Dear FLUKA experts,
I am simulating the magnet based spectrometer for proton beam. The magnetic field is homogeneous and equal to Bx = 0.2 T. The magnetic field is set by activating teh card MGNFIELD and assigning 0.2 T to Bx. In ASSIGMA for magnet refion the field is set to magnetic.
The proton beam is deflected vertically and detected on the detector screen in plane X-Y. The 0.5 MeV proton source is spatially extentend in X and Y axis with Gaussian shape with Gaussian energy spread of 0.001 GeV/c. I am checking the proton energy spectrum by using USRTRACK card in the thin region before entering the spectrometer and the beam has the energy bandwidth of interest. Then by using USRBIN card for PROTON I am detecting the proton beam distribution in the XY plane of detector, where Y axis is referring to energy (due to the deflection of magnetic field). In case of mono energetic beam I would get just a proton beam with the initial size in both X and Y axis centered on the Y pos that corresponds to the deflection of proton beam of such energy and in case of the beam with energy spread - something extended in Y axis. I am getting expected results up to 0.0008 GeV/c bandwidth, then I start to get kind of stripes in X direction. I have attached the image below. The number of stripes is increasing with increase of the bandwidth.
I used the following binning parameters: Nx:600, Ny:600 and Nz:1. I tried to increase the binning, but it did not help. What could be the reason of appearing of such numerical artifacts?
