Eur. Phys. J. A (2011) 47: 138
https://doi.org/10.1140/epja/i2011-11138-8

Letter

Spin-polarization of radioactive ¹²³In_g.s. by the tilted-foil method

¹ Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), 305-0801, Ibaraki, Japan
² Department of Physics, Osaka University, 560-0043, Osaka, Japan
³ Japan Atomic Energy Agency (JAEA), 319-1195, Ibaraki, Japan
⁴ Radioisotope Center, Niigata University, 951-8510, Niigata, Japan
⁵ Kochi University of Technology, 782-8502, Kochi, Japan

^* e-mail: yoshikazu.hirayama@kek.jp

Received: 31 August 2011
Revised: 13 October 2011
Accepted: 27 October 2011
Published online: 17 November 2011

Abstract

A spin-polarized radioactive ¹²³In (I ^π , g = 1.220(2) , T _1/2 = 5.97(5) s) beam has been successfully generated by the tilted-foil method. This nuclide is the heaviest ever polarized in its ground state by this method. Using the ISOL-based re-acceleration-type facility TRIAC, an ¹²³In_g.s. beam of 305 keV/nucleon went through a stack of 15 carbon foils with a tilt angle of 70^° , and an asymmetry of 0.76 ± 0.25% of β-decays was observed by the β-NMR technique. The asymmetry shows that the tilted-foil method combined with a re-acceleration facility is useful for producing spin-polarized beams for applications such as nuclear physics and materials science.