  Tandem or Van de Graaff accelerator with an energy of 3-MeV is typically used
for PIXE analysis. In this study, the beam line design used in PIXE analysis
was used to increase the production of isotopes instead of the typical
low-energy accelerator from a 13-MeV cyclotron. For PIXE analysis, the proton
beam should be focused at the target through the use of a nozzle after
degrading the proton beam energy from 13-MeV to 3-MeV using an energy degrader.
Previous studies have been conducted to determine the most appropriate material
and thickness of the energy degrader. Based on the energy distribution of the
degraded proton beam and the neutron occurrence rate at the degrader an
aluminum nozzle of X thickness was determined to be the most appropriate nozzle
construction. Neutrons are created by the collision of 3-MeV protons into the
nozzle after passage through energy degrader. In addition, a sufficient
intensity of proton beam is required for non-destructive analysis of PIXE.
Therefore, in order to optimize nozzle design, it is necessary to consider the
number of neutrons which arise from the collision of protons inside the nozzle,
as well as the track direction of the generated secondary neutrons, with the
primary aim of ensuring a sufficient number of protons passing through the
nozzle as a direct beam. A number of laboratories are currently conducting
research related to the design of nozzles used in accelerator fields, mostly
relating to medical fields. In this paper, a comparative analysis was carried
out for two typical nozzle shapes in order to minimize losses of protons and
generation of secondary neutrons. The neutron occurrence rate and the number of
protons after passing through the nozzle were analyzed using a Particle and
Heavy Ion Transport code System (PHITS) program, in order to identify the
nozzle which generated the strongest proton beam.
