International Nuclear Information System (INIS)

Using an ab initio pseudopotential method within a generalized gradient approximation of the density functional theory, the structural, electronic, and phonon properties of SrS in the B1 (NaCl) and B2 (CsCl) structures have been studied. The calculated lattice constants, static bulk modulus, and first-order pressure derivative of the bulk modulus are reported for both the B1 and B2 structures and compared with previous experimental and theoretical calculations. Electronic band structures and densities of states have been derived for SrS. Subsequently, a linear-response approach to the density functional theory is used to derive the phonon frequencies and densities of states.

International Nuclear Information System (INIS)

The transformation from the as-quenched amorphous to the crystalline state in Fe_7_8B_1_3Si_9 alloy has been investigated using a new-type neutron diffractometer. The time resolved diffraction patterns clearly show that this alloy crystallizes into FeSi alloy and Fe_2B in that order. The time evolution of these crystalline phases can be analyzed by the Kolmogorov-Johnson-Mehl-Avrami equation with the exponent of about 2.5 over a wide temperature range. This suggests that the crystallization occurs by the diffusion-controlled growth with a constant nucleation rate. The scaling behavior in the crystallization kinetics is also discussed. (author).

International Nuclear Information System (INIS)

The neutron capture cross sections of the stable molybdenum isotopes have been measured with high energy resolution (#DELTA#E/E < approximately 0.2%), between 3 and 90 keV neutron energy, at the 40 m station of ORELA. Average resonance parameters are extracted for s- and p-wave resonances. The s-wave neutron strength function is close to 0.5x10"-"4 for all isotopes, but the p-wave strength function exhibits a well defined peak near A approximately 95. Both s- and p-wave radiative widths decrease markedly as further neutrons are added to the closed shell. The p-wave radiative widths are generally greater than the s-wave widths showing the presence of non-statistical #gamma#-decay mechanisms. Valence neutron theory fails to explain the magnitude of the p- to s-wave radiative width disparity and doorway state processes are invoked. In ...

International Nuclear Information System (INIS)

Electron microscopic observations of neutron irradiated Nb_3Sn revealed the presence of highly disordered regions of size approximately 35 A in a much less disordered matrix. This observation is shown to provide a means of explaining quantitatively many superconducting properties of irradiated A-15 compounds. In particular Tsub(c) of the irradiated materials could be easily predicted using the mathematical formulations developed for the proximity effect. (Auth.).

CERN Document Server

Small angle neutron scattering (SANS) on the unilamellar vesicle populations (diameter 500 and 1000 angstrom) was used to characterize lipid vesicles from dimyristoylphosphatidylcholine (DMPC) at three phases (gel, ripple, and liquid). Parameters of vesicle populations and internal structure of the DMPC bilayer were characterized on the basis of the Separated Form Factor (SFF) model. Parameters of the internal bilayer structure (thickness of the membrane and the hydrophobic core, hydration, and surface area of lipid molecule) were determined on the basis of the Hydrophobic-Hydrophilic (HH) approximation of neutron scattering length density across the bilayer r(x) and of the Step Function (SF) approximation of r(x). It was demonstrated in frame of HH approximation that DMPC membrane thickness in liquid phase (T=30 degrees) depends on the membrane curvature. The dependence of the DMPC ...

UK PubMed Central (United Kingdom)

PurposeTo analyze the contributions of cytochrome P4501B1 (CYP1B1) mutations to primary congenital glaucoma (PCG) in Spanish patients.MethodsWe...Full Text Available

CERN Document Server

We present the results of three-dimensional hydrodynamical simulations of the final stages of inspiral in a black hole-neutron star binary, when the separation is comparable to the stellar radius. We use a Newtonian Smooth Particle Hydrodynamics (SPH) code to model the evolution of the system, and take the neutron star to be a polytrope with a soft (adiabatic index G=2 and G=5/3) equation of state and the black hole to be a Newtonian point mass. The only non-Newtonian effect we include is a gravitational radiation back reaction force, computed in the quadrupole approximation for point masses. We use irrotational binaries as initial conditions for our dynamical simulations, which are begun when the system is on the verge of initiating mass transfer and followed for approximately 23 ms. For all the cases studied we find that the star is disrupted on a dynamical time-scale, and forms a massive (the disc ...

Energy Technology Data Exchange (ETDEWEB)

We have measured the almost-pure incoherent scattering function of liquid and solid parahydrogen, using inelastic neutron scattering. The experiments were carried out on TOSCA, a time-of-flight, inverse-geometry, crystal-analyzer spectrometer, operating on the pulsed neutron source at ISIS (UK). The experiments have been planned taking advantage of the intrinsic incoherence introduced in the scattering process by the rotational transitions. The measured double-differential cross section gives a direct experimental access to the microscopic dynamics of condensed hydrogen. From the high-energy region of the spectrum, where the impulse approximation for the center of mass motion applies, we have been able to extract the translational mean kinetic energy. In the low-energy region, using the Gaussian approximation, we compare the experimental data in the liquid phase with the results of a model for the ...

International Nuclear Information System (INIS)

The neutron transition multipole moment, M/sub n/, for (0"+#->#2"+, 1.84 MeV) transition is inferred by measuring the (#alpha#,#alpha#') angular distribution at E/sub #alpha#/ = 50 MeV and comparing it with a microscopic distorted-wave Born approximation calculation. Proton transition densities are taken from electron scattering data. M/sub n//M/sub p/ is found to be substantially less than N/Z in agreement with the (p,p') result.

International Nuclear Information System (INIS)

To investigate the 2D/1D fusion core analysis method, a 1D neutron transport problem solver, PEACH-ID, is developed. It is a code of method of characteristics (MOC), both the usual fiat-source step characteristics (SC) scheme and linear source (LS) approximation scheme are adopted for tracking calculation along the neutron flying trajectory. Exponential function interpolation table and fission source extrapolation are adopted as two major methods to accelerate the computational process. Numerical results demonstrate that PEACH-1D is accurate and efficient, and the proposed LS scheme is able to handle quite larger mesh division and deserves much more application in the MOC codes. (authors)

Energy Technology Data Exchange (ETDEWEB)

Neutron Coded Aperture Imaging is a nondestructive imaging technique that utilizes neutrons scattered from an object through specially designed apertures. Coded Aperture Imaging is an alternative technique to Computed Tomography for three-dimensional imaging. Coded Aperture Imaging has the advantage that all of the three-dimensional information is contained in a single image, whereas Computed Tomography requires several images or projections. This technique has been implemented by other using photographic film as an image recording medium and optical reconstruction or decoding of the images. In this work, the possibility of using a real-time neutron video camera to record the images, followed by digital decoding methodology has been investigated. Because only a small fraction of the neutrons incident on the object are scattered to the neutron camera, a new ...

Energy Technology Data Exchange (ETDEWEB)

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 [sup 87]Mo 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.)

International Nuclear Information System (INIS)

One-velocity angular flux of a neutron field generated by a polarly anisotropic point source in an infinite homogeneous region is calculated in P3 approximation, using the spherical harmonics operator formalism adapted to two-dimensional spherical geometry. The problem is reduced to simple algebraic equations. For weak absorption and linearly anisotropic scattering, the solution is given in closed form. (orig.).

Energy Technology Data Exchange (ETDEWEB)

Personnel radiation monitoring is essential to the operation of any nuclear facility and work in this area continues to strive for an accurate determination of personnel dose. In particular recent attention has been focused upon the need to improve the accuracy of neutron dosimetry, mainly because of their high Relative Biological Effectiveness. In this work the feasibility of using the NE-213 liquid scintillation detector as an efficient neutron/..gamma.. ray radiation monitor is demonstrated. Derivative method spectrum unfolding used in MATXUF for on-line analysis of fast neutron spectra has also been applied to real time ..gamma.. spectrum unfolding (MATXUF2), making possible simultaneous on-line monitoring of both fast neutrons and gammas. To eliminate the negative fluxes in the unfolded ..gamma.. spectra created by the photopeak-Compton edge combination in the plateau portion of the knee response, ...

Science.gov (United States)

Personnel radiation monitoring is essential to the operation of any nuclear facility and work in this area continues to strive for an accurate determination of personnel dose. In particular recent attention has been focused upon the need to improve the accuracy of neutron dosimetry, mainly because of their high Relative Biological Effectiveness. In this work the feasibility of using the NE-213 liquid scintillation detector as an efficient neutron/gamma ray radiation monitor is demonstrated. Derivative method spectrum unfolding used in MATXUF for on-line analysis of fast neutron spectra has also been applied to real time gamma spectrum unfolding (MATXUF2), making possible simultaneous on-line monitoring of both fast neutrons and gammas. To eliminate the negative fluxes in the unfolded gamma spectra created by the photopeak-compton edge combination in the plateau portion of the knee response, correcting ...

International Nuclear Information System (INIS)

The classical theory of collisional broadening and shift parameters (?, ?) of an isolated spectral line was used to obtain simple analytical formulas for calculating both ? and ?. These formulas were obtained on the assumption that the short range interaction is effective only in the broadening while the long range is effective in the shift of the spectral line. These parameters ? and ? depend on the limiting phase shifts responsible for broadening ?b and shift ??. It was found that the values of ?b and ?? are not equal to each other as was proposed by Weisskopf ?b=??=1. The maximum and average values of ?b (?bmax, ?bav) and ?? (??max, ??av) were obtained by numerical evaluation, using different inverse power potentials. By introducing these parameters into the approximated formulas for ? and ? using Van der Waals and Lennard-Jones potential, it was found that the results of calculations for (? and ?) with different atomic ...

Energy Technology Data Exchange (ETDEWEB)

A general space- and energy-dependent formalism is developed in order to analyze zero-power neutron noise experiments in fast reactor systems. A generalized dispersion equation is combined with theoretical expressions for the experimentally measured power spectral density and variance-to-mean ratio which makes it possible to express these quantities in terms of a double moment of the Laplace and Fourier transformed Green's function of a slowing-down operator rather than those of the full Boltzmann operator. Several spatial approximations are analyzed in the context of the general formalism. In each case, the power spectral density and variance-to-mean ratio are written in terms of an appropriate fast reactor dispersion law for the medium which can be calculated from the solution to a simple slowing-down equation. The resultant expression for the power spectral density are analyzed for various combinations of ...

Energy Technology Data Exchange (ETDEWEB)

The neutron transition multipole moment, M/sub n/, for (0/sup +/..-->..2/sup +/, 1.84 MeV) transition is inferred by measuring the (..cap alpha..,..cap alpha..') angular distribution at E/sub ..cap alpha../ = 50 MeV and comparing it with a microscopic distorted-wave Born approximation calculation. Proton transition densities are taken from electron scattering data. M/sub n//M/sub p/ is found to be substantially less than N/Z in agreement with the (p,p') result.

