Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

One of the fundamental axioms of quantum mechanics is associated with the Hermiticity of physical observables 1 . In the case of the Hamiltonian operator, this requirement not only implies real eigenenergies but also guarantees probability conservation. Interestingly, a wide class of non-Hermitian Hamiltonians can still show entirely real spectra. Among these are Hamiltonians respecting parity‐time (PT) symmetry 2‐7 . Even though the Hermiticity of quantum observables was never in doubt, such concepts have motivated discussions on several fronts in physics, including quantum field theories 8 , nonHermitian Anderson models 9 and open quantum systems 10,11 , to mention a few. Although the impact of PT symmetry in these fields is still debated, it has been recently realized that optics can provide a fertile ground where PT-related notions can be implemented and experimentally investigated 12‐15 . In this letter we report the first observation of the behaviour of a PT optical coupled system that judiciously involves a complex index potential. We observe both spontaneous PT symmetry breaking and power oscillations violating left‐right symmetry. Our results may pave the way towards a new class of PT-synthetic materials with intriguing and unexpected properties that rely on non-reciprocal light propagation and tailored transverse energy flow. Before we introduce the concept of spacetime reflection in optics, we first briefly outline some of the basic aspects of this symmetry within the context of quantum mechanics. In general, a Hamiltonian HD p 2 =2mCV(x

/pdf/observation-of-parity-time-symmetry-in-optics-2qb17qrvql.pdf

Observation of parity–time symmetry in optics

Topological photonics is a rapidly emerging field of research in which geometrical and topological ideas are exploited to design and control the behavior of light. Drawing inspiration from the discovery of the quantum Hall effects and topological insulators in condensed matter, recent advances have shown how to engineer analogous effects also for photons, leading to remarkable phenomena such as the robust unidirectional propagation of light, which hold great promise for applications. Thanks to the flexibility and diversity of photonics systems, this field is also opening up new opportunities to realize exotic topological models and to probe and exploit topological effects in new ways. This article reviews experimental and theoretical developments in topological photonics across a wide range of experimental platforms, including photonic crystals, waveguides, metamaterials, cavities, optomechanics, silicon photonics, and circuit QED. A discussion of how changing the dimensionality and symmetries of photonics systems has allowed for the realization of different topological phases is offered, and progress in understanding the interplay of topology with non-Hermitian effects, such as dissipation, is reviewed. As an exciting perspective, topological photonics can be combined with optical nonlinearities, leading toward new collective phenomena and novel strongly correlated states of light, such as an analog of the fractional quantum Hall effect.

Topological Photonics

The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

The Linac Coherent Light Source free-electron laser has now achieved coherent X-ray generation down to a wavelength of 1.2 A and at a brightness that is nearly ten orders of magnitude higher than conventional synchrotrons. Researchers detail the first operation and beam characteristics of the system, which give hope for imaging at atomic spatial and temporal scales.

First lasing and operation of an ångstrom-wavelength free-electron laser

We present a detailed experimental study of the symmetry properties and the momentum space representation of the field distributions of a dielectric square resonator as well as the comparison with a semiclassical model. The experiments have been performed with a flat ceramic microwave resonator and both the resonance spectra and field distributions were measured with different antenna configurations. The momentum space representation allows for a better understanding of the symmetry properties of the field distributions and the determination of the refractive index. The length spectrum deduced from the measured resonance spectrum and the trace formula for the dielectric square resonator are discussed in the framework of the semiclassical model.

