I have been trying to plot the detection efficiency of polyethylene (the conversion layer we are using to detect fast neutrons >1 MeV) for various thickness (1300 and 2000 microns) and compare the detection efficiency when no conversion layer is used (Silicon) from the simulated data obtained by scoring the energy deposited in every pixel of a hybrid detector modeled in FLUKA.
I am scoring the total energy deposited by ionizing particles on the silicon sensor layer and storing the hits in a text file in the following manner
Primary number (neutron) | Xpos of the pixel | Ypos of the pixel | Energy deposited in the pixel |
For eg.
(157, 95, 131, 0.11980814999999995)
(164, 95, 125, 0.11980814999999995)
(207, 95, 130, 0.11980814999999995)
(531, 95, 124, 0.11980814999999995)
Then I plot the intrinsic detection efficiency defined as: (total number of pixel excited above a threshold to the total number of primaries registered) *100
I observe that the detection efficiency seems be increasing upto a point and then falling down while ideally it should be increasing linearly before plateauing (image attached).
Could somebody please help?
Cheers,
Shri
Can we see your results? As I understand,on the picture in your attachment are theoretical results?
The data obtained after processing the FLUKA simulation output has been plotted. I haven't got any experimental results yet but using the plot here ->https://postimg.org/image/6m64mkh09/
from a previous publication (where they determined the detection efficiency of polyethylene to fast neutrons).
Please help.
As you said in first post: "ideally it should be increasing linearly before plateauing"....is it possible that neutrons with energies >10MeV interacts with PE and give you a smaller number of detections (did you have that included in your simulations?)...so you don`t have plateau anymore but the detection efficiency falling down....
No I haven't included that in my simulations. I am running these simulations on FLUKA, How do I include them and there is no information that they should decrease after 10MeV.
But in my graphs it doesn't decrease but fluctuate at energy range>10MeV which is my worry.
Please help.
I do not have any experience with FLUKA so I can`t help you about that, but I think that problem can be that you did not include all the possible variables in simulation...like interaction of high energy neutron with PE...
No worries Jan. I will post the question in the FLUKA forum for help.
Thanks very much for your continued support.
Dear Srinidhi,
Please find attached a copy of a paper I published many years ago for the ICONE 8. It describes the use of HDPE as a neutron converter layer on GaAs, and maybe it will be of some help to you.
Sincerely,
Douglas
Conference Paper Development of Coated GaAs Neutron Detectors
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