IBIC2012 - List of Authors (Sawada, S.)

Paper	Title	Page
TUPB79	Use of Gafchromic Films to Measure the Transverse Intensity Distribution of a Large-area Ion Beam	1
	Y. Yuri, I. Ishibori, T. Ishizaka, A. Kitamura, S. Okumura, T. Yuyama JAEA/TARRI, Gunma-ken, Japan S. Sawada, T. Yamaki JAEA/QuBS, Takasaki, Japan
	In the TIARA AVF cyclotron facility of JAEA, it is necessary to evaluate the cross-sectional area and uniformity of a large-area uniform ion beam formed by multipole magnets both precisely and handily. A technique has, therefore, been developed to measure the two-dimensional transverse intensity distribution of the ion beam using Gafchromic radiochromic films (Ashland Inc.). In order to show available fluence ranges of the film, the coloring response of the Gafchromic films irradiated with several species of ion beams is investigated as a change in the optical density of the film. It has been found that the optical density increases linearly with the fluence, whose range is practical for materials and biological research. Thus, the relative transverse intensity distribution of ion beams can be measured using the film. Furthermore, the intensity distribution determined by the Gafchromic film is compared with the area-density distribution of track-etched pores in a polymer film from a microscopic viewpoint. It has been demonstrated that the beam uniformity obtained from the Gafchromic film is equivalent to the relative standard deviation of the microscopic pore distribution.

MOPB81	Residual Gas Ionization Profile Monitors in J-PARC Slow-extraction Beam Line	1
	Y. Sato, A. Agari, E. Hirose, M. Ieiri, Y. Katoh, M. Minakawa, R. Muto, M. Naruki, S. Sawada, Y. Shirakabe, Y. Suzuki, H. Takahashi, M. Takasaki, K.H. Tanaka, A. Toyoda, H. Watanabe, Y. Yamanoi KEK, Tsukuba, Japan H. Noumi RCNP, Osaka, Japan
	Residual gas ionization profile monitors (RGIPMs) working in 1 Pa pressure have been developed for high-intensity proton beam (maximum: 50GeV-15uA) at J-PARC slow-extraction beam line. The transverse beam profiles are measured by collecting electrons produced by ionization of 1 Pa residual gas. The electrons are guided to the segmented electrode with a uniform electrostatic field applied in the gap. A uniform magnetic field is applied parallel to the electric field to reduce diffusion of electrons travelling to the electrodes. Typical spatial resolution of the RGIPMs with a 10 cm gap, a 10 V/cm electrostatic field, and a 400 gauss magnetic field at center is 0.5 mm. The collected charge is integrated during every extraction period (typically 2 second in 6 second accelerator cycle). Subtracting background distributions measured during off-beam period, profile distributions are measured clearly. The 14 RGIPMs installed in the slow-extraction beam line are working stably for the 30 GeV-0.46 uA proton beam at current maximum. In this contribution, detailed specifications and performance of the present RGIPMs will be reported.

Paper

Title

Page

Use of Gafchromic Films to Measure the Transverse Intensity Distribution of a Large-area Ion Beam

1

Y. Yuri, I. Ishibori, T. Ishizaka, A. Kitamura, S. Okumura, T. Yuyama
JAEA/TARRI, Gunma-ken, Japan
S. Sawada, T. Yamaki
JAEA/QuBS, Takasaki, Japan

In the TIARA AVF cyclotron facility of JAEA, it is necessary to evaluate the cross-sectional area and uniformity of a large-area uniform ion beam formed by multipole magnets both precisely and handily. A technique has, therefore, been developed to measure the two-dimensional transverse intensity distribution of the ion beam using Gafchromic radiochromic films (Ashland Inc.). In order to show available fluence ranges of the film, the coloring response of the Gafchromic films irradiated with several species of ion beams is investigated as a change in the optical density of the film. It has been found that the optical density increases linearly with the fluence, whose range is practical for materials and biological research. Thus, the relative transverse intensity distribution of ion beams can be measured using the film. Furthermore, the intensity distribution determined by the Gafchromic film is compared with the area-density distribution of track-etched pores in a polymer film from a microscopic viewpoint. It has been demonstrated that the beam uniformity obtained from the Gafchromic film is equivalent to the relative standard deviation of the microscopic pore distribution.

MOPB81

Residual Gas Ionization Profile Monitors in J-PARC Slow-extraction Beam Line

1

Y. Sato, A. Agari, E. Hirose, M. Ieiri, Y. Katoh, M. Minakawa, R. Muto, M. Naruki, S. Sawada, Y. Shirakabe, Y. Suzuki, H. Takahashi, M. Takasaki, K.H. Tanaka, A. Toyoda, H. Watanabe, Y. Yamanoi
KEK, Tsukuba, Japan
H. Noumi
RCNP, Osaka, Japan

Residual gas ionization profile monitors (RGIPMs) working in 1 Pa pressure have been developed for high-intensity proton beam (maximum: 50GeV-15uA) at J-PARC slow-extraction beam line. The transverse beam profiles are measured by collecting electrons produced by ionization of 1 Pa residual gas. The electrons are guided to the segmented electrode with a uniform electrostatic field applied in the gap. A uniform magnetic field is applied parallel to the electric field to reduce diffusion of electrons travelling to the electrodes. Typical spatial resolution of the RGIPMs with a 10 cm gap, a 10 V/cm electrostatic field, and a 400 gauss magnetic field at center is 0.5 mm. The collected charge is integrated during every extraction period (typically 2 second in 6 second accelerator cycle). Subtracting background distributions measured during off-beam period, profile distributions are measured clearly. The 14 RGIPMs installed in the slow-extraction beam line are working stably for the 30 GeV-0.46 uA proton beam at current maximum. In this contribution, detailed specifications and performance of the present RGIPMs will be reported.