Michel spectrum fitter

Steps to build the Michel spectrum fitter program:

Set up CVS access

Described at http://twist.triumf.ca/private/offline/install.html, probably you already have this done.

Get the source code:

The current (2004-01-23) stable version tag is "release1":
cvs co -r release1 mcfitter

This will create a directory called mcfitter. You can place it anywhere, it does not have to be in your home dir, or in e614soft.

Compile:

Log in to a RH8 machine to get a modern C++ compiler. Dork will do. Than:

cd mcfitter
make

Note that the executable program is called chi2fitter

You should have a recent version of ROOT set up (i.e. available in PATH and with the ROOTSYS environement variable properly defined) to build the fitter. By default only ROOT histogram files can be read in. If your ROOT version was compiled with HBOOK support, you can enable HBOOK support for the fitter by changing the ENABLE_HBOOK variable in mcfitter's Makefile.

Prepare input files:

There are several histograms involved

• The one to be fit ("data")
• The reference one ("base")
• MC spectrum to be used for normalization ("eff"); can be the same as the reference spectrum.
• Several (normally 4) derivatives, one for each parameter

In addition, there are several "nthrown" numbers to be provided: one for the "eff" spectrum, and one for each derivative. You also have to specify the fiducial volume to use.

All these input data are collected in a "fit specification" file. There is an example file called "fitspec.txt" in the source code directory.

Input histograms can be in different files or some or all of them can be in the same file.

Run the program:

./chi2fitter <fit-specification-file>

The fit result is at the bottom of the output. Of course you can redirect output into a file to save it. If you defined OUTFILE in your fit specification you'll get fit residuals and some other histograms written out to that file.