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91.
Cowan TE Fuchs J Ruhl H Kemp A Audebert P Roth M Stephens R Barton I Blazevic A Brambrink E Cobble J Fernández J Gauthier JC Geissel M Hegelich M Kaae J Karsch S Le Sage GP Letzring S Manclossi M Meyroneinc S Newkirk A Pépin H Renard-LeGalloudec N 《Physical review letters》2004,92(20):204801
The laminarity of high-current multi-MeV proton beams produced by irradiating thin metallic foils with ultraintense lasers has been measured. For proton energies >10 MeV, the transverse and longitudinal emittance are, respectively, <0.004 mm mrad and <10(-4) eV s, i.e., at least 100-fold and may be as much as 10(4)-fold better than conventional accelerator beams. The fast acceleration being electrostatic from an initially cold surface, only collisions with the accelerating fast electrons appear to limit the beam laminarity. The ion beam source size is measured to be <15 microm (FWHM) for proton energies >10 MeV. 相似文献
92.
The heat capacity and magnetization of a fluid 3He monolayer adsorbed on graphite plated with a bilayer of HD have been measured in the temperature range 1-60 mK. Approaching the density at which the monolayer solidifies into a sqrt[7]xsqrt[7] commensurate solid, we observe an apparent divergence of the effective mass and magnetization corresponding to a T=0 Mott-Hubbard transition between a 2D Fermi liquid and a magnetically disordered solid. The observations are consistent with the Brinkman-Rice-Anderson-Vollhardt scenario for a metal-insulator transition. We observe a leading order T2 correction to the linear term in heat capacity. 相似文献
93.
Snavely RA Key MH Hatchett SP Cowan TE Roth M Phillips TW Stoyer MA Henry EA Sangster TC Singh MS Wilks SC MacKinnon A Offenberger A Pennington DM Yasuike K Langdon AB Lasinski BF Johnson J Perry MD Campbell EM 《Physical review letters》2000,85(14):2945-2948
An intense collimated beam of high-energy protons is emitted normal to the rear surface of thin solid targets irradiated at 1 PW power and peak intensity 3x10(20) W cm(-2). Up to 48 J ( 12%) of the laser energy is transferred to 2x10(13) protons of energy >10 MeV. The energy spectrum exhibits a sharp high-energy cutoff as high as 58 MeV on the axis of the beam which decreases in energy with increasing off axis angle. Proton induced nuclear processes have been observed and used to characterize the beam. 相似文献
94.
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96.
Examining the possibility that the enhancement of Tc in the tungsten bronzes arises from interband coupling, we find that a single density of states provides reasonable quantitative agreement with the Tc enhancement, the heat capacity and the magnetic susceptibility. 相似文献
97.
We investigate the direct effects of phonon softening on Tc in Nb3Sn. It is inadequate to explain the high Tc, which arises instead from an unusually large electron- phonon coupling to the two Γ'12 optical phonon modes. 相似文献
98.
J. Amirzadeh R.E. Ansorge M. Baubillier I.J. Bloodworth G.J. Bossen A. Burns J.N. Carney J.R. Carter C.A. Cowan G.F. Cox U. Dore Ph. Gavillet J.K. Hassall J.B. Kinson K. Knudson F. Levy P.F. Loverre R. Zitoun 《Physics letters. [Part B]》1979,89(1):125-130
We present evidence for a narrow Y1 with a mass of 3.17 GeV and a width ? 20 MeV decaying to ΣKK? + pions, ΛKK? + pions and ΞK + pions. The data come from two high statistics K?p bubble chamber experiments with a sensitivity of ≈100 eV/μbat 8.25 GeV/c and ≈ 45 eV/μbat 6.5 GeV/c. 相似文献
99.
A mechanism is proposed to explain the double phase transitions found in K2PbCu(NO2)6 and Tl2PbCu(NO2)6. The higher temperature transition is caused by the cooperative Jahn-Teller effect. The lower temperature transition occurs as the fourth order anharmonic interaction restabilizes the lattice against instabilities caused by static distortions in the third order anharmonic interaction. Calculated curves of the order parameter and heat capacity reproduce all the features in the experimental curves. 相似文献
100.
Vicic DA Anderson TJ Cowan JA Schultz AJ 《Journal of the American Chemical Society》2004,126(26):8132-8133
Reaction of two equiv of 1-adamantylzinc bromide with (dippm)NiBr2 (dippm = bis(di-isopropylphosphino)methane) led to a dinuclear metal complex containing a unique linear bridging hydride ligand. The hydride was characterized by neutron diffraction methods, which confirmed a linear bonding mode. Preliminary reactivity studies of this unusual dimer are reported. 相似文献