International Nuclear Information System (INIS)

The energy distribution of neutrons generated due to bombardment of 40 MeV alpha particles on thick elemental tantalum is measured using threshold activation detectors. A method of unfolding the neutron spectrum from the activation data based on information-entropy weighted average solution is described. The present unfolding method does not require 'a priori' information about the shape of the solution spectrum. 16 refs. (author).

International Nuclear Information System (INIS)

Evidence for triaxial nuclear shapes from families of unique-parity states in transitional odd-A nuclei around mass A=190 and A=130 is reviewed. The experimental data are analysed within the odd-A triaxial core model. Regular two-dimensional band patterns are found in experiment and are shown to be a consequence of broken axial symmetry. Recent theoretical developments are discussed including the question of how stable the triaxial shapes are.

International Nuclear Information System (INIS)

The phenomenon of radiation blistering by helium ion bombardment has been the subject of extensive studies in recent years because of its technological importance in thermonuclear fusion devices and reactors. However, the mechanism of radiation blistering is still not well understood. There are two different models of blister formation: the gas-pressure model and the lateral stress model. The former model is, however, supported by many experimental observations, the prominent one is that of Evans and Eyre who observed blisters appearing on the front and rear surfaces of a thin wedge-shaped molybdenum foil irradiated by helium ions. Their experiment also indicates that the thickness of the irradiated specimen could be important in affecting the characteristics of blisters. With this in view, we have studied the development of blisters in thin foils of tantalum by 30 MeV #alpha#-particle bombardment. (orig.).

International Nuclear Information System (INIS)

The governor model is extended to include the asymmetric shape of nuclei which allows a simultaneous analysis of the data for both the ground state and the #gamma#-vibrational bands in deformed even-even nuclei. The rotationally invariant core is assumed to be a spheroid with an axis of symmetry parallel to the axis of rotation. The calculations are carried out under the assumption of no stretching. The static #gamma#-deformation results are compared with the VMI(ARM) and Krutov values, and the calculated energies are in good agreement with the experimental data.

Energy Technology Data Exchange (ETDEWEB)

It is carried out a calculation to determine the energy spectra of secondary {sup 3}He at small atmospheric depths. It is produced in the spallation reaction of primary helium and heavier nuclei in the overlying atmosphere. It is examined the effect of the geomagnetic cut-off on the spectral shape of the secondary {sup 3}He nuclei. The calculations are being carried out for both solar minimum and maximum periods. Results from these calculations will be presented at the Conference.

Energy Technology Data Exchange (ETDEWEB)

The bibliography contains citations concerning the properties of tantalum and tantalum compound films formed by sputtering techniques. Topics include processes, and electrical, magnetic, and dielectric properties of the sputtered films. Tantalum compounds studied include nitrates, oxides, and aluminides. The structural properties of sputtered films are also discussed. (Contains a minimum of 105 citations and includes a subject term index and title list.)

International Nuclear Information System (INIS)

Nuclear shape changes can bring about rapid changes in nuclear properties. That such vibrational #-># symmetric rotor #-># asymmetric nucleus changes may be present in the A approximately 100 region is suggested by rapid, low-energy level density changes and unexpected #beta#-decay rate changes in several series of odd-odd and odd-mass fisions product nuclei. In order to define the nature of these nuclei we have performed measurements on a series of nuclei using JOSEF and Lohengrin mass separators, fast-chemistry, and n-capture #gamma#-ray techniques. Here we summarize the several features we find.

Energy Technology Data Exchange (ETDEWEB)

Hydrogen uptake and embrittlement of tantalum by electrolytically produced hydrogen is investigated on samples of varying composition and type of pretreatment. Of decisive influence on the uptake of hydrogen are the oxide layers present on the tantalum surface. By contact with platinum group metals as alloying constituents, surface coatings or anodic protection, a protection of tantalum can be obtained depending on the experimental conditions.

International Nuclear Information System (INIS)

The mass and energy distributions for low-energy p- and alpha-particle induced fission of "1"8"7","1"8"8Ir and "1"9"5Au and "3He-induced fission of sufficiently heated "1"8"8Ir and "1"9"4Au have been measured with use of fast spectrometer of complementary fragments. From Au to Ir, the shape of the mass distributions undergoes substantial changes related to specific dependence of the saddle shell corrections on A and Z fissioning nuclei. The results are compared with theoretical predictions.

International Nuclear Information System (INIS)

A generalised RIC model for the rotational - vibrational spectra of deformed even-even nuclei of ellipsoidal shape in the rare-earth region has been proposed by incorporating many important features of various microscopic models proposed earlier. The two mass-point model and the governor model moments of intertia are obtained on the basis of the proposed model with appropriate limiting values of the radius of the RIC. Also, the model moment of intertia goes to zero for spherical nuclei, thus giving no rotational spectra for such nuclei. A quantum mechanical treatment of the model on the basis of the two mass-point concept, is expected to give results which are in better agreement with experiments. (author).

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Tantalum and tantalum-based thin films have gained precedence as the diffusion barrier for copper interconnects used in the latest generation of integrated circuits (ICs). The paper presents insight and observations on the covariance of texture and grain size of wrought tantalum sputtering targets and their influence on sputtering performance. Previous studies involving deposition trials of tantalum targets of varying metallurgical character had demonstrated that both grain size and textural homogeneity is critical for assuring reliable sputtering performance of tantalum. Subsequently, a model had been proposed to prescribe how localized texture bands and orientation clusters in tantalum are effectively resistant to sputter erosion. In this paper, results of atomic force microscopy (AFM) and orientation imaging microscopy (OIM{sup TM}) analyses on the eroded ...

Energy Technology Data Exchange (ETDEWEB)

A 5.76 MeV alpha-particle group has been observed in Am and Bk sources separated from a CERN W target. The data are interpreted due to the production of long-lived isomeric states in /sup 236/Am and /sup 236/Bk which decay to /sup 236/Pu. The possibility of high spin states as well as of shape isomeric states is raised.

International Nuclear Information System (INIS)

The talk will focus on spin-dependent competition between oblate and prolate shape minima in the potential energy landscape of "1"8"0Hf (the most neutron-rich stable isotope), mediated via the alignment of valence nucleons. Results of a prompt spectroscopic study, using deep inelastic reactions with Gammasphere and CHICO, bombarding a thin "2"3"2Th target with a "1"8"0Hf beam #approx#25% above the Coulomb barrier, will be presented. Nucleon alignments in both prolate and oblate minima will be discussed, as well as the favoring of oblate collective rotation at high spins, observed through a mixing with gamma vibrations built on the prolate shape.

International Nuclear Information System (INIS)

Theoretical interpretation of fast-charged-particle spectra, observed in the #alpha#-particle-induced reactions on the s-d shell nuclei (A = 24-28), in terms of the Intranuclear Cascade Model and the GDH exciton model (ALICE) is presented. The de-excitation of the excited residual nuclei is accounted for by the evaporation process. The theoretically predicted fast-proton and #alpha#' spectral shapes compare reasonably well with the corresponding measured spectra. However, the magnitude depends critically (as expected) on the reaction cross section employed by the model. As a first step to improve the model predictability of the reaction products, a closer look at the calculation of the #alpha#-particle reaction cross sections was undertaken. A microscopic approach using the optical theorem of Glauber's theory was employed to estimate the #alpha#-induced reaction cross sections for the light target ...

Energy Technology Data Exchange (ETDEWEB)

The present state of investigations into the fragmentation of target nuclei by particles and nuclei of intermediate and high energies is reviewed.

Science.gov (United States)

Commercial introduction of new polymer materials for use as the electrolyte in solid tantalum and solid aluminum electrolytic capacitors is underway. ...

Energy Technology Data Exchange (ETDEWEB)

The refractory nature and high ductility of body centered cubic (bcc) phase tantalum makes it a suitable material for corrosion- and wear-resistant coatings on surfaces which are subjected to high stresses and harsh chemical and erosive environments. Sputter deposition can produce thick tantalum films but is prone to forming the brittle tetragonal beta phase of this material. Efforts aimed at forming thick bcc phase tantalum coatings in both flat plate and cylindrical geometries by high-rate triode sputtering methods are discussed. In addition to substrate temperature, the bcc-to-beta phase ratio in sputtered tantalum coatings is shown to be sensitive to other substrate surface effects.

British Library Electronic Table of Contents (United Kingdom)

The total area (s m) of Voronoi-Dirichlet polyhedron faces corresponding to all intermolecular contacts of one molecule in the structure of crystals and the total volume of pyramids (V m) built on such faces and containing the nuclei of atoms participating in intermolecular contacts in their vertices were determined for 19 unsaturated hydrocarbons. The differential molar heat of adsorption of the hydrocarbons on graphitized thermal carbon black was found to be linearly related to the s m or V m integral parameters of their Voronoi-Dirichlet polyhedra. Aromatic hydrocarbons on the one hand and saturated hydrocarbons, olefins, and acetylene on the other are characterized by different dependences because of the special shapes of their molecular Voronoi-Dirichlet polyhedra.

Energy Technology Data Exchange (ETDEWEB)

Electron scattering data have been used to obtain transition charge densities for the low-lying E2 transitions in /sup 88/Sr, /sup 89/Y, and /sup 90/Zr. These charge densities show a characteristic shape indicative of their microscopic constituency, modified by core-polarization effects. A good description of transitions in the even-even nuclei is obtained by using the measured single-particle transitions in /sup 89/Y as effective densities. .ID LV2086 .PG 19 22

International Nuclear Information System (INIS)

... actinides comparative evaluations deformed nuclei even-even nuclei governor

Science.gov (United States)

... The effects of these voids were more noticeable for tantalum and aluminum electrolytic capacitors, which usually exhibited severe case deformation ...

International Nuclear Information System (INIS)

Becchetti's reply to the preceding ''Comment on "4H clustering in lithium nuclei''.

Energy Technology Data Exchange (ETDEWEB)

Independent isomeric yield ratios of /sup 128/Sb were determined radiochemically in the thermal neutron induced fission of /sup 241/Pu and 34 MeV alpha particle induced fission of /sup 238/U, both involving the same compound nucleus (/sup 242/Pu). Fragment angular momenta estimated from the measured isomer ratios using the statistical model analysis showed significantly larger fragment angular momenta in the medium energy fissioning system compared to the low energy fissioning system. This has been attributed to the effect of higher excitation energy and angular momentum in the entrance channel leading to increased fragment temperature, moments of inertia and angular velocity. An attempt was made to calculate the fragment angular momentum in the medium energy fission using the Fermi gas model for the fissioning nucleus, taking into account the multichance fission, saddle shapes of the fissioning nuclei and the angular velocity components of the ...

Energy Technology Data Exchange (ETDEWEB)

The study of the {alpha}-particle energy distributions associated with ND and SD states in {sup 151,152}Dy has been carried out. The Dy isotopes were produced in the reaction {sup 37}Cl+{sup 123}Sb at 191 MeV via the ({alpha}5n) and ({alpha}4n) channels, respectively. In {sup 151}Dy the {alpha}-particle energy distributions associated to ND and SD are very different from each other, both at the low and high energy sides inducing a difference of 3 MeV in the {alpha}-particle mean energy. In {sup 152}Dy the situation is different; the {alpha}-particle spectral shapes are similar and a difference in the {alpha}-particle mean energy of only 0.7 MeV is deduced. A description in terms of energy localization of entry states is given. (orig.)

