Using frsexp as unpacker stage for FRSROOT

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The versatile unpacker generator ucesb can be used as unpacking stage for FRSROOT, R3BROOT, EXPERTROOT. etc. This allows the user to write the unpacker using a human-readable specification, rather than in C/C++ code. Thorough checking of the data format comes for free as well. For further information about ucesb, see the write-up.

Overview

1. Install ucesb (with FAIRROOT version of ROOT)
2. Compile your experiment specific unpacker and test it on data
3. Produce the header file for R3BROOT including the data structure
4. Extract the parts for each detector and level (unpack / raw)
5. Install R3BROOT or similar
6. Write detector specific readers
7. Write or modify your R3BROOT or similar steering macro
8. Run the macro

Install ucesb

Checkout the most recent version of ucesb from the git repository:

git clone http://fy.chalmers.se/~f96hajo/ucesb/ucesb.git

And also checkout the git repository with experiment unpackers:

git clone https://github.com/jose-luis-rs/frsexp.git

Check that

which root

points to your FAIRROOT installation directory!

Compile the empty ucesb unpacker using the same version of ROOT as you used for FAIRROOT.

make empty/empty

After compilation finished, make sure that the file

hbook/ext_data_clnt.o

exists. Set the environment variable UCESB_DIR to the 'unpacker' directory, e.g.

export UCESB_DIR=/u/$USER/path/to/unpacker

Put this in your .bashrc to make it permanent. R3BROOT will look for ucesb at this location.

Compile your experiment specific unpacker

Also use the same ROOT version here.

cd frsexp/frs_xxx
make

Produce the header file

Run ucesb with the struct_writer header generation option

./frs_xxx --ntuple=<signals>,STRUCT_HH,ext_h101.h

with something like UNPACK:EVENTNO,UNPACK:TRIGGER,RAW. This will produce the header file called 'ext_h101.h'. It contains the structure information for FRSROOT. The data coming from ucesb will adhere to this format.

You can skip parts of the following step, if you do the header writing like this

./frs_xxx --ntuple=<signals>,id=h101_<detector>,ext_h101_<detector>.h
# Example
./frs_april2019 --ntuple=RAW,id=h101_FRS,ext_h101_frs.h

This will already insert the correct detector names for you, if you like and only extract signals related to the specific detector.

Install R3BROOT

Installation information can be found on the R3BROOT website

Write detector specific reader classes

Have a look at frssource/FRSReader.[cxx/h]. Your detector specific reader class should almost be a copy of this, mostly replacing 'unpack' with e.g. 'raw_pos'. And you will have to make sure that in the Read() function your detector specific data containers are filled with the data from the ucesb structure.

Write or modify your FRSROOT steering macro

An existing steering macro for the FRS experiment can be found in

macros/unpack/frs/online_frs.C

It shows how the UcesbSource class is used and how Readers are added.

Run the macro

Run this:

root -l path/to/your/macro.C

=)

Questions

Via Mail.