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

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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