Pulse height spectra of Gd2O3 detector

Dear Experts,

I am trying to simulate Gd2O3 scintillator for neutron. When I add Raddecay card “error code 12 occurs”. if I remove Raddecay and associated cards, other card outputs work properly. I could not understand the reason for it.
And, when Gd capture neutrons, it emits electron, photon x-ray and gamma ray. I used “ray” function in USEBIN, USERTRACK, etc… But it seems bit odd to me. is there any other function that can use for X-ray?
Here is the full spectrum of DETECT card, how do I add the ACCUMN or ACCUMP to it on flair?
I am grateful, if anyone can help me with this questions.
Gd2O3Eu_09April21.flair (5.9 KB)

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Dear Nadeera,

In the simulation you are missing the PHYSICS card with SDUM=EVAPORAT which activates heavy fragment evaporation. This is needed for residual nuclei production and decays. This will solve the error you are getting.
Also include an additional EMFCUT card to define the PROD-CUT for photons and electrons.

Carefull with the option “RAY”, it is a pseudo-particle used in FLUKA, for instance, to scan the geometry.
It does not refer to X-rays. Both, X-rays and gamma rays are scored using the PHOTONS option.

Regarding the spectrum obtained by the DETECT card and your comment “How do I add the ACCUMN or ACCUMP to it on flair?” Could please be more precise about what you want to do?

Kind regards,

Dear Marta,

Many Thanks for the reply and advices.
In attached figure, peaks can be observed in spectrum, but i would like to convolute the recorded spectrum with the Gaussian function. For that, I am trying to include ACCUMP and ACCUMN. is there any other method to do it?

Dear Nadeera,

you may want to look at this post:

This user routine automatically applies a Gaussian broadening to the DETECT scorings.


Many Thanks for the guidelines.

Dear David,

Do we need to add dummy detect card for each detect card that we use?

Dear Nadeera,

no, only one “dummy” DETECT card is needed for the user routine to work. The energy settings and scoring regions on the “dummy” card also do not matter. The only requirement is that the “dummy” card has to be the last among the DETECT cards.


Thanks for the clarification.

Dear Experts,

I add physics card as suggested, it works.
do i need to add both , Physics card and Raddecay card for one simulation?
Adding Physics card with evaporation with no heavy fragment is enough?

Dear Nadeera,

If in your study you want to include the radioactive decays, yes, you need both cards. In your specific problem, it should be fine with the “no heavy fragment” option in the PHYSIC card.


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