On the Design and Practical Application of a Spatial Neutron Modulator for Neutron Compressive Sensing

The need for higher resolution in materials characterization is increasing faster than current technologies. When characterizing materials, the molecular interactions within a sample are of critical importance such as when studying polymer degradation in nuclear plants or molecular bonding in batteries. Currently, the most used technique is vibrational or IR spectroscopy. The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) uses a neutron vibrational spectrometer, VISION. Using neutrons for this type of spectrometry is advantageous because of increased penetration depth into a sample without degrading its structure. However, currently it is only possible to take bulk measurements. The SNS sought to use a technique called compressive sensing (CS) to increase the resolution and allow prediction material properties within a sample instead of a generalized prediction across the entire range.This thesis approaches the challenge of designing and fabricating a mechanical system, the Spatial Neutron Modulator (SNM), to operate in a high vacuum, extreme low temperature neutron beam environment. The design considers the size constraint of the beam chamber, neutron transparency of chosen materials, thermal shrinkage throughout thermal cycles, as well as off- gassing effects of materials under high vacuum.Ultimately, the system underwent proof-of-concept testing in its final form in an optical experiment before being tested in the harsh environment of the neutron beam.