NE213_Neutron detector

Dear Users,

Could anyone point me to the example file in Geant4 for Scintillation detector like the NE213 or any organic based detector?

I modified the OpNovice and B1 examples to model a cylindrical NE213 scintillator coupled to a PMT, irradiated by a general particle source (GPS) of selectable particles. The code outputs an ascii file having a pair of numbers per event; the number of optical photons created in the scintillator and the number that reach the entrance window of an attached PMT. The output file may then be processed by Octave (similar to Matlab) code (which I also have) to produce spectra and perform further analysis. NE213 optical and physical data come from various sources. If you want a copy, please let me know how to send it to you.

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Hi John,

Thank you for willing to share your experience. Yes, please!! I would love if you will share your files. I would also like to connect with you. Feel free to share it here or through my email if the files are large (https://www.linkedin.com/in/modeste-tchakoua/).

Thanks

The zipped tarball is about 16Mb, so it is too big to share here. I will contact you directly to try to email it.

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Hi John, Thank you for your share. Yes ,please. I would love if you will share your files. can you send files to my email . ma email address is cyhu0215@gmail.com thanks.

I would be happy tp do so.

thank you John. I Have a Question 。Molecular structure In simulation How do u think about?

Hi. Sorry for the long delay in replying. I have been off line for a while. I assume that you mean molecular structure of the scintillator material. This is not explicitly modelled by the code. It is implicitly included by specifying its optical parameter values (e.g., refractive index, optical absorption) which are obtained from experimental data.

Hello Sir
I try to calculate fast neutron intrinsic efficency for stilbene and BC501 . But I am not getting right value . Would you please help me with some solution or can share some content or papers which are useful for my problem . My email id bhavika@ph.iitr.ac.in

I am happy to help. How are you trying to calculate the intrinsic efficiency now?

Sir as for fast neutron we can’t comment directly for efficiency calculations. It depends on detector material and how fast neutron interact with that material .
So as for organic detectors , I have to see the nature of recoil nucleii , neutron interact by elastic and inelastic collision in TRANS-STILBENE . And I use polyenergetic 252Cf source .
So first I check with total energy deposit curve ,and by calculating area under the curve divide by neutrons incident on it .
Second I try with the neutron flux coming out from the detector . I calculate area under the curve and subtract it from incident and divide whole by incident neutron
But I am getting wrong answer

There is really not enough information to give an in depth reply. If I understand correctly what you are trying to do, the first method will not yield intrinsic efficiency. The second should in principle, but it will give the intrinsic efficiency for a neutron interaction, not the efficiency for scintillation caused by the neutron. It also is important how you actually implement what you are doing. Are you using Geant4 code and, if so, what is your geometry? How are you scoring the escaping flux? To what data are you comparing your simulation results?

Thankyou sir
Yes , Sir I am using Geant4 code .
Geometry - Trans-Stilbene(cylinder) with fix diameter = 5cm and with varying length , with 1mm Aluminium casing .
Neutron Source - point source (252Cf) and give points using /gps/hist/type energy ,beam in z direction , and placed 20 cm from detector surface .
Sir please find the attachment .
clarke2019(1).pdf (642.3 KB)

Hi. In the Clarke et. al.2019 paper, the intrinsic efficiencies (which I assume are just total number of events with signal over threshold/total number of neutrons which intersect the crystal) include the efficiency of scintillation. You should use the Geant4 optical physics processes which include scintillation to model the problem. Count the number of scintillation photons per event and accept the event if that number is over the threshold (Clarke used 36keVee which is about 36keV*8.27scintillation photons/keV= 298 photons for gamma rays on stilbene - I do not know the value for neutrons.). Count the number of events over threshold and divide by the number of events for which the primary neutron intersected the detector.

How far off the experimental values are you?

Sir I don’t know how to couple the photomultiplier tube . I am calculating efficiency by total energy absorption in detector (which I am getting very large value near 70% ) . Would you please refer me example file in Geant4 for organic detector (using PMT) .?
Thanks a lot for helping me .

I can email you my above described example for NE213. I have not done trans stilbene yet, so you will have to modify the detector construction module for that and also modify the geometry to match yours. Also, my latest version of the program only works for Geant4 10.7.0. I will try to package it and send it soon.

It would be very helpful for me if you share your files . My email id bhavika@ph.iitr.ac.in .
Thankyou Sir

Hello, I have been searching for an example to simulate scintillator photons and I saw your reply in this post. I am very much appreciative if you could send your example code for NE213 and other optical photons. I typically used stepping action to get the neutron energy spectrum. Therefore, I am very much interested in how you did use sensitive detectors or any other method. Please email me at sclee0620@gmail.com. Thank you

My solution is based on the Geant4 distribution’s OpNovice example with parts taken from the B1 example. It accumulates the number of scintillation and optical photons in SteppingAction, EventAction and RunActiion. I have not used sensitive detectors. The zipped tarball of the Geant4 and analysis code is about 30Mb which is too big to email easily. However that includes a lot of analysed spectra and data. I’ll look at throwing some of that out to make a file which can be emailed.

Thank you so much. I really appreciate your help.

If you have a problem attaching the file, please let me know. I can set up a shared place in google drive or onedrive for you to upload.

Many people refer to use a sensitive detector/multifunction sensitive detector for this job (e.g. collecting Energy deposition with the time of flight etc…) I would love to you how you did it.

Thank you