Three-Dimensional Si Imaging Array for Cold Neutrons--IntraSpec, Inc., P.O. Box 4579, Oak Ridge, TN 37830-4579; 423-483-1859
Mr. John Walter, Principal Investigator
Mr. John Walter, Business Official
DOE Grant No. DE-FG02-99ER82807
Amount: $750,000

Cold neutron scattering is rapidly gaining importance as a tool for studying structure in materials. Neutron detection arrays are used with such neutron scattering experiments to reduce counting times and increase accuracy. With the advent of stronger sources of cold neutrons, there is a need for much higher response speeds in these arrays. Existing two dimensional wire arrays are limited to about 40,000 counts/s total with 10% dead time and are handicapped by ghost images resulting from pile-up problems. This project will develop a 100 pixel sub-array which provides high rate detection, event time, and efficient data collection for the angular distribution of low-energy neutrons scattered during structure studies. Furthermore, the project will demonstrate that these sub-arrays can be combined in a relatively seamless manner to minimize dead regions between them. The Phase I project demonstrated the ability of a small Si pixel detector array to accommodate count rates well in excess of 10⁵ counts/s per pixel, as well as the capability to do the fast timing required for simultaneous neutron time-of-flight analysis. A conceptual design was developed for a 10⁴ pixel array (composed of 100 pixel sub-arrays, each with parallel processing), a 100 pixel monolithic detector array, and an ASIC parallel signal conditioning array. The Phase II project will design and produce a few neutron imaging sub-arrays with good efficiency and fast timing capability; demonstrate timing and efficiency; and show that adjacent sub-arrays can be combined with minimal dead zone between sub-arrays.

Commercial Applications and Other Benefits as described by the awardee: Instruments for studying long range structural order in materials (by detecting scattered cold neutrons) should benefit by the ability to handle very high rates without the usual problems of pile-up induced ghost images. The technology developed will also prove useful for other applications such as particle physics arrays and x-ray imaging.