IPAC2011 - List of Authors (Ikegami, K.)

Paper	Title	Page
WEPS048	Dependence of Beam Loss on Vacuum Pressure Level in J-PARC Linac	2598
	G.H. Wei KEK/JAEA, Ibaraki-Ken, Japan K. Hirano, T. Maruta, A. Miura JAEA/J-PARC, Tokai-mura, Japan K. Ikegami J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	In J-PARC linac, a 181-MeV negative hydrogen beam is supported to a succeeding 3-GeV synchrotron with normal operation power at 100-300 kW. During operation, a beam loss in the straight section of the beam transport line immediately after the linac exit is found. The residual radiation level reaches 0.3 mSv/h on the surface of the vacuum chamber several hours after the beam shutdown with the linac beam power of 12 kW. We suppose that the residual gas scattering of negative hydrogen ions generates neutral hydrogen atoms and they give rise to the beam loss by hitting the vacuum chamber wall. To confirm this speculation, the vacuum pressure level in the linac had been changed in order to find the dependence of the beam loss on it. After data analysis, we found the relationship between beam loss amplitude, which was attained from beam loss signal, and vacuum pressure was linear. Corresponding deduction and simulation has been down according to the residual gas components in linac chamber. In this paper, we present the experimental result and some simulations in this study.

Paper

Title

Page

Dependence of Beam Loss on Vacuum Pressure Level in J-PARC Linac

2598

G.H. Wei
KEK/JAEA, Ibaraki-Ken, Japan
K. Hirano, T. Maruta, A. Miura
JAEA/J-PARC, Tokai-mura, Japan
K. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

In J-PARC linac, a 181-MeV negative hydrogen beam is supported to a succeeding 3-GeV synchrotron with normal operation power at 100-300 kW. During operation, a beam loss in the straight section of the beam transport line immediately after the linac exit is found. The residual radiation level reaches 0.3 mSv/h on the surface of the vacuum chamber several hours after the beam shutdown with the linac beam power of 12 kW. We suppose that the residual gas scattering of negative hydrogen ions generates neutral hydrogen atoms and they give rise to the beam loss by hitting the vacuum chamber wall. To confirm this speculation, the vacuum pressure level in the linac had been changed in order to find the dependence of the beam loss on it. After data analysis, we found the relationship between beam loss amplitude, which was attained from beam loss signal, and vacuum pressure was linear. Corresponding deduction and simulation has been down according to the residual gas components in linac chamber. In this paper, we present the experimental result and some simulations in this study.