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991.
The present focus of the CBELSA/TAPS experiment is on meson-photoproduction off the nucleon using polarized photons and polarized targets. Here first preliminary results on the reactions γp → pπ and γp → pπ for both circularly and linearly polarized photons and a longitudinally polarized target are presented. Preliminary results for the beam asymmetry ∑ and the double polarization observable G have been extracted for both reactions using the linear polarization data. From the circular polarization data the observable E has been determined. Due to the near 4π angular coverage of the detector system these results cover almost the full solid angle. 相似文献
992.
Charge and Energy Dependences of Ionization and Transfer for Helium in Collisions with Fast Charged Projectiles
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The classical method within the independent electron model is employed to investigate (i) charge dependences of single and double ionization for helium by various charged ions A^q+ (q = 1 - 8) at impact energies of 0.64 and 1.44 MeV/u, respectively, (ii) energy dependences of transfer ionization for helium by 0.5-3 MeV/u A^8.9+ ions impact. The Lenz-Jensen model of the atom is applied instead of the Bohr model of the atom, and the impact-parameter dependences are also introduced into the calculations. Satisfactory agreement is found between theoretical and experimental data. 相似文献
993.
Structural,Magnetic and Magnetocaloric Properties of La-deficient La0.77-xSrxCa0.2MnO2 Perovskites
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La-deficient La0.77-x Ca0.2SrxMnO3 (0 〈 x 〈 0.1) polycrystalline samples are synthesized using the sol-gel technique. The crystal structures of all the samples are single orthorhombic phase with Pbnm space group. Rietveld analysis of x-ray diffraction patterns shows that the Mn-O-Mn bond angle θUn-O-Mn increases whereas the Mn-O bond length dMn--o decreases monotonically with increasing Sr^2+ content, which results in a rich overlap between Mn 3d and O2p orbitals and leads to a systematic increase of the Curie temperature in this compound. It is found that the magnetic entropy change has a maximum at x = 0.06 in La^3+-deficient La0.77-xCa0.2SrxMnO3. This may result from competition between the super-exchange interactions (Mn 4+-O2--Mn4+) and double-exchange interactions (Mn^3+-O^2- -Mn^4+) originating from the appearance of superfluous Mn^4+ ions by substitution of Sr^2+ for La^3+ in this series. Large magnetic entropy changes of 2.32 and 1.83Jkg^-1K^-1 in the x = 0.06 and x = 0.1 samples at their Tcs of 271 K and 303K upon a low magnetic field (10kOe) make these materials promising candidates at near room temperature. 相似文献
994.
995.
Entanglement Purification for Mixed Entangled Quantum Dot States via Superconducing Transmission Line Resonators
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An entanglement purification protocol for mixed entangled states is presented via double quantum dot molecules inside a superconducing transmission line resonator (TLR). In the current scenario, coupling for arbitrary double quantum dot molecules can be tuned via the TLR in the large detuning region by controlling the qubit level splitting. The TLR is always empty and only virtually excited, so the interaction is insensitive to both the TLR decay and thermal field. Discussion about the feasibility of our scheme shows that the entanglement purification can be implemented with high fidelity and successful probability. 相似文献
996.
997.
998.
The effect of configuration complex on dielectronic recombination process in highly ionized plasmas
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This paper analyses the effect of configuration complex on dielectronic recombination (DR) process in highly ionized plasmas (Xe^26+, Dy^38+, W^46+) by using the multiconfiguration relativistic Hartree-Fock method. Resonant and nonresonant radiative stabilizing transitions and decays to autoionizing levels followed by radiative cascades are included. Collisional transitions following electron capture are neglected. The remarkable difference between the isoelectronic trend of the rate coefficients for DR through 3d^94l4l′ and through 3d^94l5l′ is emphasized. The trend of DR through 3d^94l4l′ shows irregularities at relatively low temperature due to the progressive closing of DR channels as atomic number Z increases. 相似文献
999.
The structure dependence of exchange bias in ferromagnetic/antiferromagnetic (FM/AF) bilayers has been investigated in detail by extending Slonczewski's 'proximity magnetism' idea. Here three important parameters are discussed for FM/AF bilayers, i.e. interracial bilinear exchange coupling J1, interracial biquadratic (spin-flop) exchange coupling J2 and antiferromagnetic layer thickness tAF. The results show that both the occurrence and the variety of the exchange bias strongly depend on the above parameters. More importantly, the small spin-flop exchange coupling may result in an exchange bias without the interracial bilinear exchange coupling. However, in general, the spin-flop exchange coupling cannot result in the exchange bias. The corresponding critical parameters in which the exchange bias will occur or approach saturation are also presented. 相似文献
1000.
现在诱惑态已被证明是一种可以大大提高量子密钥分发安全性能的现实可行的方法.由于考虑到现实应用中激光器在调制过程中的消光比不能做到100%,以及激光器固有的自发辐射因而使得制备真空态并不是一件容易的事情. 因此本文将对理想情况下准单光子光源量子密钥分发系统应用中的诱惑态结论作了补充和扩展,提出了两个弱光强态的诱惑态方案和一个弱光强诱惑态方案.最后,将“双探测器”的理论应用在准单光子源(HSPS)光源系统中,使系统的安全传输距离可达到2215km,比使用普通探测器的系统增加了约50km. 相似文献