Conduction-Cooled Superconducting Magnet for Active-Target TPC Experiments at RAON

Abstract

A compact superconducting magnet was constructed for low-energy nuclear physics experiments at the RAON heavy-ion accelerator facility. Conduction-cooled Helmholtz coils with a radius of 40 cm generate a uniform magnetic field of up to 1.51 Tat a current of 71 A. The magnet has two crossing beam windows that allows the beam to pass either parallel (solenoid mode) or perpendicular (dipole mode) to the field direction. The magnet operates at a ramping rate of 0.01 A/s without quenching and generates a highly uniform magnetic induction within 0.1% of the central value of 1.51 T over the volume of 10 × 10 × 10 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> corresponding to the size of an active target time projection chamber. Herein, we report our first excitation test and field mapping results.