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Intense x-ray transition radiation can be generated when relativistic electrons pass through a multiple-foil target. When the foil spacing is periodic, the transition radiation can be spatially coherent with respect to the target period. The spatial coherence can be evident in the spectra and angular distributions of transition radiation from such targets. A series of experiments has measured coherent transition radiation distributions from multiple-foil targets (up to six foils) with spacings of 50 {mu}m and 100 {mu}m. The electron energy was about 75 MeV and the photon energies were about 200 eV. Agreement between calculation and experimental data is excellent.

Continued interest in high-energy {gamma} rays associated with fusion reactions has motivated an ongoing search for simple, effective measurement techniques. Past experiments have measured 16.7-MeV {gamma} rays with Compton-magnetic spectrometers. Some measurements have been performed with threshold Cherenkov detectors with enhanced sensitivity to high-energy {gamma} rays. The Compton spectrometers work quite well, but they require extensive calibrations and tend to be expensive and cumbersome. The threshold Cherenkov detectors are simpler to calibrate and physically compact, but have poor spectral definition and are vulnerable to background signals. This report is to describe a new type of {gamma}-ray detector, the MOLE, that may retain the simplicity of a threshold Cherenkov detector while still having sufficient energy discrimination to be effective for measuring high-energy {gamma}-rays in the presence of lower-energy {gamma}-ray fluxes.

An intercalated graphite was prepared by reaction of polycrystalline graphite with AsF 5 followed by reaction with NO 2 SbF 6 . At −73%, four narrow lines are found in the 19 F n.m.r. spectrum at +124.1, +112.7, +66.7, and +46.8 ppm (relative to CFCl 3 ). These lines are attributed to SbF 6 − , SbF 5 , AsF 6 − in rapid chemical exchange with AsF 5 , and AsF 3 , respectively. This demonstrates the use of n.m.r. for the qualitative analysis of the chemical species present in the interlamellar space. As the temperature is increased, the lines broaden (except for that of AsF 3 ) and subsequently narrow, indicating, further, that chemical exchange of fluorine is occurring among SbF 6 − , SbF 5 , AsF 6 − and AsF 5 . At 22 °C the exchange rate is ∼ 10 3 s −1 for SbF 6 − and >3 × 10 3 s −1 for the other species. The data are interpreted in terms of a model in which fluorine exchange between SbF 6 − and the fluoro-arsenic species occurs via SbF 5 .

Trois courtes experiences (6 mois a 1 an) sont effectuees pour preciser l'importance de cette predation sur la structure des biocenoses des substrats durs intertidaux de la Nouvelle Galles du Sud (Australie). Difficultes dans l'interpretation des resultats

As a prerequisite for models of foraging behaviour of the whelk, Morula marginalba Blainville (Muricidae), the effects of variation in density of prey on the rate of feeding of the predator were examined in field conditions for three coexisting species of prey. Densities of prey used were those at which the prey, two limpets and a barnacle, occurred naturally in the rocky intertidal habitat. Large limpets, Cellana tramoserica (Sowerby) can resist attacks by predatory gastropods by raising the mantle over the outside of the shell. These experiments showed that no C. tramoserica were killed by Morula marginalba even at very great densities and with no alternative prey present. For the small limpet Patelloida latistrigata (Angas), one of the whelk's most highly preferred prey, juveniles were eaten 1.4 times as fast as adults. Fitting the random predator equation gave greater attack coefficients and shorter handling times for juvenile than adult limpets. Sizes of both predator and prey affected rates of eating barnacles, Tesseropora rosea (Krauss), but not in a simple way. Whelks of 15-mm aperture length ate adult barnacles 4.2 times faster than did 12-mm whelks, but there was no significant difference in the rates at which the two sizes of snail ate juvenile barnacles. Rates of feeding on T. rosea and Patelloida latistrigata increased significantly with prey density. These results form a basis for including the density of prey in models of spatial dispersion of the predatory gastropod Morula marginalba .

A simple-to-use graphical method for estimating the sound pressure level in the shadow zone of a rigid straight-edged barrier for sound radiated from a point source located in a large room is presented and discussed. Also presented is a means based on the graphs introduced for evaluating the noise reduction potential of a barrier in a room or factory work space.

In this paper details of the design, construction and performance of a microphone probe for sound measurement in flames and inaccessible places are presented.

We have observed dHvA frequencies in several samples of stage 2 graphite-AsF 5 intercalation compound. A consistent interpretation is given in terms of two nested hole surfaces located at each of the 6 corners of the 2D graphite zone. A fractional ionization f = 0.42 is obtained, consistent with spin susceptibility, with the Blinowski-Rigaux analysis of reflectivity, and with recent chemical results.