Energy Technology Data Exchange (ETDEWEB)

Heavy ion irradiation on tantalum metal target with 57 MeV {sup 11}B{sup 4+} leads to the production of no-carrier-added radioisotopes of platinum, {sup 187,188}Pt and iridium, {sup 187,188}Ir in the matrix, which have been effectively separated from the bulk target and from each other with suitable anion exchangers employing liquid-liquid extraction (LLX). Also {sup 188,189}Pt and {sup 188,189}Ir radionuclides have been produced, from their short-lived precursors {sup 188,189}Au, in {sup 12}C{sup 6+} irradiated tantalum matrix. Gamma-spectroscopy has been utilised to determine the production, extent of separation and purity of the radiotracers at different stages of the experiment. (orig.)

Energy Technology Data Exchange (ETDEWEB)

Short communication. 3 refs.

International Nuclear Information System (INIS)

... angular momentum cranking model even-even nuclei gadolinium 156 governor

Science.gov (United States)

The corrosion behavior of Ta, Ti, and Zr in inorganic acids, bases, chlorides and miscellaneous salts, waters and gases, and organic acids and miscellaneous organic chemicals is summarized. (W.L.H)

International Nuclear Information System (INIS)

The effect of a substrate on the results of measuring tantalum coating thickness in two-layer compositions according to gamma radiation scattered by the substrate is studied. It is shown that by means of an albedo-radiometer realizing the physical model absorber-scatterer one can determine the thickness (application uniformity) of tantalum coatings up to 150-300 #mu#m depending on the substrate material (plexiglas, aluminium, iron, copper). In case of testing coatings on substrates of alloys and high-alloy steels in order to ensure high accuracy of measrurement it is expedient with the above albedo-radiometer to determine the value of the backscattered radiation flux for the substrate before coating application.

Energy Technology Data Exchange (ETDEWEB)

We demonstrate a preparative method which produces highly-monodisperse Pt-nanoparticles of tunable size without the external addition of seed particles. Hexachloroplatinic acid is dosed slowly to an ethylene glycol solution at 120 C and reduced in the presence of a stabilizing polymer poly-N-vinylpyrollidone (PVP). Slow addition of the Pt-salt first will first lead to the formation of nuclei (seeds) which then grow further to produce larger particles of any desired size between 3 and 8nm. The amount of added hexachloroplatinic acid precursor controls the size of the final nanoparticle product. TEM was used to determine size and morphology and to confirm the crystalline nature of the nanoparticles. Good reproducibility of the technique was demonstrated. Above 7nm, the particle shape and morphology changes suddenly indicating a change in the deposition selectivity of the Pt-precursor from (100) towards (111) crystal faces and breaking up of ...

Energy Technology Data Exchange (ETDEWEB)

To improve mirrors coating, we have modeled sputtering of binary oxide targets using TRIM code. First, we have proposed a method to calculate TRIM input parameters using on the one hand thermodynamic cycle and on the other hand Malherbe`s results. Secondly, an iterative processing has provided for oxide steady targets caused by ionic bombardment. Thirdly, we have exposed a model to get experimental sputtering yields. Fourthly, for (Ar - SiO{sub 2}) pair, we have determined that steady target is a silica one. A good agreement between simulated and experimental yields versus ion incident angle has been found. For (Ar - Ta{sub 2} O{sub 5}) pair, we have to introduce preferential sputtering concept to explain discrepancy between simulation and experiment. In this case, steady target is tantalum monoxide. For (Ar - Ta+O{sub 2}) pair, tantalum sputtered by argon ions in reactive oxygen atmosphere, we have to take into account new concept of oxidation ...

International Nuclear Information System (INIS)

The structure functions (SF) of nuclei determined within the framework of the flucton model with rescaling (FMR) are compared with new experimental data of the ITEP on cumulative #pi#-meson yield in a wide range of the scale variable X (1nuclei, and the hypothesis about limiting fragmentation is verified. It is shown that the agreement between theoretical calculations for SF nuclei ratios obtained in analysis of deep inelastic lepton scattering by nuclei within the FMR framework and experimental data on #pi#"+-meson production on Be, Al, Cu, Ta nuclei in cumulative region has confirmed the hypothesis of limiting fragmentation.

International Nuclear Information System (INIS)

... minutes living radioisotopes nuclear reactions nuclei nucleons odd-odd nuclei

UK PubMed Central (United Kingdom)

BackgroundMany molecules of interest are flexible and undergo significant shape deformation as part of their function, but most existing methods of molecular shape comparison (MSC)...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Reactively sputtered tantalum nitride (Ta/sub 2/N) has been investigated as a diffusion barrier between Pd/sub 2/Si and aluminum and CoSi/sub 2/ and Al. Ta/sub 2/N is found to be an excellent matallurgical diffusion barrier for the two systems up to 555 /sup 0/C, with no intermixing observed in Rutherford backscattering and Auger electron spectroscopic studies. Schottky barrier devices n-Si/Pd/sub 2/Si/Ta/sub 2/N/Al were excellent and showed no deterioration after annealing at 500 /sup 0/C. However, similar devices with CoSi/sub 2/ contacts and Ta/sub 2/N barrier showed a creation of high contact resistance between the silicide and the as-deposited nitride.

International Nuclear Information System (INIS)

... of Sciences (Poland) [5.48 Megabytes] NUCLEAR PHYSICS AND RADIATION

International Nuclear Information System (INIS)

Experimental data pertaining to nuclei with A=203 are compiled and evaluated.

Energy Technology Data Exchange (ETDEWEB)

Unconditional estimates are suggested for the age of radioactive nuclei and hence for the age of the Universe.

International Nuclear Information System (INIS)

... odd nuclei organic compounds radiation effects radioisotopes synthesis

Science.gov (United States)

A number of alloys of zirconium have been investigated as part of a program aimed at improving the high-temperature tensile and creep strength of zirconium. These alloys include aluminum, beryllium, lead, magnesium, molybdenum, niobium, tantalum, tin, titanium, tungsten, vanadium, and zinc, binary and ternary alloys. The data indicate that aluminum, lead, molybdenum niobium, tin, titanium, tungsten, and vanadium can be used successfully to harden zirconium, and that aluminum, tin, titanium, and vanadium are particularly effective in maintaining the strength of zirconium at elevated temperatures.

International Nuclear Information System (INIS)

We investigate how 'extra' or 'excess' central light in the surface brightness profiles of cusp or power-law elliptical galaxies relates to the profiles of ellipticals with cores. The envelopes of cusp ellipticals are established by violent relaxation in mergers acting on stars present in gas-rich progenitor disks, while their centers are structured by the relics of dissipational, compact starbursts. Ellipticals with cores are formed by the subsequent merging of the now gas-poor cusp ellipticals, with the fossil starburst components combining to preserve a dense, compact component in these galaxies as well (although mixing of stars smooths the transition from the outer to inner components in the profiles). By comparing extensive hydrodynamical simulations to observed profiles spanning a broad mass range, we show how to observationally isolate and characterize the relic starburst component in core ellipticals. Our method recovers the younger starburst population, demonstrating that ...

Energy Technology Data Exchange (ETDEWEB)

An approach of acidification was examined on formation of hydrogen-producing granules and biofilms in upflow column-shaped reactors. The reactors were fed with synthetic glucose wastewater and operated at 37 C and pH 5.5. The acclimated anaerobic culture was inoculated in four reactors designated R1, R2, R3 and R4, with R3 and R4 filled with granular activated carbon as support medium. To unveil the roles of acidification, microbial culture in R2 and R3 was subject to an acid incubation for 24 h by shifting the culture pH from 5.5 to 2.0. The experimental results suggested that the acidification substantially accelerated microbial granulation, but not biofilm formation. Microbial activities were inhibited by the acid incubation for about 78 h, resulting in the retarded formation of biofilms of the acidified culture. Reducing culture pH resulted in improvement in cell surface physicochemical properties favoring microbial adhesion and immobilization. Zeta potential ...

Energy Technology Data Exchange (ETDEWEB)

Neutron time-of flight spectra were measured from 90 MeV protons and 140 MeV alpha-particle bombardment of Al, Ni, Zr, and Bi at laboratory angles between 20/sup 0/ and 130/sup 0/. The proton induced neutron spectra reveal three distinct energy regions; a low energy evaporation region, a high-energy region dominated by quasi-free scattering processes and an intermediate-energy region dominated by multi-step, pre-equilibrium processes. In the latter two regions, the spectra show strong angular dependence. The alpha-induced neutron spectra show these same distinct energy regions plus an exponential fall-off above the beam energy per nucleon. The high-energy portions of the forward-angle neutron and proton cross sections are in ratios consistent with the assumption that single nucleon-nucleon scattering dominates. For heavy-mass targets, the low-energy evaporation regions show neutron yields larger than proton yields. The proton-to-neutron ratios observed in the high-energy continua are ...

International Nuclear Information System (INIS)

Complete energy spectra and angular distributions of the light charged particles (A < or = 4) were measured for the bombardment of "2"7Al, "5"8Ni, "9"0Zr, "2"0"9Bi, and "2"3"2Th with 140 MeV #alpha# particles. The spectral shapes of a given emitted particle are very similar for all target nuclei except in the region of the evaporation peak. The slopes of the energy spectra in the forward direction become steeper as the mass of the observed particle decreases and vary very rapidly with angles. The experimental data can be characterized by compound nuclear evaporation processes at low energies, or at backward angles, and by direct reactions, nonequilibrium components and projectile breakup processes at high energies and forward angles. The breakup cross section for #alpha# particles is found to be appreciable. The total yield of light charged particles is approximately a factor approx. 2 to 3 larger than the total reaction cross section for ...

Energy Technology Data Exchange (ETDEWEB)

The angular ..gamma gamma..-correlations for nuclei of Sr even-even isotopes with A=82, 84, 86, 88 were measured. Multipole structurs of ..gamma..-transtion series and th coefficients multipole mixing were determined.

International Nuclear Information System (INIS)

It is shown that the available data on x, Q"2, and A dependence of nuclear structure functions and for their ratios (EMS effect) can be described in terms of the flucton model with rescaling of parton distributions in nuclei. The x, Q"2 and A dependence of nuclear structure functions in the cumulative range (x >1) is predicted.

International Nuclear Information System (INIS)

Probabilities of flucton production have been calculated for the 1p-shell nuclei and its modification by the Yastrov method. The results obtained are in a qualitative agreement with the data resulting from the analysis of experiment in an assumption of a flucton mechanism of proton-nuclear inclusive reactions with the production of cumulative particles.

Energy Technology Data Exchange (ETDEWEB)

The high-energy reaction cross sections of Li and Be isotopes are calculated using a simplified Glauber model and densities constrained by the empirical binding energies. We find excellent agreement with experiment, reproducing the large increase for the most neutron-rich nuclei.

