NAI(Thallium doped) Scintillator Calibration?

[Monsoon]

I'm currently taking intermediate Lab II (Physics 414) and we're currently working on Gamma Ray Spectroscopy. We are tasked with manually calibrating a NA-I Scintillator doped with Thallium in order to determine the isotope composition of an unknown source. My partner and I have been thinking for a few days and it seems that everything we come up with is wrong, and google has been of little help this time around. Does anyone have any ideas on how to go about this?

edit: we have 7 known sources to assist us... (Co60, Ba133, Cs137, Na22, Mn54, Cd109, Co57)

[malawi_glenn]

Pretty hard to help you if you haven't even said what you have done, showing spectra and so on. And this is probably a "too big" task to ask for help here, I mean it takes some time to through all possible peaks from your candidates etc.

So first: specify the question, the more general you are, the less probable it is that someone will answer.

Second: this is a coursework question and should not belong here.

I am telling you all this since you are new here.

[Vanadium 50]

Think about why you have 7 known sources.