Comparison of the intensities of the 19 F and 1 H NMR spectra of the graphite intercalation compound prepared by reaction of highly-oriented pyrolytic graphite with NO 2 PF 6 dissolved in CH 3 NO 2 showed that the number of CH 3 NO 2 molecules present per PF 6 − ion varied from 1.64 to 1.14 depending upon sample preparation. The 1 H NMR spectra of CH 3 NO 2 in single pieces of HOPG intercalated with PF 6 − , AsF 6 − , or SbF 6 − show 1:2:1 triplets due to dipolar splittings resulting from partial ordering of the CH 3 NO 2 molecules with the molecular symmetry axis parallel to the graphite planes.

Metallic polymeric sulfur nitride may be halogenated at room temperature to give a series of highly conducting polymers which are also metals. Compositions such as (SNBr0.25)x, (SNBr0.4)x and (SNBr0.55)x may be obtained under varying conditions. The conductivity of (SNBr0.4)x is ten times greater than that of (SN)x itself. Crystalline silvery films of the flexible semiconducting polymer, trans 'polyacetylene', take up halogens with enhanced optical and electrical properties. (CHBr0.05)x and (CHI0.22)x have four and seven orders of magnitude greater room temperature conductivities respectively, than trans-(CH)x.

Like some other species of intertidal muricid gastropods, Morula marginalba Blainville, a common predatory whelk on rocky shores in eastern Australia, sometimes forms aggregations, usually in a pool or crevice. A model was formulated to explain the occurrence of these aggregations, which form at different times in different locations. According to the model, M. marginalba aggregate when environmental conditions are unsuitable for feeding. Feeding whelks sit on a prey item through several high and low tide periods. They are thus exposed for part of their feeding time to the aerial environment and could be stressed by heat and desiccation. Unfavourable environmental conditions cause the snails to cease foraging and seek shelter. Where suitable shelters are sparse and numbers of whelks are large, aggregations are seen in crevices. To test this proposed model, study areas were marked on shores where crevices were distinct from feeding areas, and counts were made of the numbers of snails sheltering and foraging every one to three days for a period of 25 days. On shores protected from wave-action, sheltering and foraging behaviour alternately predominated in a cyclical manner with a two-weekly or tidal rhythm. The cycles were out of phase, however, in different habitats. In an unshaded, mid-tidal location, virtually all of the M. marginalba were foraging when low tides were around dawn and dusk, and were sheltering in crevices when low tides were around midday. In a shaded, high-intertidal location, most whelks foraged when submersion was long during spring tides, and sheltered during the long emersion of neap tides. These findings agreed well with the predictions. The sheltering behaviour of the predators is discussed with respect to patterns of mortality of prey. Whelks only forage for part of the time, and because feeding is interrupted by the need to return to shelter, feeding excursions must start from shelter. If crevices are widely spaced, relative to the speed at which the snails can move, places far from shelter should receive less or later predation than those close to shelter.

The first observation of the angular distribution of coherent (resonant) transition radiation at soft-X-ray photon energies (1 to 3 keV) is reported. Two different radiators were constructed, each consisting of stack of eight foils of 3.5- mu m-thick mylar. One of the radiators was designed to demonstrate interfoil coherence and had foil-to-foil spacing of 8.5 mu m throughout the stack. The other radiator had large random spacings that prevented coherent interference between foils. These radiators were irradiated with electron beams with energies ranging from 63 to 97 MeV, and their angular distributions were compared. The distributions were symmetrical around the axis of the transition-radiation cone. For the coherent case the angle of peak photon emission was found to increase with increasing electron-beam energy; for the incoherent case the angle was found to decrease with increasing electron energy. The coherent case is contrary to the normally expected behavior and can be used as the basis of an electron beam-energy diagnostic. >

In this paper we explore the effect of variations in reaction conditions on the basal resistivity ϱ a of graphite intercalated with HNO 3 and AsF 5 . In the former case, the reaction rate is varied over a wide range by diluting the reactant vapor with inert gas. In the latter case, several variations which might be expected to alter the fractional ionization are explored. None of these treatments produces a significant effect, from which we conclude that intrinsic values of ϱ a are being obtained with these compounds. Further improvements in ϱ a will therefore rely on development of new materials.

