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1.
J. Bendahán C. Broude E. Dafni G. Goldring M. Hass E. Naim M. H. Rafailovich 《Hyperfine Interactions》1987,34(1-4):139-142
The parity-violating mixing of the 17/2– and 17/2+ levels in93Tc nuclei, polarized by the tilted multifoil interaction, was measured by the observation of the forward-backward-ray asymmetry. The nuclear polarization, induced by the tilted multifoils, was measured directly for the neighboring88,90Zr isomers. The forward to backward asymmetry was determined to be A=(2.5±2.1) 10–3 which implies a parity violating matrix element ¦H
PV
)¦=(4.0±3.7)meV. 相似文献
2.
The total syntheses of the epoxy cyclic hemiacetal structures 8 and 9, which are isomeric with the structure 6 proposed for the phomactin known as Sch 49028 isolated from the marine fungus Phoma sp. are described. Neither of these structures showed spectroscopic data consistent with those reported for the purported natural product, adding credibility to the proposal that the structure Sch 49028 does not exist in nature and that its NMR spectroscopic data should have been assigned as phomactin A (1). 相似文献
3.
G. Goldring 《Hyperfine Interactions》1981,9(1-4):115-126
Conclusion It has been demonstrated that the effect of a tilted multifoil array on an ensemble of nuclei approaches a regular precession in a field of magnitude pH in the direction of the tilt axis. The magnitude of the precession can, under certain circumstances, be considerably larger than in a transient field, the only other method available today for measurements in the picosecond range. The technology of multifoil arrays has not been fully mastered to date, the immediate objective being the construction of arrays which keep their shape and spacings for many hours in a particle beam. 相似文献
4.
A total synthesis of phomactin A (1) based on a Cr(II)/Ni(II) macrocyclisation from the aldehyde vinyl iodide 11, leading to 12, followed by elaboration of the epoxyketone 16, which then undergoes spontaneous pyran-hemiacetal formation on deprotection, is described. 相似文献
5.
6.
A total synthesis of the PAF antagonist phomactin A (1), isolated from the marine fungus Phoma sp. is described. The synthesis is based on a Cr(II)/Ni(II) macrocyclisation from the aldehyde vinyl iodide 14, leading to the key phomactatrienol intermediate 16a, followed by elaboration of 16a to the epoxyketone 21, which undergoes spontaneous pyran and hemiacetal ring formation to 1 on deprotection with DDQ. 相似文献
7.
Yuval Berg Sharone Goldring Shaul Pearl Ady Arie 《Applied physics. B, Lasers and optics》2013,111(3):425-428
A new method for Q-switching an all-fiber laser is presented. It is based on induced acoustic long period grating operating on a null coupler, which acts as acoustically controlled tunable output coupler. Q-switching is achieved by switching on and off the acoustic wave in a burst mode, thereby generating laser pulses that are ~400 times shorter than the acoustically controlled coupler’s rise time. Output pulse energy of 22 μJ and temporal width of ~100 ns were measured at a wavelength of 1.54 μm. 相似文献
8.
Gvirol Goldring 《Hyperfine Interactions》1992,75(1-4):355-365
Tilted foil polarization has up to now been mostly applied to nuclear reaction products recoiling out of a target traversed
by a primary particle beam. Being a universal phenomenon it can be applied equally well to beams of particles, primary or
secondary, radioactive or other. There are however some technical considerations arising from the nature of the beam particles.
Radioactive beams are associated with ground state nuclei. They usually have low nuclear spin and as a consequence-as will
be shown later-low polarization. Secondary beams are usually low in intensity and do not impose any constraints on the foils
they traverse; unlike intense primary heavy ion beams which, if they traverse the foils, essentially limit the foil material
to carbon. We review here briefly the tilted foil polarization process and then discuss an experiment with an isomer beam.
Finally we review experiments with radioactive beams, past, present and planned for the future. 相似文献
9.
K.-H. Speidel G.J. Kumbartzki W. Knauer R. Kuhnen G. Kraft J. Gerber M.B. Goldberg G. Goldring A. Zemel 《Nuclear Physics A》1980,344(1):176-184
Energy levels in 160Er and 159Er were excited in the reactions 28Si(136Xe, 4n)160Er and 28Si(136Xe, 5n)159Er, and the product nuclei, recoiling with a velocity v = 0.07c were stopped in a plunger instrument after traversing a volume of hydrogen gas. The angular distribution of de-excitation γ-rays was studied as a function of flight time and gas pressure. Appreciable perturbations were detected in 160Er at times as short as 2 ps and in an angular momentum region as high as 12?. No perturbation could be detected in the level of 159Er even after 12 ps, signifying a low value for the g-factor of this level. 相似文献
10.
Nd:YAG laser pumped at 946 nm 总被引:1,自引:0,他引:1
A Nd:YAG laser crystal was pumped at 946 nm and lased at 1064 nm. This pump-lase format was investigated in order to reduce the quantum defect between the pump and laser photons as compared to other pump schemes of this material. To the best of our knowledge, this is the first realization of this scheme. A room temperature absorption coefficient and linewidth of approximately 0.075 cm(-1) and approximately 1 nm for 1% at. Nd(+3) concentrations were measured for the 946 nm absorption line. Those parameters impose both narrow-bandwidth pumping and a long absorption path. By increasing the laser crystal temperature above room temperature, the absorption cross sections at 946 and 938 nm increase due to enhanced thermal population of the upper energy level of the ground manifold. The possibility of exploiting this phenomenon to enhance the pump absorption is also discussed. 相似文献