X-ray spectroscopy in atomic collision experiment using superconducting tunnel junctions

• Published in: Physica. C, Superconductivity Superconductivity, 2002-08, Vol.372, p.391-394
• Main Authors: Ikeda, Tokihiro, Nakai, Yoichi, Otani, Chiko, Sato, Hiromi, Oyama, Hitoshi, Kanai, Yasuyuki, Takizawa, Yoshiyuki, Iwai, Yoshio, Morishita, Yuichiro, Oku, Takayuki, Oshima, Nagayasu, Watanabe, Hiroshi, Miyasaka, Hiromasa, Kawai, Kazuhiko, Kato, Hiroshi, Shimizu, Hirohiko M, Yamazaki, Yasunori
• Format: Article
• Language: English
• Subjects: Atomic physics; Highly charged ion; SQUID amp; Superconducting tunnel junction; X-ray
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/S0921-4534(02)00707-4

A superconducting tunnel junction (STJ) is a newly developed X-ray detector which has advantages of not only high energy-resolution but also timing information and high counting-rates. The STJ fabricated in RIKEN has a layered structure of Nb (200 nm-thick, lower electrode)/Al (50 nm)/AlOx/Al (50 nm)/Nb (150 nm, upper electrode). Its sensitive region has an area of 100×100 μ m 2. The output signals were amplified by either a charge-sensitive amplifier or a SQUID amplifier. We used the STJ to measure X-rays emitted in collisions of highly charged ions with various solid targets. The ions used were Ne, O and Ar of 10 kV/q extracted from an ECR ion source at RIKEN. The X-ray spectra from 500 to 900 eV were obtained with an energy-resolution of 20–30 eV at a counting-rate higher than 500 counts/s.