Investigation of a Dielectric Square Resonator with Microwave Experiments

(Received5April 1993)Theapplicability of the Monte Carlo program GEANT3 for the calculation of low energy, thick target bremssstrahlung isinvestigated. Theresults of GEANT3,version 15, showvery good correspondence to those of the well established EGS4code. Incontrast it is shown that GEANT3,version 11, leads to erroneousangular distributions, total intensities and even spectral shapesfor angles far from the critical angle. The use of the 115In(,y,y')115In' reaction for an absolute calibration of bremsstrahlungspectra is also demonstrated. This methodrelies onthereconstruction of the isomer yield excitation function from a set of115Inlevels with well characterized properties. It canbe utilized for continuous photon spectra up to about3MeV.1. IntroductionRecently considerable interest has been shown inthe field of resonantphotoabsorption experiments us-ingthicktarget bremsstrahlungwith energies ofseveralMeV. This hasbeen motivated bythe discovery [1] oflow-lying collective magnetic dipole transitions, the socalled "scissors mode"[2], as well as theobservationofenhanced electric dipole transitions in heavydeformednuclei [3]. Forboth problems nuclear resonance fluo-rescence(NRF)provides anideal experimental tool [4].Another field of experimental activity is the investiga-tion of resonant photoexcitation of isomers [5] whichhas an impact on fields as varied as 1'-ray laser re-search [6], nuclear astrophysics [7-10] and nuclearstructure [11-14].While the study of (y,y') reactions has a long his-tory, its usefulness has always been hampered by thelack of experimental methods with adequate accuracyforanabsolute calibration offluxes andspectral distri-butions of intense photon continua. Commonly thesecontinua are thick target bremsstrahlung or Comptonspectra of strong radioactive sources. It has thereforebecome increasinglypopular to useMonteCarlo (MC)simulationswhichprovideanappropriatesolution evenfor complex geometries [15].* Corresponding author.** Worksupportedby the Bundesministeriumfur Forschungund Technologie (BMFT) under contract number06DA641Iandby theDepartmentof Defensethrough theNaval Research Laboratory,.0168-9002/94/$07.00 C1994 - Elsevier Science B.V. All rights reservedSSDI0168-9002(93)E1089-GIn NRFexperiments independent data of "refer-ence" nuclei with well measured transition strengthscovering the relevant excitation energy region can beused for a sampling of the unknown photon spectraandforanormalization of theflux. It wasfound[16,17]that a simulation withthe MCprogram GEANT3[18]described the shapes of the forward thick targetbremsstrahlung spectra rather well. However, investi-gations of the photoexcitation of isomers usually in-volve more complex geometries which lead to a sensi-tivity not only on the spectral shapes, but also on thespectral distributions. Additionally, the total flux mustbeknownto calibrate theexperimental results (see e.g.refs. [5,13]). In this work, the analysis was based onanother electron-photon shower MCprogram, EGS4[19]. Thecode is widely used in medicalphysics and itsbasic correctness hasbeenverified experimentally [20].Athoroughcomparison of theresults obtainedwithboth programs for identical geometries revealed mas-sive differences which questioned the conclusionsdrawn in refs. [16,17]. Therefore, one purpose of thepresent work is adetailed presentation of results fromthecalculations ofthicktarget bremsstrahlungwiththeMCcodes GEANT3 and EGS4. In particular, resultsfromthe recently released version 15 of GEANT3arecompared to those of the earlier version 11, on whichthecalculations described in refs. [16,17] werebased.In the secondpart an experimental method for theabsolute calibration of thick target bremssstrahlungspectra applicable upto endpointenergies Eo =3MeVis presented. It relies onthe measurementof theyieldexcitation function of the 115In isomer obtained in

Absolutecalibration oflow energy,thicktargetbremsstrahlung

The Darmstadt IR FEL is designed to generate wavelengths between 3 and 10 μm and driven by the superconducting electron linear accelerator. The pulsed electron beam has a peak current of 2.7 A leading to a small signal gain of 5%. Currently, investigations of the energy transfer process inside the undulator are performed using the 1D time-dependent simulation code FAST1D-OSC. We present simulation results for the power vs. different desynchronization and tapering parameters as well as a comparison with experimental data from the S-DALINAC IR-FEL. Furthermore, a compact autocorrelation system assuring a background-free measurement of the optical pulse length is described. In a first test experiment at FELIX, the autocorrelator has been tested at wavelengths 5.7 ≤λ≤9.0 μm. The frequency doubling in a 2 mm-long ZnGeP 2 -crystal resulted in a time resolution of 300 fs and a conversion efficiency of 5%.© 2003 Elsevier Science B.V. All rights reserved. PACS: 41.60. Cr; 42.60. Fe; 42.65. Ky; 42.65. Re

/pdf/investigation-of-short-pulse-effects-in-ir-fels-and-new-25nil72rns.pdf

Investigation of short pulse effects in IR FELs and new simulation results

The Superconducting Darmstadt Linear Accelerator (S-DALINAC) is a 130 MeV superconducting recirculating electron accelerator serving several nuclear and radiation physics experiments as well as driving an infrared free-electron laser. For the experiments an energy stability of 10 −4 should be reached. Therefore noninvasive beam position monitors will be used to measure the beam energy. For the measurement the differences in flight time of the electrons to the ideal particle are compared, that means in the simulations the longitudinal dispersion of the beam transport system is used for the energy detection. The results of the simulations show that it is possible to detect an energy difference of 10 −4 with this method. The results are also verified by measurements.

https://epaper.kek.jp/e04/papers/tuplt022.pdf

Beam dynamics simulations at the s-dalinac for the optimal position of beam energy monitors ∗

Examples of recent experiments with microwave resonators in two- and three-dimensions in which we study the quantum manifestation of classical chaos in systems with few degrees of freedom are presented. We show the application of random matrix theory and periodic orbit theory to dierent experimental systems, the spectral features of coupled billiards with varying strength and results on Anderson localization in a simple Bloch-like lattice. ?2001 Elsevier Science B.V. All rights reserved.

/pdf/quantumchaosandwavedynamicalchaosintwo-and-three-3lg2c43buy.pdf

Achim Richter

Papers

Investigation of a Dielectric Square Resonator with Microwave Experiments

Absolutecalibration oflow energy,thicktargetbremsstrahlung

Investigation of short pulse effects in IR FELs and new simulation results

Beam dynamics simulations at the s-dalinac for the optimal position of beam energy monitors ∗

Quantumchaosandwavedynamicalchaosintwo-and three-dimensionalmicrowavebilliards (