UK PubMed Central (United Kingdom)

We calculate the expected fluxes of cosmic ray nuclei with charge 5 ≤ Z ≤ 28 at various depths in the earth's atmosphere, taking into account the initial charge distribution,...Full Text Available

International Nuclear Information System (INIS)

... radioisotopes coincidence methods energy-level transitions gamma radiation

International Nuclear Information System (INIS)

... alpha reactions angular distribution energy-level transitions iridium 185 iridium

International Nuclear Information System (INIS)

... range 01-10 nuclei photons radiation sources recoils resonance scattering

CERN Document Server

PAMELA is a space telescope orbiting around the Earth since June 2006. The scientific objectives addressed by the mission are the measurement of the antiprotons and positrons spectra in cosmic rays, the hunt for anti-nuclei as well as the determination of light nuclei fluxes from Hydrogen to Oxygen in a wide energy range and with very high statistics. In this paper the charge discrimination capabilities of the PAMELA Time-Of-Flight system for light nuclei, determined during a beam test calibration, will be presented.

UK PubMed Central (United Kingdom)

In vivo, mammalian lenses have the capacity to effect fully reversible changes in shape, and possibly volume, during the accommodation process. Isolated lenses also change shape...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

It is shown that the available experimental data on the x, Q/sup 2/, and A dependences of the structure functions of nuclei and their ratios (the EMC effect) can be described by the flucton model with rescaling of the parton distributions in nuclei. The x, Q/sup 2/, and A dependence of the nuclear structure functions in the cumulative region (x>1) is predicted.

Energy Technology Data Exchange (ETDEWEB)

A microscopic calculation of the level density is performed, based on a combinatorial evaluation using a realistic single-particle level scheme. This calculation relies on a fast Monte Carlo algorithm, allowing to consider heavy nuclei (i.e., large shell model spaces) which could not be treated previously in combinatorial approaches. An exhaustive comparison of the predicted neutron s-wave resonance spacings with experimental data for a wide range of nuclei is presented.

International Nuclear Information System (INIS)

Muon captures by nucleon pairs via meson-exchange currents produce a high energy excitation tail in heavy nuclei. The muon induced fission by these excitations is calculated in several subactinide nuclei with high threshold fission barriers. The probability for delayed fission ranges from 4 x 10"-"5 to 4 x 10"-"3 for the isotopes considered. (orig.).

International Nuclear Information System (INIS)

Differences of the deformation parameters for the 2"+_1 states of even-even spherical nuclei extracted from electromagnetic excitation #beta#sup(em)_2 and from proton scattering #beta#sup(pp')_2 are discussed. It is found that the ratio #beta#sup(pp')_2/#beta#sup(em)_2 is equal to about unity and that there is a small isotope dependence for several incomplete shell nuclei. (orig.).

International Nuclear Information System (INIS)

Purpose: The lifelong persistence of foreign bodies within the arteries may contribute to restenosis. Thus,biodegradable devices might decrease recurrence rates. Methods: Eleven polyhydroxybutyrate biodegradable stents and 13 tantalum stents were implanted into the iliac arteries of New Zealand white rabbits for up to 30 weeks. After killing the animals,the specimens were harvested, fixed in formalin, processed in paraffin,and stained. Results: Polyhydroxybutyrate instigated intense inflammatory and proliferative reactions with an increase in collagen (2.4- to 8-fold vs native segments), thrombosis and in-stentlumen narrowing (375.5-606.6 mm vs 655.6 #+-# 268.8 mm in native segments). The elastic membranes were destroyed in all specimens. The tantalum stents increased the in-stent lumen progressively (769.7 #+-# 366.6 mm vs 1309.9 #+-# 695.3 mm),penetrated the external elastic membrane, and increased mural collagen content (6- to 8.6-fold vs ...

International Nuclear Information System (INIS)

The description is presented of binary phase diagrams of titanium alloyed with the following elements: silver, aluminium, arsenic, gold, boron, barium, beryllium, bismuth, carbon, calcium, cadmium, cobalt, chromium, copper, iron, gallium, germanium, hydrogen, hafnium, indium, iridium, potassium, lithium, magnesium, manganese, molybdenum, nitrogen, sodium, niobium, nickel, oxygen, osmium, phosphorus, lead, palladium, platinum, plutonium, rhenium, lanthanium, cerium, preseodymium, neodymium, gadolinium, erbium, terbium, thulium, lutetium, rhodium, ruthenium, scandium, silicon, tin, strontium, tantalum, technetium, thorium, uranium, vanadium, tungsten, yttrium, ytterbium, zinc and zirconium.

Energy Technology Data Exchange (ETDEWEB)

The theoretical principles underlying the formation of oxide and, in particular, anodic oxide coatings on metals produced by chemical oxidation, anodizing in solutions, and anodizing in cold plasmas are reviewed. The mechanisms and conditions of anodic oxidation are described, and the structure of anodic oxide coatings on aluminum, magnesium, beryllium, zinc, cadmium, iron, cobalt, nickel, titanium, zirconium, tantalum, and chromium alloys is examined. Attention is also given to various applictins of anodized coatings. 54 references.

CERN Document Server

Shaping has proven to be a powerful but precarious means of improving reinforcement learning performance. Ng, Harada, and Russell (1999) proposed the potential-based shaping algorithm for adding shaping rewards in a way that guarantees the learner will learn optimal behavior. In this note, we prove certain similarities between this shaping algorithm and the initialization step required for several reinforcement learning algorithms. More specifically, we prove that a reinforcement learner with initial Q-values based on the shaping algorithm's potential function make the same updates throughout learning as a learner receiving potential-based shaping rewards. We further prove that under a broad category of policies, the behavior of these two learners are indistinguishable. The comparison provides intuition on the theoretical properties of the ...

Energy Technology Data Exchange (ETDEWEB)

A new two-body interaction recently derived for nuclei in the 0f1p shell by fitting two-body matrix elements to 494 energy levels in A=41-66 nuclei, is used to investigate the neutron-rich nuclei in the vicinity of the doubly closed nuclide {sup 48}Ca. This study is of fundamental interest in providing a test for the new effective interaction away from the stability line. Masses and binding energies are calculated for a variety of neutron-rich nuclei and compared with experimental data, where available. In addition level schemes for {sup 50-52}Ca, {sup 51-52}Sc and {sup 51-52}Ti have been calculated and are compared with available experimental data. In general a good correspondence between theory and experiment is found, but some systematic discrepancies are apparent. ((orig.)).

International Nuclear Information System (INIS)

A review of the experimental work performed at the GASP array with the purpose of the identification and first spectroscopic measurements of the heaviest even-even N = Z and odd-A N = Z + 1 nuclei (mass larger than 80) is made. Systematic experiments in this mass region led to the first study of seven such nuclei: "8"8Ru, "8"1Zr, "8"5Mo, "8"9Ru, "9"1Rh, "9"3Pd, and "9"5Ag, and extensive data on many other nuclei in their neighborhood. The systematic evolution of the level structures in both even-even and odd-A nuclei, between N #approx# Z #approx# 40 and N #approx# Z #approx# 47 is briefly presented. The possibility that effects of the neutron-proton pairing have been observed, as well as the type of collectivity observed in this region are discussed. (author)

International Nuclear Information System (INIS)

We investigate the effects of single-particle structure and pairing on the equilibration of positive and negative-parity level densities for the even-even nuclei "5"8","6"2","6"6Fe and "5"8Ni and the odd-A nuclei "5"9Ni and "6"5Fe. Calculations are performed using the shell model Monte Carlo method in the complete fp-gds shell-model space using a pairing+quadrupole type residual interaction. We find for the even-even nuclei that the positive-parity states dominate at low excitation energies due to strong pairing correlations. At excitation energies at which pairs are broken, single-particle structure of these nuclei is seen to play the decisive role for the energy dependence of the ratio of negative-to-positive parity level densities. We also find that equilibration energies are noticeably lower for the odd-A nuclei "5"9Ni and "6"5Fe than for the neighboring even-even ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

A lock out assembly for a circuit breaker which consists of a generally step-shaped unitary base with an aperture in the small portion of the step-shaped base and a roughly S shaped retaining pin which loops through the large portion of the step-shaped base. The lock out assembly is adapted to fit over a circuit breaker with the handle switch projecting through the aperture, and the retaining pin projecting into an opening of the handle switch, preventing removal.

Energy Technology Data Exchange (ETDEWEB)

The generalized hybrid derivative coupling model has been applied to explore various ground state properties of different nuclei. In this work we have confined our calculation only to the model characterized by the hybridization parameter {alpha} = 1/4 which gives better results than the other models of the same class, as we have seen earlier, for nuclear matter calculations. The binding energy, single-particle energy spectra, density and charge radii of different doubly closed nuclei like {sup 16}O, {sup 40}Ca, {sup 48}Ca, {sup 90}Zr, {sup 132}Sn, {sup 208}Pb have been studied. The success of this model, in describing the doubly closed nuclei, motivates us to extend this calculation further in the case of open shell nuclei after incorporating the pairing interaction and using a BCS transformation. We have calculated the binding energy for such nuclei. We have also studied the ...

International Nuclear Information System (INIS)

The improved facilities of the ISOLDE isotopic separator on-line with the 600 MeV synchrocyclotron at CERN opened the possibility to reach nuclei very far from stability (as far as 22 neutrons deficient in the Cs region and 27 neutrons deficient in the Hg region). Simultaneously the development of on-line spectrometry allowed the study of nuclei with very short half-lives and low counting rates. Results recently obtained in the odd-A iridium region are presented after a short summary of recent on-line devices developments and results. (Auth.).

Energy Technology Data Exchange (ETDEWEB)

The process of inelastic scattering of hot plasma electrons with energies upto 3 keV by a pair of close-lying nuclear levels (..delta../ital E/less than or equal to2keV), one of whichis isomeric, is discussed. The transition cross sections in the nuclei/sup 242/Am, /sup 171/Lu, and /sup 73/Se are calculated. Estimates of the numberof isomeric nuclei de-excited as a result of electron-stimulated processes in aplasma with parameters characteristic of present-day experiments in controlledthermonuclear fusion are given.

Energy Technology Data Exchange (ETDEWEB)

It is possible to produce energetic beams of radioactive nuclei, as secondary beams, from the heavy-particle compound accelerator called BEVALAC. These beams can be focused into experimental areas without significant contamination using suitable magnetic filters and proper beam-optics. Properly selected high-energy beams of radioactive nuclei (those which defay by positron emission) can provide a truly unique opportunity to evaluate the effectiveness of these beams in localizing the Bragg peak on a tumor volume - necessary in heavy-particle therapy. Preliminary data are presented here to demonstrate the possible use of these beams in radiotherapy treatment-planning verification.

International Nuclear Information System (INIS)

The distributions of the effective numbers of 6q-fluctons in the energy, momentum and distance to the center of mass of nucleus are studied. Many characteristics of these distributions are shown to be universal, i.e. independent of the flucton size. The saturation of the flucton density in A > 80 nuclei and other peculiarities are found, which define different behavior of the effective numbers of fluctons and deuterons. This fact provides an explanation of the known underestimate by a factor of 1.5-6 of the cross sections of hard inclusive (p, p'd) process on nuclei calculated in the quasi-elastic approximation.

International Nuclear Information System (INIS)

Properties of unique parity states in odd-proton (_7_7Ir, _7_9Au) and odd-neutron nuclei (_7_8Pt) are investigated in the framework of the interacting boson-fermion approximation model. The core (boson)-particle (fermion) interaction is represented by a quadrupole-quadrupole interaction and an exchange term, which takes into account the effects of the Pauli exclusion principle. The even-even core nucleus is described in terms of the IBA-1 hamiltonian. The change in the properties of the corresponding odd-A nuclei can be interpreted in terms of a transition of the core hamiltonian between the O(6) and SU(3) limiting cases. (orig.).