Energy Technology Data Exchange (ETDEWEB)

The use of chemically selective laser ionization combined with {beta} -delayed neutron counting at CERN/ISOLDE has permitted identification and half-life measurements for 623-ms {sup 61}Mn up through 14-ms {sup 69}Mn . The measured half-lives are found to be significantly longer near N=40 than the values calculated with a quasiparticle random-phase-approximation shell model. Gamma-ray singles and coincidence spectroscopy has been performed for {sup 64,66}Mn decays to levels of {sup 64,66}Fe , revealing a significant drop in the energy of the first 2{sup +} state in these nuclides that suggests an unanticipated increase in collectivity near N=40 . {copyright} {ital 1999} {ital The American Physical Society }

Science.gov (United States)

The theory of a method of determination of the reactivity from power spectral density measurements with /sup 252/Cf and the results of experiments with a critical assembly mock-up of a liquid-metal fast breeder reactor and with uranium (93.2 wt % /sup 235/U) metal cylinders and a sphere are presented. This method of reactivity determination has an advantage over existing methods in that it determines the reactivity only from properties of the reactor at the subcritical state of interest and thus does not require a calibration near delayed criticality. In these experiments the reactivity was varied by changing the fissile loading or the amount of neutron absorber inserted; for the LMFBR mock-up, the reactivity varied to approximately 75 dollars subcritical, and for the uranium metal assemblies, to approximately 30 dollars subcritical.

UK PubMed Central (United Kingdom)

BackgroundThe objective of this study was to gain insight into the molecular mechanism of induced cell death (apoptosis) by PYRROLO [1,2-b][1,2,5]BENZOTHIADIAZEPINES...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Inactivation of aflatoxin B1 was studied by using gamma radiation and hydrogen peroxide. A 100-krad dose of gamma radiation was sufficient to inactivate 50 micrograms of aflatoxin B1 in the presence of 5% hydrogen peroxide, and 400 krad was required for total degradation of 100 micrograms of aflatoxin in the same system. Degradation of aflatoxin B1 was confirmed by high-pressure liquid chromatographic and thin-layer chromatographic analysis. Ames microsomal mutagenicity test showed loss of aflatoxin activity. This method of detoxification also reduces the toxin levels effectively in artificially contaminated groundnuts.

International Nuclear Information System (INIS)

Data on the recovery of Tsub(c) for several neutron irradiated A-15 compounds are presented. A model for the mechanism of recovery is suggested and has been applied to isothermal annealing data at 550"0C on a sample of Nb_3Ge and to isochronal annealing (200"0C-900"0C) data on V_3Si, Nb_3Ge and Nb_3Sn subjected to varying doses of fast neutrons and on Nb_3Al of various compositions subjected to the same dose. The recovery is assumed to take place by vacancy assisted reordering and occurs in several stages. The major low temperature stage is attributed to irradiation induced vacancies, while at high temperatures there are depleted and recovery is ascribed to the motion of thermal equilibrium vacancies. Activation energies deduced for these processes, approximately 1 eV for vacancy motion and approximately 1-2 eV for vacancy formation, are consistent with what is known about diffusion in the A-15 ...

Energy Technology Data Exchange (ETDEWEB)

The flux of cosmic ray antiprotons with kinetic energies between /approximately/1 and 15 GeV is /approximately/5 times greater than the flux predicted on the basis of the leaky-box model. This excess is attributed to secondary antineutron production in compact sources. Because the antineutrons are not confined by the magnetic field of the compact source, they leave the interaction site, decay in interstellar space and account for the apparent excess cosmic ray antiproton flux. The escape and decay of neutrons produced in association with the antineutrons is a source of cosmic ray protons. Observations of the angular variation of the intensity and spectral shape of 100 MeV ..gamma..-rays produced by neutron-decay protons in the reaction p + p ..-->.. ..pi../sup 0/ ..-->.. 2..gamma.. could reveal compact-source cosmic ray production sites. COS-B observations of spectral hardening near point sources, ...

UK PubMed Central (United Kingdom)

BackgroundThe status of estrogen receptor-b1; (ERb1;) is critical to the clinical prognosis and therapeutic approach in breast cancer. ERb1;-negative breast cancer...Full Text Available

UK PubMed Central (United Kingdom)

Mutations of ephrin B1 in humans result in craniofrontonasal syndrome. Because little is known of the role and mechanism of action of ephrin B1 in bone, we examined the function of osteoblast-produced...Full Text Available

UK PubMed Central (United Kingdom)

The mechanism of inactivation of cytochrome P450 2B1 (CYP2B1) by 4-tert-butylphenylacetylene (BPA) has been characterized previously to be caused by the covalent binding of a reactive...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The schematic model is extended to open-shell nuclei. The quasiparticle random-phase approximation plus core polarization are used to calculate multipole matrix elements M/sub n/ and M/sub p/. Calculated trends in the ratio of deformation parameters ..beta../sub n//..beta../sub p/ are compared with experimental ratios for several sets of isotopes and isotones. The systematics indicate a rather abrupt change toward equality of ..beta../sub n/ and ..beta../sub p/ when N or Z is changed from a closed-shell value.

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.).

International Nuclear Information System (INIS)

In most conceptual fusion power reactor designs, it is proposed to use beryllium as a neutron multiplier in the blanket. Detailed chemical composition of beryllium is necessary for evaluation of the tritium breeding ratio, and estimating the activation and transmutation of beryllium in the fusion reactor. In the present report, special attention was paid to a detailed analysis of impurities in beryllium, relevant to the tritium breeding ratio evaluation. Two different methods were used for the study of impurities: an analysis of the local sample by the ICP-MS method, and an integral analysis of the beryllium assembly, using the pulsed neutron method. The latter method was proposed as the most effective way of analyzing the integral effect to impurities in beryllium on production of the tritium on the lithium-6. The evaluation of the integral effect was based on time behaviour observations of the thermal neutron flux, ...

Energy Technology Data Exchange (ETDEWEB)

The primary E1, M1 and E2 ..gamma..-radiation in /sup 87,88,89/Sr observed after thermal neutron capture was compared with the predictions of single particle and giant resonance models. The nuclei feature a wide range of neutron binding energies between 6.3 and 11.1 MeV, which makes a 5.5 MeV spectrum of primary transition energies available for investigation. The (n, ..gamma..) reaction was used to estimate the parameters of the spin-flip M1 giant resonance in strontium. The total energy weighted M1 strength of this resonance exceeds the results of shell model and random phase approximation calculations for /sup 90/Zr by a factor of 3-4. The E1 strengths were found to agree with the established giant dipole resonance model. The few data on primary E2 transitions do not allow to differentiate between the giant quadrupole resonance and the single particle models.

Energy Technology Data Exchange (ETDEWEB)

The use of radiochemical detectors in the A approx. = 90 mass region to measure 14 MeV neutron fluences is investigated from the standpoint of cross section sensitivities. Specifically, /sup 90/Zr and /sup 89/Y neutron-induced cascades leading to the production of /sup 89/Zr, /sup 88/Zr, /sup 88/Y, and /sup 87/Y are studied in a one-energy-group approximation, and the sensitivities of the measured ratios R/sub Z/ = /sup 88/Zr//sup 89/Zr and R/sub Y/ = /sup 87/Y//sup 88/Y to the input cross sections are delineated. The most sensitive cross section in each cascade is the cross section that dominates the production of the final isotope in the chain. Only one of the isomeric levels in /sup 90/Zr contributes importantly to the Zr cascade. Burnback (n,..gamma..) and burnup (n,p) reactions are also considered. The (n,..gamma..) effects are small, but (n,p) effects can be substantial due to low energy enhancements of (n,p) cross ...

International Nuclear Information System (INIS)

We have measured the transverse asymmetry A_T_"' in the quasielastic "3He-vector(e-vector,e"') process with high precision at Q"2 values from 0.1 to 0.6 (GeV/c)"2. The neutron magnetic form factor G_M"n was extracted at Q"2 values of 0.1 and 0.2 (GeV/c)"2 using a nonrelativistic Faddeev calculation which includes both final-state interactions (FSI) and meson-exchange currents (MEC). Theoretical uncertainties due to the FSI and MEC effects were constrained with a precision measurement of the spin-dependent asymmetry in the threshold region of "3He-vector(e-vector,e"'). We also extracted the neutron magnetic form factor G_M"n at Q"2 values of 0.3 to 0.6 (GeV/c)"2 based on plane wave impulse approximation calculations.

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Austenitic 316LN alloy was ion-irradiated using the unique Triple Ion Beam Facility (TIF) at ORNL to investigate radiation damage effects relevant to spallation neutron sources. The TIF was used to simulate significant features of GeV proton irradiation effects in spallation neutron source target materials by producing displacement damage while simultaneously injecting helium and hydrogen at appropriately high gas/dpa ratios. Irradiations were carried out at 80, 200, and 350 C using 3.5 MeV Fe{sup ++}, 360 keV He{sup +}, and 180 keV H{sup +} to accumulate 50 dpa by Fe, 10,000 appm of He, and 50,000 appm of H. Irradiations were also carried out at 200 C in single and dual ion beam modes. The specific ion energies were chosen to maximize the damage and the gas accumulation at a depth of {approximately} 1 {micro}m. Variations in microstructure and hardness of irradiated specimens were studied using transmission electron ...

International Nuclear Information System (INIS)

We investigate the possibility of kaon condensation in the dense interior of neutron stars through the s-wave interaction of kaons with nucleons. We include nucleon-nucleon interactions by using simple parametrizations of realistic forces, and include electrons and muons in #beta#-equilibrium. The equation of state above the condensate threshold is derived in the mean field approximation. The conditions under which kaon condensed cores undergo a transition to quark matter containing strange quarks are also established.The critical density for kaon condensation lies in the range (2.3-5.0)#rho#_0, where #rho#_0=0.16 fm"-"3 is the equilibrium density of nuclear matter. The critical density depends largely on the value of the strangeness content of the proton, the size of which is controversial. For too large a value of the strangeness content, matter with a kaon condensate is not sufficiently stiff to support the lower limit of 1.44 M_o_e_d_o_t ...

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The effective fraction of delayed photoneutrons ({beta}{sup ph}) has been theoretically defined and experimentally determined in various different configurations of the LWR-PROTEUS critical facility. The peculiarity lies in the fact that the reactor has D{sub 2}O in only one of the four fuelled zones, thus D({gamma},n)H reactions take place mainly in this region. The work is divided into three parts. The first part is devoted to the description of the LWR-PROTEUS facility and to the measurements of {beta}{sup ph}. These experimental values are derived from standard inverse-kinetics analysis of neutron flux decay experiments for each of seven different configurations, with nine additional groups of neutron precursors to account for photoneutron effects. In the second part, the coupled neutron and gamma Boltzmann equations are reduced to exact point kinetics equations using the photon infinite-velocity ...

