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1.
Jeremy Haefner 《Proceedings of the American Mathematical Society》1996,124(4):1013-1021
Let be a ring graded by a group . We are concerned with describing those -graded rings that are graded equivalent to -crossed products. We give necessary and sufficient conditions for when a strongly graded ring is graded equivalent to a crossed product, provided that the 1-component is either Azumaya or semiperfect. Our result uses the torsion product theorem of Bass and Guralnick. We also construct various examples of such rings.
2.
Dynamic wave-front correction is applied before each shot on a 100-TW, 30-J/300-fs high-power laser facility by use of an adaptive-optics system. This system allows us to increase the repetition rate of high-energy lasers while maintaining excellent and constant beam focusability with a Strehl ratio of >0.75 despite the amplifiers' not being in thermal equilibrium. The best results in terms of the highest Strehl ratio and intensities are obtained when locking the system on wave-front sensing after pulse recompression. 相似文献
3.
Th. Kuehl R. Bock S. Borneis E. Brambrink H. Brand J. Caird E. M. Campbell K. Cassou E. Gaul S. Goette C. Haefner T. Hahn H. M. Heuck D. H. H. Hoffmann D. Javarkova A. Klisnick H.-J. Kluge S. Kunzer T. Merz P. Neumayer P. Nickles M. D. Perry D. Reemts D. Ros M. Roth S. Samek W. Sandner G. Schaumann F. Schrader W. Seelig A. Tauschwitz R. Thiel D. Ursescu P. Wiewior U. Wittrock B. Zielbauer 《Hyperfine Interactions》2005,162(1-4):55-62
The high-energy high-power laser system PHELIX (Petawatt High Energy Laser for heavy Ion eXperiments) [1] is currently under construction at the Gesellschaft fuer Schwerionenforschung mbH (GSI) Darmstadt. With PHELIX GSI will
offer the unique combination of a high-current, high-energy (GeV/u) heavy-ion beam with an intense laser beam. This will open
the door to a variety of fundamental science issues in the field of atomic physics, plasma physics and nuclear physics. The
project will gain further interest in the near future by the dramatic increase of the accelerator performance with the starting
FAIR project at GSI [2]. This paper reports the current status of the project as well as the laser architecture. The proposed physics program and
a first experiment carried out with PHELIX, the realization of a transient collisionally excited x-ray laser [3], will also be reviewed briefly. 相似文献
4.
Self-injection length in La0.7Ca0.3MnO3-YBa2Cu3O7-δ ferromagnet-superconductor multilayer thin films
We have carried out extensive studies on the self-injection problem in barrierless heterojunctions between La0.7Ca0.3MnO3 (LCMO) and YBa2Cu3O7-δ (YBCO) thin films. The heterojunctions were formed in situ by sequentially growing LCMO and YBCO films on 〈100〉 LaAlO3 (LAO) substrate using a pulsed laser deposition (PLD) system. YBCO micro-bridges with 64 μm width were patterned both on
the LAO (control) and LCMO side of the substrate. Critical current, I
c, was measured at 77 K on both the control side as well as the LCMO side for different YBCO film thickness. It was observed
that while the control side showed a J
c of ∼ 2 × 106 A/cm2, the LCMO side showed about half the value for the same thickness (1800 ?). The difference in J
c indicates that a certain thickness of YBCO has become ‘effectively’ normal due to self-injection. From the measurement of
J
c at two different thicknesses (1800 ? and 1500 ?) of YBCO films both on the LAO as well as the LCMO side, the value of self-injection
length (at 77 K) was estimated to be ∼ 900 ?. To the authors’ best knowledge, this is the first time that self-injection length
has been quantified. A control experiment carried out with LaNiO3 deposited by PLD on YBCO did not show any evidence of self-injection. 相似文献
5.
K. J. Moody W. Brüchle M. Brügger H. Gäggeler B. Haefner M. Schädel K. Sümmerer H. Tetzlaff G. Herrmann N. Kaffrell J. V. Kratz J. Rogowski N. Trautmann M. Skålberg G. Skarnemark J. Alstad M. M. Fowler 《Zeitschrift für Physik A Hadrons and Nuclei》1987,328(4):417-422
We have observedγ-rays following the β?-decay of243Np and244Np after chemical isolation of neptunium isotopes from the products of the reaction of 835 MeV136Xe with244Pu. The ground-state of 1.85-min243Np hasJ=5/2. The decay of 2.29-min244Np (probableJ π=7?) populates high-spin members of the ground state rotational band in244Pu. 相似文献
6.
J. Haefner A. del Rí o J. J. Simó n 《Proceedings of the American Mathematical Society》1997,125(6):1651-1658
This paper investigates the ring-theoretic similarities and the categorical dissimilarities between the ring of row finite matrices and the ring of row and column finite matrices. For example, we prove that two rings and are Morita equivalent if and only if the rings and are isomorphic. This resembles the result of V. P. Camillo (1984) for . We also show that the Picard groups of and are isomorphic, even though the rings and are never Morita equivalent.
7.
Rumpel M Haefner M Schoder T Pruss C Voss A Osten W Ahmed MA Graf T 《Optics letters》2012,37(10):1763-1765
We report on the generation of beams with azimuthal polarization using resonant grating waveguide structures (GWSs) inside an Yb:YAG thin-disk laser (TDL) oscillator. Two different GWS concepts were used to select the polarization of the emitted beam. The first uses the resonant reflection principle, and the second is based on the leaky-mode approach already reported in our previous work. Up to 93 W and 103 W of output power were extracted from a TDL with an optical efficiency, η(oo), of 36.2% and 40.1% using the first and the second approaches, respectively. In both cases, a pure azimuthal polarization and a beam quality factor, M2, of about 2.2 were measured. The design, fabrication, and different experimental results, as well as the laser performances for both GWSs, are discussed in the present Letter. 相似文献
8.
P. Neumayer W. Seelig K. Cassou A. Klisnick D. Ros D. Ursescu T. Kuehl S. Borneis E. Gaul W. Geithner C. Haefner P. Wiewior 《Applied physics. B, Lasers and optics》2004,78(7-8):957-959
A transient collisionally excited X-ray laser has been put into operation using the front end of the PHELIX laser system as a pump laser. Strong lasing at 22 nm has been observed in nickel-like zirconium. PACS 42.60.-v; 42.55.Vc; 42.62.Fi 相似文献
9.
10.
Jeremy Haefner 《代数通讯》2013,41(2):445-481
We give necessary conditions for a map to be irreducible (in the category of finitely generated, torsion free modules) over a non-local, commutative ring and sufficient conditions when the ring is Bass. In particular, we show that an irreducible map of ZG, where G is a square free abelian group, must be a monomorphism with a simple cokernel. We also show that local endomorphism rings are necessary and sufficient for the existence of almost split sequences over a commutative Bass ring and we explicitly describe the modules and the maps in those sequences. The results in this paper enable us to describe the Auslander-Reiten quiver of a non-local Bass ring in [8]. 相似文献