CERN Document Server

The coherent $\\omega$-meson photoproduction from nuclei is proposed as a phenomenological method to evaluate the momentum dependence of $\\omega$-meson mass shift and width in nuclear matter. We analyze available data on un-separated coherent and incoherent $\\omega$-meson photoproduction from nuclei and extract the imaginary part of the the complex forward $\\omega{N}$ scattering amplitude, which is proportional to the in-medium $\\omega$-meson width. The accuracy of the currently available data is not sufficient to evaluate the real part of forward $\\omega{N}$ scattering amplitude and reconstruct the momentum dependence of the mass shift of the $\\omega$-meson.

International Science & Technology Center (ISTC)

Experimental and Theoretical Study of the Residual Nuclide Production in 40-2600 MeV Proton-Irradiated Thin Targets of ADS Basic Materials

International Nuclear Information System (INIS)

The analysis of elastic and inelastic scattering of #alpha# particles with energy of 50 MeV by nuclei with mass numbers A=54-124 and of "3He particles by the nucleus "6"4Ni is given in the framework of the optical model. The parameters of multipole deformations for lower states are determined. The parameters for quadrupole and octupole deformations of the potential for the nucleus "1"1"2Sn are extracted, the values of the hexadecupole deformation #beta#_4 of the potential for nuclei "9"4Zr, "1"2"0","1"2"4Sn are found. Information is extracted on the ratio of deformation parameters for the neutron and proton components in lower collective states (2_1"+, 3_1"-) of nuclei with A=90-124.

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This report discusses the experimental setup of experiment 814 at Brookhaven AGS. This experiment involves the collision of silicon ions with target nuclei. The detector systems are discussed primarily. (LSP)

Science.gov (United States)

will soon recreate by slamming lead nuclei into one another. S@BL image Irrelevant Regulators Pinpointing the interactions of genes with their assumed regulators grows ever more...

International Nuclear Information System (INIS)

The available nuclear structure information for all nuclei with mass number A=242 is presented. Various decay and reaction data are evaluated. Adopted data, levels, spin and parity assignments are given.

International Nuclear Information System (INIS)

Detailed level and decay schemes are presented for the nuclei of the A = 101 mass chain. The level properties obtained from decay and reaction experiments are shown in the drawings. Experimental methods, references, and comments are given in the text.

International Nuclear Information System (INIS)

Russian 1987. p. 99-100. USSR Sabalyauskas, L.Yu. Vanagas, VV Guseva,

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Doubly decoupled structures in doubly odd deformed nuclei are reexamined and shown to be composed of a pseudo-spin aligned neutron and a decoupled proton. (orig.).

International Nuclear Information System (INIS)

Russian 1984. p. 351. USSR Burtebaev, NT Dujsebaev, AD Ivanov, GN

International Nuclear Information System (INIS)

(21 Jan 1974). Netherlands Lega, J. Macq, PC Louvain Univ. (Belgium)

Science.gov (United States)

creating such active galactic nuclei as quasars. Strangely, the center of this fiery whirlpool is offset from the exact center of the galaxy - for a reason that for now remains an...

International Nuclear Information System (INIS)

Russian 1979. p. 328. USSR Burtebaev, NT Dujsebaev, AD Ivanov, GN

Energy Technology Data Exchange (ETDEWEB)

We investigate ordering properties of two-dimensional granular materials using several shapes created by welding ball bearings together. Ordered domains form much more easily in two than in three dimensions, even when configurations lack long-range order. The onset of ordered domains occurs near a packing density of 0.8, a phenomenon observed previously for disks. One of our shapes, the trapezoid, has packings that remain disordered and near the transition density even after annealing by shaking. Although random packings are unstable for disks and many other shapes in two dimensions, trapezoid packings provide an approach to studying two-dimensional randomness. We also find that the rotational symmetry of a shape is an excellent predictor of how easily it orders, and a potential guide to identifying two-dimensional shapes that remain random after annealing.

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Although computer simulation has played a central role in the study of nucleation and growth since the earliest molecular dynamics simulations almost 50 years ago, confusion surrounding the effect of finite size on such simulations have limited their applicability. Modeling solidification in molten tantalum on the BlueGene/L computer, we report here on the first atomistic simulation of solidification that verifies independence from finite size effects during the entire nucleation and growth process, up to the onset of coarsening. We show that finite size scaling theory explains the observed maximal grain sizes for systems up to about 8,000,000 atoms. For larger simulations, a cross-over from finite size scaling to more physical size-independent behavior is observed.

UK PubMed Central (United Kingdom)

A robust technique for determining the principal axes of a 3D shape represented by a point set, possibly with noise, is presented. We use techniques from robust statistics to guide the classical...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

An asymmetrical shaped capillary die made exclusively of graphite is used to grow silicon ribbon which is capable of being made into solar cells that are more efficient than cells produced from ribbon made using a symmetrically shaped die.

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Microscopic non-energy weighted sum-rules for the total rates of the neutrinoless ..mu..-e conversion process are constructed in the frame of the shell model for closed shell nuclei. For non-closed shell nuclei the relevant rates were obtained by interpolation. Also the contribution of the coherent process to the total ..mu..-e conversion rate is calculated and discussed.

International Nuclear Information System (INIS)

The CLARA-PRISMA setup, composed of an array of 25 Clover detectors placed at the target position of the magnetic spectrometer PRISMA, has recently concluded its campaign to study the structure of moderately neutron-rich nuclei. In this contribution, results obtained in the vicinity of the doubly-magic nucleus "4"8Ca are presented, together with results obtained for the heavy iron isotopes. The perspectives offered by the forthcoming operation of the AGATA Demonstrator Array coupled to PRISMA are also discussed. (author)

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The nucleon decay of subbarrier single-particle states with large angular momentum and parity opposite to that of the shell in soft spherical nuclei is considered. It is shown that the reduced probabilities of the nucleon decay into the ground state (0{sup +}) and into the first excited (2{sup +}) state of the daughter nucleus have qualitatively different energy dependences. (orig.).

International Nuclear Information System (INIS)

Nucleon decay of underbarrier one-quasiparticle states with large angular momentum in soft spherical nuclei is considered. It is shown that energy dependences of differential probabilities of nucleon decay to the ground (0"+) and first excited (2"+) states of daughter nucleus differ qualitatively from each other due to strong interaction between quasiparticles and low-lying quadrupole states.

International Nuclear Information System (INIS)

Based on a hypothesis of multiquark states in nuclei, the nucleus structure functions are considered and the results are compared with experiment. It is shown that the multiquark state contributions are sufficiently high (Up to 20% in deuterium and 40% in iron) and must possess a greater, than in a nucleon, sea of quark-antiquark pairs. Also the comparison with the cumulative particle production cross sections is performed. The predictions are given for a further experimental test of that hypothesis.

International Nuclear Information System (INIS)

A method of auxiliary spectrum is modified so that matrix elements of the reaction matrix in final nuclei are determined by means of algebraic operations alone (inversion of matrices). No differential equations need to be solved; Pauli's exclusion principle is accurately taken into account. A single-particle potential may be of any kind, but a two-particle interaction must have no solid core.

International Nuclear Information System (INIS)

Sixteen actinide nuclei: U-234 and -236; Np-237; Pu-236, -237, -238, -242, and -244; Am-241, -242* and -243; and Cm-241, -242, -243, -244, and -248, have been evaluated for ENDF/B-V with particular attention given to the fast fission and capture cross sections. Seven nuclei have not appeared on ENDF/B before and major changes for previous ENDF/B files have been made.

Energy Technology Data Exchange (ETDEWEB)

Cross sections for elastic scattering of 12 GeV protons from /sup 40/Ca nuclei have been calculated using the flucton model. The influence of the collective flucton nucleon correlations on the calculated cross sections is examined. The calculated cross sections are in significant disagreement with the experimental data. This may be considered as an argument against the flucton model.

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The contribution of pulsar accelerated nuclei to the cosmic rays inside the Galaxy is calculated assuming that a significant part of the pulsar rotational energy is lost on acceleration of iron nuclei extracted from the surface of the neutron star. Different models of the galactic pulsar population are discussed. It is shown that the best description of the observed cosmic ray spectrum and the mass composition between a few 10{sup 15} eV and a few 10{sup 18} eV is obtained for the model B of Lorimer et al. (1993)

Science.gov (United States)

of increasing numbers of vortices as a function of the thickness. Vortices are these whirlpool shaped structures. They are interesting because they come paired with...

International Nuclear Information System (INIS)

We calculate parity-dependent level densities for the even-even isotopes "5"8","6"2","6"6Fe and "5"8Ni and the odd-A nuclei "5"9Ni and "6"5Fe using the shell model Monte Carlo method. We perform these calculations in the complete fp-gds shell-model space using a pairing+quadrupole residual interaction. We find that, due to pairing of identical nucleons, the low-energy spectrum is dominated by positive parity states. Although these pairs break at around the same excitation energy in all nuclei, the energy dependence of the ratio of negative-to-positive parity level densities depends strongly on the particular nucleus of interest. We find equilibration of both parities at noticeably lower excitation energies for the odd-A nuclei "5"9Ni and "6"5Fe than for the neighboring even-even nuclei "5"8Ni and "6"6Fe.

International Nuclear Information System (INIS)

The nuclear shapes of transitional Mo isotopes are calculated by means of a model based on the cranking approximation and the Strutinksy method. The recent experimental results of the high-spin spectroscopy and lifetime measurement of "8"7Mo are studied in detail and explained by the evolution of the #gamma#-deformation with the quasiparticle configurations. The shape calculations with the modified-harmonic-oscillator potential give a critical neutron number N #>=# 47 for the spherical shape of the Mo isotopes. (orig.).

British Library Electronic Table of Contents (United Kingdom)

Several recent studies have documented that non-human primates can individuate objects according to property and/or kind information in much the same way as human infants do from around one year of age when they begin to acquire language. Some studies suggest, however, that only some properties are used for the individuation of food items: color, but not shape. The present study investigated whether these findings reveal a true competence problem with shape properties in the food domain or whether they merely reveal a performance problem (e.g., lack of attention to shapes). We tested 25 great apes (chimpanzees, bonobos and gorillas) in two food individuation tasks. We manipulated subjects? experience with differences in color and shape properties of food items. Results indicated (i) that a...

Energy Technology Data Exchange (ETDEWEB)

A focused ion beam (FIB) is used to accurately sculpt predetermined micron-scale, curved shapes in a number of solids. Using a digitally scanned ion beam system, various features are sputtered including hemispheres and sine waves having dimensions from 1-50 {micro}m. Ion sculpting is accomplished by changing pixel dwell time within individual boustrophedonic scans. The pixel dwell times used to sculpt a given shape are determined prior to milling and account for the material-specific, angle-dependent sputter yield, Y({theta}), as well as the amount of beam overlap in adjacent pixels. A number of target materials, including C, Au and Si, are accurately sculpted using this method. For several target materials, the curved feature shape closely matches the intended shape with milled feature depths within 5% of intended values.