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The results of photoemission spectroscopy using molybdenum and tantalum samples have been obtained from the new beamline 2B1 at Pohang Light Source. Beamline 2B1 is based on a spherical grating monochromator (SGM) which is equipped with five gratings. The photon energy range from 184 to 1100 eV was covered in this work using two gratings (Gratings 4 and 5). The photon energy resolution has been deduced from Ta Fermi-level spectra and 3d spectra of Mo.

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

The swelling and in-reactor creep behaviors of the PCA alloy have been determined from the irradiation of pressurized tube specimens in the FFTF reactor. These data have been obtained to a peak neutron fluence corresponding to approximately 80 dpa in the FFTF reactor for irradiation temperatures between 400 and 750/sup 0/C. Diametral measurements performed on the unstressed specimens indicate the possible onset of swelling in the PCA alloy for irradiation temperatures between 400 and 550/sup 0/C and at a neutron fluence corresponding to approx.50 dpa. The creep data suggest a non-linear fluence dependence and linear stress dependence (for hoop stresses less than 100 MPa) which is consistent with the in-reactor creep behavior of many cold worked austenitic stainless steels. These PCA creep data are compared to available 316 SS in-reactor creep data. The in-reactor creep strains for PCA are significantly less than observed in ...

CERN Document Server

The He-shell flash convection in AGB stars is the site for the high-temperature component of the s-process in low- and intermediate mass giants, driven by the Ne22 neutron source. [...] The upper convection boundary plays a critical role during the H-ingestion episode that may lead to neutron-bursts in the most metal-poor AGB stars. We address these problems through global 3-dimensional hydrodynamic simulations including the entire spherical He-shell flash convection zone (as oposed to the 3D box-in-a-star simulations). An important aspect of our current effort is to establish the feasibility of our appoach. We explain why we favour the explicit treatment over the anelastic approximation for this problem. The simulations presented in this paper use a Cartesian grid of 512^3 cells and have been run on four 8-core workstations for four days to simulate ~5000s, which corresponds to almost ten convective turn-over times. The ...

International Nuclear Information System (INIS)

The fission cross section of /SUP 242m/ Am has been measured from 0.005 eV to 20 MeV using time-of-flight techniques at the Oak Ridge Electron Linear Accelerator. A hemispherical plate fission ionization chamber with five pairs of plates contained three deposits totaling 507 #mu#g of /SUP 242m/ Am, one deposit of 168 #mu#g "2"3"5U, and a ''weightless'' deposit of "2"5"2Cf, which served as a monitor of chamber performance. The fission of "2"3"5U, served as the cross-section standard for energies above 101 keV while "6Li(n,#alpha#), normalized to "2"3"5U fission in the 7.8- to 11.0-eV interval, served as a shape standard below 101 keV. Approximately 360 h of data were obtained at a flight path distance of 9.1 m, primarily with 40-ns bursts. Particular attention was paid to correction of backgrounds, especially inscattered-neutron-induced events. The fission resonance integral was found to be 1800 + or - 65 b.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

International Nuclear Information System (INIS)

The /sup 40/Ca(p,n)/sup 40/Sc reaction was studied at 134 MeV. Neutron energy spectra were measured by the time-of-flight technique with resolutions of 220 keV at angles from 0"0 to 41"0 and 415 keV out to 62"0. The 2"-,3"-,4"-,5"- band of states based on the (f/sub 7/2/,d/sub 3/2//sup -1/) 1p1h structure was observed at low excitation energies, in good agreement with known analog states in /sup 40/Ca and /sup 40/K. The shapes of the cross-section and analyzing-power angular distributions are in good agreement with distorted-wave impulse-approximation calculations using simple 1p1h (Tamm-Dancoff approximation) shell-model wave functions. A relatively strong transition to a state at E/sub x/ = 2.3 MeV with L = 3 is identified tentatively as a 4"- state with the predominant 1p1h structure (1f/sub 7/2/,2s/sub 1/2//sup -1/).

Energy Technology Data Exchange (ETDEWEB)

Real time neutron radiography has been used to study the dynamic behavior of two phase flow and measure the time averaged vapor fraction in a heated metal tube containing boiling steam water operating at up to 15 bar pressure. The neutron radiographic technique is non-intrusive and requires no special transparent window region. This is the first time this technique has been used in an electrically heated pressurized flow loop. This unique experimental method offers the opportunity to observe and record on videotape, flow patterns and transient behavior of two phase flow inside opaque containers without disturbing the environment. In this study the test sections consisted of stainless steel tubes with a 1.27 cm outer diameter and wall thicknesses of 0.084 cm and 0.124 cm. The experiments were carried out at the Pennsylvania State University 1 megawatt TRIGA reactor facility utilizing a Precise Optics neutron radiography ...

International Nuclear Information System (INIS)

A survey is given on studies of the phonon spectra of several A-15 compounds by inelastic neutron scattering on polycrystalline samples. Comparison of the results for V_3Si, V_3Ge, N_3Ga, Nb_3Sn and Nb_3Al at 297 K lead to the conclusion that the interatomic forces are to a good approximation the same for all compounds with 4.75 valence electrons but are reduced by about 20% for those with 4.5 valence electrons. For all compounds investigated a softening of the phonon frequencies on cooling is observed which is most pronounced for those materials with the highest T/sub c/ values. From a comparison of the results with the experimentally determined Eliashberg function of Nb_3Sn information is derived about the energy dependence of the electron-phonon coupling function #alpha#"2.

International Nuclear Information System (INIS)

The magnetic scattering spectra of RAgSb_2 (R = Ho, Er, Tm) intermetallic compounds are measured and their crystal electric field parameters are determined using inelastic neutron scattering. It is revealed that the ground state is a nonmagnetic singlet for the HoAgSb_2 compound, a Kramers doublet with a strongly anisotropic g factor for the ErAgSb_2 compound, and a quasi-doublet (random doublet) characterized by an extremely anisotropic g factor for the TmAgSb_2 compound. The exchange interaction is estimated in the molecular field approximation. The magnetic properties of the RAgSb_2 compounds are analyzed in terms of the energy level schemes and eigenfunctions determined in this study. The calculated anisotropic magnetic susceptibilities for all compounds are in good agreement with the experimental data obtained for single crystals.

British Library Electronic Table of Contents (United Kingdom)

In [W. Ye, F. Wu, H.W. Yang, Phys. Lett. B 647 (2007) 118] prescission protons and ? particles of high-isospin 206Pb were shown to be almost independent of the dissipation strength Formula Not Shown . Subsequently, in [P.N. Nadtochy, et al., Phys. Lett. B 685 (2010) 258] prescission light charged particles (LCPs) were shown to have approximately the same sensitivity as neutrons to Formula Not Shown for 206Pb and 204Hg nuclei. In this Letter we point out that the reason for the apparent contradictory conclusions is that the authors in the latter did not compute the changes in the absolute yields of prescission LCPs multiplicities with increasing Formula Not Shown and compare them with typical experimental uncertainties. It is shown that the expected changes are very small in the case of ne...

International Nuclear Information System (INIS)

A variety of critical experiments were constructed of enriched uranium metal during the 1960s and 1970s at the Oak Ridge Critical Experiments Facility (ORCEF) in support of criticality safety operations at the Y-12 Plant. The purposes of these experiments included the evaluation of storage, casting, and handling limits for the Y-12 Plant and providing data for verification of calculation methods and cross-sections for nuclear criticality safety applications. These included solid cylinders of various diameters, annuli of various inner and outer diameters, two and three interacting cylinders of various diameters, and graphite and polyethylene reflected cylinders and annuli. Of the hundreds of delayed critical experiments, one experiment was comprised of a stack of approximately 7-inch-diameter metal discs. The bottom of the stack consisted of uranium with an approximate height of 4-1/8 inches. The top of the stack consisted of beryllium with an ...

UK PubMed Central (United Kingdom)

b1;7 neuronal nicotinic acetylcholine receptors (b1;7-nAChR) form Ca²⁺-permeable homopentameric channels modulating cortical network activity and cognitive processing....Full Text Available

UK PubMed Central (United Kingdom)

AimsRosiglitazone and fenofibrate, specific agonists of the peroxisome proliferator activated receptors-γ (PPARγ) and -b1; (PPARb1;),...Full Text Available

UK PubMed Central (United Kingdom)

The retinoic acid receptor-related orphan receptors b1; and γ (RORb1; (NR1F1) and RORγ (NR1F3)) are orphan nuclear receptors and perform critical roles in regulation of development,...Full Text Available

UK PubMed Central (United Kingdom)

The expression status of the estrogen receptor alpha (ERb1;) and that of the epidermal growth factor receptor Her-2/neu frequently correlate inversely in breast cancers. While ERb1;-dependent...Full Text Available

UK PubMed Central (United Kingdom)

b1;-Galactosidases from thermophilic organisms have gained interest owing to their applications in the sugar industry. The b1;-galactosidases AgaA, AgaB and AgaA A355E mutant from Geobacillus...Full Text Available

UK PubMed Central (United Kingdom)

High reactivity toward b1;-chymotrypsin is observed for derivatives of β-arylpropionic acids of varied structure—L-b1;-acylamido compounds, D-cyclized compounds, and, now,...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Dose-response studies of the radiosensitivity of spermatogonial stem cells in various epithelial stages after irradiation with graded doses of fission neutrons of 1 MeV mean energy were carried out in the Cpb-N mouse. These studies on the stem cell population in stages IX-XI yielded simple exponential lines characterized by an average D0 value of 0.76 +/- 0.02 Gy. In the subsequent epithelial stages XII-III, a significantly lower D0 value of 0.55 +/- 0.02 Gy was found. In contrast to the curves obtained for stem cells in stages IX-III, the curves obtained in stages IV-VIII indicated the presence of a mixture of radioresistant and radiosensitive stem cells. In stage VII, almost no radioresistant stem cells appeared to be present and a D0 value for the radiosensitive stem cells of 0.22 +/- 0.01 Gy was derived. Previously, data were obtained on the size of colonies (in number of spermatogonia) derived from surviving stem cells. Combining these data with data from the ...

International Nuclear Information System (INIS)

A variety of critical experiments were constructed of enriched uranium metal during the 1960s and 1970s at the Oak Ridge Critical Experiments Facility (ORCEF) in support of criticality safety operations at the Y-12 Plant. The purposes of these experiments included the evaluation of storage, casting, and handling limits for the Y-12 Plant and providing data for verification of calculation methods and cross-sections for nuclear criticality safety applications. These included solid cylinders of various diameters, annuli of various inner and outer diameters, two and three interacting cylinders of various diameters, and graphite and polyethylene reflected cylinders and annuli. Of the hundreds of delayed critical experiments, two were performed that consisted of uranium metal annuli with a solid beryllium metal core. The outer diameter of the annuli was approximately 13 or 15 inches with an inner diameter of 7 inches. The diameter of the core was ...

