Click on the run-number button for the high-temperature run 1152 and investigate the run header information, especially the names and ordering of the data histograms. Select various Spectrum types and look at the range from 0 to 0.1 µs with 0.2 ns bins. Eventually choose Spectrum type 4 (Histograms 1,3,2,4) with a RRF frequency of 406 MHz and a packed bin size of 0.05 µs to display the whole time range in the RRF.
Now click on "Plot FFT" and adjust the FFT parameters and options until you get a sharp, symmetric line in the FFT, plotting the Real part of the amplitude. (Allow pop-ups in your browser!) Then click on a few other runs at different Ts and see if their FFTs look different.
When you know which runs you want to fit, click Zip & Download Runs at the bottom of the Run List window to bring the selected runs into your computer; then unzip the download into the directory where you want to fit them.
If you are working on bnqrexp.triumf.ca, the zip/unzip step is not required, as all runs are directly accessible in the /data/<beamline>/<year>/ directories on that host; unfortunately this is not available on the workstations in Hennings.
Use musrgui or (on bnqrexp.triumf.ca) physica ['t0', 'bkgd' and 'early' commands] to determine the t = 0 bin, background bin range and good data bin range. Checking one run should be sufficient. Prepare your fit-control template file, for either musrfit (.msr) or msrfit (.i), starting from another such file. In general there will be three Signals (at different frequencies) in the Spectra (Histograms 1,3,2,4). You should let each Signal have its own initial phase, amplitude, frequency and exponential relaxation rate. Fit in the RRF(s) of your choice.
Note: you may need to use different RRFs at some temperatures.