Tests of a large air-core superconducting solenoid as a nuclear-reaction-product spectrometer

Abstract

An air-core superconducting solenoid, with a diameter of 0.2 m and a length of 0.4 m, has been configured for use as a heavy-ion reaction-product spectrometer (E/A≤5 MeV/u) near θ=0 °. The spectrometer has a large solid angle (10–35 msr) and properties suitable for time-of-flight measurements with flight paths ≳ 2 m. The performance of the spectrometer was established using α-particle sources and nuclear-reaction products from heavy-ion collisions. The characteristics of air-core magnets are compared to those of steel-yoke magnets. The simplicity and ease of operation of the air-core magnet, without significant problems from the (axial) fringe fields, suggests that larger air-core magnets with dΩ≥20 msr and capable of focusing ions with E/A≥30 MeV/u are feasible. Other applications of solenoids and combinations of solenoids with radial electric-field lenses (ELCO lenses) are also discussed, including designs which focus more than one charge state simultaneously.