Quantum momentum distribution and kinetic energy in solid 4He.
We present measurements of neutron scattering from solid 4He at high momentum transfer. The solid is held close to the melting line at molar volume 20.87 cm3/mol and temperature T=1.6 K. From the data, we determine the shape of the momentum distribution, n(k), of atoms in the solid and the leading final state contribution to the scattering. We show that n(k) in this highly anharmonic, quantum solid differs significantly from a Gaussian. The n(k) is more sharply peaked with larger occupation of low momentum states than in a Maxwell-Boltzmann distribution, as found in liquid 4He and predicted qualitatively by path integral Monte Carlo calculations. The atomic kinetic energy is =(24.25+/-0.30) K. If n(k) is assumed to be Gaussian, as is usually the practice, a 10% smaller is obtained.
Quantum effects in deep inelastic neutron scattering.
Presentation de l'approximation des impulsions (IA) qui est utilisee pour interpreter les mesures de diffusion inelastique profonde de neutrons. La diffusion predite est identique a celle qui pourrait etre obtenue a partir d'un gaz d'atomes non interactifs ayant une distribution de quantite de mouvement des atomes dans le systeme cible. Hypotheses fondamentales et validite de l'IA. Non validite de l'hypothese de l'IA dans un systeme quantique a la temperature zero. On montre que les effets de l'etat initial causes par la rupture de l'IA a basses temperatures, rendent compte des asymetries observees et du deplacement des pics par rapport aux predictions. On montre que les effets des etats finaux sont negligeables. Discussion des conditions pour lesquelles les effets de l'etat initial sont negligeables
Parameters for low energy operation of CESR
We present a detailed design for operation of the Cornell Electron Storage Ring, CESR, in the energy range covering the /spl psi/ resonances and the Charm and Tau thresholds, as well as reaching to the upper Y resonances near 11 GeV. The addition of 18 m of super-ferric wiggler magnets will partially restore low energy beam emittance and damping times. Installation of superconducting quadrupoles in the interaction region and the addition of high performance superconducting RF cavities will enhance performance at all energies. Studies of optics, beam dynamics, wiggler and vacuum system performance, beam stability, and beam-beam effects confirm operation with a luminosity of 3/spl times/ 10/sup 32/ CM/sup -2/ sec/sup -1/ at 1.88 GeV.