International Nuclear Information System (INIS)

Neutron-hole states in /sup 87/Sr were studied by means of the /sup 88/Sr("3He,#alpha#)/sup 87/Sr reaction at 36 MeV. Angular distribution measurements were carried out from 3"0 to 41"0 (lab) and analyzed with the zero-range distorted-wave Born approximation method. Spectroscopic factors have been determined for about 50 discrete levels in /sup 87/Sr located below 6 MeV excitation energy and for the three lowest isobaric analog states 2p(3/2, 1f(5/2, and 2p(1/2 observed around 11 MeV. Many l = 1 and l = 3 discrete levels are observed in the 3--6 MeV excitation energy range. In addition, a large part of the 1f-2p strength is found to lie in the higher-lying continuum up to 13 MeV (about 10% and 40% for the l = 1 and 3 contributions, respectively). The distribution of the 1f-2p neutron-hole strength is compared to previous data on neighboring nuclei /sup 89/Zr and /sup 91/Mo. In addition, angular distributions for some ...

UK PubMed Central (United Kingdom)

SummaryBrown fat is specialized in energy expenditure, a process that is principally controlled by the transcriptional co-activator PGC-1b1;. Here we describe a molecular...Full Text Available

UK PubMed Central (United Kingdom)

Recommended treatment of chronic hepatitis B with interferon-b1; and/or nucleos(t)ide analogues does not lead to a satisfactory result. Induction of HBV-specific T cells by therapeutic...Full Text Available

UK PubMed Central (United Kingdom)

It has been suggested for quality assurance purposes that linac output variations for helical tomotherapy (HT) be within �b1;2% of the long-term average. Due to cancellation of systematic...Full Text Available

UK PubMed Central (United Kingdom)

The purpose of this study was to determine whether resistance exercise training-induced reductions in inflammation are mediated via melanocortin 3 receptor expression in obese (BMI 32.7 �b1; 3.7)...Full Text Available

UK PubMed Central (United Kingdom)

When autotrophically growing cultures of Chlorella are treated with levulinic acid, δ-aminolevulinic acid is excreted into the medium, providing a direct demonstration of b1;-aminolevulinic...Full Text Available

UK PubMed Central (United Kingdom)

The quantitative experimental uncertainty in the structure of fully hydrated, biologically relevant, fluid (L_b1;) phase lipid bilayers has been too large to...Full Text Available

UK PubMed Central (United Kingdom)

A protein evolution strategy is described by which double-stranded DNA fragments encoding defined E. coli protein secondary structural elements (b1;-helices, β-strands...Full Text Available

UK PubMed Central (United Kingdom)

A Monascus pilosus strain was selected for production of intracellular b1;-galactosidase. Optimum conditions for mycelial growth and enzyme induction were determined. Galactose...Full Text Available

British Library Electronic Table of Contents (United Kingdom)

Estrogen metabolism is suggested to play an important role in estrogen-induced breast carcinogenesis. Epidemiologic studies suggest that diets rich in phytoestrogens are associated with a reduced risk of breast cancer. Phytoestrogens are biologically active plant compounds that structurally mimic 17b-estradiol (E2). We hypothesize that phytoestrogens, may provide protection against breast carcinogenesis by altering the expression of estrogen-metabolizing enzymes cytochrome P450 1A1 (Cyp1A1) and 1B1 (Cyp1B1). Cyp1A1 and Cyp1B1 are responsible for the metabolism of E2 to generate 2-hydroxyestradiol (2-OHE2) and 4-hydroxyestradiol (4-OHE2), respectively. Studies suggest that 2-OHE2 and 2-methoxyestradiol may protect against breast carcinogenesis, while 4-OHE2 is carcinogenic in rodent models....

UK PubMed Central (United Kingdom)

The theory that the b1;β dimer is the functional unit of cooperativity in hemoglobin has been tested by determination of the oxygen equilibrium curve of stable deoxy dimers, obtained by...Full Text Available

UK PubMed Central (United Kingdom)

Host cells use metabolic signaling through the LXRb1; nuclear receptor to defend against Listeria monocytogenes infection. 25-Hydroxycholesterol is a natural ligand of LXRs that...Full Text Available

UK PubMed Central (United Kingdom)

The structural properties of brain extracellular space (ECS) are summarised by the tortuosity (λ) and the volume fraction (b1;). To determine if these two parameters were independent,...Full Text Available

UK PubMed Central (United Kingdom)

The asymmetric organocatalytic b1;-sulfenylation of substituted piperazine-2,5-diones is reported, with cinchona alkaloids as chiral Lewis bases and electrophilic sulfur transfer reagents....Full Text Available

UK PubMed Central (United Kingdom)

PurposeTo address the roles of the stromal derived factor-1 (SDF-1) b1; in the course of experimental corneal neovascularization (CNV).MethodsCNV...Full Text Available

UK PubMed Central (United Kingdom)

Benzodiazepine withdrawal anxiety is associated with potentiation of b1;-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptor (AMPAR) currents in hippocampal CA1 pyramidal...Full Text Available

Science.gov (United States)

... Page 2. Boston Scientific CRM 11/17/09 MADIT-CRT Clinical Report APPENDIX B 2 CONFIDENTIAL ... B-2 Primary Effectiveness B-2.1 Validation of Assumptions ...

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 ...

UK PubMed Central (United Kingdom)

The accumulation of b1;-1,4-polyglucans is an important strategy to cope with transient starvation conditions in the environment. In bacteria and plants, the synthesis of glycogen and starch occurs...Full Text Available

UK PubMed Central (United Kingdom)

We have previously shown that a T to G transversion at the second T of the conalbumin "TATA" box drastically decreases specific initiation of transcription by RNA polymerase B (1). We now report that...Full Text Available

UK PubMed Central (United Kingdom)

In the yeast Saccharomyces cerevisiae, a and b1; mating-type information is stored in transcriptionally silenced cassettes called HML and HMR....Full Text Available

UK PubMed Central (United Kingdom)

OBJECTIVESTo examine the association between b1;-blocker use and sexual dysfunction among men participating in a population-based cohort of...Full Text Available

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

International Nuclear Information System (INIS)

Neutron radiography and neutron radioscopy are rapidly becoming the valuable tools for nondestructive testing and basic research. The Phoenix Memorial Laboratory has developed a neutron facility capable of both film neutron radiography and real time neutron radioscopy, and has used this facility to study several phenomena of interest to the researchers in many areas. Neutrons can be used for imaging the phenomena that X-ray cannot image, such as the presence, absence or movement of hydrogenous materials inside metals such as aluminum or steel. There are three basic methods for obtaining images using neutrons: high resolution film neutron radiography, real-time neutron radioscopy and transfer film neutron radiography. The neutron radiography facility at ...

International Nuclear Information System (INIS)

Formation of the soft magnetic nanostructure in amorphous Fe_1_4Ni_4_0Zr_7B_1_2 alloy due to heat treatment is studied by the Moessbauer, differential scanning calorimetry, and X-ray diffraction techniques. Annealing at temperatures 520-580 "oC leads to the formation of extremely soft nanocrystalline alloy as revealed by the rf-Moessbauer measurements. The superparamagnetic behaviour was observed for the alloy annealed at 620-640 "oC. At higher annealing temperatures good soft magnetic properties deteriorate. (author)

Energy Technology Data Exchange (ETDEWEB)

The authors have developed a high-sensitivity real-time neutron radiography (NR) system by the use of the low power reactor of Kinki University. The system was constructed with a high efficiency neutron-photon converter, an image intensifier and a SIT TELEVISION camera. Some digital image processing techniques were applied for improving the quality of the real-time neutron images. By the use of this system, dynamic neutron imaging was performed successfully under the condition of a weak neutron field that was about two orders of magnitude lower than that of the standard NR system. The neutron flux, calculated from the fluctuation of the neutron response of the images, was nearly equal to the value measured by the foil activation method. From this fact, the efficiency for the neutron detection of the imaging system was ...

International Nuclear Information System (INIS)

We calculated the energies of asymmetric nuclear matter at zero and finite temperatures with the cluster variational method. At zero temperature, the expectation value of the two-body Hamiltonian composed of the kinetic energies and the AV18 two-body forces is calculated with the Jastrow wave function in the two-body cluster approximation. The obtained two-body energy is in good agreement with the result with the Fermi Hypernetted Chain (FHNC) calculation by Akmal et al. The energy caused by the UIX three-body forces is treated somewhat phenomenologically so that the total energy reproduces the empirical saturation point. Furthermore, the parameters included in the three-body energy are readjusted so that the Thomas-Fermi (TF) calculations with use of the obtained energy of nuclear matter reproduce the gross feature of the experimental data on atomic nuclei. The nuclear species in the neutron star crust obtained by the TF calculation are ...

CERN Document Server

We investigate strong nonlinear damping effects which occur during high amplitude oscillations of neutron stars, and the gravitational waves they produce. For this, we use a general relativistic nonlinear hydrodynamics code in conjunction with a fixed spacetime (Cowling approximation) and a polytropic equation of state (EOS). Gravitational waves are estimated using the quadrupole formula. Our main interest are $l=m=2$ $f$-modes subject to the CFS (Chandrasekhar, Friedman, Schutz) instability, but we also investigate axisymmetric and quasi-radial modes. We study various models to determine the influence of rotation rate and EOS. We find that axisymmetric oscillations at high amplitudes are predominantly damped by shock formation, while the non-axisymmetric $f$-modes are mainly damped by wave breaking and, for rapidly rotating models, coupling to non-axisymmetric inertial modes. From the observed nonlinear damping, we derive upper limits for the ...

International Nuclear Information System (INIS)

Theoretical prediction of nuclear masses is analyzed as a pattern recognition problem on the N-Z plane. A global pattern is observed by plotting the differences between measured masses and Liquid Drop Model (LDM) predictions. After unfolding the data by removing the smooth LDM mass contributions, the remaining microscopic effects have proved difficult to model, although they display a striking pattern. These deviations carry information related to shell closures, nuc]ear deformation and the residual nuclear interactions. In the present work the more than 2000 known nuclear masses are studied as an array in the N-Z plane viewed through a mask, behind which the approximately 7000 unknown unstable nuclei that can exist between the proton and neutron drip lines are hidden. We show here that employing a Fourier transform deconvolution method these by masses can be predicted with similar accuracy than standard methods. We believe that a more general ...

