMT), we can monitor each FEB and obtain a fixed value of RHV of ~ 25'000. This is important because that's the value present when a FEB is not detecting any FEB so....it would be useful to detect which FEB is not working when a problem arises.
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● Gerald wrote down the name of some files used by Howard in his PC:
● 0.Slowcontrol.sh, 1.CROCE.hwcf <----File which can be set ON or OFF, it was chosen OFF---> not put (this time):
WPL HV TARGET (0)
WR HV TARGET 48200 (usually for test).
● 0.5 CROCE ----> FE (1,2,3,4)
● UOT PMT (changes voltage)
RHV Actual----->25058 right now (this is the important-to-consider level of reference when no PMT is connected to a FEB, as was commented previously).
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The MINERνA Data Acquisition System and Infrastructure (Read-out Electronics)
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● This document discusses the MINERνA data acquisition system (DAQ)in two steps:
● First, the custom electronics are described, followed by a description of the DAQ software and computing architecture.
● The initial specifications for the DAQ readout system asked for a readout rate of 100 kB/s∼ with a duty factor defined by one 10 microsecond beam spill every 2.2 seconds . ∼Fortunately, those specifications were surpassed as our initial estimate for required data throughput was low by about a factor of five.
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● The DAQ, Slow-Controls (SC) & Near-Online monitoring ("nearline") are built around MINERvA-Specific Readout Electronics.
● Minerva uses plastic-scintillator as its fundamental detector technology.
● Light is delivered via Wavelength-Shifting_Fiber (WLS) to Hamamatsu R7600 64-channel (hay 64 hilos de plastico transparentes) multi-anode photomultiplier tubes (PMTs).
● A small number of single-anode PMTs are also mounted for a "Veto-Wall" detector that sits in front of the main Minerva Detector.
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WLS
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PMTs
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VETO WALL
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● Each PMT is read out by a Front-End-Board (FEB) mounting 6 Application-Specific Integrated Circuit (ASIC) chips (TriP-t chips) that digitize & store Charge (Q) using pipeline ADCs.
● Input charges from the PMT anodes are divided into high, medium, and low gain channels using a capacitive divider to increase the dynamic range.
--->The high gain is 1.25 fC/ADC, the
medium is 4 fC/ADC, and the low is 15.6 fC/ADC.
● The FEBs generate the high voltage for most of the PMTs using an on-board Cockroft-Walton (CW) generator.
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● The control circuitry resides on the FEB while the CW chain itself resides on the base (on the PMT board), with appropiate taps for each dynode.
● A small number of the PMTs are single-anode & use resistor-base technology for voltage control.These PMTs are used to read out the Veto Wall and employ a separate voltage control system discussed below.
● All FEB operations are controlled by a Spartan 3E Field-Programmable Gate Array (FPGA) chip.
-->The FPGAs decode timing signals received over the unshielded twisted pair (UTP) cables, sequence the Trip-t chips a& decode & respond appropriately to communication frames received over the data link.
● -->The FPGA also controls the CW and other aspects of FEB operation.
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● CRATE controller Interface talks to PC & CRATE, the CRIM controls Time & Gates, CROCE reads & controls the readout faster than the CROCs (~20xfaster ) because there is no traffic between PC & CROCE. At the FTBF there are 3 CROCEs.
● For data collection, the boards are daisy-chained together (into “chains”) using standard UTP ethernet networking cables with a custom protocol and Low Voltage Differential Signaling (LVDS).
● Of the four pairs in the cable, one is dedicated to timing, including clock and encoded signals, one is dedicated for data, one is used to indicate the sync-lock status of the data Serializer/Deserializer
(SERDES) and one for a test pulse.
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MEETING WITH HOWARD ON 02/24● Today we saw how to install a PMT, 1st connecting the 8 DDKs (Japanese)
connectors at the back of the PMT. Those connectors were cleaned with 100% Ethanol.
● We were told about the importance of the Period, how the CW provides HV (High-Voltage).
● We installed an FEB to the other side of the PMT. This device is going to stored Charge within its TripTs (to then be digitized).
● One of the FEBs was not working properly (only 1 green light appeared when even if we reseted again many times).
● Howard filled within his computer (in the Elog) a form in which he specified the FEB that was failing & specified the new-one (the codes). To check----->Form fill FEB SWAP (Min-data TEst Beam). Run 384, Subrun 4.
● We have to be careful about numerations of Chains & Channels: CHAIN IN THE CROCE (1-4) & IN THE SOFTWARE (0-3) (CHAIN). "Be careful about this numeration of CHAINS & CHANNELS": Channel=Chain +1
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● *Procedures for testing PMT, no cross talk
● *Load File Power on configuration----->ON (to take data), OFF (cable on PMT).
● *WR HV Enable (0 off HV, 1 on HV).
● *WR HV Target (value of HV).
● One shoot (300) current table {Dispatcher acquisitor manager}.
● FLASH Return to Service instructions.
● Flash Reset Firmware 91----->Now is running.
● FEB not properly plug-in----> 25'000 overshoot the voltage.
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What Howard told me on 02/25● We need to fill 3 Forms in order to specify we replaced a FEB:
1)Electronic Form--->He already filled in within the Elog.
2)Paper-Form
3)Another Electronic-Form (for the TB & MD)
● Exist a Calibration for each FEB.
● DocDB (4086-v54)--->Document of mounted PMTs.
● When there is a replacement in a FEB || PMT--->That File has to be updated.
