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

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.

● 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.

● 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).

The MINERνA Data Acquisition System and Infrastructure (Read-out Electronics)

● 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.

● 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.

WLS

PMTs

VETO WALL

● 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.

● 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.

● 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.

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

● *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.

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

● 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.

Especificación de los FEBs

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.

● 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.

● 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?

RESULTS

● 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.

Where the Results are stored?● @mnvtbonline@mnvtbonline1.fnal.gov

● 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:

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.

● *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

● *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.