International Nuclear Information System (INIS)

We analyze cross sections for quasielastic inclusive scattering of electrons on nuclei and show that the observed isolated peaks for relatively low Q"2 are unique for the lightest targets. Focusing, in particular, on D and "4He, we investigate in two ways to what measure the above peaks can be allocated to nucleon-elastic processes. We first compute approximate upper limits for the nucleon-inelastic background in the quasielastic region due to inclusive #DELTA# excitation, and find those to be small. Far more precise is a semiphenomenological approach, where the dominance of nucleon-elastic processes is translated into a set of stringent requirements. We show that those are very well fulfilled for recent D data, and to a somewhat lesser extent for older D and "4He data. With knowledge of G_E_,_M"p and information on G_E"n, we then extract G_M"n and find agreement with values obtained by alternative methods. We discuss the sensitivity of the extraction method and ...

International Nuclear Information System (INIS)

Nuclei in the mass-180 region have many high-#OMEGA# single-particle levels close to the Fermi energy and are, therefore, prime candidates for high-K isomers. Since both neutron and proton level densities are rather low, one should expect blocking and particle-number fluctuations to be rather important. We have performed good-particle-number calculations and have shown that the simpler blocked BCS theory gives a good approximation to the multi-quasiparticle spectra if the pairing strength is chosen appropriately. This has allowed us to perform a systematic theoretical study of this mass region. Residual spin-spin interactions are shown to be essential in reproducing the energies and even the correct order of known states. Good agreement has been found for "1"7"5Hf, "1"7"6Hf and "1"7"7Ta, where extensive data already exist. Predictions for new high-K states near the yrast line are made for these nuclei and for "1"7"8W. (orig.).

International Nuclear Information System (INIS)

Isomers have been populated in "2"4"6Cm and "2"5"2No with quantum numbers K"#pi#=8"-, which decay through K"#pi#=2"- rotational bands built on octupole vibrational states. For N=150 isotones with (even) atomic number Z=94-102, the K"#pi#=8"- and 2"- states have remarkably stable energies, indicating neutron excitations. An exception is a singular minimum in the 2"- energy at Z=98, due to the additional role of proton configurations. The nearly constant energies, in isotones spanning an 18% increase in Coulomb energy near the Coulomb limit, provide a test for theory. The two-quasiparticle K"#pi#=8"- energies are described with single-particle energies given by the Woods-Saxon potential and the K"#pi#=2"- vibrational energies by quasiparticle random-phase approximation calculations. Ramifications for self-consistent mean-field theory are discussed.

Energy Technology Data Exchange (ETDEWEB)

Burnable poisons are used in nuclear reactors to produce a more level distribution of power in the reactor core and to reduce to necessity for a large control system. An ideal burnable poison would burn at the same rate as the fuel. In this study, separation of neutron-absorbing isotopes was investigated in order to eliminate isotopes that remain as absorbers at the end of fuel life, thus reducing useful fuel life. The isotopes Gd-157, Dy-164, and Er-167 were found to have desirable properties. These isotopes were separated from naturally occurring elements by means of plasma separation to evaluate feasibility and cost. It was found that pure Gd-157 could save approximately $6 million at the end of four years. However, the cost of separation, using the existing facility, made separation cost- ineffective. Using a magnet with three times the field strength is expected to reduce the cost by a factor of ten, making isotopically separated burnable ...

International Nuclear Information System (INIS)

... compilation fission products j codes mixed oxide fuels neutron reactions

Energy Technology Data Exchange (ETDEWEB)

Presented are results of a test of a method for measuring neutron fluences using detectors with fissionable nuclides. The investigations show the soundness of of using neutron-activation detectors of the type Am for mesurements in nuclear installations for values of thermal-neutron fluence of from 10/sup 13/ to 10/sup 20/ neutrons/cm/sup 2/ with exposure for up to several months. The proposed method can be used for prolonged measurements in strong fields of both thermal and fast neutrons.

Energy Technology Data Exchange (ETDEWEB)

Following a recent refurbishment of the NPL Thermal Neutron Facility, the spectrum of the epithermal and fast neutron component of the beam produced by the thermal column of this facility was measured over the energy range from thermal to 20 MeV using a Bonner sphere spectrometry system. The effect of the presence of epithermal and fast neutrons on the measured response of commonly-used thermal neutron dosemeters was calculated. (author)

Energy Technology Data Exchange (ETDEWEB)

As an explosion develops in the collapsed core of a massive star, neutrino emission drives convection in a hot bubble of radiation, nucleons, and pairs just outside a proto-neutron star. Shortly thereafter, neutrinos drive a wind-like outflow from the neutron star. In both the convective bubble and the early wind, weak interactions temporarily cause a proton excess (Y{sub e} {approx}> 0.50) to develop in the ejected matter. This situation lasts for at least the first second, and the approximately 0.05-0.1 M{sub {circle_dot}} that is ejected has an unusual composition that may be important for nucleosynthesis. Using tracer particles to follow the conditions in a two-dimensional model of a successful supernova explosion calculated by Janka, Buras, and Rampp (2003), they determine the composition of this material. most of it is helium and {sup 56}Ni. The rest is relatively rare species produced by the decay of ...

International Nuclear Information System (INIS)

Full text of publication follows: The effect of neutron irradiation on the thermal conductivity of silicon carbide can be dramatic depending on the irradiation temperature and fluence the material is subjected to, and may be a critical factor defining it's use in fusion systems. Historically there have been several papers describing the effect of neutron irradiation on thermal conductivity degradation of SiC, predominately in the low to intermediate temperature ranges. Practically all of this work has been at temperatures lower than the application temperature for SiC being considered by the conceptual fusion reactors. This paper provides new data on the thermal conductivity of high quality CVD silicon carbide irradiated in a range of doses and temperature spanning the proposed fusion reactor temperature range. Specifically, an irradiation was carried out from fractions milli-dpa to approximately 8 dpa in the HFIR with ...

International Nuclear Information System (INIS)

TRIGA-SSR is a steady state research and material test reactor that has been in operation since 1980. The original TRIGA fuel was HEU (highly enriched uranium) with a U"2"3"5 enrichment of 93 per cent. Almost all TRIGA HEU fuel bundles are now burned-up. Part of the spent fuel was loaded and transferred to US, in a Romania - DOE arrangement. The rest of the TRIGA fuel bundles have to be temporarily stored in the TRIGA facility. As the storage conditions had to be established with caution, neutron and thermal hydraulic evaluations of the storage conditions were required. Some criticality evaluations were made based on the SAR (Safety Analysis Report) data. Fuel constant axial temperature approximation effect is usual for criticality computations. TRIGA-SSR fuel bundle geometry and materials model for SCALE5-CSAS module allows the introduction of a fuel temperature dependency for the entire fuel active height, using different materials for each ...

Energy Technology Data Exchange (ETDEWEB)

A neutron imaging system (NIS) has been recently installed at the University of Texas TRIGA reactor facility. The imaging system establishes new capabilities for beam diagnostics at the Texas Cold Neutron Source (TCNS) for real-time neutron radiography (RTNR) and for neutron computed tomography (NCT) research. The NIS will also be used for other research projects. The system consists of two subsystems as follows: (1) Thomson 9-in. neutron image intensifier (NII) tube sensitive to cold, thermal, and epithermal neutrons, (2) image-processing unit consisting of vidicon camera, two high-resolution monitors, image enhancement and measurement processor, and video printer. The NIS is installed at the cold neutron beam of the TCNS for testing and cold neutron beam diagnostics.

International Nuclear Information System (INIS)

Optimal neutron energy for boron neutron capture therapy (BNCT) has been studied. Epithermal neutron is superior to thermal neutrons in treating deep-seated tumors. Design of the epithermal neutron column for BNCT has been performed by using a two-dimensional transport calculation code. Aluminum and heavy water are used as moderation materials. A thermal neutron column is also designed using heavy water as thermalization material. The configuration of the facility for treatment and research of BNCT and also for basic radio-biological studies of neutrons has been presented. (author).

International Nuclear Information System (INIS)

Gamma-ray spectrometric analysis was employed to determine the nuclides formed in thorium by neutron irradiation. Thorium sample was irradiated by neutron from a pure thermal neutron field, neutron field of Cd ratio of about 4, and epithermal neutron field, respectively. The former irradiation was carried out in a thermal neutron column provided for medical uses of neutrons, and the latters were done in the F-ring position of TRIGA II research reactor of Musashi Institute of Technology. The gamma-ray spectra were obtained and analyzed by employing a fully automatic gamma-ray analysis system named ''GAMA: giant frog:-SYSTEM'' developped by Musashi Institute of Technology. The formation of Pa-233 (U-233) was discussed quantitatively with respect to the difference of the neutron field. (author).

Energy Technology Data Exchange (ETDEWEB)

This paper reviews the effects of neutron irradiation on thermal and mechanical properties and bulk tritium retention of armour materials (beryllium, tungsten and carbon). For each material, the main properties affected by neutron irradiation are described and the specific tests of neutron irradiated armour materials under thermal shock and disruption conditions are summarized. Based on current knowledge, the expected thermal and structural performance of neutron irradiated armour materials in the ITER plasma facing components are analysed.

Energy Technology Data Exchange (ETDEWEB)

The Albedo Theory was applied in order to develop an one-group algorithm for coupled neutron-gamma shielding calculations. The configuration analyzed consists of multilayered plane systems, where a incident neutron current generates gamma radiation through neutron-gamma reactions. The results obtained by Albedo Method and ANISN code have shown excellent agreement. (author)

CERN Document Server

We investigate monoenergetic gamma-ray signatures of Z^1 dark matter annihilations in a non-minimal Universal Extra Dimensions model. The self-interactions of the non-Abelian Z^1 gauge boson give rise to a large number of contributing Feynman diagrams that do not exist for annihilations of the Abelian gauge boson B^1, which is the standard Kaluza-Klein dark matter candidate. We find that the annihilation rate is indeed considerably larger for the Z^1 than for the B^1. Even though relic density calculations indicate that the mass of the Z^1 should be larger than the mass of the B^1, the predicted fluxes are of the same order of magnitude. We compare our results to existing experimental limits, as well as to future sensitivities, for image air Cherenkov telescopes, and we find that the limits are reached already with a moderately large boost factor. However, the ...

Energy Technology Data Exchange (ETDEWEB)

A high-purity, intense, fast-neutron source has been developed at our laboratory. We describe two inexpensive, straightforward methods of determining the total number of neutrons produced and we review precautions to be taken in applying these methods. (orig.).

International Nuclear Information System (INIS)

Neutron radiography is a non-destructive test method to examine a material by using the dependency of neutron attenuation on the nuclear characteristics of the atoms composing the object material. There are two categories of neutron radiography; static neutron radiography and dynamic neutron radiography. The static neutron radiography is a technique to observe a standing object by using a camera or a film cassette. The dynamic neutron radiography(DNR) is a technique to observe a moving object usually by using a camera. Depending on the camera frame rate, the dynamic neutron radiography is categorized into the real time neutron radiography(RTNR) and the high speed neutron radiography(HSNR). The frame rate for RTNR is 30 frames/s and that for HSNR is usually more that 500 ...

