Worlds brightest cold neutron spectrometer: MACS Collin Broholm, Johns Hopkins University, DMR 0116585

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Neutral, magnetic, and heavy, neutrons are an ideal probe of structure and dynamics in materials.

Neutron – solid interactions are however weak so intense beams are needed.

MACS will provide atomic scale structural and dynamic information from small samples under extreme thermodynamic conditions and comprehensive high statistics data for large crystalline samples.

Funded by NSF Major Research Instrumentation, NIST, and JHU, the Multi Axis Crystal Spectrometer, MACS, has achieved a world record for cold monochromatic neutron flux.

At 5×108 n/cm2/s the flux on sample exceeds the current record by an order of magnitude.

The central component is the doubly focusing MACS monochromator. Built at JHU with the involvement of graduate and undergraduate students, it comprises 357 orientable graphite platelets that direct neutrons to the sample.

A new method for multiplexing cold neutron spectroscopy at a reactor source was developed and implemented. Twenty monochromatic detection channels will operate in parallel for an order of magnitude efficiency gain.

Multi-channel energy dispersive neutron detectionCollin Broholm, Johns Hopkins University, DMR 0116585

The key component is the double crystal graphite analyzer. It is as effective as a conventional single bounce analyzer yet compact to enable multiplexing.

Each neutron scattered from the sample carries structural and/or dynamic information. MACS optimizes detection through multiplexing.

These advances expand the applicability of inelastic neutron scattering to probe atomic scale motion in solids.