[534] Cryomagnet for Spectroscopy

Prior information notice

ESS intends to procure the design and construction of a vertical field split coil superconducting magnet with a minimum central magnetic field of 10.5-14 Tesla and a variable temperature insert (VTI). The latter shall allow normal operation down to 1.5 K or the insertion and cooling of a dilution and/or He3 ultralow temperature (ULT) insert (ULT inserts not part of this tender). The magnet will be used to perform scientific experiments with high magnetic fields and (very) low temperatures on neutron-scattering instruments. The magnet will be principally used on the neutron spectroscopy instruments CSPEC and TREX, so very low background scattering is extremely important. For this reason, the magnet will sit inside a vacuum tank containing the neutron detector assemblies. In addition, material in the main and scattered neutron beam paths must be minimised and detector coverage maximised. A small amount of blocked scattering within the detector range is permitted, to provide additional coil support. This must however be kept to a minimum, and the full horizontal range available with two possible magnet orientations. These instruments are designed to have highly non-magnetic environments, but the supplier will perform simulations to verify both static and dynamic magnetic forces where appropriate and design the magnet to work in the instrument environment. Dynamic forces may occur in the event of an accidental quench. Key specifications: • Alternative offers for 3 fields: 10.5T, 12T, 14T • Symmetrical field • Vertical opening: +/- 7° • Horizontal detector coverage: -36° to +144°, with maximum 2 obstructions in that range, of minimum possible angular range. No more than one obstruction in the 0°-90° range. • Two alternative beam paths to provide full horizontal detector coverage. • 50 mm diameter accessible sample space, within VTI • Sample size 1cm x 2 cm (h x v) • Temperature range 1.5 K – 300 K • Recondensing helium bath, zero boiloff in standby mode. Expected delivery date mid 2027.