Attached herewith flair and input file for my geometry and also my scored usrbin (region wise) file.My target is to get dose equivalent in various thickness of concrete for the given beam and target at zero degree and 90 degree so as to get attenuation length in both the direction.However during scoring I could not get dose equivalent after first layer of concrete(for both the angles). your kind suggestion in this regard is highly solicited.Thanks in advance
In principle, your file does not show any significant problem. I see that you decided to do a region importance biasing to enhance the probability of neutrons to penetrate deep. The problem is that within the first layer of concrete you stop all the neutrons. It is a lot of shielding indeed.
If your goal is to study neutron penetration at such depths, I recommend discretizing your geometry more finely and ramping up the importance binning in a smoother progression (e.g. 1, 2, 4, …). Keep in mind that you should not expect a fast simulation, since even a single meter of concrete already gives a transmission factor on the order of 10⁻³.
To better see this, you can do a 1D plot to observe the DOSE-EQ profile as a function of z:
I also noticed that you used a truncated cone for part of your geometry. In that case, make sure that neither the apex nor the base radius is set to zero.
