The statistical theory of nuclear reactions in the limit of isolated resonances

The random matrix theory of statistical nuclear reactions — formulated by Verbaarschot, Weidenmüller and Zirnbauer — is considered in the limit of isolated resonances. This means more technically: the correlation between the elmentsS _ab andS _cd ^* of the scattering matrix is calculated in the limit of very small transmission coefficientsT _c in all open channelsc.     

The chirality of exceptional points

Exceptional points are singularities of the spectrum and wave functions of a Hamiltonian which occur as functions of a complex interaction parameter. They are accessible in experiments with dissipative systems. We show that the wave function at an exceptional point is a specific superposition of two configurations. The phase relation between the configurations is equivalent to a chirality which should be detectable in an experiment. Received 9 April 2001 and Received in final form 19 July 2001     

Evaluation of a ruthenium oxyquinolate architecture for dye-sensitized solar cells

Synthesis of the [Ru(dcbpy)(2)(OQN)](+) complex is reported in which dcbpy and OQN(-) are the bidentate 4,4'-dicarboxy-2,2'-bipyridyl and 8-oxyquinolate ligands, respectively. Spectroscopic, electrochemical, and theoretical analyses are indicative of extensive Ru(OQN) molecular orbital overlap due to degenerate Ru d(π) and OQN p(π) mixing. [Ru(dcbpy)(2)(OQN)](+) displays spectroscopic properties remarkably similar to those of the N3 dye, making it a promising candidate for application in dye-sensitized solar cell devices. However, its solar power conversion efficiency requires further optimization.     

Exceptional points in a microwave billiard with time-reversal invariance violation

We report on the experimental study of an exceptional point (EP) in a dissipative microwave billiard with induced time-reversal invariance (T) violation. The associated two-state Hamiltonian is non-Hermitian and nonsymmetric. It is determined experimentally on a narrow grid in a parameter plane around the EP. At the EP the size of T violation is given by the relative phase of the eigenvector components. The eigenvectors are adiabatically transported around the EP, whereupon they gather geometric phases and in addition geometric amplitudes different from unity.     

Autocorrelation function of fluctuating nuclear cross sections in the presence of isospin mixing

Using results derived earlier, we investigate the influence of isospin mixing in the compound nucleus upon the autocorrelation functions for isospin-allowed and isospin-forbidden reactions. We exhibit how these functions depend on the degree of isospin mixing, and that they need not have the simple lorentzian form commonly considered. The available experimental data relating to the compound nucleus ³⁰P are examined in the light of these results.     

Unexpected interference patterns observed in the 12C(14N, 13N)13C reaction at energies close to the Coulomb barrier

The reaction ¹²C(¹⁴N, ¹³N)¹³C has been measured at 28, 32, 34 and 36 MeV beam energies. The energy dependence of the measured interference pattern cannot be reproduced by DWBA calculations which take account of the interference between proton and neutron transfer. A rather strong asymmetry of the angular distributions about θ_c.m. = 90° has been observed.     

Fission characteristics of the composite system 32S+50Ti: (I). Correlations between coincident fragments

The characteristics of “fission-like” processes observed in the bombardment of ⁵⁰Ti with ³²S ions of 140 MeV energy are investigated in a coincidence experiment between a time-of-flight telescope and a position sensitive ΔE-E ionization chamber. Coincident particles were identified and their energy and angular correlations in and normal to the reaction plane were measured. The experiment proves the binary nature of the mass division. Both the width and the average value of the total kinetic energy distribution are consistent with the values extrapolated from fission of heavier nuclei. An average number of 3±1 nucleons are emitted during the reaction; α-particle emission is not an important decay mode.     

HL—1M装置1998年物理实验进展报告

报道了ＨＬ－１Ｍ装置１９９８年度物理实验的进展情况。主要包括等离子体密度极限,中性束注入加热,离子回旋共振加热,低温杂波离子加热,多发弹丸注入,超声分子束注入等实验的情况。