studies of photonuclear reactions. Programs in electron and x-ray beam dosimetry, accelerator research, and production and use of monoenergetic positron and photon beams are in preparation. Collaborative programs with groups from six different universities are or will soon be in operation. A major improvement during the year for time-of-flight experiments has been the development of enhanced short pulse linac operation. Beam pulse lengths of three to five nanoseconds and beam currents in excess of two amperes at the end of the accelerator are now possible. Delivery of energy analyzed beams (2 percent) in excess of one ampere to experiments with these pulse lengths is routine. NBS Reactor.-On December 7, 1967 the National Bureau of Standards Reactor (NBSR) achieved criticality for the first time. This was the culmination of more than nine years of planning and over four years of construction. The NBSR, a high-flux, tank type, heavy water cooled and moderated machine will operate initially at a power of 10 MW (thermal) and will have a flux of 1014 n/cm2/s. Several months of low power testing are required to determine the characteristics of the reactor before operating at high power. When NBSR becomes fully operational, it will be used for neutron diffraction and scattering experiments in the area of materials research and for studies in radiochemistry. 4 MeV Accelerator.-The experimental flexibility of the NBS 4MeV Van de Graaff accelerator has been increased by the addition of a new 18-in. diameter electron scattering chamber. This chamber, which may be used for electron scattering experiments, dosimeter irradiations and charged particle detector calibrations, provides such features as a remotely operated target viewing system to determine incident beam position, scattering ports every 30° from 0 to 180°, and complete electrical insulation for current measurements. The accelerator system has also been equipped with a beam centering feedback system to automatically maintain beam location, independent of small changes in the operating parameters of the accelerator. Further updating of the accelerator voltage stabilizing system is also underway. Isotope Separator.-The new electromagnetic separator has been used for the preparation of pure, thin, mass-identified sources of stable and radioactive isotopes. Sources which were made with the isotope separator were used in Mössbauer, photonuclear reaction, nuclear orientation, and range distribution studies. The ion implantation of sulphur in semiconductors such as gallium arsenide and cadmium sulfide resulted in the production of materials with desirable properties. An investigation of the radiation damage to metal chelates has been started. Reactor operators using fuel handling tools to lock fuel elements into the core of the NBS reactor. Control room can be seen in the background. Technician on left is observing the operation in the core through a periscope. Synchrotron Move.-During this year the major effort of moving the NBS 180-MeV synchrotron from the Washington site to Gaithersburg was essentially completed. Efforts are now underway to achieve or better the beam currents previously available before experimental programs using the accelerator resume. Technical Assistance to Others Studies for Other Agencies Standard Nuclear Instrument Module System.-The standard Nuclear Instrument Module (NIM) System, developed in conjunction with the National Laboratories of the U.S. Atomic Energy Commission, has had a tremendous impact on the entire nuclear instrumentation field and has revolutionized the manner in which experiments are performed in nuclear physics. Practically all modular nuclear in strumentation currently produced in the United States is in accordance with this standard. The NIM System is also the dominant modular nuclear instrumentation system worldwide. The NIM System development was undertaken as a result of an NBS report issued in December 1963 that pointed out interchangeability problems that accompanied the advent of transistorized modular instruments and recommended that a coordinated effort be initiated to produce a standard module system to reduce these difficulties. Specifications for standard modules to assure mechanical and electrical interchangeability were drawn up in 1964; laboratory and industry utilization began at the end of that year. By 1966 the NIM System had been adopted by practically all U.S. nuclear instrument manufacturers and was responsible for a considerable export market in nuclear instruments. Radioactive Contamination of Materials.-An extensive study is being carried out on behalf of the USAEC to determine the extent of low-level contamination in chemical reagents and commercial materials, including the study of variations with time, nature, manufacturing practice and geographical origin. Over 500 samples have been studied to date. Conferences Molecular Dynamics and Structure of Solids Conference.-The Molecular Dynamics and Structure of Solids Conference was held at the National Bureau of Standards site in Gaithersburg, Md., on October 16-19, 1967. Sessions were attended by approximately 250 people from Government, industry, and universities. Objectives of the symposium were to: Encourage interdisciplinary cooperation by demonstrating the correlation of various techniques applied to the study of molecular dynamics and structure of solids. Stimulate among participants an appreciation of techniques outside their own specialties. Promote a more complete understanding of the materials of interest. Neutron Cross Sections and Technology Conference.-The second conference on "Neutron Cross Sections and Technology" was held at the Shoreham Hotel, Washington, D.C., on March 4-7, 1968. Approximately 350 persons from Government, universities, and industry attended the Conference. The purpose of the second conference was to provide a common meeting area for the exchange of information among nuclear scientists and engineers interested in neutron cross sections. The conference program was designed to consider all aspects of neutron cross sections, the need for accurate measurements, and their determination by theoretical and experimental techniques and their applications. APPENDIXES ORGANIZATION OF THE NATIONAL BUREAU OF STANDARDS 1 1 The Bureau is headed by a Director who is appointed by the President with the advice and consent of the Senate. The Director is assisted in the overall management of the Bureau by a Deputy Director. In addition there is an Associate Director for Administration who is responsible for the planning and operation of facilities and of administrative management services in support of the Bureau's technical programs. Technical program activities are conducted in three Institutes and a Center for Radiation Research. Each is headed by a Director who is responsible for the development and direction of research programs and central national services essential to the fulfillment of a broad segment of the Bureau's mission. These major organizational units are: (1) The Institute for Basic Standards, which includes 12 divisions (5 in Boulder, Colo.), each serving a classical subject matter area of science and engineering; also 3 administrative divisions serving technical divisions located in Boulder, Colorado; (2) The Institute for Materials Research, which consists of 6 divisions, organized primarily by technical field; (3) The Institute for Applied Technology, which includes 16 divisions oriented to high-technology industries; and (4) The Center for Radiation Research, which includes 4 divisions concerned with the theory and application of radiation. DIRECTOR DEPUTY DIRECTOR Assistant to the Deputy Director 1 820-738 06811 |