Problem with photonuclear physics phys:p in MCNP

[Nour_wahban]

TL;DR

I'm trying to activate cobalt 59 to cobalt 60 and obtain its peaks, but the phys:p is not working.

I'm working on a very basic setup to activate cobalt 59 with neutrons emitted from californium 252. MCNP is giving me the following warnings:
warning. photonuclear physics may be needed (phys:p).
warning. material 3 is not used in the problem.
could anyone help me understand where the problem is. I've attached the input file.

 

[Astronuc]

TL;DR Summary: I'm trying to activate cobalt 59 to cobalt 60 and obtain its peaks, but the phys:p is not working.

warning. photonuclear physics may be needed (phys:p).

I suspect that one may have to consider photoneutron reactions from the gammas emitted by ²⁵²Cf. Most photoneutron thresholds are above 7 MeV.
See - https://journals.aps.org/prc/abstract/10.1103/PhysRevC.10.795

This is a useful reference: https://www.osti.gov/servlets/purl/1323135
MatMCNP: A Code for Producing Material Cards for MCNP

About photoneutrons
https://www.sciencedirect.com/topics/physics-and-astronomy/photoneutrons

A gamma photon with energy sufficiently large to overcome the neutron binding energy (about 7 MeV in most nuclides) may cause a (γ, n) reaction.

 

[Alex A]

You will see a lot of warnings and you should chase them. Warnings often show up a bigger problem. That said, this one is usually a comment, not a warning. It can usually be ignored, unless you know it's a common event in the problem, but again I don't think I've seen it as an actual warning, so I don't know. Might be related to the use of a distribution function for your neutron source energy.

phys:p is a more complicated card that doesn't just turn on and off photonuclear physics, but a lot of other stuff. It also tends to change between versions so you have to check the right manual to make sure the switch is the one you want.
The default for 6.3, according to the manual is PHYS:p 100 0 0 0 0 J 0
I am guessing the safest way to turn on photonuclear physics would be,
PHYS:p 100 0 0 -1 0 J 0
That according to the manual is an unbiased 'sample every collision' photonuclear treatment.
This might slow things down and probably won't affect the results much.

I do not see an issue with material 3. In the def there are only 3 spaces for the extra lines, but & is used to continue the previous line, so that is absolutely fine. Material 3 is used in cell 3. You should not be getting that error with that input file as best as I can tell.

Hope that helps!

Edit, Just to check, you are after the fast activation spectrum (n,gamma) right? You are not going to see Co-60 decay, because the program doesn't handle time like that.