[436] Odin and Heimdal T0 Chopper Rotors

ODIN and HEIMDAL are two of the initial 15 instruments within the construction scope of the ESS, and they both require a T0 chopper. The T0 chopper system is designed to block fast neutrons and gamma radiation from the prompt source pulse. Fast neutrons arrive at the chopper position immediately after the proton pulse strikes the target. To attenuate the fast neutrons to the required level, the T0 chopper must be able to place an attenuator mass of high cross-section material (or arrangement of materials) in the neutron beam during the brief time the fast neutrons are present. Such a chopper also rotates sufficiently fast to leave the beam completely unblocked when neutrons of the desired wavelengths are travelling through the chopper position. T0 typically rotates at some multiple or submultiple of the source frequency, 14 and 28 Hz in this case, and is kept in phase with the source.. The subject of this work is the supply of two (2) T0 rotors; it concerns the production of each component according to the General Arrangement drawing and part drawings. The Buyer will provide all the drawings, and the rotor assemblies delivered shall meet all requirements specified