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Mass distributions of fragments in the low-energy fission of nuclei from {sup 187}Ir to {sup 213}At have been analysed. This analysis has shown that shell effects in symmetric-mode fragment mass yields from the fission of pre-actinide nuclei could be described if one assumes the existence of two strongly deformed neutron shells in the arising fragments with neutron numbers N{sub 1}{approx}52 and N{sub 2}{approx}68. A new method has been proposed for quantitatively describing the mass distributions of the symmetric fission mode for pre-actinides with A{approx}180-220. (orig.) 28 refs.

Energy Technology Data Exchange (ETDEWEB)

The observed inhibition of M4 transitions in A approx. 90 nuclei has represented a long standing theoretical problem. In particular by calculating first- and second-order configuration mixing contributions to the inhibited M4 lifetimes of /sup 89/Y and /sup 87/Sr, it is found that the first-order perturbative treatment of the residual interaction usually used in shell-model calculations is unjustified in this case. Using random-phase approximation techniques, the renormalization effects of collective (''giant'') M4 resonances in /sup 88/Sr on the low energy M4 transitions in /sup 89/Y and /sup 87/Sr are investigated. It is concluded that the observed retardation of M4 lifetimes in these nuclei is consistent with the manifestation of nuclear spin polarization.

International Nuclear Information System (INIS)

The mass asymmetry of fragments from nuclear fission of heavy nuclei is reviewed. While mass asymmetry is a common and well-known phenomenon for low-energy fission of the lighter actinides, more recent experiments have demonstrated that, for the heaviest actinides, the mass distribution switches to a symmetric one. On the other hand, it has been discovered that, though for fissioning nuclei with mass numbers A< or #approx#225 the mass distribution is basically symmetric, an asymmetric component is clearly to be identified for nuclei down to the Pb-region. In the absence of a generally accepted dynamical theory of fission, the above experimental findings are discussed in terms of static energy considerations. Triggered from the outset by the structure of the potential energy surface at the saddlepoint, the energy balance at the scission point between the available energy (Q-value) of the reaction and the Coulomb and ...

Energy Technology Data Exchange (ETDEWEB)

The energy, angular momentum, and distance (measured from the center of mass of the nucleus) distributions of the effective number of 6/ital q/-fluctons are investigated and it is shown that many of the characteristics of these distributions are universal, i.e., independent of the flucton size. ''Saturation'' of the flucton density in nuclei with mass /ital A//approx gt/80 and certain other features that determine the difference between the behaviors of the effective numbers of fluctons and deuterons are reported. This is used to explain the well known underestimation (by a factor of 1.5--6) of the cross section for the hard inclusive (/ital p/, /ital p/'/ital d/) process on nuclei calculated in the quasielastic formalism. See S. G. Kadmenskii and V. I. Furman, /ital Alpha/ /ital decay/ /ital and elated/ /ital nuclear/ /reactions/ (in Russian), Energoatomizdat, Moscow, 1985.

International Nuclear Information System (INIS)

Elastic scattering of 22 MeV alpha particles by "2"3Na, sup(24-25-26)Mg, "2"7Al and "2"8Si has been measured between 24"0 and 174"0 lab. Partial angular distributions, from 120"0 to 174"0, were also measured at incident energies of 18.4 and 20.7 MeV for "2"4Mg, and 18.9 and 20.5 MeV for "2"8Si. The most striking feature of the data is the large angle behaviour: spin-zero nuclei display more pronounced backward oscillations and the cross section rises more steeply towards 180"0 for 4n nuclei than for the others. (Z.M.).

International Nuclear Information System (INIS)

Short note. 4 refs.; 1 tab.

International Nuclear Information System (INIS)

several authors tried to drive codes to construct nuclear level scheme of nuclei using a set of measured gamma -ray transitions and known energy levels, Ritz combination principle proved to be useful in constructing a more complete decay scheme. In this thesis the energy level schemes of some nuclei have been investigated by the measurements of the gamma - ray energies and use of Ritz combination code. The nuclei under investigation are "110m Ag (253 d)"110 Cd and "166m Ho (1200 yr) "166 E r. On the basis of the suggested level at 2249.02 keV by the Ritz code new positions of the two gamma-ray transitions at 677.5 and 706.6 KeV are found in decay scheme of "110m Ag. Also by this code, new position for the 994.84 KeV gamma-ray transition were established to depopulate the level at 1075.2 KeV.

International Nuclear Information System (INIS)

Starting with a #LAMBDA#-nucleus potential, a semi-empirical formula, which gives a fairly satisfactory account of the ground state #LAMBDA#-binding energy of light hypernuclei, if the very light nuclei are ignored has been obtained. (author).

UK PubMed Central (United Kingdom)

The standard nomenclature that has been used for many telencephalic and related brainstem structures in birds is based on flawed assumptions of homology to mammals. In particular, the outdated...Full Text Available

UK PubMed Central (United Kingdom)

We describe the characteristics of the rapidly rotating molecular disk in the nucleus of the mildly active galaxy NGC4258. The morphology and kinematics of the disk are delineated by the point-like...Full Text Available

International Nuclear Information System (INIS)

Russian 1984. p. 349. USSR Burtebaev, NT Dujsebaev, AD Knyaz'kov, OM

Energy Technology Data Exchange (ETDEWEB)

We summarize some initial results in our investigation of the nuclear physics issues of gamma-ray lasers. We describe what is known thus far from existing experimental data and illustrate how theoretical models may be employed for systematic searches of candidate nuclei.

International Nuclear Information System (INIS)

Detailed level and decay schemes and the experimental reaction and decay data on which they are based are presented for nuclei with mass number A = 242; the experimental data are evaluated. Adopted values for level and #gamma#-ray energies, #gamma#-intensities, as well as other nuclear properties are given.

Energy Technology Data Exchange (ETDEWEB)

It is shown that a natural consequence of the binary pulsar's evolution is a neutron star collision. Such a collision is expected to eject neutron-rich matter of an r-process character. Taking reasonable estimates for the number of such events over the history of the galaxy, it may be that they account for all of the r-process nuclei.

International Nuclear Information System (INIS)

The Schroedinger equation for nuclear quadruple surface vibrations is linearized with the consequence that a new spin degree of freedom appears in the wave function of the linearized equation. This spin is called collective spin and has a value of 3/2. The linearized Schroedinger equation for quadrupole vibrations is used for the description of certain collective aspects of even-odd "1"8"7","1"8"9","1"9"1Ir nuclei which have a spin 3/2 in their ground state. As a potential we use the #gamma#-soft collective potential of the neighboring even-even nuclei, which is inserted into the linearized Schroedinger equation via a scalar coupling. This leads to a collective spin-dependent fine structure splitting of the energy levels governed by a collective SO(5) spin-orbit coupling and a correction to the kinetic energy. Further, we consider explicitly spin-dependent potentials which effectively describe the interaction of the valence nucleon with the ...

International Nuclear Information System (INIS)

Russian 1986. p. 334. USSR Burtebaev, NT Dujsebaev, AD Sadkovskij,

Energy Technology Data Exchange (ETDEWEB)

An application of the renormalized random phase approximation to nuclear structure is presented for the semi-magic nuclei /sup 88/Sr and /sup 90/Zr. It is reported the outcome for the microscopic approach in comparison with the semiphenomenological version for the particle-hole forces.

UK PubMed Central (United Kingdom)

Bacteria and fungi are ubiquitous in the atmosphere. The diversity and abundance of airborne microbes may be strongly influenced by atmospheric conditions or even influence atmospheric conditions themselves...Full Text Available

International Nuclear Information System (INIS)

Russian 1977. p. 178. USSR Feofilov, GA Denisov, AE Kolalis, RP Sadkovskij,

International Nuclear Information System (INIS)

Ammonia adsorption on the external surface of C_3_0B_1_5N_1_5 heterofullerene was studied using density functional calculations. Three models of the ammonia-attached C_3_0B_1_5N_1_5 together with the perfect model were optimized at the B3LYP/6-31G"* level. The optimization process reveals that dramatic influences occurred for the geometrical structure of C_3_0B_1_5N_1_5 after ammonia adsorption; the B atom relaxes outwardly and consequently the heterofullerene distorts from the spherical form in the adsorption sites. The chemical shielding (CS) tensors and nuclear quadrupole coupling constants of B and N nuclei were calculated at the B3LYP/6-311G"*"* level. Our calculations reveal that the B atom is chemically bonded to NH_3 molecule. The B atom in the NH_3-attached form has the largest chemical shielding isotropic (CSI) value among the other boron nuclei. The C_Q parameters of B nuclei at the interaction sites are ...

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The statistical {gamma}-spectra of highly excited even-even rare earth nuclei are simulated applying appropriate level density and strength function to a given nucleus. Hindrance effects due to K-conservation are taken into account. Simulations are compared to experimental data from the {sup 163}Dy({sup 3}He,{alpha}){sup 162}Dy and {sup 173}Yb({sup 3}He,{alpha}){sup 172}Yb reactions. The influence of the K quantum number at higher energies is discussed. 21 refs., 7 figs., 2 tabs.

International Nuclear Information System (INIS)

#pi#"#+-# and K"#+-# cumulative production in pA #-># #pi#"#+-#+x and pA #-># K"#+-#+x reactions at 10.14 GeV proton beam energy on nuclei (Be-Ta) was invesigated. Measurements were conducted using FAS-1 focusing hadron spectrometer. Invariant cross sections of #pi#"#+-# and K"#+-# cumulative production, values of ratio of this cross sections, dependences of production cross sections for pions and kaons on cumulative number and mass number of nucleus target, as well as on transverse momentum are measured. Difference of cumulative meson spectra occurring in different nuclei fragmentation is discussed in terms of flucton model. 17 refs.; 14 figs.

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A method for the determination of different ''bare'' characteristics of the one-particle motion and one-particle basis in magic nuclei is described. The method is based on separating out the mixing with phonons from the phenomenological one-particle characteristics. By means of a generalization of the procedure for localization of the mass operator, relations linking the bare and phenomenological characteristics are obtained. The radial dependence of these characteristics in finite nuclei and the influence of the quasiparticle--phonon interaction on the phenomenological characteristics are studied. Calculations are performed for the neutrons in /sup 208/Pb.

CERN Document Server

The possibility of the existence of stable tetrahedral deformations at spin zero is investigated using the Skyrme-HFBCS approach and the generator coordinate method (GCM). The study is limited to nuclei in which the tetrahedral mode has been predicted to be favored on the basis of non self-consistent models. Our results indicate that a clear identification of tetrahedral deformations is unlikely as they are strongly mixed with the axial octupole mode. However, the excitation energies related to the tetrahedral mode are systematically lower than those of the axial octupole mode in all the nuclei included in this study.

International Nuclear Information System (INIS)

A ''coherent flucton'' nuclear model is proposed which provides for new possibilities for particle scattering studies on nuclei. It is based on the data of nuclear matter density distribution and is used for calculating the ground state energy of Fermi system terminals. The ''coherent flucton'' model is applied to the distribution of 1 GeV protons on "2"8Si, "3"2S, "4"0Ca, "4"8Ca, "5"8Ni, "2"0"8Pb nuclei. The calculations by the model agree well with experimental data.

