How can i see the distribution like this?

Hi Experts,
I am using GPS for my application. but i am getting the distribution like the first one in the image.
But i want to see the distribution like the third one.
Then how can i get this type of distribution. can anyone please help me with this.
This is my primary.mac file.
primary.txt (25.7 KB)

look at the primary.mac of the radioprotection advanced example.


means i am getting GPS like this, it seems it is concentrating at a point inside the sphere but i want that it should incident only on the sphere like earlier image in this thread (example 3).
also i am sure is it originating from the center of the sphere or from outside the sphere and coming inward ?
or it is why because i am setting the radius of GPS very less ?
Can you please correct me ?

In radioprotection, the theta of emission is limited to have incident radiation in a region of interest. That’s why it looks like that the primary radiation is incident towards the center (it is biased). The results are then corrected. In the radioprotection example, the radiation is originated from the surface of a sphere with a very large radius w.r.t. the region of interest ( detector) and then incident inwards (again theta is limited). The angular distribution is cosine. These conditions allow to model an isotropic incident radiation field.