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AbstractAbstract

[en] The authors present results on WW production in p bar p collisions at √s=1.8 TeV. The WW cross section is measured. The result is consistent with the standard model prediction

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1993 joint meeting of the American Physical Society and the American Association of Physics Teachers; Washington, DC (United States); 12-15 Apr 1993; CONF-9304297--

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[en] With coherent potential approximation method the effect of the substitutional disorder in the pseudo one-dimensional conductors on the Peierls transition temperature (Tsub(p)) and superconductive transition temperature (Tsub(c)) has been calculated. The favourable condition for searching for somewhat high Tsub(c) superconductors in these systems has been discussed. (author)

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Aug 1981; 16 p

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AbstractAbstract

[en] Ferromagnetic resonance experiments were performed at room temperature on amorphous ultrathin films of Fe/sub x/B/sub 100-x/ (x = 50, x = 70) at two frequencies (f = 9.515 GHz and f = 24.03 GHz). Two different configurations were employed, with the applied field being either parallel or perpendicular to the film surface. The amorphous Fe-B ultrathin film samples were successfully fabricated by d.c. sputtering deposition techniques. Their thicknesses range from about 18 A to 77 A. General formulas for the free energy were derived from Hamilton's principle and were adapted to amorphous materials. The ultrathin nature of the samples allows one to employ a surface inhomogeneity model, which involves only surface anisotropy, and to ignore any volume inhomogeneities. No approximation beyond the usual linearization of the equation of motion and the assumption of the uniformity of the microwave field throughout the sample was involved. It was found that in ultrathin films the observed FMR modes were surface-induced modes in the parallel configuration and spin-wave modes in the perpendicular configuration

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1986; 157 p; University Microfilms Order No. 86-01,311; Thesis (Ph. D.).

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Report

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Thesis/Dissertation

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AbstractAbstract

[en] The prime objective of this thesis is to investigate, for the first time, baryon physics, in the leading order of 1/N

_{c}expansion (N_{c}being the number of colors), from the πρωα_{1}chiral soliton model, consistent with the low-energy features of quantum chromodynamics (QCD) and the known meson properties, as collected in the newest data base of the 1992 Particle Data Group (PDG). The πρωa_{1}f_{1}meson effective action, used in this work, is based on the hidden gauge symmetry formalism, and has the most general form in the anomalous sector, with fourteen independent terms. After fixing three or four parameters of these, using meson properties according to the 1992 PDG, the nucleon and the Delta(1232) resonance are examined as topological solitons in this effective action, varying all free parameters to give optimal baryon properties. The diagonal and off-diagonal electroweak and strong properties of nucleons are calculated in the πρωa_{1}Skyrme model; these include the nucleon electroweak form factors, diagonal and transitional form factors for nucleon and the Delta resonance, of interest to experiments at emerging continuous wave electron accelerator like CEBAF. Baryon physics is found to be very sensitive to the treatment of the φ meson nonstrange strong decay data; the recent method, proposed by Jain et al., is found to lead to rather unsatisfactory results, if this formalism is fit with the data from the 1992 PDG. There is a strong correlation found between the soliton mass and the axial vector coupling of nucleons, g_{A}, as in the πρω chiral soliton model: Reasonable g_{A}values give too large soliton mass and vice versa; varying the free parameters of the approach cannot eliminate this problem. Finally, if the φ meson nonstrange strong decay data is ignored, there emerges a reasonable description for most baryon physics propertiesPrimary Subject

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1993; 120 p; Rensselaer Polytechnic Institute; Troy, NY (United States); Available from University Microfilms, P.O. Box 1764, Ann Arbor, MI (United States). Order No. 94-05,705; Thesis (Ph.D.).

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Miscellaneous

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Thesis/Dissertation

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Zhang, L. H.; Sui, M. L.; Zhang, L.; Hu, K. Y.; Li, D. X.

Funding organisation: (United States)

Funding organisation: (United States)

AbstractAbstract

[en] Ultrathin Pb films supported by Al film were made by using cold-rolling and ion-beam thinning techniques. The morphological instability of the Pb film under electron-beam irradiation was investigated by means of in situ transmission electron microscopy observations. It has been found that under electron-beam irradiation, Pb films with an incoherent Pb/Al interface spheroidized into Pb particles, but those with a semicoherent Pb/Al interface were stable in morphology. The morphological stability of thin films depends on the microstructure and the thermodynamic property of the interphase boundary. A critical interfacial energy for the spheroidization of thin films was determined based on a thermodynamics analysis. [copyright] 2001 American Institute of Physics

Source

Othernumber: APPLAB000078000023003621000001; 009119APL; The American Physical Society

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Journal Article

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Applied Physics Letters; ISSN 0003-6951; ; v. 78(23); p. 3621-3623

