1210.6483 (T. Sonoda et al.)

Development of a resonant laser ionization gas cell for high-energy,
short-lived nuclei    [PDF]

T. Sonoda, M. Wada, H. Tomita, C. Sakamoto, T. Takatsuka, T. Furukawa, H. Iimura, Y. Ito, T. Kubo, Y. Matsuo, H. Mita, S. Naimi, S. Nakamura, T. Noto, P. Schury, T. Shinozuka, T. Wakui, H. Miyatake, S. Jeong, H. Ishiyama, Y. X. Watanabe, Y. Hirayama, K. Okada, A. Takamine

A new laser ion source configuration based on resonant photoionization in a gas cell has been developed at RIBF RIKEN. This system is intended for the future PArasitic RI-beam production by Laser Ion-Source (PALIS) project which will be installed at RIKEN's fragment separator, BigRIPS. A novel implementation of differential pumping, in combination with a sextupole ion beam guide (SPIG), has been developed. A few small scroll pumps create a pressure difference from 1000 hPa - 10^-3 Pa within a geometry drastically miniaturized compared to conventional systems. This system can utilize a large exit hole for fast evacuation times, minimizing the decay loss for short-lived nuclei during extraction from a buffer gas cell, while sufficient gas cell pressure is maintained for stopping high energy RI-beams. In spite of the motion in a dense pressure gradient, the photo-ionized ions inside the gas cell are ejected with an assisting force gas jet and successfully transported to a high-vacuum region via SPIG followed by a quadrupole mass separator. Observed behaviors agree with the results of gas flow and Monte Carlo simulations.

View original: http://arxiv.org/abs/1210.6483