NSRL Data Acquisition System

 Data Acquisition using the nsrlDataAcquisition System

Introduction

The NSRL DAQ has been rebuilt to be a stand-alone system, that is simple
to set-up for users, and simple to run.

Download

A copy of the public software is available here.  It is a gzipped tar file containing everything you need to build a copy of the NSRL data acquisition software.  After gunzipping and untarring the file, follow the instructions in the AAAREADME file to create an executable file for your own use. 

Quick Instructions

Setting Up

  1. Provide an event trigger to the TDC module in the right-most slot
    of the VME crate. This trigger is daisy-chained to all other VME
    modules that need it. If you are using it as an ADC gate also,
    verify that the timing and width are correct.
  2. A Spill signal (Booster-T0) should already be provided to Channel
    15 of the VME Scaler V560. You don't need to do anything here.
  3. Plug your signal cables into the appropriate modules, ADC/TDC/Scaler.


Running the Program

  1. From a linux terminal, logging in as nsrl, type
    nsrlDataAcquisition. This will pop open a GUI to control the daq.
    Enter the information about the beam species, energy, and other
    info, and click on SAVE to save the configuration file.
  2. Click on START CAPTURE.
  3. Click on START DATA CONSOLE
  4. Click on ANALYZE.


 Offline Analysis

  1. Data files are stored in
    /operations/app_store/nsrlDataAcquisition/data and given unique
    names made up out of the ion species, energy, date, and a cycle
    number that is incremented with every run. These files should not
    be modified. To work on the data, copy files to the directory
    /home/cfsb/nsrl/daq/data and work with them there.
  2. NTuples can be made out of the ascii data files using the routine
    make_ntuple. Just go to the directory and type ...
    1. "make_ntuple".
    2. Enter the file name of the ascii data file
    3. Enter the name of the ntuple file you want to write to.
    4. Enter, one by one when prompted, the labels for the words in
      the event record.
    5. Run paw on the output file.

Detailed instructions

Signals for analysis must be brought to the VME Crate in the Physics
Lab. There are modules in the VME crate for digitizing Photomultiplier
signals (QDCs), Silicon detectors (Peak sensing ADCs), Timing (TDCs),
and scalers for counting.

The system requires two signals to process events:

  1. Event Trigger
  2. Readout Trigger

The "Event Trigger" causes the information to be digitized, i.e. it
serves as the Common Start for the TDCs. It also serves as the
Integration Gate width for the QDCs, and Peak search window for the peak
sensing ADCs. It is not used by the Scaler modules. This pulse should be
a discriminated phototube pulse, or output of a coincidence unit, or
logic gate. It should be at least 20 nanoseconds long. This same pulse
(it can be shaped or stretched) serves as the Integrastion Gate for the
QDC. Note: the falling edge of the QDC Gate must come at least 15 ns
before the singal to be integrated. There are analogue delay modules and
delay lines in the rack to be used as delay lines for the singal inputs
to the QDCs or ADCs to give them the correct timing relative to the
Gates. The event trigger must be plugged into the right-most VME module,
in slot 20. It is a VME TDC V775N. The event trigger must be plugged
into the lemo input labelled GATE/COMM. Note: there are two such input;
either one will work. They are daisy-chained together. The second
GATE/COMM connector is then available to use as an output for providing
event triggers to all other VME modules used in the event.

The "Readout Trigger" is used to tell the computer when to read out the
VME crate. In general, the system was designed with the NSRL Beam Spill
Structure in mind, i.e. events come during the ~300 millisecond spill
and then there is no event for ~3.7 seconds. To minimize readout
deadtime, all events are store on-board the VME modules until there is a
Readout Trigger. The "Readout Trigger" is usually provided by the
Booster-T0 which is regenerated in the Dosimetry control room with a
V-102 module. It is a TTL level, and it needs a level shift for VME. Any
simple NIM-level pulse can be used to trigger readout of the data buffer
on the VME crate, should the BT0 not be available for any reason, on
should the user want readout at intervals other than every 4 seconds.
The readout trigger pulse must be plugged into Channel 15 of the VME
Scaler module V560 (there are two of them, so use the Left-most module).


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Last Modified: October 9, 2012
Please forward all questions about this site to: NSRL Web Administrator