Study of 51Ca via three-neutron transfer

Low-lying levels in ⁵¹Ca have been studied via the reaction ⁴⁸Ca(¹⁸O, ¹⁵O)⁵¹Ca at a beam energy of 108 MeV. Recoiling ⁵¹Ca nuclei were detected in coincidence with ¹⁵O ejectiles, largely removing the substantial background from target contaminants that was encountered in previous work. The lowest ⁵¹Ca level identified is 1.01 ±0.11 MeV less bound than the ground state, according to a recent measurement of the ground state mass using the ⁴⁸Ca(¹⁴C, ¹¹C)⁵¹Ca reaction. Consider- ations of the difficulty in identifying the ground state peak suggest that published values of the mass excess should be viewed with caution, and that a definitive mass measurement is still required in order to resolve questions on the structure of the neutron-rich calcium isotopes. A total of six energy levels in ⁵¹Ca have been identified, and their mass excesses measured. Only two of these levels have been observed previously, via the (¹⁴C, ¹¹C) reaction. Striking differences in selectivity between the (¹⁸O, ¹⁵O) and (¹⁴C, ¹¹C) transfer reactions are discussed.     

The resonance pole and the residue of the scattering amplitude while the Coulomb forces gradually decrease

Trajectories for the S-wave pole of the scattering amplitude are constructed in the complex planes of the resonance momentum and of the renormalized vertex constant squared. They correspond to transitions from the resonance states to the virtual states of the singlet deuteron and the doublet triton while the Coulomb interaction gradually decreases to zero. The effective-range theory and a Yukawa-potential model are used. Physical reasons for the differences between the corresponding trajectories for Np and Nd systems are found. The results obtained explain why the resonances in the doublet Nd scattering are more difficult to detect in experiments in comparison with the well-studied singlet NN resonances.     

On the self-consistent Pomeron pole

A model is considered in which a Pomeron is regarded as a self-consistent intercept one Regge pole resulting from a Bethe-Salpeter-like equation in Reggeon theory. The absorptive nature of a two Pomeron cut is crucial for realization of self-consistency. For zero mass Pomerons the model predicts the vanishing of the triple Pomeron coupling and softening of Pomeron cut contributions to inclusive reactions in triple and di-triple Regge regions.     

极点配置法弹性平板有源隔声系统优化

对混响声场中的弹性平板有源隔声系统进行优化。根据激励频率范围确定受控模态阶次,在模态空间中建立系统降阶方程,基于极点配置方法,采用分布式系统增加受控模态的阻尼,降低低频共振声传输。同时设计模态滤波器,为控制器提供所需的状态信息。为提高控制效能,本文对传感器和作动器布放位置进行优化,尝试不同极点配置方案,并对耦合控制与独立模态控制方法的隔声效果进行比较。仿真结果显示,极点配置法有源隔声可以有效降低共振声传输,优化布放和独立模态控制方式下,控制力明显降低。优化后的有源隔声系统效能有所提升。     

3,3 resonance and Nucleon pole model forpp→ppπ0 andpp→pnπ+

The Nucleon pole and 3,3 resonance pole contributions are considered for the reactionspp→ppπ⁰ andpp→pnπ ⁺ at low and medium incident proton energies. The total and various differential cross sections are calculated, also for polarized nucléons, and compared with experimental data.     

The unstable system withN states and the propagator matrix with a pole of higher order

Starting from the general quantum-mechanical laws, the general form of the mass-matrix for a special unstable system withN states and of the propagator with higher order pole is derived.     

Theory of the Magnetomechanical pole effect

The vibration frequencies of a magnetized reed can be affected by a magnetic field due to the periodic change in the interaction energy between the field and the reed. This effect was first studied by Berry and Pritchet who called it the pole effect according to a simplifying assumption made in evaluating this interaction energy. We gave here an exact first-order theory for the case of clamped-free and free-free flexural vibrations. We also give experimental evidence and the corresponding theory for a similar effect occurring with torsional vibrations.     

Solutions of the multichannel unitarity equations describing the addition of a resonance and background: Application to a pole model of photoproduction

Addition of a resonance and background in the multichannel case is investigated. The generalization of a method, which correctly unitarizes a pole model of πN elastic scattering, is found. Application is made to photoproduction, showing that a pole model can account for the resonant multipoles in the Δ region. The γNΔ coupling constant required is nearly that predicted by the quark model.