title: Cross-section fluctuations in open microwave billiards and quantum graphs: The counting-of-maxima method revisited.
abstract: The fluctuations exhibited by the cross sections generated in a compound-nucleus reaction or, more generally, in a quantum-chaotic scattering process, when varying the excitation energy or another external parameter, are characterized by the width Γcorr of the cross-section correlation function. Brink and Stephen [Phys. Lett. 5, 77 (1963)] proposed a method for its determination by simply counting the number of maxima featured by the cross sections as a function of the parameter under consideration. They stated that the product of the average number of maxima per unit energy range and Γcorr is constant in the Ercison region of strongly overlapping resonances. We use the analogy between the scattering formalism for compound-nucleus reactions and for microwave resonators to test this method experimentally with unprecedented accuracy using large data sets and propose an analytical description for the regions of isolated and overlapping resonances.
authors.affiliation: Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Dietz
authors.affiliation: Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Richter
authors.affiliation: Indian Institute of Science, Bangalore 560012, India.
authors.forename: R
authors.initials: R
authors.lastname: Samajdar