Morula marginalba Blainville is a common predatory gastropod on rocky shores of southeastern Australia. Mean size of Morula varied in accordance with the species of prey present, both within a shore where a variety of prey were available, and among shores each dominated by a single species of prey. Growth of tagged whelks varied among populations both with respect to the asymptotic size reached by the adult whelks, and the rate of approaching this size. Sampling and short-term experiments on growth in an area with a mixed assemblage of prey confirmed these trends. Mortality also varied significantly among populations, but independently of the pattern of growth. The size structure of a population can be understood as an interaction of the mean and variance of the asymptotic size, and the rate at which animmals in any population approach this size, in comparison with the rate of mortality. Since these can vary independently in relation to different species of prey, a great range of size structures is possible in different habitats. Recruitment of Morula can vary greatly from year to year, and the success of recruitment into any one population apparently bears no relationship to success in others. These findings are discussed with regard to generalizations about population models, life-history characteristics, and predator-prey interactions.

Elastic and inelastic neutron scattering are reported for stage 1 and 2 Li-graphite. The principal results are as follows: 1. (1) No evidence was found for the previously reported stacking transition in LiC 6 ; the normal AαAα ...stacking persists down to 10 K. 2. (2) The C -parameter of LiC 6 increases rapidly with increasing T (1.5% between 300 and 490 K). This may be a precursor to the Li order-disorder transition which occurs above 500 K. 3. (3) Upon heating above 520 K, stage 2 transforms into a dilute stage 1 phase, as predicted by Safran. 4. (4) The dispersion of the LA phonon propagating along c shows a 40% increase in sound velocity relative to pure graphite, as compared with 10% for RbC 8 . This confirms the existence of strong interlayer interactions in LiC 6 .

Electrical transport and optical reflectance studies have been carried out on metallic derivatives of (SN)x; (SNBr0.4)x and (SNBr0.25)x. The average room temperature conductivity of (SNBr0.4)x is 3.8 × 104 (ω-cm)-1 with temperature dependence characteristics of metallic behavior. Resistance ratios depend on sample perfection. Analysis of the optical reflectance data for light polarized along the (SN)x chains yields [ h ]ω p = 4.8 eV indicating little or no charge transfer upon bromination.

The c-face of highly oriented pyrolytic graphite (HOPG) has been implanted with a high energy beam (25 keV) of F+ ions at a fluence of 3×1017 ions/cm2. The implanted face turns blue and exhibits modified optical properties (sharp Drude edge, high reflectivity below the edge) associated with metallic behavior. The optical properties are roughly the same as those engendered in third stage intercalation compounds of graphite with electron acceptors and by analogy with these compounds the fluorine is thought to be present largely as F− ions. X-ray photoelectron spectra of the implanted host have also been obtained. Relative signal intensities of the F 1s and F 2s levels reflect the strong F depth concentration gradient in the samples. The large C 1s:F 1s intensity ratio implies that only very modest etching of the sample surface has taken place during implantation. The sputtering coefficient of graphite is estimated from XPS data to be no greater than 0.3 for these implantation conditions.

It is shown that when dimensional concepts are developed within the context of elementary group theory they enjoy a concrete foundation. Furthermore, the utilization of groups for this purpose enables a generalization of dimensional analysis to be formulated as an aspect of a far-reaching theory that has been herefore invoked principally for similarity analyses . Specifically, it is shown that for applications wherein the governing equations are in view a systematic procedure can be invoked which yields conclutions that are in every instance at least as general as those obtained via more conventional dimensional approaches. For those applications wherein the governing equations are not in view, a novel pi-theorem , which evolves naturally as a part of the theory introduced here may be utilized.

The core level binding energies of AsF 3 and AsF 5 gas have been measured and the ΔBE(F 1s-As 3d) shift between the two molecules has been found to be over twice as large as the value previosly reported. Core data lavel has also been recorded for antimony pentafluoride gas. It is anticipated that these data will be useful in evaluating the nature of polymerdopant interactions.

The investigation of two poorly understood but technologically important physical properties of silicate glasses and related materials is described. The use of Electron Paramagnetic Resonance to investigate the nature of radiation-induced damage in glasses exposed to a variety of high-energy radiation sources is discussed first. Second, the measurement of the nonlinear index of refraction coefficient in a variety of optical materials related to the design of high-power laser systems is described. The radiation damage investigations rely heavily on the comparison of experimental results for different experimental situations. The comparison of EPR lineshapes, absolute spin densities and power saturation behavior is used to probe a variety of microscopic and macroscopic aspects of radiation damage in glasses. Comparison of radiation damage associated with exposure to gamma rays and fast neutrons (and combinations thereof) are interpreted in terms of the microscopic damage mechanisms which are expected to be associated with the specific radiations. Comparison of radiation damage behavior in different types of glasses is also interpreted in terms of the behavior expected for the specific materials. The body of data which is generated is found to be internally self-consistent and is also generally consistent with the radiation damage behavior expected for specific situations.more » A new and versatile technique for measuring the nonlinear index of refraction coefficient, n/sub 2/, in optical materials is described. The technique utilizes a 1 ns pulsed neodymium-glass laser system and time-resolved interferometry to determine the ratio of the coefficient n/sub 2/ of sample materials to the n/sub 2/ of CS/sub 2/. This method avoids some of the complications associated with performing absolute measurements of n/sub 2/ and allows the use of a relatively simple experimental technique. The measurements determine the nonlinear index ratios of the samples with an accuracy of about +-15 percent.« less

