Results of the RIST experiment to design a high power target for the production of radioactive nuclear beams

C J Densham,S Metcalf,H Ravn And The Isolde Group,R A Burridge,H Price,G R Murdoch,I S K Gardner,T A Broome,T G Walker,J R J Bennett,D D Warner,J Kay,T W Aitken,W R Evans,V Panteleev,M Holding,G M Mcpherson,P Drumm

doi:10.1063/1.52484

Abstract

The results of the RIST experiment, to design a high power tantalum foil target for the production of radioactive nuclear beams (RNB), are presented. The target was constructed from 6000 tantalum foil discs (25 μm thick) and spacer washers, diffusion bonded together to form a rigid structure. A target of similar geometry was successfully tested at the ISOLDE facility, CERN, and produced RNB yields and release times at least as good as a normal ISOLDE target. Tests using the ISIS proton beam demonstrated a method to overcome high voltage fluctuations induced by the pulsed proton beam. Operation in a mass separator produced beams of stable ions from a surface ionizer. Thermal tests using electron beam heating showed that the finned target surface gives an enhanced emissivity which radiates 24 kW (design value) at 2300 K, equivalent to running with the 800 MeV proton beam from ISIS at a current of 100 μA.

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