Fast-Timing Large-Area Detector for Neutron Scattering

The two reflectometers at SNS serve rapidly growing communities in the fields of nanoscience, membrane bioscience, surfactant chemistry, etc. Unique capabilities of these instruments include ultrahigh neutron intensity for in-plane diffraction and off-specular/grazing-incidence small-angle scattering measurements, and the combination of reflectometry and high-angle diffraction for resolving large-scale and nanoscopic structural/magnetic features under the same experimental conditions. While the data rates and the Q-range covered by these instruments at a single scattering angle are sufficiently high to permit real time kinetic studies on many systems, currently installed detectors do not meet the performance requirements for such studies. The development at RMD of advanced neutron scintillators that demonstrate high absorption efficiency for neutrons and exhibit neutron-gamma discrimination by pulse shape (PSD) and pulse height (PHD), combined with recent advances in large-area picosecond resolution photosensors, has nowmade it possible to develop detectors with the potential to realize a transformational impact on neutron detection and imaging. By combining these new technologies, we will develop a detector that simultaneously provides high detection efficiency for thermal neutrons, nanosecond temporal resolution, tileable large area modules, and sub-millimeter spatial resolution while supporting necessary count rates available at the reflectometer instruments. The Phase I research demonstrated feasibility of the proposed detector by synthesizing high performance scintillation materials in special morphology, and by establishing their high efficiency, superior spatial resolution, necessary count rate, and neutron-gamma discrimination properties. Scintillators integrated into various readout sensors formed prototype detectors that were evaluated at ORNL-HFIR to ensure efficacy of the approach. Phase II project is a logical extension of the Phase I work and will focus on large area growth of the identified best performing scintillator composition and the development of a cost-effective readout for special large-area photosensor. A deliverable detector module will be assembled and tested at the ORNL-HFIR. Commercial applications and other benefits: Large area neutron detectors with fast timing, high spatial resolution, and high efficiency are needed for numerous applications, ranging from non-destructive testing to baggage scanning at entry ports. In addition to safeguarding nuclear facilities, ensuring effective MC&A in facilities, and allowing radiography/tomography in new approaches for spent-fuel storage and processing, improved scintillators and non-3He detectors are critically important to homeland security, nuclear and high-energy physics research, and the development of new sources to effectively address our nations future energy needs. The proposed detectors will also allow scientific research leading to the development of new drugs, materials, and systems that directly impact healthcare and quality of life.