Improved understanding of the three-dimensional structure of proteins is of well-recognized value in the treatment of disease and in the development of new therapeutic drugs. Precise measurement of hydrogen atom positions within the molecule is central to delineation of such structure and particularly the biological activity of the molecule. Among crystallography techniques, single crystal neutron diffraction (SCD) has the unique ability to provide this information. A major national facility the Spallation Neutron Source (SNS) is due for completion in 2006 and will increase available neutron flux by at least an order of magnitude, thereby enabling practical small crystal size and markedly decreased acquisition times. However, specifications of all current neutron imaging detectors fall far short of those required at such an intensive facility, jeopardizing the realization of this cutting edge crystallographic technique. We propose a novel position-sensitive neutron detector utilizing boron coated straws that can form the basis of a low-cost, large area detector. Phase I feasibility studies have proven that a basic elemental 2 mm straw detector can meet or exceed all requirements for the SCD experiment station at SNS. In phase II a modular array consisting of 200 elemental 2 mm detectors, 50 cm in length will be developed. Following testing at a national laboratory a full scale panel consisting of 11 of these modules and providing an area coverage of 50 x 50 cm2 will be constructed in a form compatible with the needs of the SCD. In phase III, funding will be sought from SNS and other sources to construct and deliver the 20 detectors required to fully equip this experiment station and bring it to full capability for protein structural work at an unprecedented level of production.
