Extension of the HVE 1 MV multi-element AMS system for low background

Abstract

HVE has extended its 1MV multi-element AMS system to enhance its performance on elements like 10Be and 14C as well as actinides like Pu. The original system is very compact, but had some inherent limitations on e.g. background and the mass resolution of the injector magnet. With the extension, system performance has improved in several aspects: For actinide measurements, the low-energy spectrometer is equipped with a 120° magnet featuring a high mass resolution (M/ΔM>1000) and a high bending power (340amu at 35keV), supporting e.g. injection of 244Pu19F5. For 3H AMS, all magnets are equipped with Hall-probe control. The accelerator is equipped with a dual gas stripper system. The high energy spectrometer was extended by a 30 degree magnet removing ions scattering in the high-energy ESA. This has improved the background for 10Be AMS by two orders of magnitude down to the low 10−16. For 14C AMS the magnet allows using charge state 1+ by suppressing scattered 13C to a level also in the low 10−16. The new system has a footprint of 10.4m×4.9m, including a second ion source in the injector and provisions for future implementation of an isobar separator for anions (ISA) for e.g. 36Cl measurements. The first extended system will be delivered to the Aarhus AMS 14C Dating Centre.