H. L. Harney

EVIDENCE FOR NEUTRINOLESS DOUBLE BETA DECAY

The data of the Heidelberg–Moscow double beta decay experiment for the measuring period August 1990–May 2000 (54.9813 kg y or 723.44 molyears), published recently, are analyzed using the potential of the Bayesian method for low counting rates. First evidence for neutrinoless double beta decay is observed giving first evidence for lepton number violation. The evidence for this decay mode is 97% (2.2σ) with the Bayesian method, and 99.8% c.l. (3.1σ) with the method recommended by the Particle Data Group. The half-life of the process is found with the Bayesian method to be

PT Symmetry and Spontaneous Symmetry Breaking in a Microwave Billiard

T_{1/2}^{0\nu} = (0.8\hbox{--}18.3)\times 10^{25}~{\rm y}

The chirality of exceptional points

(95% c.l.) with a best value of 1.5 × 1025y. The deduced value of the effective neutrino mass is, with the nuclear matrix elements from Ref. 1, = (0.11–0.56) eV (95% c.l.), with a best value of 0.39 eV. Uncertainties in the nuclear matrix elements may widen the range given for the effective neutrino mass by at most a factor 2. Our observation which at the same time means evide...

Spectroscopic factors from analogue resonances

We demonstrate the presence of parity-time (PT) symmetry for the non-Hermitian two-state Hamiltonian of a dissipative microwave billiard in the vicinity of an exceptional point (EP). The shape of the billiard depends on two parameters. The Hamiltonian is determined from the measured resonance spectrum on a fine grid in the parameter plane. After applying a purely imaginary diagonal shift to the Hamiltonian, its eigenvalues are either real or complex conjugate on a curve, which passes through the EP. An appropriate basis choice reveals its PT symmetry. Spontaneous symmetry breaking occurs at the EP.

Exceptional Points in a Microwave Billiard with Time-Reversal Invariance Violation

Abstract: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.

Fission characteristics of the composite system 32S + 50Ti: (II). Energy and angular dependence

Abstract Three methods for the determination of spectroscopic factors from data on isobaric analogue resonances (IAR) are compared It is shown numerically that, in general, all three lead to different values of the spectroscopic factor. The differences amount to as much as 50% if the same potentials are used The reasons for these differences are exhibited, and their physical origin is discussed It turns out that the discrepancies arise from (1) the treatment of internal mixing, (11) the statistical assumptions which are introduced in order to perform the averaging over the fine structure of the IAR, (111) the treatment of a single-particle resonance which often occurs in the proton channel some MeV below the IAR. The differences could partly be resolved if the resonance mixing phase could be determined experimentally

Reaction and fusion cross sections for 32S on 27Al and 48Ti

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.

An approximate treatment of recoil effects in heavy ion transfer reactions

Abstract Angular distributions, mass distributions and excitation functions have been measured for the heavy fragments 35 ≦ A ≦ 60 produced in the bombardment of 50 Ti by 32 S at beam energies between 121 and 166 MeV. The angular distributions are of the form ( sinθ ) −1 for all masses, although slight deviations do occur. The mass distributions exhibit a striking energy dependence with a strong trend towards symmetric mass divisions at high energies. The excitation functions agree qualitatively with the predictions of the rotating liquid drop model.

A statistical model analysis of fluctuations in the elastic and inelastic proton scattering on 54Cr and 56Fe

Abstract Elastic scattering and evaporation residues have been measured for the system 32 S + 27 Al at E c.m. = 66.4, 73.2 MeV and 32 S + 48 Ti at E c.m. = 96.0 MeV. Reaction cross sections have been obtained by use of the optical theorem and are found to be about 60 % larger than the fusion cross sections.

Quantum Chaotic Scattering in Microwave Resonators

Abstract A DWBA formalism is developed that allows for recoil and finite range effects in transfer reactions between heavy ions. Under the assumption of strong absorption and with a local momentum approximation a formula for the transition matrix element is derived that may be incorporated into conventional DWBA codes. Additional complications essentially appear in the angular momentum structure which allows for both natural and unnatural angular momentum transfers. Both target and projectile are treated symmetrically. The approximations specific to the present treatment are thoroughly discussed and shown to be realistic.