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Time-Of-Flight Spectrometer NEAT

NEAT was built between 1987 and 1993 as one of the key instruments funded within the BER reactor upgrade project. Due to its innovative design such as variable slit disc choppers, supermirror coated “eye-of-the needle” guide section to allow for shorter pulses for best resolution, and a unique optional multidetector with up to 8 m distance from the sample for small angle scattering, NEAT delivered one of the highest counting rates worldwide in 1993 and had, for the first 10 years of its operation, an equivalent flux and somewhat better resolution than the other best in class instrument, IN5 at ILL. In 2004 a substantial increase of flux was achieved on NEAT with the improvement of the chopper configuration. Equipped with the sophisticated sample environments at BENSC including a broad range of temperatures, pressures and magnetic fields up to 5 Tesla, NEAT has been in consistent high demand by users. The spectrometer serves about 30 experiments yearly and produced more than 100 scientific publications in the last 10 years of operation.

New scientific challenges, in particular in the field of nanoscale phenomena, are leading to demands for instrumentation with higher power and new capabilities, particularly for in situ studies. These challenges have already motivated an upgrade of IN5 at the ILL. The primary spectrometer has been enhanced by installing an advanced supermirror guide section improving the incoming flux by nearly a factor of 10 and a further upgrade in detector area is planned. Several new NEAT-type instruments have been built at various neutron centres, such as PSI (Focus), NIST (CNCS) and FRM-II (TOF-TOF) with performance lying between current NEAT and the upgraded IN5. In light of its key importance, a redesign of NEAT was proposed that will bring much higher data collection power and essential new capabilities, thus providing a leading next generation instrument for users and in-house research in a central research area.