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AbstractAbstract

[en] The m+n dimensional flat superspace is considered and graded linear groups with their graded algebra are calculated. The 4+4 dimensional graded de-Sitter spacetime is discussed geometrically by its embedding in 5+4 dimensional flat superspace, and its isometry subgroup OSp(114) has been calculated. We have used the isomorphism between the algebra of Sp(4,R) and SO(3,2) to express the generators Ssup(ab) of SO(3,2) in terms of the generators hsup(αβ) of the symplectic group Sp(4,R); then it is easy to obtain the graded de-Sitter algebra from the ortho-symplectic algebra OSp(114). Finally, by contraction we obtain the graded Poincare algebra, that is, the superalgebra with which we are familiar. (author)

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Sep 1981; 12 p

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AbstractAbstract

[en] A method based on the tight-binding approximation is developed to calculate the electron-phonon matrix element for the disordered transition metals. With the method as a basis the experimental Tsub(c) data of the amorphous transition metal superconductors are re-analysed. Some comments on the superconductivity of the disordered materials are given

Original Title

Tight-binding approximation

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Aug 1981; 11 p

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Zhang, L.; Lanza, R.C.

Massachusetts Inst. of Tech., Cambridge, MA (United States)

Massachusetts Inst. of Tech., Cambridge, MA (United States)

AbstractAbstract

[en] The authors have developed a near field coded aperture imaging system for use with fast neutron techniques as a tool for the detection of contraband and hidden explosives through nuclear elemental analysis. The technique relies on the prompt gamma rays produced by fast neutron interactions with the object being examined. The position of the nuclear elements is determined by the location of the gamma emitters. For existing fast neutron techniques, in Pulsed Fast Neutron Analysis (PFNA), neutrons are used with very low efficiency; in Fast Neutron Analysis (FNS), the sensitivity for detection of the signature gamma rays is very low. For the Coded Aperture Fast Neutron Analysis (CAFNAreg

_{s}ign) the authors have developed, the efficiency for both using the probing fast neutrons and detecting the prompt gamma rays is high. For a probed volume of n^{3}volume elements (voxels) in a cube of n resolution elements on a side, they can compare the sensitivity with other neutron probing techniques. As compared to PFNA, the improvement for neutron utilization is n^{2}, where the total number of voxels in the object being examined is n^{3}. Compared to FNA, the improvement for gamma-ray imaging is proportional to the total open area of the coded aperture plane; a typical value is n^{2}/2, where n^{2}is the number of total detector resolution elements or the number of pixels in an object layer. It should be noted that the actual signal to noise ratio of a system depends also on the nature and distribution of background events and this comparison may reduce somewhat the effective sensitivity of CAFNA. They have performed analysis, Monte Carlo simulations, and preliminary experiments using low and high energy gamma-ray sources. The results show that a high sensitivity 3-D contraband imaging and detection system can be realized by using CAFNAPrimary Subject

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1998 Nuclear Science Symposium; Toronto, ON (Canada); 8-14 Nov 1998

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AbstractAbstract

[en] The Skyrme model allows one in principle to discover properties of baryons from mesons and glueballs alone, consistent with the low energy features of QCD. The authors extend their previous work and examine the nucleon and Delta(1232) as topological solitons, starting with a realistic π-ρ-ω-A chiral effective Lagrangian, having the resultant advantages of chiral invariance and vector/axial-vector dominance in the electroweak physics. They calculate a variety of static and transition properties of these baryons, in the leading order in the N

_{c}^{-1}physics in the present contextPrimary Subject

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1993 joint meeting of the American Physical Society and the American Association of Physics Teachers; Washington, DC (United States); 12-15 Apr 1993; CONF-9304297--

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AbstractAbstract

[en] Different models of single-mode laser were investigated in the situation of cross-correlation between the real and imaginary parts of the quantum noise. It was found that the amplitude equations of different models contain the same novel term. So the amplitude equations of all kinds of models could be written into a general form, which is called as the new amplitude equation. Further we use this new amplitude equation to research specifically the transient properties of white-gain model, the analytical results of the mean, variance, and skewness of first-passage-time (FPT) distributions for the white-gain model are presented, and compared with experimental measurements together with the other two theoretical results. We can conclude that: - because of the presence of the novel term containing the cross-correlation coefficient λ

_{q}between the real and the imaginary parts of the quantum noise, the expression of mean, variance, and skewness of FPT will change according to different value of λ_{q}; - when λ_{q}=0.15, the agreement between the theoretical curve we obtained with experimental result is more better than the two others. So the new amplitude equation we derived can well describe the transient process of a single-mode laserPrimary Subject

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S0375960103001245; Copyright (c) 2003 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)

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