A NeUtron MOnochromator, NUMO, for (D,T) fusion diagnostics is described. The monochromator consists of CH/sub 2/ (n,p) converter foil, a sector-magnet monochromator and Faraday cup detector. This system can be used to study some details of (D,T) fusion reaction history. 6 refs., 5 figs.

Monoclinic crystals of metallic (SN) x may be synthesized by the solid state polymerization of S 2 N 2 at room temperature. The monoclinic form may be converted to an orthorhombic form by mechanical shearing. When monoclinic (SN) x is heated at 145° it depolymerizes to a gaseous, very reactive isomer of S 4 N 4 which re-polymerizes on room temperature glass or plastic substrates to give golden, metallic (SN) x films. Crystals of (SN) x have a large conductivity at room temperature which shows the temperature dependence characteristic of metals, increasing rapidly with decreasing temperature. When (SN) x is treated with bromine vapor at room temperature it is converted to shiny black crystals of (SNBr 0.55 ) x which lose bromine on pumping at room temperature to give compositions in the range (SNBr y ) x (y ˜ 0.3−0.4). Simultaneous heating and pumping yields copper-colored crystals of (SNBr 0.25 ) x . All the brominated species are apparently metals having a higher conductivity than (SN) x Conductivity and optical reflectance measurements strongly suggest that the brominated polymers are more anisotropic in their metallic properties than (SN) x .

Semen analysis of 59 ejaculates was undertaken. The ejaculates included pre-vasectomy semen postvasectomy necrospermic ejaculates and postvasectomy azoospermic ejaculates. Analysis after centrifuging revealed no significant changes in the activity of lactic dehydrogenase or glucose-phosphate isomerase or in the amount of protein or fructose in the 3 groups of semen. There was a significant negative correlation between time of ejaculation and enzyme activity.

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The enzymatic activity of glucose-phosphate isomerase was measured in cervical mucus from women using a diaphragm no contraception (controls) an IUD or some steroid method and from postcoital women. Determination of activity was performed through colorimetric measurement of fructose 6-phosphate formed from glucose 6-phosphate using the enzyme. The cycle was divided into the proliferative phase (days 1-11) the ovulatory phase (days 12-16) and the secretory phase (days 17-32). Among the diaphragm users and non-contraceptors whose enzyme activity was the least of the first three groups activity was significantly greater (p is less than 0.01) during the secretory phase than during either of the other phases. First phase activity in the IUD women was significantly greater (p is less than 0.01) than either second or third phase activity. No significant differences were found among the phases in the steroid women but this groups activity was consistently higher than the activity of the diaphragm or non-contraceptive or IUD group. Postcoital samples had less activity than random samples obtained on days 14 15 and 16 from non-contraceptors. Since semen contains a large activity the results shed doubt on the view that semen enters cervical secretion; or the results might reflect the greater amount of mucus in the postcoital samples. Enzymatic activity increased following secretion or administration of progesterone in the control and steroid groups but not in the IUD group. Since the enzyme takes part in the glycolytic pathway by catalyzing the reversible conversion of glucose 6-phosphate to fructose 6-phosphate the absence of fructose in human cervical mucus is puzzling. The suggested absence of glucose 6-phosphate was confirmed when fructose was formed after small quantities of glucose 6-phosphate were added to cervical secretion.

Use of vasectomy led to interest in the possible immunologic of biochemical changes in postvasectomized semen. A study of 66 ejaculates was made. After routine semen analysis leucine aminopeptidase and aspartate aminotransferase were correlated with sperm court. Semen may vary and the activity of some enzymes and motility are related to sperm concentration. No differences in protein fructose isocitric dehydrogenase or alanine aminotransferase were found. The significant difference in the amount of enzymatic activity of LAP was higher in the normal specimens decreased in the semen of oligospermic males and the postvasectomy semen and was least in the infertile group.

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