Scaler   Data   Class   Package   for   Hall A

Robert Michaels, rom@jlab.org, Jefferson Lab Hall A, Jan 2003

This file:     hallaweb.jlab.org/equipment/daq/THaScaler.html

SCALER   DATA   IN   HALL   A

In Hall A we have crates of scaler data, see also dstruct.html (write-up about data structure).   The present class package is intended to analyze those data and works either as a standlone code suite, or within the context of the new Root/C++ analyzer .

DESIGN   GOALS

The scaler package combines features of existing codes.   The usage covers several implementations:

• Works within context of full analyzer, or standalone.
• A time dependent channel mapping to account for movement of channels or addition of new channels.   This map exists in an ASCII file   scaler.map   which I maintain.   This allows all experiments to use the same software with no cumbersome changes of indices, etc.
• Adding new scalers is easy, see comments in the code.
• Source of data may be either THaEvData (event data object), or directly from CODA file, or from VME crate online, or the end-run "scaler history file", depending on context.
• Optional displays of rates, counts, history -- xscaler style. This is the class THaScalerGui.
• Several examples exist for looking at data online, analyzing a CODA file, computing charge, deadtime, helicity correlations, etc. The examples are a good form of documentation.

DOCUMENTATION

• The design is well expressed through the public interface of the header file THaScaler.h

• A good way to get started is to look at the following examples:
  • Reading the scaler history file and printing stuff out.
  • Reading a CODA file and computing stuff.
  • Computing the charge asymmetry (helicity correlated).
  • Reading from VME directly online and printing stuff.
  • computing deadtime from scalers in a CODA file.
  • A less trivial example:   Filling ntuple with rates to analyze scalers from Left or Right spectrometer for e99117.

DOWNLOAD

Download the tar file (updated 31-Jan-03) from www.jlab.org/~rom/hana_scaler_2.0.tar   untar it and see the README.   If using with the Hall A Root/C++ analyzer, put it in a subdirectory under the main directory.   A copy will be maintained on the adaq account on the adaq cluster for experiments to use online.

PROGRAMMING NOTES

Here are some detailed notes on how to program with THaScaler class.     You will need the hana decoder at www.jlab.org/~rom/hana_decode_2.0.tar   (or whatever is the most recent version). To run standalone (independent of main analyzer), do this:

• In hana_decoder directory, uncomment the line "export STANDALONE = 1" in Makefile
• "make" the decoder.
• Copy library to hana_scaler, e.g.: cp libdc.a ../hana_scaler_VERS/libdc_local.a
• Similarly uncomment "export STANDALONE = 1" in hana_scaler Makefile
• "make" the scaler executibles.

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  Robert Michaels   --   e-mail: rom@jlab.org