Mini µLan Readout Overview

The mini µLan DAQ provides the data readout and online analysis for six WFDs and one MTDC in a single VME crate. The DAQ is running on a 1GHz dual-Pentium in a rack-mount box and is connected to the VME crate by a Struck PCI-to-VME optical interface. The acquistion uses the MIDAS package for data readout and the ROOT package for online analysis. The raw data from the MIDAS readout is stored as MIDAS (.mid) format files and the processed data from the ROOT analysis is stored as ROOT (.root) format files.

Data is collected in cycles of fills and reads. First the acquisition writes a "1" via the parallel port to start acquiring data. Then after a 100ms delay the acquisition writes a "0" via the parallel port to stop acquiring data and start data readout. The flashing green/red lights on the WFDs indicate the fill (green light) and read (red light) cycle is active.

Mini µLan Data Overview

The WFDs have three types of input pulses. They are the scintillator pulses, marker pulses, and roll-over triggers. The scintillator pulses feed the WFD signal inputs 1-4, the marker pulses feed the WFD test inputs, and roll-over triggers feed the WFD external input. In standard data taking:

  • The marker pulses are triangular waveforms (~100ns rise, ~100ns fall, 0.5Volt amplitude) that arrive following the start of fill. Their purpose is to line-up the WFD data in phase zero and phase one.
  • The roll-over triggers initiate the recording of minimum-length islands of WFD data every 300 microsecs. Their purpose is to record the roll-overs of the 16-bit (327 microsec) clock in the WFD. We get about 300 roll-overs per fill.
  • The signal pulses are the Michels, Cosmics, LEDs, ..

Note the roll-over triggers will generate the bulk of the data, about 1MB/sec for 6 WFDs.

Mini µLan On-line Analysis

The raw WFD/MTDC data from the MIDAS readout program is stored in .mid files as banks of ADC data and time/discriminator data for each phase of each channel of each WFD. The online analysis has two components, one that turns the raw fill-by-fill data into processed event-by-event data, and one for monitoring and plotting of the signal pulses themselves and their amplitude spectra, time spectra, etc.

    The online ROOT processor:
  • combines the WFD data from phase 0 and phase 1 to make phase-merged waveforms (i.e. 2 x 200 MHz -> 400 MHz)
  • stores individual islands of waveform data as raw events in raw event ROOT branches (one for each WFD channel)
  • stores values of pulse parameters (time, area, etc) as fitted events in fitted event ROOT branches (one for each channel)
  • saves the raw event branches and fitted event branches as a ROOT tree in an .root file.
    The online ROOT analyzer:
  • provides plotting of digitized islands of WFD data for monitoring, etc.
  • provides statistics on markers, roll-overs, signals, for monitoring, etc.
  • provides plots of raw times, amplitudes, widths, pedestals, etc.
  • provides definitions of inner-outer coincidences and plotting of times and amplitudes for lifetime analysis, etc.

Note the processing of raw MIDAS data files into processed ROOT data files is only "semi-online", i.e. the processing to a .root file starts when the writing of the .mid file stops. In short the .root files are one run behind the .mid files.

Starting the MIDAS Acquisition from Scratch

  1. Login to mulandaq PC on account mulan.
  2. Start MIDAS
    # Go to acquistion directory mulandaq/mulanfe
    cd mulandaq/mulanfe
    # Start the MIDAS data logger
    mlogger -D
    # Start the MIDAS web server
    mhttpd -D -p 8081
    # Pop-up a netscape browser and go to
    # Start the MIDAS front-end

    Now you're ready to collect data by using the web-page interface to start runs, stop runs, etc. For MIDAS help see

    Note the MIDAS event rate is the µLan fill rate which is 10/sec.

  3. Setting WFD parameters
    On the MIDAS status page

    WFD settings - click here for access to WFD disriminator thresholds, zero suppression, pulse stretch, etc.

    WFD enabled - click here to enable or disable the individual WFD channels.

    Note for modifying a number of settings its easier to use odbedit. For example on typing

    cd Equipment/Wfd/Settings
    save currentsettings.odb
    load newsettings.odb

    The odbedit save command stores the current WFD settings in a text file currentsettings.odb and the odbedit load command reloads the new WFD settings from a text file newsettings.odb. Just edit the .odb files to define new WFD settings.

Starting the ROOT Analyzer from Scratch

  1. MIDAS->ROOT processor # Login to mulandaq PC with account mulan # Go to acquisition directory mulandaq/midas2root cd midasdaq/midas2root # Run ROOT processor to create the .root files from the .mid files ./muroot
  2. Note the processing of MIDAS raw data files into ROOT processed data files is "semi-online", i.e. the processing to a .root file starts when the writing of the .mid file stops. In short the .root files are two runs behind the .mid files.

  3. Running the ROOT analyzer # Login to mulan1 PC with account mulan # Go to analyzer directory kentucky/minimulan cd kentucky/minmulan # Run ROOT analyzer ./muroot
  4. # To look at the individual pulses from a WFD channel, e.g. for run 99 and channel 0T


    # To look at the pulses statistics on roll-overs, markers, signals, etc, e.g. for run 99 and channel 0T


    # To look at the various plots of areas, times, etc, for individual hits and coincidence hits, e.g. for run 99 and channel 0T


    # The processing of a .mid file into a .root file can be done by hand via, e.g. for run 99


    In the above commands the WFD channels are denoted by "0T" through "5T" and "0B" through "5B". The top channels get inputs from the outer tiles and the bottom channels get inputs from the inner tiles.

Fixing Problems

In case of trouble some useful tools are (one has to be looged on mulandaq PC and be in /home/mulan/mulandaq/mulanfe directory)


This command cleans-up the Midas clients, MIDAS shared memory, and MIDAS online database. Its helpful when communications with MIDAS get confused.


This command will step through all channels of all WFDs, write to the WFD memory, read back the WFD memory, and check the read and write are consistent. Its a useful tool for initializing WFDs are switching off the VME crate or verifying the crate and WFDs are working.

./crate_power --reboot

This command will reboot the VME crate.

./module_cleanup (must be run as a root, hardly ever needed)
These tools are run from the  ~/mulandaq/mulanfe directory.

Cabling Arrangement

  Wfd0top    Wfd1top    Wfd2top    Wfd3top    Wfd4top    Wfd5top

 Hex1Outer0 Hex1Outer1 Hex1Outer2 Hex1Outer3 Hex1Outer4 Hex1Outer5
 Hex2Outer0 Hex2Outer1 Hex2Outer2 Hex2Outer3 Hex2Outer4 Hex2Outer5
 Pen1Outer0 Pen1Outer1 Pen1Outer2 Pen1Outer3 Pen1Outer4
 Pen2Outer0 Pen2Outer1 Pen2Outer2 Pen2Outer3 Pen2Outer4

  Wfd0bot    Wfd1bot    Wfd2bot    Wfd3bot    Wfd4bot    Wfd5bot

 Hex1Inner0 Hex1Inner1 Hex1Inner2 Hex1Inner3 Hex1Inner4 Hex1Inner5
 Hex2Inner0 Hex2Inner1 Hex2Inner2 Hex2Inner3 Hex2Inner4 Hex2Inner5
 Pen1Inner0 Pen1Inner1 Pen1Inner2 Pen1Inner3 Pen1Inner4
 Pen2Inner0 Pen2Inner1 Pen2Inner2 Pen2Inner3 Pen2Inner4