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oslocyclotronlab / rhosig.py

Tools for matrix decomposition in the Oslo Method
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Spin sum in decomposition (fit)? #9

Open fzeiser opened 5 years ago

fzeiser commented 5 years ago

@jorgenem and I wondered whether we need to include a sum depending on the population cross-section (or spin-parity distribution) and intrinsic spin-parity distribution in the fitting to the 1Gen matrix.

Created a test branch, where I implemented this in a hacky way: 30dfec9 This way we can see the effects, at least for one implementation.

Current assumption:

Results for this case:

Does not change very much but a bit, see next post with ideas!

A) Visualizing the sum and it's impact along the nld and Eg axis spin_sum Note: Bug in the axis below: Should state Eg instead of Ex spin_sum_projections

B) Effect on the fitted matrix does_it_work_spin_sum matrices_compared_spin_sum

C) Effect on the NLD and GSF nld_spin_sum gsf_spin_sum

Ok, actually, you can't see the effect, as I didn't post the previous "picture" yet. But it basically just has an effect at low energies of the NLD and highest energies for gsf.

fzeiser commented 5 years ago

So the effect is most visible for the lowest/highest energies. I guess we should implement a smoothing in Ex and Eg direction according to the detector resolution.

Here come the corresponding pictures from the master branch, ie. where z(Ex,Eg)=1 does_it_work_master matrices_compared_master

nld_master gsf_master

fzeiser commented 5 years ago

@jorgenem : This could also be a very natural way to include the population cross-section into the Oslo Method ;P

fzeiser commented 5 years ago

Issue: Need to take care of integer/half integer spins. For 240 Pu this was probably wrong now.

fzeiser commented 5 years ago

For curiosity I gave it a try to see what happens if I equally populate spins up to J=0.5 or J=4.5 (note the different scales!)

The effect of z: Jpop_max=0.5 spin_sum_projections_popTo1 Jpop_max=4.5 spin_sum_projections_popTo4

And the effect on the extracted gSF (keeping the same 1Gen matrix) Jpop_max=0.5 gsf_spin_sum_popTo1

Jpop_max=4.5 gsf_spin_sum_popTo4

So the gSF get quite a different slope for higher gamma-ray energies (propagates from the nld)! This is consistent to what we have observed previously. There is one thing to note. Now I generated the true 1Gen matrix my populating all Js proportionally to Jint, however I analyze(fit the gSF) as if I had populated the only up to Jpop_max (and these, equally). Therefore we see that the gSF from the fit get's a smaller slope for high Eg's for Jpop_max=0.5 then for Jpop_max=4.5 and not the other way around (which we see in the experiment...)