Theory of Auger decay by laser-dressed atoms

We devise an ab initio formalism for the quantum dynamics of Auger decay by laser-dressed atoms which are inner-shell ionized by extreme ultraviolet (XUV) light. The optical dressing laser is assumed to be sufficiently weak such that ground-state electrons are neither excited nor ionized by it. However, the laser has a strong effect on continuum electrons which we describe in strong-field approximation with Volkov waves. The XUV light pulse has a low peak intensity and its interaction is treated as a one-photon process. The quantum dynamics of the inner-shell hole creation with subsequent Auger decay is given by equations of motion (EOMs). For this paper, the EOMs are simplified in terms of an essential-states model which is solved analytically and averaged over magnetic subshells. We apply our theory to the M_4,5 N_1 N_2,3 Auger decay of a 3d hole in a krypton atom. The orbitals are approximated by scaled hydrogenic wave functions. A single attosecond pulse produces 3d vacancies which Auger decay in the presence of an 800nm laser with an intensity of 10^13 W / cm^2. We compute the Auger electron spectrum and assess the convergence of the various quantities involved.Comment: 19 pages, 7 figures, 1 table, RevTeX

Ramsey method for Auger-electron interference induced by an attosecond twin pulse

We examine the archetype of an interference experiment for Auger electrons: two electron wave packets are launched by inner-shell ionizing a krypton atom using two attosecond light pulses with a variable time delay. This setting is an attosecond realization of the Ramsey method of separated oscillatory fields. Interference of the two ejected Auger-electron wave packets is predicted, indicating that the coherence between the two pulses is passed to the Auger electrons. For the detection of the interference pattern an accurate coincidence measurement of photo- and Auger electrons is necessary. The method allows one to control inner-shell electron dynamics on an attosecond timescale and represents a sensitive indicator for decoherence.Comment: 5 pages, 5 figures, RevTeX4.1, revise

Functional model-based design of embedded systems with UniTi

Advancing the field of embedded systems requires a rigorous approach to their design. This is because embedded systems are complex, diverse and challenging. Although many tools exist, none support the following four essential features: (i) the modelling of multiple domains, (ii) accurate inclusion of time, (iii) mathematical definitions, and (iv) model transformations. In addition, such a tool must underlie a sound design flow that adequately supports the complexity of designing embedded systems.\ud \ud In this thesis we propose a design flow and a modelling and simulation framework called UniTi that manages complexity in a top-down fashion; a problem is split up into sub-problems that are solved individually and then combined. This design flow and framework is based on model-based design, i.e. a single reference model is iteratively and incrementally developed and refined during the design process. Our approach is a functional approach, not only because it is practical and useful, but also because it has a mathematical basis supported by a functional language, i.e. computations are considered as evaluations of mathematical functions.\ud \ud In this work we specialise the design for the application domain of beamforming applications, for which we propose a generic platform. Two adaptive algorithms for tracking are developed in the context of this platform. A tiled reconfigurable architecture is used, as the tiles provide scalability and reconfigurability provides flexibility. The environment and analogue hardware are represented in the continuous time (CT) domain, while digital hardware is represented in the discrete time (DT) domain and software in the dataflow (DF) domain.\ud \ud We formally define the CT, DT, and DF domains for UniTi. It also supports exact time delays in the CT domain by representing signals as functions of time. Model components, represented as signal transformations, are composed using function composition instead of value-passing, with unified sequential, parallel and feedback composition by re-defining the dataflow model to match with CT and DT components and signals. As a consequence, mixed-domain models are executable for simulation. Finally, UniTi provides support for model transformations.\ud \ud The result of this work is a functional model-based design approach for designing, modelling, and simulation of embedded systems

GSCC targeted inspections of Approved Mental Health Professionals (AMHP) courses in England (2011-12)

The General Social Care Council (GSCC) has duties under Section 19 of the Mental Health Act 2007 to approve Approved Mental Health Profession (AMHP) training. This function will transfer to the Health Professions Council on 31 July 2012. The GSCC carried out a targeted inspection between March 2011 and February 2012 of all 22 AMHP programmes across England. This was to ensure at the point of transfer all courses were sufficiently meeting standards. There had been a number of issues and concerns raised about inconsistencies in the quality of AMHP programmes. The inspection process involved consulting all stakeholders concerned in delivering and using the programmes, including AMHP candidates, service users and carers. Each programme has their inspection report on the GSCC website. The key findings of these inspections are that the majority of the 22 programmes are meeting the standards expected and where they are not, action has been taken to ensure that prior to transfer of the GSCC’s AMHP inspection function, all programmes will meet the standards and not require regulatory intervention. There is inconsistency in the length and attached credit of each AMHP programme, although this did not seem to impair the threshold standard required for being competent in the AMHP role. This composite report features the overall outputs from the inspections