International Nuclear Information System (INIS)

Dietary supplements of about 5 g/kg of a number of amino acids increased tissue lead concentrations in newly weaned rats but decreased them in older rats. The retention of both oral and intraperitoneal lead was affected. The uptake of "2"0"3Pb by tissues was reduced when methionine was given in the diet over a period of 5 weeks or when it or ethionine was given by mouth 24 h before the activity was measured. In the liver the fraction of the total activity found in the nuclei and mitochondria was increased by methionine, but in the kidney only the fraction found in nuclei was increased.

International Nuclear Information System (INIS)

The nuclei "8"1Zr and "8"5Mo with T_z=1/2 have been reinvestigated via their #beta#-delayed proton emissions with p-#gamma# coincidence measurement. The half-life of "8"1Zr has been measured to be 5.3#+-#0.5 s, which agrees with one of the two previous values. For "8"5Mo, the measured half-life is 3.2#+-#0.2 s, which revises the previous value. (orig.).

Energy Technology Data Exchange (ETDEWEB)

A technique for calculation of the total weight of quark clusters-fluctons: in nuclei is developed. Blokhintsev's formula is justified microscopically and refined by introduction of spin-charge and quark factors. It is shown that the large values of the correlation radius (R/sub C/approx. =0.75 fm or 1.0 fm) derived from experimental data in various papers using this formula correspond to )similarreverse arrowto)2.5 times smaller internucleon distances in the flucton (0.3--0.4 fm), i.e., the hardness of fluctons is caused by unsuppressed manifestation of hidden color at such distances (the corresponding probabilities are presented)

International Nuclear Information System (INIS)

"2H, "4He, "1"6O, "4"0Ca, "8"0Zr, "1"4"0Yb, "2"2"4112, "3"3"6168 nuclei are invesigated in terms of flucton model. Effective numbers of nuclear fluctons and deuterons are calculated. Values of complete effective numbers of low-radius deuterons and fluctons with S=1 spin and T=0 isospin are presented. Investigation results of inclusive reactions of quasi-elastic knock-out of deuterons by fast protons are discussed. 9 refs.; 1 fig.; 1 tab.

International Nuclear Information System (INIS)

The wide-angle spectra of the 134-MeV (p,n) reaction on "4"8Ca, "5"4Fe, "8"8Sr, and "2"0"8Pb are each dominated by the excitation of a single state at low excitation energy. These excitations correspond to the ''0h#omega#'' stretched states and are seen to be fragmented much less than ''1h#omega#'' stretched states in medium- and heavy-mass nuclei. The normalization factors required for comparison with distorted-wave impulse-approximation calculations are >0.50 and indicate that these are the purest particle-hole states known in these nuclei.

International Nuclear Information System (INIS)

This review describes the basic theory and some recently developed techniques for the study of quadrupole nuclei with half integer spins in powder materials. The latter is connected to the introduction of the double rotation (DOR) by A. Samoson et al. (1) and to the introduction of the multiple quantum magic-angle spinning (MQ MAS) technique by L. Frydman et. al. (2). For integer spins, especially the solid-state deuterium magnetic resonance, we refer to the review of G.L. Hoatson and R.L. Vold: ''"2H-NMR Spectroscopy of Solids and Liquid Crystals'' (3). For single crystals we refer to O. Kanert and M. Mehring: ''Static quadrupole effects in disordered cubic solids''(4) and we would like also to mention the ''classic'' review of M.H. Cohen and F. Reif: ''Quadrupole effects in NMR studies of solids'' (5). Some more recent reviews in the field under study are D. Freude and J. Haase ''Quadrupole effects in solid-state NMR'' (6). Ch. Jager: ''Satellite Transition ...

International Nuclear Information System (INIS)

New rare earth metal rich cadmium compounds RE_4CoCd and RE_4RhCd (RE = Tb, Dy, Ho) were prepared by high-frequency melting of the elements in sealed tantalum tubes. The samples were studied by x-ray powder and single-crystal diffraction. All the compounds crystallize with Gd_4RhIn-type structure, with space group F4-bar3m. The structures are built up from rigid three-dimensional networks of condensed, cobalt (rhodium) centred trigonal RE_6 prisms. The voids left by these networks are filled by Cd_4 cluster units and the coordination number 14 polyhedra of the RE1 atoms. The terbium and dysprosium compounds in both series undergo antiferromagnetic ordering, whereas the holmium compounds exhibit ferromagnetic ordering. The magnetic ordering in these compounds is characterized by broad peaks around the transition temperatures. The results of detailed crystallographic investigations and preliminary magnetic and specific heat studies are presented and discussed in this ...

British Library Electronic Table of Contents (United Kingdom)

TaC-4wt.% CNT composites were synthesized using spark plasma sintering. Two kinds of CNTs, having long (10-20mm) and short (1-3mm) length, were dispersed by wet chemistry and spray drying techniques respectively. Spark plasma sintering was carried out at 1850^oC at pressures of 100, 255 and 363MPa. Addition of CNTs leads to an increase in the density of 100MPa sample from 89% to 95%. Short CNTs are more effective in increasing the density of the composites whereas long CNTs are more effective grain growth inhibitors. The longer CNTs are more effective in increasing the fracture toughness and an increase up to 60% was observed for 363MPa sample. Hardness and elastic modulus are found to increase by 22% and 18% respectively for 100MPa samples by addition of long CNTs. Raman spectroscopy, SEM...

British Library Electronic Table of Contents (United Kingdom)

Ultra fine tungsten carbide and cobalt powders were milled by high energy planetary ball mill at different ball to powder weight ratios (BPR) to produce particles of WC-10wt%Co hard metal in nanometer scale size. Microstructural characterizations by TEM show that the particle size of tungsten carbide was achieved to 32nm after milling at 15 BPR during 10h. In order to reduce the WC grain growth during the sintering process, tantalum carbide was added to the hard metal as a WC grain growth inhibitor. The nano hard metal powders were compacted at 200MPa pressure and sintered at 1370-1450degreeC temperatures in a high purity hydrogen atmosphere. The results show that the addition of 0.6wt% of TaC improves the hardness and fracture toughness from 1493 HV30 and 11.8MPam (for TaC free sample) to...

Energy Technology Data Exchange (ETDEWEB)

The two-dimensional Eulerian hydrodynamic code 2DE with the shock initiation of heterogeneous explosive burn model called Forest Fire, is used to model numerically the interaction of jets of steel, copper, tantalum, aluminum, and water with steel, water, and explosive targets. The calculated and experimental critical condition for propagating detonation may be described by the Held V/sup 2/d expression (jet velocity squared times the jet diameter). In PBX 9502, jets initiate an overdriven detonation smaller than the critical diameter, which either fails or enlarges to greater than the critical diameter while the overdriven detonation decays to the C-J state. In PBX 9404, the jet initiates a detonation that propagates only if it is maintained by the jet for an interval sufficient to establish a stable curved detonation front. The calculated penetration velocities into explosives, initiated by a low-velocity jet, are significantly less than for non-reactive solids of ...

Science.gov (United States)

The relationship between processing, microstructure, and properties was studied for A-15 compounds in multifilamentary composites produced by solid-state diffusion and in thin-film samples produced by vapor deposition. Grain sizes of A-15 superconducting compounds were measured by transmission electron microscopy of multifilamentary composites reacted at various temperatures. Critical current densities at 4.2 K and fields up to 6 T were found to be similar for niobium-tin, vanadium-gallium, and vanadium-silicon of the same grain size. Study of the Cu-V-Si phase diagram led to the production of improved multifilamentary vanadium-silicon conductors. The effects of various alloying elements on A-15 layers produced by solid-state diffusion were studied. The most promising new observation was that tantalum can be incorporated into niobium-tin reaction layers, leading to an enhancement of critical currents at high fields. The critical temperature of vapor-deposited, ...

Science.gov (United States)

The bone mineral areal content and the ultimate compressive strength were determined in 109 lumbar vertebrae from 36 subjects. The bone mineral areal content was related to the number, shape, and localization of the Schmorl's nodes detected in the x-rayed and sectioned vertebral bodies. One type of node, irregular in shape and localization, occurred only in the vertebrae with low bone mineral areal content values and thus in vertebrae with relatively low compressive strength. A second type of Schmorl's nodes, regular in shape and localization, did not reflect any general weakness of the vertebral bodies. PMID:6623194

Energy Technology Data Exchange (ETDEWEB)

Spray forming is an advanced materials processing technology that converts a bulk liquid metal to a near-net-shape solid by depositing atomized droplets onto a suitably shaped substrate. By combining rapid solidification processing with product shape control, spray forming can reduce manufacturing costs while improving product quality. De Laval nozzles offer an alternative method to the more conventional spray nozzle designs. Two applications are described: high-volume production of aluminum alloy strip, and the production of specialized tooling, such as injection molds and dies, for rapid prototyping.

Energy Technology Data Exchange (ETDEWEB)

Micro-compression specimens, 1O-15{mu}m in diameter by 20-30{mu}m in height, were produced from individual parent grains in a polycrystalline U-13at%Nb shape-memory alloy using the focused ion beam (FIB) technique. The specimens were tested in a nanoindentation instrument with a flat diamond tip to investigate stress-strain behavior as a function of crystallographic orientation. The results are in qualitative agreement with a single-crystal accommodation strain (Bain strain) model of the shape-memory effect for this alloy.

UK PubMed Central (United Kingdom)

Axon outgrowth and guidance to the proper target requires the coordination of filamentous (F)-actin and microtubules (MTs), the dynamic cytoskeletal polymers that promote shape change and locomotion....Full Text Available

International Nuclear Information System (INIS)

(1973). Germany Rebel, H. Schweimer, GW Kernforschungszentrum Karlsruhe

UK PubMed Central (United Kingdom)

Sensory systems must form stable representations of the external environment in the presence of self-induced variations in sensory signals. It is also possible that the variations themselves may provide...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

This report discusses: shape coexistence in {sup 184}Pt; nuclear structure of {sup 187}Ir; g-factors of excited states; OLNO-2; and refrigerator development.

UK PubMed Central (United Kingdom)

Our global impact is finally receiving the scientific attention it deserves. The outcome will largely determine the future course of evolution. Human-modified ecosystems are shaped by our activities...Full Text Available

UK PubMed Central (United Kingdom)

This article examines how politics and science interacted against a background of uncertainty to shape policy in the case of environmental contamination by polybrominated biphenyls (PBB) in Michigan....Full Text Available

UK PubMed Central (United Kingdom)

Even when a healthy individual is studied, his/her erythrocytes in capillaries continually change their shape in a synchronized erratic fashion. In this work, the problem of characterizing the cell...Full Text Available

UK PubMed Central (United Kingdom)

The bacterium Serratia marcescens produces a plethora of multicellular shapes of different colorations on solid substrates, allowing immediate visual detection of varieties. Such a...Full Text Available

Science.gov (United States)

A method for the calculation of excitation functions and isomer ratios, for shape isomers, in heavy ion induced reactions is proposed. The calculated values of excitation functions and isomer ratios agree very well with the experimental values for the reaction /sup 238/U(/sup 11/B, alpha 3n)/sup 242/Am. (auth)

International Nuclear Information System (INIS)

Large, complex, high purity ceramic shapes are required by a variety of emerging technologies for their electrical insulation and high temperature strength properties coupled with their refractoriness and purity. Ceramic sealant bonding, using crystalline and vitreous sealant materials, has recently shown significant potential for joining technical ceramics to form the required shapes. Materials and techniques for joining technical ceramics including alumina, magnesia, zirconia and thoria are discussed. (orig.).

