[en] The free field radiation environment from the White Sands Missile Range Fast Burst Reactor (FBR) has been measured. One experiment investigated the environment 170 meters from the reactor and a second experiment determined the environment seven meters from the FBR. The threshold foil activation technique followed by SAND-II unfolding was employed to measure the neutron spectra. Increased foil masses and radiochemical separation techniques were used. A calibration experiment using an NBS calibrated ²⁵²Cf neutron source was also performed. This experiment ties all of the neutron spectra experiments, using the threshold foil activation method and SAND-II unfolding, to a neutron source of known spectral shape and intensity. This ²⁵²Cf experiment also demonstrates the validity of using radiochemical techniques. The gamma component of the radiation environment was determined by LiF thermoluminescence dosimeters (TLD). From the TLD data and the neutron spectra data the total dose at 170 and seven meters was calculated. Results give good agreement with theoretical transport calculations and other experimental determinations

[en] Arkansas Nuclear One (ANO) is a two-unit nuclear power-generating station. Unit One (ANO-1) was designed by Babcock and Wilcox (B and W), and Unit Two (ANO-2) was designed by Combustion Engineering. During operation of ANO-1, corrosion products and feedwater contaminants are introduced into the Once-Through Steam Generators (OTSG). As the feedwater is changed to steam inside the OTSG, most of this material is left behind. Power was reduced on ANO-1 in June, 1981, to maintain downcomer water level within the operating range. Visual inspections confirmed heavy deposits on tubes, and on the fifth and sixth tube support plates in the ANO-1A OTSG. The option Arkansas Power and Light Company (AP and L) has chosen for the ultimate removal of these deposits is chemical cleaning. The total AP and L chemical cleaning plan is divided into a four-phase program. Feedwater nozzles were replaced, the orifice plate openings were increased by 25%, and several controlled flushings were performed in April and May, 1982. The combination of these activities returned ANO-1 to 100% power. ANO-1 remained at full power until the refueling outage in January, 1983. Since full power was restored, the cleaning has been postponed until further testing can be performed and evaluated. It still appears that chemical cleaning is inevitable

[en] Careful measurements were made of the resistivity vs. temperature in a sample of polycrystalline YBa₂Cu₃O/sub 7-δ/ and the data were fitted to a theoretical expression for the fluctuation-enhanced conductivity in the normal state. From this fit, a value was inferred for the zero-temperature Ginzberg-Landau coherence length zeta (0) of 21 +/5 5A

[en] The mass-yield distribution for the neutron-induced fission of ²³⁸U by degraded fission spectrum neutrons with an average energy of 1.52 MeV has been measured radiochemically for 26 mass chains in the region A = 89 to 153. Germanium-lithium gamma-ray spectroscopy coupled with beta-particle counting techniques was used to determine the absolute activities of each nuclide measured. The absolute cumulative fission yield of mass chain 140 (¹⁴⁰Ba-¹⁴⁰La) was determined to be 6.07 +- 0.24, and all other reported yields were measured relative to that value. Measured yields ranged from a maximum of 6.33 +- 0.55 for ¹⁰³Ru on the light mass wing and 6.54 +- 0.28 for ¹³³I on the heavy mass wing to a minimum of 0.030 +- 0.007 for ¹²¹Sn in the valley region. Results from this investigation provide a consistent set of cumulative mass yields from ²³⁸U fission induced by a well-characterized neutron spectrum

[en] The mass-yield distribution for the neutron-induced fission of ²³⁸U by degraded fission spectrum neutrons with an average energy of 1.52 MeV has been measured radiochemically for 26 mass chains in the region A = 89 to 153. Germanium-lithium gamma-ray spectroscopy coupled with beta-particle counting techniques was used to determine the absolute activities of each nuclide measured. The absolute cumulative fission yield of mass chain 140 (¹⁴⁰Ba--¹⁴⁰La) was determined to be 6.07 +- 0.24 percent, and all other reported yields were measured relative to that value. Measured yields ranged from a maximum of 6.33 +- 0.55 percent for ¹⁰³Ru on the light mass wing and 6.54 +- 0.28 percent for ¹³³I on the heavy mass wing to a minimum of 0.030 +- 0.007 percent for ¹²¹Sn in the valley region. Results from this investigation provide a consistent set of cumulative mass yields from ²³⁸U fission induced by a well-characterized neutron spectrum

[en] Measurements of the zero-field resistive transition of Bi₂Sr₂CaCu₂O₈ single crystals suggest that a bulk zero-resistance state develops through a sequential process characterized by two transition temperatures. The upper transition corresponds to Josephson coupling of parallel CuO bilayers, and the lower transition to the conventional Kosterlitz-Thouless dissociation of bound vortex excitations. Measurements using a ''flux transformer'' electrode geometry indicate a pronounced peak in the secondary voltage, which is suppressed by an external magnetic field

[en] Random percolative disorder has been introduced into 300x300 arrays of Nb-Au-Nb proximity-coupled junctions. Our measurements of dc transport properties show that large amounts of random disorder, although depressing T_c and broadening the resistive transition, do not alter the scale invariance of the phase transition. These results are described by a model which rescales the Josephson lattice by the percolation correlation length. The relevance of the observations to granular thin films is discussed

[en] Reply to D. Browne and B. Horovitz preceding Comment [Phys. Rev. Lett. 61, 1259 (1988)]

[en] We have measured the low-field magnetoresistance and current-voltage characteristics of polycrystalline Y₁Ba₂Cu₃O₇√/sub δ/ near the superconducting-normal transition. The development of a fully superconducting state occurs via an intermediate phase about 2 K in width. Within this intermediate phase, sample dissipation is highly non-Ohmic and exhibits extreme sensitivity to small magnetic fields. The nonlinear I-V characteristics describe a new phase with zero resistance and zero critical current which seems to arise from the presence of strong junction disorder

[en] The development of processes for depositing diamond in large sizes offers the promise of optics with a combination of intrinsic superior properties. These properties include optical transmission over a large wavelength range due to a wide electronic bandgap and forbidden first order phonon induced absorption, the ability to withstand high laser powers due to high optical transmissivity and high thermal conductivity, and great mechanical strength due to large elastic moduli. Polycrystalline diamond of high optical quality can now be produced by various enhanced chemical vapor deposition (CVD) techniques in sizes many cm in diameter and in thicknesses of the order of one mm. Key to the use of diamond as an optical material is our ability to evaluate the defects that influence the properties. A variety of techniques are used to investigate the defect content. These include optical absorption spectroscopy, Raman spectroscopy, transmission electron microscopy, electronic carrier lifetime, and thermal conductivity. Use of CVD diamond in an aircraft environment of rain and sand erosion is currently limited by the strength of the material which is in the range 200 to 400 MPa. Despite its lower than expected strength, diamond has excellent resistance to thermal shock. Even if all of the technical limitations for producing high quality CVD diamond for optical applications are overcome, the cost of production is still very high; large scale use will require a significant drop in price. A particular impediment is the high cost of polishing diamond