Differences in the Vertical and Microphysical Evolution of Volcanic and Pyrocumulonimbus Stratospheric Aerosol Plumes as Observed by CALIOP and CATS Satellite Lidar

For some time, volcanic eruptions have been thought to be the only significant direct injectors of aerosols in the stratosphere. However, recent fire seasons have featured fire events resulting in large volcanic-sized pyrocumulonimbus plumes of smoke aerosols reaching many kilometers into the lower stratosphere. To understand and model the effects of these pyrocumulonimbus events on stratospheric composition and climate, a natural analogy lies with better studied volcanic events; however, differences in plume composition may limit this comparison. Using satellite lidar from both CATS and CALIOP, we show that the stratospheric aerosol plumes from the record-setting Pacific Northwest pyrocumulonimbus event of 2017 and the Calbuco volcanic eruption of 2015 evolve differently both vertically and microphysically. Specifically, depolarization ratios indicate that this pyrocumulonimbus events aerosol particles became more irregularly shaped over time in contrast to volcanic aerosols which become more spherical over time. Accounting for these changes in aerosol properties may be significant in assessing the effects of pyrocumulonimbus events on the Earths radiative balance and aid in refining stratospheric aerosol typing algorithms to differentiate volcanic from pyrocumulonimbus plumes

A four-lidar view of Cirrus from the FIRE IFO: 27-28 October 1986

The four ground-based lidar systems that participated in the 1986 FIRE IFO were configured in a diamond-shaped array across central and southern Wisconsin. Data were generally collected in the zenith pointing mode, except for the Doppler lidar, which regularly operated in a scanning mode with intermittent zenith observations. As a component of the cirrus case study of 27 and 28 October 1986 selected for initial analysis, data collected by the remote sensor ensemble from 1600 (on the 27th) to 2400 UTC (on the 28th) is described and compared. In general, the cirrus studied on the 27th consisted of intermittent layers of thin and subvisual cirrus clouds. Particularly at Wausau, subvisual cirrus was detected from 11.0 to 11.5 km MSL, just below the tropopause. At lower levels, occasional cirrus clouds between approx. 8.0 to 9.5 km were detected from all ground sites. Preliminary analysis of the four-lidar dataset reveals the passage of surprisingly consistent cloud features across the experiment area. A variety of types and amounts of middle and high level clouds occurred, ranging from subvisual cirrus to deep cloud bands. It is expected that the ground-based lidar measurements from this case study, as well as the airborne observations, will provide an excellent data base for comparison to satellite observations

Auger decay in krypton induced by attosecond pulse trains and twin pulses

Using attoscience, we study the electron correlations responsible for Auger decay in krypton atoms. The Auger decay is induced by a pulse train or a twin pulse composed of subpulses of attosecond duration. During the Auger decay an optical dressing laser may be present. Interference effects between the ejected Auger electron wave packets are predicted

Lidar cloud studies for FIRE and ECLIPS

Optical remote sensing measurements of cirrus cloud properties were collected by one airborne and four ground-based lidar systems over a 32 h period during this case study from the First ISCCP (International Satellite Cloud Climatology Program) Regional Experiment (FIRE) Intensive Field Observation (IFO) program. The lidar systems were variously equipped to collect linear depolarization, intrinsically calibrated backscatter, and Doppler velocity information. Data presented describe the temporal evolution and spatial distribution of cirrus clouds over an area encompassing southern and central Wisconsin. The cirrus cloud types include: dissipating subvisual and thin fibrous cirrus cloud bands, an isolated mesoscale uncinus complex (MUC), a large-scale deep cloud that developed into an organized cirrus structure within the lidar array, and a series of intensifying mesoscale cirrus cloud masses. Although the cirrus frequently developed in the vertical from particle fall-streaks emanating from generating regions at or near cloud tops, glaciating supercooled (-30 to -35 C) altocumulus clouds contributed to the production of ice mass at the base of the deep cirrus cloud, apparently even through riming, and other mechanisms involving evaporation, wave motions, and radiative effects are indicated. The generating regions ranged in scale from approximately 1.0 km cirrus uncinus cells, to organized MUC structures up to approximately 120 km across