Study of beam profile modification for beam uniformization using multipole magnets

Yuri, Yosuke; Okumura, Susumu; Yuyama, Takahiro; Agematsu, Takashi; Miyawaki, Nobumasa; Ishibori, Ikuo; Ishizaka, Tomohisa

The development of the uniform-beam irradiation system using multipole magnets is now in progress at the TIARA AVF cyclotron facility. It is necessary that the transverse intensity distribution of the beam should be initially Gaussian to form a uniform beam. However, the beam extracted from the cyclotron is not always Gaussian but asymmetric. We have, therefore, carried out experiments on the modification of the initial beam profile using a scatterer. The beam was multiply scattered by a thin foil installed at a location of the beam transfer line. The transverse profile was measured by profile monitors, installed in separate positions It is found that the transverse profile is approached toward Gaussian distribution, dependent on the betatron phase advance from the scatterer to the profile monitor.