Energy Technology Data Exchange (ETDEWEB)

A black neutron detector of novel design has been constructed and tested as a neutron flux monitor. The neutron time-of-flight (TOF) technique was used to measure the zero degree neutron spectrum from a subnanosecond pulsed proton beam on a thick metallic lithium target. We describe the detector, discuss the shielding arrangement and electronics, determine the low-energy cut-off. We calculate the efficiency, show spectra and compare measured zero degree differential cross-section of the {sup 7}Li(p, n{sub 0}){sup 7}Be reaction with recommended published cross-sections. (orig.).

International Nuclear Information System (INIS)

A method and apparatus for nuclear borehole logging, and in particular, neutron porosity logging, uses a neutron source, and a pair of spaced lithium detectors, preferably Li"6I crystal or Li"6 doped glass, to detect neutrons emitted from a borehole formation being logged. The spectrum developed by the lithium detectors is processed to remove the gamma ray background radiation and the hydrogen absorption peak, thus allowing a more accurate neutron count. A Gaussian curve is fitted to the neutron peak of the spectrum, the curve eliminating the hydrogen absorption peak. The area under this Gaussian curve represents the neutron count. (author).

British Library Electronic Table of Contents (United Kingdom)

Determination of thermal to fast neutron flux ratio (ffast) and fast neutron flux (phi-fast) is required for fast neutron reactions, fast neutron activation analysis, and for correcting interference reactions. The ffast and subsequently phi-fast were determined using the absolute method. The ffast ranged from 48 to 155, and the phi-fast was found in the range 1.03x1010-4.89x1010 n cm-2 s-1. These values indicate an acceptable conformity and applicable for installation of the fast neutron facility at the MNA research reactor.

Energy Technology Data Exchange (ETDEWEB)

A neutron collimator system is being designed as part of a neutron imaging facility for computed tomography and real-time neutron radiography research at the through beam port of the University of Texas TRIGA reactor. Lack of sufficient information about collimator systems in a through port from the literature necessitated the use of Monte Carlo calculations using the MCNP code 3 to search for optimal design configuration and materials that maximize the thermal neutron intensity at the image plane while minimizing the fast neutrons and gamma radiation.

British Library Electronic Table of Contents (United Kingdom)

Human heat shock protein 27 (Hsp27, HspB1) is an anti-apoptotic protein characterized for its tumorigenic and metastatic properties, and now referenced as a major therapeutic target in many types of cancer. Hsp27 biochemical properties rely on a structural oligomeric and dynamic organization. Downregulation by small interfering RNA or inhibition with dominant-negative mutant have proven their efficiency to counteract the anti-apoptotic and protective properties of Hsp27. In this study, we report the isolation and characterization of Hsp27-targeted molecules interfering with its structural organization. Using the peptide aptamer (PA) strategy, we isolated PAs that specifically interact with Hsp27 and not with the other members of the small heat shock protein family. In mammalian cell cultur...

International Nuclear Information System (INIS)

(1973). United Kingdom Baldwin, TO Dunn, JE Southern Illinois Univ.,

International Science & Technology Center (ISTC)

Development of Technology for Producing High-Effective Nitride Fuel UN with Controlled Microstructure for Advanced Fast Neutron Nuclear Reactors

International Nuclear Information System (INIS)

... states helium 3 reactions ion sources mev range 10-100 neutron spectrometers

Energy Technology Data Exchange (ETDEWEB)

The delayed neutrons from neutron-induced fission in /sup 232/U, /sup 237/Np, /sup 238/Pu, /sup 241/Am, /sup 242/Am/sup m/, /sup 245/Cm, and /sup 249/Cf were studied for the first time; those from /sup 232/Th, /sup 233/U, /sup 235/U, /sup 238/U, /sup 239/Pu, /sup 241/Pu, and /sup 242/Pu were measured again. The data were used to develop an expression for the prediction of the absolute delayed neutron yield, and the prediction of delayed neutron emission with time. This approach accurately predicts observed delayed neutron yields and decay characteristics. A fission product yield model was used in conjunction with delayed neutron emission probability to analytically predict delayed neutron characteristics. The results of this analysis are in excellent agreement with experimental values.

Energy Technology Data Exchange (ETDEWEB)

It is shown numerically that on a time scale of order 1 msec a neutron star with pion condensation will undergo separation into a core and an envelope with a sharp interface. The envelope will not, however, be ejected.

Energy Technology Data Exchange (ETDEWEB)

The neutron star parameters in the model extended by the inclusion of {delta} meson and additional nonlinear vector meson interactions are studied.

UK PubMed Central (United Kingdom)

Pseudomonas syringae is a gram-negative bacterial plant pathogen that is dependent on a type III protein secretion system (TTSS) and the effector proteins it translocates into plant...Full Text Available

UK PubMed Central (United Kingdom)

Werner syndrome (WS) is a rare disorder characterized by the premature onset of several pathologies associated with aging. The gene responsible for WS codes for a RecQ-type DNA helicase and is believed...Full Text Available

UK PubMed Central (United Kingdom)

(E)-b1;-Bisabolene synthase is one of two wound-inducible sesquiterpene synthases of grand fir (Abies grandis), and the olefin product of this cyclization reaction...Full Text Available

UK PubMed Central (United Kingdom)

Two novel crystal structures of Zea mays protein kinase CK2b1; catalytic subunit, one in complex with the specific inhibitor 4,5,6,7-tetrabromobenzotriazole (TBB) and another...Full Text Available

UK PubMed Central (United Kingdom)

The declaration of the human influenza A pandemic (H1N1) 2009 (H1N1/09) raised important questions, including origin and host range b;1],...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundTo evaluate whether P2X receptors are involved in responses to noxious pulp stimulation, the P2X₃ and P2X_2/3 receptor agonist b1;,β-methyleneATP...Full Text Available

UK PubMed Central (United Kingdom)

The effects of neuroactive steroids on the function of GABA_A receptors were studied using cell-attached records of single channel activity recorded from HEK293 cells transfected with b1;1...Full Text Available

UK PubMed Central (United Kingdom)

The immunolocalization of the low density lipoprotein receptor-related protein 1 (LRP1) and its ligand alpha 2-Macroglobulin (b1;₂M) was examined in tissues from human donor...Full Text Available

UK PubMed Central (United Kingdom)

β-Hexachlorocyclohexane (β-HCH) is the most recalcitrant among the b1;-, β-, γ-, and δ-isomers of HCH and causes serious environmental pollution problems....Full Text Available

UK PubMed Central (United Kingdom)

The b1;-proteobacterial strain Sphingobium japonicum UT26 utilizes a highly chlorinated pesticide, γ-hexachlorocyclohexane (γ-HCH), as a sole source of carbon...Full Text Available

UK PubMed Central (United Kingdom)

In the isolated rat mesenteric bed, the 1 min perfusion with 100 nm anandamide, a concentration that did not evoke vasorelaxation, elicited an acute release of 165.1 �b1; 9.2 pmol nitric...Full Text Available

UK PubMed Central (United Kingdom)

PurposePrevious studies have demonstrated that in 129b1;3Cx46^−/− mice, age-related nuclear cataract is formed. In...Full Text Available

UK PubMed Central (United Kingdom)

Background and purpose:Theoretically, three b1;₁-adrenoceptor subtypes can interact at the signalling level to alter vascular contraction or at the molecular level...Full Text Available

International Nuclear Information System (INIS)

Published in summary form only.

International Nuclear Information System (INIS)

... VDPEAZ (Bonn 2010 issue) NUCLEAR PHYSICS AND RADIATION PHYSICS

Energy Technology Data Exchange (ETDEWEB)

Recent developments in design and production of thermal neutron detectors based on a crystalline Si diode coupled to a Gd converter are reviewed. The most significant results of neutron test measurements carried out on prototype systems and pointing out the performances of the device are reported. Progress through various detection schemes and technological solutions for the production of a real time neutron counter for routine operation are outlined.

Science.gov (United States)

The research sponsored by this grant was conducted in two fields of high-energy astrophysics:

International Nuclear Information System (INIS)

We describe the continued development of a portable, real-time neutron spectrometer. The spectrometer is composed of two distinct detector systems: a Helium 3 gas filled proportional counter for the lower neutron energy interval between 20 KeV and 2 MeV and a bulk silicon solid state detector for the higher energy interval between 2 MeV and 500 MeV. Modeling and experimental results with mono-energetic neutron beams are reported.

Science.gov (United States)

The thermal evolution predicted by current models of the superfluid-crust interaction is noted to

International Nuclear Information System (INIS)

... bf3 counters data multi-channel analyzers multivibrators neutron spectrometers

Energy Technology Data Exchange (ETDEWEB)

A 68 MeV neutron transmission experiment on iron has been analyzed with MCNPX using the Los Alamos LA150 neutron data library, the ECN/BRC 150 MeV neutron data library and with the intranuclear cascade code LAHET. The clear improvement of using the data libraries is confirmed. Also, other materials present in LA150 have been checked using the same MCNPX set-up. 10 refs.

International Nuclear Information System (INIS)

... defects doped materials germanium infrared radiation monocrystals neutron

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

International Nuclear Information System (INIS)

In 1998, research began at Idaho National Engineering and Environmental Laboratory to investigate the application of "6Li and "7Li isotopes to the measurement of neutron and gamma radiation. Various size pairs of "6Li and "7Li based detectors were exposed to mixed neutron and gamma radiation. Experiments demonstrated that these detectors could be used to measure low level neutron radiation in the presence of high level gamma radiation. (author)

International Nuclear Information System (INIS)

The field of neutron imaging has a broad scope of applications and has played a pivotal role in visualizing and quantifying hydrogenous masses in metallic matrices. The field continues to expand into new applications with the installation of new neutron imaging facilities. In this scope, a neutron imaging facility for computed tomography and real-time neutron radiography is currently being developed around 2.0 MW TRIGA MARK-II Reactor at Maamora Nuclear Research Centre in Morocco (CENM). The neutron imaging facility consists of a neutron collimator, a real-time neutron imaging system and imaging process systems. In order to reduce the gamma-ray content in the neutron beam, the reactor tangential channel was selected. For power of 250 kW, the corresponding thermal neutron flux measured at the inlet of ...

Energy Technology Data Exchange (ETDEWEB)

A thermal neutron imaging facility for real-time neutron radiography and computed tomography has recently been developed and built at the University of Texas TRIGA reactor. Herein the authors present preliminary results of radiography and tomography test experiments. These preliminary results showed that the beam is of high quality and is suitable for radiography and tomography applications. A more detailed description of the facility is given elsewhere.