International Nuclear Information System (INIS)

New surface photometry of all known elliptical galaxies in the Virgo cluster is combined with published data to derive composite profiles of brightness, ellipticity, position angle, isophote shape, and color over large radius ranges. These provide enough leverage to show that Sersic log I #propor to# r "1"/"n functions fit the brightness profiles I(r) of nearly all ellipticals remarkably well over large dynamic ranges. Therefore, we can confidently identify departures from these profiles that are diagnostic of galaxy formation. Two kinds of departures are seen at small radii. All 10 of our ellipticals with total absolute magnitudes M_V_T #<=# -21.66 have cuspy cores-"missing light"-at small radii. Cores are well known and naturally scoured by binary black holes (BHs) formed in dissipationless ("dry") mergers. All 17 ellipticals with -21.54 #<=# M_V_T #<=# -15.53 do not have cores. We find a new distinct component in these galaxies: all coreless ellipticals ...

International Nuclear Information System (INIS)

We measured the volume of the supratentorial ventricles in 39 consecutive children with myelomeningocele (MMC) and associated hydrocephalus, using a stereological method based on the Cavalieri theorem of systematic sampling. We distinguished the following groups: newborns before and after cerebrospinal fluid shunting (14), a somewhat larger group of newborns with an untreated MMC-associated hydrocephalus (25) and a group of shunted children at a mean age of 1.5 years (28). We paid special attention to the shape of the lateral ventricles, looking separately at the anterior and posterior halves. The measurements were compared with a healthy control group (10) and with children with hydrocephalus unrelated to MMC (15). The average volume ratio of the posterior to the anterior half of the lateral ventricles was 1.05 #+-# 0.39 in non-hydrocephalic children, 1.11 #+-# 0.55 in untreated hydrocephalic children without MMC, and 2.15 #+-# 0.65 in MMC-associated hydrocephalus ...

Energy Technology Data Exchange (ETDEWEB)

The energy-integrated reaction cross-sections of several neutron-rich nuclei ({sup 17-22}N, {sup 19-24}O, {sup 21-27}F, {sup 23-30}Ne, {sup 26-33}Na, {sup 28-35}Mg, {sup 31-38}Al, {sup 33-40}Si, {sup 36-42}P, {sup 39-44}S, {sup 42-45}Cl, {sup 45,46}Ar), measured at intermediate energy (30-65 A-bar MeV), via direct method, are presented. Silicon detectors have been used as the active target as well as for particles identification. The reduced strong absorption radii r{sub 0}{sup 2} are extracted and compared to the data available from the literature. New measurements for 19 nuclei ({sup 27}F, {sup 27,30}Ne, {sup 33}Na, {sup 28,34-35}Mg, {sup 36-38}Al, {sup 38-40}Si, {sup 41-42}P, {sup 42-44}S, {sup 45}Cl) are revealed. From the study of the isospin dependence of the reduced strong absorption radius, a new quadratic parameterisation of the nuclear radii in the closed shell regions N=8 and N=28, is proposed. According to this parameterisation, the ...

International Nuclear Information System (INIS)

Inelastic scattering of #alpha#-particles in 22-24 MeV energy range on "1"8o o, "1"9f, "2"0Ne, "2"2Ne nuclei is investigated. Measurements of excitation functions were conducted for the beam of Leningrad University cyclo otron at several angles in 15-165 deg range of laboratory system with 2.5 deg spacing. The error of determining absolute cross sections equals +-20% for "2"2Ne and +-12% for other nuclei. Angular distributions have the differaction character, are similar in form for all nuclei, the values of differential cross- -sections don't exceed the rutherford values. The dependence of integral cross-sections on the energy of level excitation is similar to the exponential d dependence of cross-sections of production of the given element isotopes on the gergy difference of masses of final nuclear products in the reactions of deeply inelastic transfers with heavy ions. The observed isotopic effect in the value of ...

International Nuclear Information System (INIS)

Nuclear structure information for all nuclei with mass number A = 216 is summarized. Evaluated data and the adopted levels and spin and parity assignments are given. Only the #alpha#-decay mode has been observed for all nuclei in this mass chain. Possible epsilon-capture and/or #beta#-decay are expected to be quite weak for most of them. An upper limit of 0.6 percent was set by 68Va18 for "2"1"6Th epsilon-decay from #alpha#-yields. The compilers estimate any epsilon-capture decay from "2"1"6At to "2"1"6Po to be less than 1.5 x 10"-"6 percent; similarly, #beta#-decay from "2"1"6At to "2"1"6Rn ground state is expected to be less than 0.0004 percent, and allowed #beta#"- to any yet unobserved level in "2"1"6Rn can be estimated to be less than 0.005 percent from expected log ft values. Level scheme information for all nuclei is from #alpha#-decays of their parents with A = 220. #alpha#-parents are shown on the drawings above ...

International Nuclear Information System (INIS)

We studied the magnetic dipole moments #mu# of even-odd C isotopes, ranging from proton-rich to neutron-rich nuclei, with antisymmetrized molecular dynamics (AMD). The results are in good agreement with the experimental data. In the "9C ground state the total intrinsic spin of the protons is found to be nonzero (S_p#not =#0), which is unusual in even-odd nuclei. The interesting point is that the spin-orbit force breaks slightly the coupling off of intrinsic spins of the even nucleon group in isospin T=3/2 nuclei. This result is consistent with the newly measured #mu# data that, when combined with "9Li data, indicate an unusual left-angle #sigma# right-angle value larger than unity. A #mu# moment -1.05#mu#_N of "1"7C is theoretically predicted. We also show a good reproduction of E2 transition data. copyright 1996 The American Physical Society.

CERN Document Server

The non-thermal supernova remnant RX J1713.7-3946 (G347.3-0.5) has recently been shown to be a site of cosmic ray (CR) electron acceleration to TeV energies (Muraishi et al. 2000). Here we present evidence that this remnant is also accelerating CR nuclei. Such nuclei can interact with ambient interstellar gas to produce high energy gamma-rays via the decay of neutral pions. We associate the unidentified EGRET GeV gamma- ray source 3EG J1714-3857 with a massive (~3*10 5 Mo) and dense (~500 nucleons cm -3) molecular cloud interacting with RX J1713.7-3946. Direct evidence for such interaction is provided by observations of the lowest two rotational transitions of CO in the cloud; as in other clear cases of interaction, the CO(J=2-1)/CO(J=1-0) ratio is significantly enhanced. Since the cloud is of low radio and X-ray brightness, CR electrons cannot be responsible for the bulk of its GeV emission there. A picture thus emerges where both electrons ...

Energy Technology Data Exchange (ETDEWEB)

Particle shape is an important parameter in numerous civil, environmental, and petroleum engineering applications. In ground-water flow, the shape of individual particles comprising the soil affects the soil`s pore size distribution and, hence, the important flow characteristics such as hydraulic conductivity and headloss. A model for delineating the relative importance of particle size, particle shape, and porosity, (and their interactions), in explaining the variability of hydraulic conductivity of a granular porous medium is developed and tested. Three types of porous media are considered in this work: spherical glass beads; granular sand; and irregularly shaped, shredded glass particles. A reliable method for quantifying the three-dimensional shape and packing of large samples of irregular particles based on their angle of repose is presented. The results of column experiments ...

International Nuclear Information System (INIS)

An analysis of the total photoabsorption cross section for nuclei ranging from "4He up to "2"3"8U has been performed in the energy range 0.2-1.0 GeV. Mean total photoabsorption cross sections have been obtained by summing up the contributions from partial photoreactions, and found to follow an A"1-dependence in the 0.2-1.0 GeV range. A review of the available total photoabsorption cross section data is also presented. Comparisons have been made with cross section values calculated by considering both the quasi-deuteron and #pi#-meson photoproduction mechanism of primary nuclear photointeraction. (orig.).

International Nuclear Information System (INIS)

The linearized collective Schroedinger equation for nuclear quadrupole surface vibrations incorporates a new spin degree of freeedom with a spin value of 3/2. We use this equation to describe the low energy spectrum of certain even-odd Ir nuclei which have a spin 3/2 in their ground state. For that purpose we explicitly introduce collective spin-dependent potentials which simulate the interaction of the valence nucleon with the core. The linearized Schroedinger equation is transformed into an effective Schroedinger equation with collective spin-dependent potentials. Already collective spin-orbit couplings of SO(3) and SO(5) type are sufficient to reproduce the lowest excited states of even-odd Ir nuclei. (orig.).

International Nuclear Information System (INIS)

We report here results of an application of single-nucleon stripping reactions at high energies (65 MeV/u) in inverse kinematics to obtain spectroscopic factors. From measurements of the partial cross-sections for ground and excited states in residual nuclei formed in one-proton stripping reactions, single particle orbits and occupancies of light nuclei have been studied in the s-d shell. Single proton stripping cross-sections of "2"5Al and "2"6","2"7","2"8P on a Be target have been measured using the S800 spectrograph and the NaI(Tl) array at the NSCL. These results indicate that this technique may provide a general tool for the intermediate energy range analogous to transfer (pick-up) reactions at low-energy.

British Library Electronic Table of Contents (United Kingdom)

Reduced systems such as brain slices offer a powerful approach to study the physiology of auditory neurons in great detail. However, when studying auditory nuclei in reduced systems such as brain slices, especially highly active auditory brain stem nuclei, one has to be aware that the unphysiological lack of activity in the reduced system compared to the in-vivo situation has a number of important effects on the neurons under investigation, and thus on the data that are measured. Most importantly, the lack of chronic activity in the slice preparation has important effects on the properties of short-term plasticity of the synapses. The main purpose of this article is to discuss how spontaneous activity in auditory neurons, or the lack thereof, can affect the data measured.

International Nuclear Information System (INIS)

Progress in experimental investigations of high spin excitations in spherical and transitional nuclei in the A = 180 to 204 mass range is described. Most of the experiments were performed by in-beam #gamma#-ray spectroscopy using beams of "3He, "4He, and "1"2C ions from the Michigan State University cyclotron. The main results of studies of the nuclei "1"9"5 "1"9"7 "1"9"9 "2"0"1 "2"0"2 "2"0"3Pb, "1"9"6 "1"9"7 "1"9"9 "2"0"0Hg and "1"8"6 "1"8"7 "1"8"8 "1"8"9Pt are summarized.

British Library Electronic Table of Contents (United Kingdom)

A study of elliptical flow is carried out for different mass asymmetries of colliding nuclei using the reactions of Formula Not Shown ( Formula Not Shown ), Formula Not Shown ( Formula Not Shown ) and Formula Not Shown ( Formula Not Shown ). The present reactions are simulated at incident energies between 50 and 250 MeV/nucleon within the framework of isospin-dependent quantum molecular dynamics model. For the present analysis, total mass of colliding pairs is kept fixed and mass asymmetry is varied between 0.3 and 0.7. The elliptical flow shows a transition from in-plane to out-of-plane in the mid rapidity region with incident energy. The transition energy is found to increase with the mass asymmetry for light charged particles. A good agreement is obtained with experimental measurements.

