The Charging Cavaliers

Useful links

Data paths and work directories

First things first: Do not save any data on the Desktop or home directory. If we find files there, they will be immediately moved to the work directory...and given a random name wink

  • Your world: /eos/user/b/bl4scc
  • Beam spot histograms: /eos/user/b/bl4sccalignment
  • Temporary files (can be deleted at any time): /eos/user/b/bl4scc/tmp
Please keep these folders nice and clean

How to access data


  • Open putty
  • Make sure that in Connection->SSH->X11, "Enable X11 forwarding" is ticked
  • In session: type as Host Name
  • Click Open
  • Username is bl4scc
  • Open a terminal
  • Type ssh -Y
  • If it asks you to confirm the connection, type yes

Setup environment

  • Once connected to lxplus type: source (or for the lazy ones, type source setupC and then hit the TAB key)
  • You are now in your work folder, ROOT is now available

Starting root and looking at files

  • You can start ROOT by simply typing root
  • new TBrowser starts the graphical user interface
  • If you want to inspect one or more files type root FILENAME1 FILENAME2..... They will then immediately show up in the TBrowser


Scaler Mapping

Channel Signal
0 T1
1 T2
2 Muon veto
3 Beam
4 H
5 T1+T2
6 Beam veto halo
8 BHT+Muon Veto
15 Time

QDC mapping

Channel Signal Attenuation hunt [db] Att calib [db]
0 FCPT1 2.5 11
1 FCPT2 0 8
5 FCPD1 9 23
6 FCPD2 9 26

QDC data

In the data files there are two TTrees ("QDCval") and four histograms.

First, let me quickly explain the data that comes from the QDC and how it has to be used.

  • The QDC basically integrates the waveform (charges a capacitor) and digitises the voltage level of the capacitor. In order to reach a proper linearity even for small signals another small but constant signal is added to the input which results in a non-zero value even when there is nothing connected. This pedestal value has to be subtracted from the recorded signal. You will find the pedestal values in the "env" tree.
  • The next step is then to correct for the different attenuations of the PMT signals that we set to exploit the full dynamic range of the QDC channels. The correction formula is
    and again you can find the attenuation values in the "env" tree.
  • The corrected data is in the "QDCval" tree (so in principle you do not need the values from "env", but they are still there if you want to play with them).
  • Sometimes the signal could not be digitised properly. In that case the value is set to -1000 or less, so you can easily filter out these events.

There are two histograms per PMT, one shows the original values minus pedestal and the other one is already corrected for the attenuation.

In the hunt folder there are ROOT files for the single runs and two more, combining several runs

  • QDC_hunt.root = 1506857636, 1506863723, 1506870177, 1506877543, 1506892728, 1506908270
  • QDC_italian_runs.root = 1506866356, 1506867864, 1506868985


             -syyhs-  .:oyhdhhhhhhy/                                  
    -dydhhmmddddddmMMMMhos:.  `+mMNhy+:                               
     -od. `-+ydmNNmdy+..y-....`-Nmmmmhss                              
                 oMMMMm-+-   .:omdhhMmssso/:.                         
               /hNMMMMm :/.    -mo+smds//dds/----/+                   
        -dmmMMMMMMMNMMMMMMms:`://-`-+yNNyymddNy. `o/                  
     .ymNMMMNNMMMMMMNMMMMMMMMNy+ydMMMMNhhdNMMMN+`  -o                 
      sMMMMMMMMM:``hMMMd:-.`                   `.-:yMMMN`             
      .mMMMMMMMy```+MMMN`                          hMMNh              
  -mNm-/NMMMMMM-```.NMMM/       ommmmmmmmm/       `MMMN/              
   .-/dNMMMMMMMs``.`yMMMy       sMMMMMMMMM/       +MMMN`              
     -mmNMMMMMMNdNNs/MMMN`      sMMMMMMMMM/       yMMNy               
      /oss+dMMMNMMs-`mMMM/      +MMMMMMMMM:      `NMMN:               
        `-/NNMNMMMMMmmMMMh`      :smMMMds-       sMMMm                
          `oy: .+dMMMMMMMNm+`       `-`        :hMMNN-                
                  .+hMMMMMMMNds/.         `-+yNNMMMMM/                
                           `/yNMMMMMMMMMh+- -oMMMMMMMMs    -h.        
                              `:yNMMMMMMMMMN+ sMMMMMMMN`  oMMm`       
                                                 .omMMMMMd:  -mMs     
                                                    :sNm/     `sN+    
                                                      `         -m/   

Expert section

Here be dragons

VME addresses

  • V560: 0x2000000
  • V792: 0x0
  • V1290: 0x4000000
  • V1472: 0x9000000


  • FCPD PMT1 in beam direction right: 6094, U_nom=2271V (5000A/lm), 2400V (10000A/lm)
  • FCPD PMT2 in beam direction left: 6093, U_nom=2170V (5000A/lm), 2293V (10000A/lm)

PMT U[V] Comments
uV 2080
T1 2060
T2 2030
F1 2100
F2 2200
H0 2140 BL4S 30mm
H1 2060 ATLAS 15mm

-- BranislavRistic - 2017-09-27

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Topic revision: r11 - 2018-10-21 - InaChalupkova
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