Science.gov (United States)

Not Available

Science.gov (United States)

ice could be responsible for the formation of martian gullies. Tomorrow's picture: whirlpool ...

International Nuclear Information System (INIS)

A multi-group neutron-gamma cross-section library in DTF-IV format is supplemented with electron production matrix to generate a coupled neutron-gamma-electron library. This is realized by estimating the contributions from Compton scattering, pair production and photoelectric effect to the electron production cross-sections. A novel application of this new library, which involves transport of neutrons, gammas and electrons, for estimating the Compton current due to a pulse of radiation in air is discussed.

Energy Technology Data Exchange (ETDEWEB)

This paper presents the results of an experiment conducted in the BN-350 fast reactor in Kazakhstan that involved the irradiation of argon-pressurized thin-walled tubes (0--2000 MPa hoop stress) constructed from Fe-16Cr-15Ni-3Mo-Nb stabilized steel in contact with the sodium coolant, which enters the reactor at {approximately}270 C. Tubes in the annealed condition reached 75 dpa at 335 C, and another set in the 20% cold-worked condition reached 81 dpa at 360 C. Upon disassembly all tubes, except those in the stress-free condition, were found to have failed in an extremely brittle fashion. The stress-free tubes exhibited diameter changes that imply swelling levels ranging from 9 to 16%. It is expected that stress-enhancement of swelling induced even larger swelling levels in the stressed tubes. The embrittlement is explained in terms of the sensitivity of the swelling regime to displacement rate and the large, unprecedented levels of swelling reached at 335--360 C ...

Energy Technology Data Exchange (ETDEWEB)

To get a considerable reduction of the radiotoxicity due to americium, a thermal neutron fluence of 2.10{sup 22} cm{sup -2} or a fast neutron fluence of 2.10{sup 24} cm{sup -2} is required. Irradiation in a thermal neutron flux leads to lower masses of {sup 234}U and precursors and of {sup 237}Np and precursors, but to higher curium masses and much higher neutron emission rates than irradiation in a fast neutron flux. Therefore, irradiation in a fast neutron flux has preference when multiple recycling is adopted. When once-through burning is applied, irradiation in a thermal neutron flux can be applied. Then irradiation in a heavy water reactor (HWR) has preference above irradiation in a PWR or in a high temperature gas-cooled reactor (HTGR). (authors) 4 refs.

Science.gov (United States)

An explanation is given of what a loop heat pipe (LHP) is, and how it works. It is then shown that neutron imaging (both real time neutron radioscopy and single exposure neutron radiography) is an effective experimental tool for the study of LHPs. Specifically, neutron imaging has helped to identify and correct a cooling water distribution problem in the condenser, and has enabled visualization of two-phase flow (liquid and vapor) in various components of the LHP. In addition, partial wick dry-out, a phenomenon of great importance in the effective operation of LHPs, is potentially identifiable with neutron imaging. It is anticipated that neutron radioscopy and radiography will greatly contribute to our understanding of LHP operation, and will lead to improvement of LHP modeling and design. PMID:15246420

Energy Technology Data Exchange (ETDEWEB)

An explanation is given of what a loop heat pipe (LHP) is, and how it works. It is then shown that neutron imaging (both real time neutron radioscopy and single exposure neutron radiography) is an effective experimental tool for the study of LHPs. Specifically, neutron imaging has helped to identify and correct a cooling water distribution problem in the condenser, and has enabled visualization of two-phase flow (liquid and vapor) in various components of the LHP. In addition, partial wick dry-out, a phenomenon of great importance in the effective operation of LHPs, has been identified with neutron imaging. It is anticipated that neutron radioscopy and radiography will greatly contribute to our understanding of LHP operation, and will lead to improvement of LHP modeling and design.

International Nuclear Information System (INIS)

A novel system for real-time radiation monitoring in reactor or accelerator facilities has been studied using an imaging plate. The authors made a feasibility study on a new neutron detection system using both photostimulated luminescence (PSL) and prompt luminescence (PL) generated in a neutron imaging plate (NIP) when the NIP is irradiated by neutrons. A readout system consisting of a semiconductor laser and a photomultiplier tube was fabricated for the purpose. It was confirmed that the system can measure both PSL and PL, where Am-Li was used as a neutron source. It may be possible to establish a new wide-range neutron monitoring system using the developed system as a PL mode normally, and as a PSL mode in case of intense neutron dose that cannot be measured in a PL mode because of saturation of the detection system. (author)

International Nuclear Information System (INIS)

The registration of secondary cosmic ray neutrons is a convenient tool for the investigation of primary cosmic ray variations and for meteorological effects as well. At present a large network of neutron monitors exists, aiming at studies of cosmic ray variations which are related to interplanetary conditions and geomagnetic activity. At the same time cosmic ray variations may be related to some atmospheric processes. In this connection, using the data from two neutron monitors (a standard and a lead free one), a gamma detector from Moscow station and lead free neutron monitor at BEO Moussala, we studied the correlations between rain flows and neutron flux. In this study we used daily averages on the basis of 10 min data for the neutron flux, corrected for barometric pressure and data from local meteo-stations. The preliminary analysis indicates a correlation ...

International Nuclear Information System (INIS)

The University of Virginia's real-time neutron radiography facility was characterized by measurement of the total neutron flux, gold/cadmium ratio, neutron/gamma ratio, and the effective collimar length-to-aperture diameter (L/D) ratio. The real-time neutron imaging system and collimator were further characterized by measuring the modulation transfer function (MTF) of the system. The collimator effectiveness was measured by using the MTF to determine the ''unparallelism'' of the neutron beam. The computer-based image processing system allowed rapid calculation of the MTF and the collimator effectiveness. The results of these measurements, using no collimator and a simple tube collimator, demonstrated the method's ability to determine the effective L/D ratio. The MTF measurement scheme provided a fast, reliable, and reproducible means of monitoring any changes in the real-time ...

Energy Technology Data Exchange (ETDEWEB)

Manned-space missions bring an exposure due to corpuscular radiations of which nature is quite different from what we encounter in the ground environment. In the space environment, many secondaries are produced through interactions of cosmic ray primaries with the spacecraft wall and other surrounding materials. Among this large variety of radiation components in the space, the contribution of neutrons to the radiation exposure of astronauts has remained to be studied. Up to today, efforts to measure neutron dose equivalent have been made using passive detector systems. Considering uncertainties involved in current measurements and estimations of high energy neutrons, and their increasing importance for future manned missions, it is necessary to measure neutron spectrum in the spacecraft under realistic conditions. The neutron spectra have never been measured on board a spacecraft, ...

International Nuclear Information System (INIS)

The semiclassical approximation with straight-line trajectories is applied to the Coulomb ionization of K, L and M shells by heavy charged particles. The calculational aspects are discussed in detail. Scaling relations for the experimentally relevant quantities are derived. The theoretical predictions are compared with experiment. The relation of the present work to the earlier results of the semiclassical approximation and partial-wave Born approximation is discussed in detail. (author).

British Library Electronic Table of Contents (United Kingdom)

This article examines the question of finding the best quadratic function to approximate a given function on an interval. The prototypical function considered is f(x) = ex. Two approaches are considered, one based on Taylor polynomial approximations at various points in the interval under consideration, the other based on the fact that three non-collinear points determine a unique quadratic function. Three different techniques for measuring the error in the approximations are considered.

Energy Technology Data Exchange (ETDEWEB)

Full text: In 1995, we demonstrated the use of pretargetting three steps method and biotinylated tetracycline using radiolabelled {sup 99m}Tc-DTPA-biocytinamide for the detection of tumour cells in (C57B1/6 x BALB/C) F1 mice with E-3 thymoma. The three steps were (1) IP injection of biotinylated-tetracycline conjugate (1:1) ratio, (2) 96 hours later Avidin/Streptavidin was injected, and (3) 24 hours after (2), {sup 99m}Tc-biocytinamide -cDTPA was injected. Mice were sacrificed 16/24 h after (3) by cervical dislocation. Biodistribution of radioactivity tumour to blood, liver, bone were T:B1= 15.0, T:Li= 5.08, T:Bo=15.0. The percentage of injected dose per g was T= 3.15% and B1= 0.21%. To prolong circulation of Avidin and therefore its uptake into tumour, Avidin was covalently bound to polyethylene-glycol (PEG20 KD) at the molar ratio of PEG:Avidin 100:1 and ...

Energy Technology Data Exchange (ETDEWEB)

The applications of neutron reflectometry to study dynamic phenomena at surface and interfaces have been restricted so far. This was mainly due to the low intensity of neutron sources, but now high-intensity spallation neutron sources are under construction in Japan (J-PARC) and US (SNS). We are planning to install a spin-echo option on the J-PARC neutron reflectometer with horizontal sample geometry for studies of dynamics of surfaces and interfaces. This option is based on the resonance spin-echo method and aimed at dynamics up to hundreds of nanoseconds. In this contribution, the plan and status of development are introduced together with the principle and characteristics of this option.

International Nuclear Information System (INIS)

A helium-3 proportional detector was equipped with the experiment of Liaw-type electrolytic cell contained eutectic LiCl-KCl molten salt saturated by LiD electrolytic to collect the informations of the rate and the energy distribution of possible neutron produced during the electrolysis processes. For long time monitoring, the significant reproducible neutron bursts appeared at several runs of cells during electrolytic processing. The neutron counting rate increased about a factor of two above the level of the background measurement. The pulse height signals were verified of neutron energy ranging from thermal up to 350 keV. (author).

Energy Technology Data Exchange (ETDEWEB)

Measurements were made of the cross section for /sup 242/Am/sup m/ fission induced by neutrons in the energy range 0.04< or =E/sub n/< or =4.52 MeV as well as by neutrons with E/sub n/roughly-equal14.8 MeV. An electrostatic generator and a low-voltage accelerating tube were used to generate the quasimonochromatic neutrons. Measurements in the low-energy region were made by using the time-of-flight technique in neutrons from a nuclear explosion. Results of the measurements are compared with previously published data.

International Nuclear Information System (INIS)

This paper analyzes fission neutron multiplicity for the /sup 242m/Am(n,f) reaction. The fission neutron multiplicity, v bar, of /sup 242m/Am(n,f) was measured relative to that of /sup 235/U(n,f) using the neutron time-of-flight facility at the Lawrence Livermore National Laboratory 100-MeV electron Linac. A comparison of the measured energy dependence of v-bar is made with semi-empirical models of neutron emission from the actinides. 22 refs.

International Nuclear Information System (INIS)

Inelastically scattered neutron spectra and angular distributions measured for a number of nuclei at the 9.1 and 14.4 MeV incident neutron energies are fitted well as a sum of neutron evaporation spectrum and the direct interaction part. For the last one the practical scheme of parametrization based on direct interaction theory is presented. The relative contribution of direct interactions in double differential cross sections and parameters of neutron evaporation spectra have been evaluated. All results have a simple physical interpretation and may be useful at interpolating of data in a wide energy interval.