● The software is labeled in terms of CRATE, CROC, CHAIN, FEB (I will show this in a picture).
● The CW on the board of the PMT supplies:
*HV (High-Voltage)*Mechanism to get signal out of the tube.It also eliminates the us of HV in all the detector, All Voltage<50V
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● The problem right now seems to be in the PMT, perhaps it's a light leak, the PMT we are analyzing has low Period.
● Cross-Talk failures: The PMT is bad, we need some SPARES?
● If there is a problem during the DAQ the order to find the problem is the following: 1)Run-Control, 2)Use a Script to Reset, 3)Slow-Control.
● OBS: SC may work, but not necessarily the DAQ.
● If you can Download the Configuration-File---->DAQ is going to run.
● HV ON---->To take Data before you Start a Run.
● HV OFF--->If you are checking the Detector.
● Howard's Guess about the current problem: No Light-Leak, the PMT itself is wrong...to be confirmed on 02/26.
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Especificación de los FEBs
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MEETING ON 02/26
● We were analyzing a PMT, we were worry about any possible light-leak. So we took measurements in 2 scenarios: i)The PMT completely covered (no light inside) & ii)The PMT uncovered (so light entered) in order to see any difference, which would indicate there is a light leak.
● We shouldn't damage the PMTs by providing high Voltage (higher than 800V) to them.
● ADC-counts: Analog-to-Digital converter.
● OBS: Dran current only occurs if there is HV (High-Voltage).
● CW--->it generates little current whilst providing HV, this works only for neutrino-Experiments, the Gain is a function of the Voltage on the PMT.
● In a Phototube, we have 2 important parameters: i)Quantum_Efficiency & ii)Gain.
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● Quant-Efficiency----->measures the probability to convert 1 photon into an electron, is a property of the material, not on the Voltage (the glass painted at the end of the 64 transparent cables). It is ~ 13%.
● GAIN----->Measures the amount of Charge we get from a photon. It's proportional to the Voltage.
● So--------> The relevant factor (which we expect to be High) is the product GAINxQuant-Effic. This because we need enough LIGHT to measure CHARGE.
● OBS: Each CROCE has 4 CHAINs (Set of FEBs Daysi-chained) as a maximum.
● The Slow-Control (SC) tells you what is Found. Download the needed CONFIGURATION-FILE (MANDATORY FOR TAKING DATA, it provides the parameters for doing it & you need it to Start a RUN). If you want to take Data, you should use HV-ON, otherwise use HV-OFF (like in the present case).
● We performed a PEDESTAL to analyze the PMT connected to the 4th FEB.
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● Another important Document to Read----->Doc DB 9269 v-3: “Procedures for Testing PMTs”. (Attached to the BLOG).
● At the page 3 of that Document---->Important Commands (the order is important) to write in a Terminal.
● In the Run-Control: HV-OFF, Run-Mode=One Shot, Current-State (HW config)=No download config-file.
● A DST (Root-file) was generated.
● Each Trip-T chip has 16 channels,There is a pedestal for each of these. At different pedestals, we test different Hardware.
● You expect groups of 16, for 1 Trip-T the situation is slightly different.
● We test for Cross-Talk. At the End the problem was not a Light-Leak but the Low-Period. The System decides the period for each FEB?
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RESULTS
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● There was no difference in the pixel-pattern when there is or not LIGHT. So there is no Light-Leak, the problem is in the PMT itsel.
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Where the Results are stored?● @[email protected]
● ssh -X , setup.....,----->make a root file.
● H1:Tarp (no tarp)----->Not light-leak, ---->Inclusion: PMT drain current.
● OBS: One cable at the 4th FEB was lose and at the beginning it didn't permit us perform the pedestal.....here Howard is fixing it:
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Friday 27---->We are doing the PMT-analysis by ourselves.
● Step by Step instructions for testing a PMT:● (1)In this case we removed the old PMT, and connected a new one to
the FEB-03(the other FEB-4 has a loose cable).● Obs: PMTs shouldn't be exposed to room-light (to much UV may
damage it because of the high-freq of this radiation).● 2)Once the PMT is connected and all FEB are connected to the
power-supply, we Log-in into the tbonline: username: tbonline, password: axial2009.
● *We open a Terminal and go to: source slowcontrol● *Click FE 3 (HV Actual is 40).● *Download the Configuration-File● *WR HV Pulse Width: If it is 30, we have not downloaded the config-
file, ● Once we do this it changes to 25.
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● *WR HV Enable(1)=1 (To enable the HV)
● (check the parameter at FE:3)
● *Write All FEBs (Obs: The period is controlled manually).
● *Actions--->Start monitoring All HVs.
● *Period Auto: makes sense only if connected to a PMT.
● *Actions---->Stop all monitor.
●
● *Open up > .run_control.sh
●
● *One-Shot <----- Config<----- Request control.
●
● *Run = 388 (this is a default value, don't change it!).
● (You want to analyze the run).
●
● *Start---->Dismiss
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● *Set-up the online (commands in a terminal to analyze the RUN):
● --->source setup.minerva.sh
● --->cd PMT_Labf/
● --->./HakeDST_labF.sh -r 388(the run number) -s 1(the # of subrun)
● --->The DST has been create, then we use Root:
● --->root -l file_just created.
● --->Analyze board 3 (photo)
● --->.q
● Create a File---->log file
● Obs:The CW is draining for 2 reasons:
● 1)Light -leak
● 2)The PMT can be draining current.
● *Show the Pedestal-figure
● *Create a File of what we did.
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