Energy Technology Data Exchange (ETDEWEB)

The half-lives of short-lived nuclei produced by 14 MeV or thermal neutron bombardments were measured with a Ge detector, a Spectrum Multi-Scaler (Laboratory Equipment Corporation SMS-48) and a High-Rate Spectroscopy Amplifier (EG and G ORTEC Model 973) in the multi-scaling mode. The corrections for pile-up and dead-time losses were performed by applying source and pulser methods. The half-lives of {sup 91m}Mo, {sup 97m}Nb, {sup 138}Cs, {sup 139}Ba, {sup 174}Tm and {sup 203m}Pb were determined with accuracy of 0.22-0.6% and the accuracy has been much improved. (author)

International Nuclear Information System (INIS)

The ground state masses of thirty-nine neutron-rich nuclei from "5"1Ca to "7"2Ni have been measured using the Time-of-Flight Isochronous (TOFI) spectrometer. Eight of these masses have been measured for the first time and thirty-one are remeasurements of neutron-rich nuclei previously reported. Good agreement between these results and a previous TOFI experiment was observed except for the most neutron-rich isotopes of vanadium through iron with the present results being more bound and in better agreement with theory. The low binding energy of "6"8Ni, as indicated by an unreasonably low two-neutron separation energy, suggests the presence of a high-lying, long-lived isomeric state in this nucleus. (orig.).

International Nuclear Information System (INIS)

The proton and neutron densities, root-mean-square (rms) radii of proton density and neutron density, and neutron skin thickness of "4"-"1"0He, "6"-"1"1Li, and "7"-"1"2Be isotopes are calculated using Skyrme-Hartree-Fock method with SLy4, SLy5, SLy6, and SLy7 force parameters. The evaluated results are compared with experimental data. Also, the results of halo nuclei ("6","8He, "1"1Li, and "1"1Be) are compared with the results of other isotopes for selected nuclei having the same neutron configuration.

Science.gov (United States)

The effect of treatment of Na-forms of zeolites with HCl solutions and of heat treatment of their NH/sub 4/-forms on the stability of aluminum-oxygen tetrahedra has been studied in this work by high-resolution NMR on /sup 29/Si nuclei, using the synthetic zeolites X, Y, and M (mordenite) as the objects of the study. The exchange capacity with respect to Na/sup +/ ions was determined by analyzing the equilibrium solutions after contact of the samples with 0.5 NH/sub 4/Cl solution on a flame photometer. The high-resolution /sup 29/Si NMR spectra of polycrystalline samples were recorded on an SKhR-200 spectrometer with a superconducting solenoid at a frequency of 39.75 MHz with ultrafast mechanical rotation (3 kHz) of the sample at the magic angle to the external magnetic field. The results obtained are given.

International Nuclear Information System (INIS)

A technique is developed for calculation of the total weight of the quark clusters-fluctons in atomic nuclei. The microscopical proof of Blochintsev formula is carried out and its refinement is obtained (spin-charge and quark factors enter the formula). It is shown that high values of the correlation radius (R_c #approx =# 0.75 fm or 1.0 fm in various papers) obtained from the experimental data making use of the above formula correspond to internucleon distances in flucton of 0.3-0.4 fm, which is by a factor of #approx# 2.5 lower. This means that the flucton hardness is due to free manifestation of hidden color at those distances (the appropriate probabilities are presented).

International Nuclear Information System (INIS)

Experimental studied of deep-inelastic scattering of neutrino, antineutrino, #mu#-mesons, electron reactions on He, D, Al, Fe, Au, Be, C, Ca, Ag, N nuclei conducted in recent years at different laboratories the world for consideration of modern status of the problems of R(x, Q"2) = #sigma#sub(L)/#sigma#sub(T) parameter variation and for study on nuclear effects in structural functions of nucleons are described in the review. Experimental information on measurements of the R parameter by data on EMS and SLAK groups is analyzed. It is noted that experimental data on measuring R contain essential errors that hampers unambiguous interpretation of data on nucleon structure. Present experimental data and predictions for explanation of the EMS effect are analyzed from the view point of quark and flucton models of a nucleus.

Energy Technology Data Exchange (ETDEWEB)

We consider particle evaporation and fission of an ensemble of hot, rotating compound nuclei as a stochastic process. We derive a set of coupled differential equations formed by a Fokker-Planck equation describing fission, and master equations for calculating particle evaporation. From these equations, we are able to determine multiplicities of prefission neutrons, protons and {alpha}-particles, their energy spectra and their angular momentum distributions. A comparison of our results with experimental data provides us with information regarding the reduced friction coefficient {beta}, the fission barrier height and the level density parameter. For different iridium isotopes, ({sup 181,185,187}Ir), {sup 185}Os and {sup 158}Er, we obtain as an upper limit {beta}{<=}8.0x10{sup 21} s{sup -1}. (orig.).

International Nuclear Information System (INIS)

Differential cross sections of the (#alpha#, t) reactions on "4"5Sc, "5"1V, and "5"9Co nuclei are measured in the 10-71 deg, 10-155 deg, and 10-171 deg angular ranges, respectively, with 27.2 MeV alpha particles. The cross sections have also been calculated on the basis of the distorted wave theory. The possibility of an unambiguous choice of the optical potential for alpha particles is discussed. The angular distribution calculations using several combinations of the optical potentials in the inlet and outlet channels of the reactions show that consistence between the calculations and the measurements is achieved (especially in angular range, less than 90 deg, if one of the potentials is chosen to be a sufficiently deep one.

International Nuclear Information System (INIS)

This paper tests the Environmental Kuznets Curve hypothesis for four local (SOx, NOx, CO, VOC) and two global (CO2, GHG) air pollutants. Using a new panel data set of thirty OECD countries, the paper finds that the postulated inverted U-shaped relationship between income and pollution does not hold for all gases. A meaningful Environmental Kuznets Curve exists only for CO, VOC and NOx, where for CO2 the curve is monotonically increasing. For GHG there is indication of an inverted U-shaped relationship between income and pollution, but still most countries are on the increasing path of the curve and hence the future development of the curve is uncertain. For SOx it was found that emissions follow an U-shaped curve. Based on the empirical results, the paper concludes that the Environmental Kuznets Curve does not hold for all gases, it is rather an empirical artefact than a regularity.

Energy Technology Data Exchange (ETDEWEB)

The detection of explosives is a notoriously difficult problem, especially at stand-off distances, due to their (generally) low vapor pressure, environmental and matrix interferences, and packaging. We are exploring optimal dynamic detection to exploit the best capabilities of recent advances in laser technology and recent discoveries in optimal shaping of laser pulses for control of molecular processes to significantly enhance the standoff detection of explosives. The core of the ODD-Ex technique is the introduction of optimally shaped laser pulses to simultaneously enhance sensitivity of explosives signatures while reducing the influence of noise and the signals from background interferents in the field (increase selectivity). These goals are being addressed by operating in an optimal nonlinear fashion, typically with a single shaped laser pulse inherently containing within it coherently locked control and probe ...

Science.gov (United States)

Ni-free shape memory alloys are promising functional materials for medical applications. A newly developed Ti-Mo based shape memory alloy shows superelasticity after thermomechanical treatment. However, the microstructure evolution and precipitation during thermomechanical processes are still not well understood. In the present paper, compressive deformation behavior at a series of temperatures of 298K - 973K and tensile deformation behavior of the alloy after aged at 573K - 973K have been investigated systematically. It is found that the compressive yield stress and ultimate compressive strength change with the deformation temperature. The ultimate tensile strength and yield stress of aged specimens also change with the aging temperature following a non-linear relationship. Microstructures of aged specimens as well as effects of lattice softening and aging-induced precipitates on the deformation behavior have been investigated and discussed.

CERN Document Server

We describe a method of determining the system parameters in non-eclipsing interacting binaries. We find that the extent to which an observer sees the shape of the Roche-lobe of the secondary star governs the amount of distortion of the absorption line profiles. The width and degree of asymmetry of the phase-resolved absorption line profiles show a characteristic shape, which depends primarily on the binary inclination and gravity darkening exponent. We show that, in principle, by obtaining high spectral and time resolution spectra of quiescent cataclysmic variables or low mass X-ray binaries in which the mass-losing star is visible, fitting the shape of absorption line profiles will allow one to determine not only the mass function of the binary, but also the binary inclination and hence the mass of the binary components.

Science.gov (United States)

... s the matter with Kansas?Legislative debates over stem cell research in Kansas and MassachusettsBonnie StabileSchool of Public Policy, ... examines the contextual factors shaping legislative debates affec...

UK PubMed Central (United Kingdom)

Auditory neurons in the superior colliculus (SC) respond preferentially to sounds from restricted directions to form a map of auditory space. The development of this representation is shaped...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundEpidemiological studies have shown a J- or U-shaped relation between alcohol and type 2 diabetes and coronary heart disease (CHD). The underlying mechanisms are not clear....Full Text Available

UK PubMed Central (United Kingdom)

Summary of recent advances (abstract)Nucleic acid-based nanotechnology has always been perceived as novel, but has begun to move from theoretical demonstrations to practical applications....Full Text Available

UK PubMed Central (United Kingdom)

The classic evolutionary theory of aging explains why mortality rises with age: as individuals grow older, less lifetime fertility remains, so continued survival contributes less to reproductive fitness....Full Text Available

Energy Technology Data Exchange (ETDEWEB)

This report discusses: shape coexistence in {sup 184}Pt; nuclear structure of {sup 187}Ir; g-factors of excited states; OLNO-2; and refrigerator development.

Energy Technology Data Exchange (ETDEWEB)

Monodisperse noble metal nanoparticles are of tremendous interest for numerous applications, such as surface-enhanced Raman spectroscopy, catalysis or biosensing. However, preparation of monodisperse metal nanoparticles is still a challenging task, because typical preparation methods yield nanoparticle ensembles with broad shape and/or size distributions. To overcome this drawback, tailoring of metal nanoparticles with laser light has been developed, which is based on the pronounced shape- and size-dependent optical properties of metal nanoparticles. I will demonstrate that nanoparticle tailoring with ns-pulsed laser light is a suitable method to prepare nanoparticle ensembles with a narrow shape and/or size distribution. While irradiation with ns-pulsed laser light during nanoparticle growth permits a precise shape tailoring, post-grown irradiation allows a size tailoring. For example, the initial ...

UK PubMed Central (United Kingdom)

BackgroundRecent advances in the understanding of the maternal and paternal heritage of south and southwest Asian populations have highlighted their role in the colonization of Eurasia...Full Text Available

International Nuclear Information System (INIS)

The cosmic ray neutron spectrum at sea level has been measured by the method of pulse shape discrimination in anthracene scintillator. The exponent of the differential spectrum was found to be 2.2+-0.1. (Auth.).

UK PubMed Central (United Kingdom)

One selection pressure shaping sequence evolution is the requirement that a protein fold with sufficient stability to perform its biological functions. We present...Full Text Available

Science.gov (United States)

retrieve detailed aerosol and cloud particle size distribution and shape ...... but on rain types, and hydrometeor characteristics. ..... of ice streams, decreasing sea ice cover in the Arctic, poleward movement of forest cover, and ...

Science.gov (United States)

A cartridge case is made by making up an aqueous slurry of cellulosic fibers, forming the fibers into a mat and molding the mat or preform into final shape by use of a die at up to 165 degrees F.