Energy Technology Data Exchange (ETDEWEB)

Recently the real-time neutron radiography system of the Kyoto University Reactor (KUR) has been developed and practically applied to penetrating the side plates of the MTR type reactor fuels and investigation of moving objects. In this paper an application of the KUR neutron TV system to neutron computed tomography (NCT) is described. By using the NTV system, projection data can be acquired in a single measurement and simultaneously the projection image can be observed on a CRT monitor. The Fourier-convolution technique is used to produce the reconstructed image and its image has a good enough quality for revealing water in a small hole of 1.5 mm in diameter.

Energy Technology Data Exchange (ETDEWEB)

The effects of various approximations used in performing augmented-plane-wave calculations were studied for elements of the fifth and sixth columns of the Periodic Table, namely V, Nb, Ta, Cr, Mo, and W. Two kinds of approximations have been checked: (i) variation of the number of k points used to iterate to self-consistency, and (ii) approximations for the treatment of the core states. In addition a comparison between relativistic and nonrelativistic calculations is made, and an approximate method of calculating the spin-orbit splitting is given.

International Nuclear Information System (INIS)

As part of a general study of personnel neutron dosimetry systems, three British and two German TL albedo dosimeters were compared. They range from simple albedo devices to multi-element devices which detect combinations of incident and albedo neutrons. They were exposed to beams of mono-energetic neutrons, a thermal neutron column and a "2"5"2Cf source. The variation in response with neutron energy above 0.1 MeV was similar for all dosimeters. The resuls show that in general multi-component dosimeters fo not provide enough information to deduce the effective energy of incident neutrons. The choice of single or multi-element dosimeters for particular types of environment is discussed. The Harvey dosimeter has the most acceptable thermal neutron response of the simpler devices. For neutron energies below 0.5 MeV its ...

International Nuclear Information System (INIS)

A system for real-time neutron radiography of moving objects is described. It comprise a source adapted to generate a continuous uninterrupted series of neutron pulses. Each pulse has a predetermined peak power and duration compatible with the framing times of a real-time video imaging system. A transporter moves an object to be examined to bring sequentially position selected portions of the object in the path of the pulses. Where the object itself has moving components, pulses are sequentially incident on the object. According to any dissimilarities, the object will alter the intensity of the neutrons passing therethrough. In order to record separately the changes in the neutron intensity, for each pulse, an imager is positioned to receive the neutron beam pulses which have been altered by their passage through the object and produce images indicating intensity alterations. A ...

International Nuclear Information System (INIS)

When the history of neutrons is considered, three large discoveries are recalled, that is, the discovery of neutrons by Chadwick in 1932, the discovery of the nuclear fission of uranium by Hahn and Strassmann in 1938, and the continuation of chain reaction in nuclear fission by Fermi and others in 1942. In neutron capture reaction, the reaction cross section can become very large. The fields of research, to which neutrons have contributed most as the experimental probe, are neutron activation analysis and neutron diffraction. The development of the prompt gamma ray analyzer at the JRR-3M in Japan Atomic Energy Research Institute is reported. This method eliminates the various defects in ordinary neutron activation analysis. By installing the cold neutron source with hydrogen cooling in the JRR-3M, the new field of ...

Energy Technology Data Exchange (ETDEWEB)

A technique was developed that permits fluid flow to be visualized even where the flow is completely shrouded by metal. The technique employs real-time neutron radiography, which is similar to x-ray radiography except a collimated beam of neutrons is used. Various combinations of neutron-opaque tracer materials were tested with neutron-transparent fluid. Neutron opaque tracers, such as solid particles, fluid droplets, and streaklines were imaged through metal walls as they convected in neutron-transparent ambient fluid. Visualization of bubbles/voids were evaluated for possible future applications. Surface-flow patterns were also imaged by using neutron-opaque tufts. These techniques were evaluated for image contrast, resolution, and the ability to accurately track fluid flow fields. The techniques were also modeled to optimize contrast in ...

Energy Technology Data Exchange (ETDEWEB)

The US Department of Energy (DOE) sponsors an extensive research program to improve the methods, dosimeters, and instruments available to DOE facilities for measuring neutron dose and assessing its effects on the work force. The Total Dose Meter was recently developed for measuring in real time the adsorbed dose of mixed neutron and gamma radiation and for calculating the dose equivalent. The Field Neutron Spectrometer was developed to provide a portable instrument for determining neutron spectra in the workplace for flux-to-dose equivalent conversion and quality factor calculation. The Combination Thermoluminescence/Track Etch Dosimeter (TLD/TED) was developed to extend the effective neutron energy range of the conventional TLDs to improve detection of fast-energy neutrons. An Optically Stimulated Luminescence Dosimeter is presently being developed for ...

Energy Technology Data Exchange (ETDEWEB)

Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive neutron detection systems. The main reason for having neutron detection capability is to detect fission neutrons from plutonium. The currently deployed radiation portal monitors (RPMs) from Ludlum and Science Applications International Corporation (SAIC) use neutron detectors based upon 3He-filled gas proportional counters, which are the most common large neutron detector. There is a declining supply of 3He in the world, and thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated. Four technologies have been identified as being currently commercially available, potential alternative neutron detectors to replace the use of 3He in ...

Energy Technology Data Exchange (ETDEWEB)

The themal neutron sensitivities of SEI and Toshiba FD-P10-7 radiophotoluminescent silver activated metaphosphate glass dosimeters have been measured and studied theoretically. The graphite thermal neutron column attached to the AEEW reactor NESTOR was utilised as a source of thermal neutrons with minimal fast neutron and gamma-ray contamination. Both the neutron removal and gamma correction measurement techniques were applied and these gave consistent results. It was found that the thermal neutron sensitivity of the Toshiba dosimeters is comparable to the most neutron intensitive thermoluminescent materials available. Because of their larger size and higher silver concentration, however, SEI dosimeters are an order of magnitude more neutron sensitive. The neutron sensitivity of FD-7 glass has not ...

Energy Technology Data Exchange (ETDEWEB)

The authors review two types of simulators for the analysis of cosmic ray neutron-induced soft errors (SE's). One of them is the neutron-induced soft error simulator (NISES). A recently proposed nuclear reaction theory forms the foundation for the nuclear reaction database used in NISES. The other simulator, the simplified simulator MBGR, is based on a modified version of the burst generation rate (BGR) model. Both simulators accurately simulate neutron-induced SE rates (SER's). MBGR actually provides an easier and quicker estimation of neutron-induced SER's than NISES. On the other hand, NISES covers more applications; it simulates neutron-induced charge collection, multiple-bit SE, and [alpha]-induced SE analysis.

International Nuclear Information System (INIS)

One of the significant factors of neutron radiographic image degradation is scattering blur from the object. A practical method is described to enhance image quality by eliminating the overlapping of scattered thermal neutrons component from the objects in ETRR-2 neutron radiography facility, using aluminum Gd-coated antiscatter grid. The MCNP code was used to determine the optimum grid dimensions that will reduce the scattered thermal neutrons from the object. An experiment was performed to determine the optimum grid height and irradiation time that gives the best image with acceptable geometric unsharpness. Using the MCNP code it was found that 97% of the scattered neutrons were removed by the grid. The wall dimensions and Gd coating are so small that the facility resolution cannot detect the image pattern superposition on the film.

Energy Technology Data Exchange (ETDEWEB)

Japan Atomic Energy Research Institute (JAERI) is developing the world`s strongest spallation neutron source using high power proton accelerator and promoting a neutron science project for comprehensive studies on basic science and nuclear transmutation of high-level radioactive nuclide from nuclear power stations. For this purpose, JAERI organized the Special Taskforce for Neutron Science and OMEGA Project in April 1996 and reorganized it to Center for Neutron Science in April 1997. During this period, various research plans using the spallation neutron source are proposed and facilities necessary for research are studied by mainly research groups of JAERI. This report describes research plans and results of the preliminary conceptual design study on proposed facilities plan. (author)

Energy Technology Data Exchange (ETDEWEB)

A thermal neutron imaging facility for real-time neutron radiography and computed tomography has recently been developed at the University of Texas TRIGA reactor. Extensive Monte Carlo design calculations were used to determine optimal design parameters of the neutron collimator system to avoid costly trial and error. Thermal neutron flux determined by gold foil activation is 5 {times} 10{sup 6} n/cm{sup 2}{center_dot}s at the primary imaging location with beam size of 22.5 cm in diameter. The collimation ratio can be varied from 125 to 235. The neutron-to-gamma ratio is 7.8 {times} 10{sup 6} n/cm{sup 2}{center_dot}mR. The facility has been tested for radiography and tomography applications and is now fully operational.

International Nuclear Information System (INIS)

A successful boron neutron capture treatment (BNCT) of a patient with multiple liver metastases has been first given in Italy, by placing the removed organ into the thermal neutron column of the Triga research reactor of the University of Pavia. In Finland, FiR 1 Triga reactor with an epithermal neutron beam well suited for BNCT has been extensively used to irradiate patients with brain tumors such as glioblastoma and recently also head and neck tumors. In this work we have studied by MCNP Monte Carlo simulations, whether it would be beneficial to treat an isolated liver with epithermal neutrons instead of thermal ones. The results show, that the epithermal field penetrates deeper into the liver and creates a build-up distribution of the boron dose. Our results strongly encourage further studying of irradiation arrangement of an isolated liver with epithermal neutron fields.

Energy Technology Data Exchange (ETDEWEB)

An apparatus for non-invasively inspecting an object, such as an item of luggage, for explosives material is described. It comprises a multi-channel thermal neutron inspection system having a plurality of neutron irradiation chambers. Simultaneous operation of several channels increases the maximum system throughput several times. Each chamber has a lithium neutron source which is stimulated to neutron production by a proton beam. Beam switching magnets are energised by pulsing to divert a common proton beam to each source in turn. The initial beam is generated by a radio frequency quadrupole accelerator. The advantages of this system are very low residual source activity and controllable neutron production thereby minimising safety hazards. The irradiation chamber may contain several different gamma ray detectors to identify the elements present in explosives material. In addition, ...

CERN Document Server

A new methane cold neutron source has been tested at the IBR-2 pulsed reactor at the Frank Laboratory of Neutron Physics. In a paper the results of experiments at neutron diffractometers HRFD and DN-2 which are placed at the IBR-2 from the methane moderator side are given. A comparison with the results obtained with the conventional water comb-like moderator is performed. The perspectives of the cold source for various kinds of neutron diffraction experiments, including atomic and magnetic structural analysis and real time experiments are discussed. It is shown, that for a huge number of the experiments which are performing at both HRFD and DN-2 the methane cold neutron source provides the better conditions than water comb-like moderator.