This page describes how to get a spin up/down curve from the raw NMR data from the LabView vi. This procedure can be used for both helium and water (just to fit the lineshape for water).
The raw datafile is of the form
x-10-24-11-32pm.dat, for
the x-channel (of the SR844 lockin amplifier) on the 24th of October at 11:32 PM. Get all
the data files into one directory along with the files create_file_list.pl,
fit_helium_list.C
and spin_up.C
or spin_dn.C.
From
within the directory do perl
create_file_list.pl. It will ask you to input the
number of lasers that were on during the measurements (e.g. 0 for the
spin down measurement.) for every file. After that is done, it'll
create a file in the same directory called nmr_files.lst. Sort (the contents of) this
file by doing sort -n nmr_files.lst >
nmr_files_n.lst. So now you'll have a file named
nmr_files_n.lst in your directory. This file is the input for the
next operation viz. to fit the data.
Troubleshoot:
If the perl script does not run/gives errors, check the path of the
perl binary in your account. To check it, do which perl. Usually it
is /usr/bin/perl, and then the first line of the perl script should
look like this
#!/usr/bin/perl
If the path is different, then change the first line of the script to the appropriate path.
Now
start ROOT. Then run the C++ file fit_helium_list.C.
This will start to fit the data in the individual files to the square
root of a Lorentzian (the standard NMR fit). After it fits a file,
it'll ask you if the fit is ok or not. Say y for yes, n for no. If
the fit is ok and you say y, it'll proceed to fit the next file. If
the fit is not ok and you say n, it'll ask you to feed in the peak
position and height, and then will fit it again. Keep doing this till
the fit is ok. Once this is over, you'll find another file in your
directory called nmr_fits.dat. This file is the input for the final
spin_up.C
or spin_dn.C
which give you the final curves with the lifetimes/spin-up times.
I'll put up the files for water here soon.