Strange issues in some gamma ray intensities

[walte...@gmail.com]

Hi Everyone,

I am a very novice user to PyNE, but am trying to use it to automate some processes for more robust and repeatable analysis (mainly involving fission product yields and gamma-ray emission).

There seems to be two ways to get the gamma ray emission energies and intensities:

• Material.gammas() 
• data.gamma_energy() and gamma_photon_intensity()

For many nuclides (e.g., Co60), this seems to give the same thing:

   

    nuc='Co60'

    Es=data.gamma_energy(nucname.id(nuc))

    Intensities=data.gamma_photon_intensity(nucname.id(nuc))

    for E,inten in zip(Es,Intensities):

        print("%6.1f %10.4f" %(E[0],inten[0]))

Yields the result (omitting some for brevity)

1173.2    99.8500

1332.5    99.9826

Now if I do the same thing using the material method:

    mat.from_atom_frac({nuc : 1.0})

    #print(mat)

    g=mat.gammas()

    lam=data.decay_const(nuc)

    for g in g:

        print("%6.1f %10.4f" %(g[0],g[1]/lam))

I get the exact same numbers:

1173.2    99.8500

1332.5    99.9826

However, for a few examples there's some funny business going on, e.g., Cd115 :

Material method:

  35.6     0.0153

 231.4     0.7400

 260.9     1.9400

 336.2     1.0000

 492.4     8.0300

 527.9    27.4500

 856.2     0.0022

 

Data method:

  35.6     1.5340

 231.4    74.0000

 260.9   194.0000

 336.2   100.0000

 492.4   803.0000

 527.9  2745.0000

 856.2     0.2200

All of the data method values seem to be just 100x the material values (and way over 100%)... Furthermore, looking at the NNDC decay gammas:

It is clear that the 336 keV value is off (and suspiciously equal to 100), and the 35.6 value is off, while everything else is spot on. 

It seems pretty strange as to how it may be so different for some of these nuclides vs others? And some gamma lines only?

Also some other nuclides (e.g., As82M) will give gammas just fine with the data method, but the material method will cause a runtime error:

 RuntimeError                              Traceback (most recent call last)

<ipython-input-34-14999e3f4fa9> in <module>

     17     mat.from_atom_frac({nuc : 1.0})

     18     #print(mat)

---> 19     g=mat.gammas()

     20     lam=data.decay_const(nuc)

     21     for g in g:

material.pyx in pyne.material._Material.gammas()

RuntimeError: 

Any insight into these issues would be greatly appreciated. It had been extremely useful for automation purposes until I noticed a bunch of gamma rays >100% throwing a wrench into the analysis.

Thanks!

Will

[walte...@gmail.com]

Upon looking at the ENDSF file on NNDC, it looks like the 35.6 and 336 keV intensities might have just been errors in the data that has since been corrected. But that still leaves the factor of 100 issue for some isotopes. What is the process for updating the PyNE data?

115IN    115CD B- DECAY (53.46 H)      1978HE08,1967BA18,1974BO2612NDS    201906

115IN  H TYP=UPD$AUT=BALRAJ SINGH$CIT=ENSDF$CUT=03-JUN-2019$

115IN  H TYP=FUL$AUT=JEAN BLACHOT$CIT=NDS 113, 2391 (2012)$CUT=1-Sep-2012$

115IN c  Previous dataset in 2012Bl10 evaluation corrected and updated by

115IN2c  B. Singh (McMaster), June 03, 2019.

115IN c  Literature (NSR) search did not indicate any newer experimental studies

115IN2c  of this decay. The Q value has been adopted from 2017Wa10. Revised

115IN3c  mixing ratio of 35.6-keV transition has been deduced using BrIccMixing

115IN4c  code. E5 admixture in the 336-keV transition from the isomer is deduced

115IN5c  from conversion data, and discussed in terms of realistic B(E5)

115IN6c  transition probability. The |b feedings and log| {Ift} values have been

115IN7c  re-evaluated. 2013Ha24 is a theoretical study of {+115}Cd decay with

115IN8c  the calculation of partial half-lives of possible 4th-forbidden decays

115IN9c  to 1418 and 1449 levels, both with J|p=9/2+. Note that none of these

115INAc  two levels have been populated in the available experimental studies

115INBc  of the decay of the ground state of {+115}Cd.

115IN d  Following revisions made to the dataset:

115IN d  1. Photon intensities of the 35.6|g and 336.3|g corrected.