Light Emission from Materials in MCNP Simulations

[oksuz_]

Hi,

I am trying to model the distribution of the light emission from a material when excited with neutrons in MCNP. I have been searching literature and found not many things. Could anyone provide me with sources from which I can get info?

Thank you in advance.

 

[Astronuc]

I am trying to model the distribution of the light emission from a material when excited with neutrons in MCNP. I have been searching literature and found not many things. Could anyone provide me with sources from which I can get info?

Is one referring to a liquid or crystal scintillator with which to detect neutrons?

 

[oksuz_]

It is a plastic scintillator. And there will be a amorphous silicon behind it. I am not sure whether mcnp takes into account scintillation though.

 

[Astronuc]

It is a plastic scintillator. And there will be a amorphous silicon behind it. I am not sure whether mcnp takes into account scintillation though.

Is this a borated plastic scintillator?

I'm not sure if this answers your question, but it is nevertheless of interest, and probably in the direction of your question.

https://ne.oregonstate.edu/sites/ne.oregonstate.edu/files/frey.pdf
Use of BC-523a Liquid Scintillator for Simultaneous Neutron Spectroscopy and Gamma Counting with the Implementation of a Neutron History Reconstruction Algorithm


By Wesley Frey, Department of Nuclear Engineering and Radiation Health Physics
Oregon State University

Are you asking if MCNP tallies the optical emissions of the scintillator, as opposed to tracking the neutron/gamma interactions?

 

[oksuz_]

Its molecular formula is C9H10, and It does not contain boron.

Thank you for the source. It will definitely be helpful.

My aim is to track the emitted light originated from the neutron-scintillator interaction.

 

[Astronuc]

My aim is to track the emitted light originated from the neutron-scintillator interaction.

I don't believe MCNP directly calculates the optical (from scintillation) response from the medium. However, LANL, which maintains MCNP is developing a tool-kit to enable the calculation of the detector response. The model is called DRiFT.

https://mcnp.lanl.gov/pdf_files/la-ur-16-27166.pdf
• DRiFT treats each particle separately to properly determine the amplitude and shape of the resulting pulse.
• The PTRAC particle’s electron equivalent energy (MeVee) is determined for the specific particle type and original energy using quenching data specified in input.
• The scintillation yield (12,000 photons/MeVee for EJ-301) is used to determine the mean number of photons produced.

So it is matter of determining the photon per MeVee, which I take to be the energy dissipated by the particle interaction. In your case, the energy will come from the recoil of a proton by the neutron, which you can model with MCNP.

Various authors cite: Aoyama, T.; Honda, H.; Kudo, C.M.; Takeda, N. Energy response of a full-energy-absorption neutron spectrometer using boron-loaded liquid scintillator BC-523. Nuclear Instruments & Methods in Physics Research, Sections A: Accelerators, Spectrometers, Detectors and Associated Equipment. 333A: 492-501; 1993.

Apparentley Aoyama et al used MCNP to model a scintillation detector, which used BC-523. That relies on (n,α) reaction with boron, whereas one is attempting to model an (n,p) reaction.