Photon collisions with atoms and ions within an intermediate-energy R-matrix framework

Recent experimental advances in light technology necessitate the availability of sophisticated theoretical models which can incorporate an accurate treatment of double-electron continua. We describe here a new intermediate-energy R-matrix approach to photoionisation and photo-double-ionisation and illustrate its feasibilty by application to photoionisation and photo-double-ionisation of He, and photodetachment and photo-double-detachment of H^-. Results are shown to be in excellent agreement with previous theoretical and experimental studies. This work is a key step in the development of a multipurpose R-matrix code for multiple-electron ejection. © 2012 American Physical Society

Structure and interactions of ultracold Yb ions and Rb atoms

In order to study ultracold charge-transfer processes in hybrid atom-ion traps, we have mapped out the potential-energy curves and molecular parameters for several low-lying states of the Rb, Yb+ system. We employ both a multireference configuration interaction and a full configuration interaction (FCI) approach. Turning points, crossing points, potential minima, and spectroscopic molecular constants are obtained for the lowest five molecular states. Long-range parameters, including the dispersion coefficients, are estimated from our ab initio data. The separated-atom ionization potentials and atomic polarizability of the ytterbium atom (ad=128.4 atomic units) are in good agreement with experiment and previous calculations. We present some dynamical calculations for (adiabatic) scattering lengths for the two lowest (Yb, Rb+) channels that were carried out in our work. However, we find that the pseudopotential approximation is rather limited in validity and only applies to nK temperatures. The adiabatic scattering lengths for both the triplet and singlet channels indicate that both are large and negative in the FCI approximation.

Cavity cooling of atoms: Within and without a cavity

We compare the efficiencies of two optical cooling schemes, where a single particle is either inside or outside an optical cavity, under experimentally-realisable conditions. We evaluate the cooling forces using the general solution of a transfer matrix method for a moving scatterer inside a general one-dimensional system composed of immobile optical elements. Assuming the same atomic saturation parameter, we find that the two cooling schemes provide cooling forces and equilibrium temperatures of comparable magnitude.

Scattering theory of multilevel atoms interacting with arbitrary radiation fields

We present a generic transfer matrix approach for the description of the interaction of atoms possessing multiple ground state and excited state sublevels with light fields. This model allows us to treat multi-level atoms as classical scatterers in light fields modified by, in principle, arbitrarily complex optical components such as mirrors, resonators, dispersive or dichroic elements, or filters. We verify our formalism for two prototypical sub-Doppler cooling mechanisms and show that it agrees with the standard literature.

Magneto-optical trapping and background-free imaging for atoms near nanostructured surfaces

We demonstrate a combined magneto-optical trap and imaging system that is suitable for the investigation of cold atoms near surfaces. In particular, we are able to trap atoms close to optically scattering surfaces and to image them with an excellent signal-to-noise ratio. We also demonstrate a simple magneto-optical atom cloud launching method. We anticipate that this system will be useful for a range of experimental studies of novel atom-surface interactions and atom trap miniaturization.

Strategies for Effective Management of Health and Safety in Confined Site Construction

The overall aim of this research is to identify and catalogue the numerous managerial strategies for effective management of health and safety on a confined, urban, construction site. A mixed methods methodology was adopted using interviews and focus group discussions on three selected case studies of confined construction sites. In addition to these, a questionnaire survey was used based on the findings from the interviews and the focus group discussions. The top five key strategies include (1) Employ safe system of work plans to mitigate personnel health and safety issues; (2) Inform personnel, before starting on-site, of the potential issues using site inductions; (3) Effective communication among site personnel; (4) Draft and implement an effective design site layout prior to starting on-site; and (5) Use of banksman (traffic co-ordinator) to segregate personnel from vehicular traffic. The construction sector is one of the leading industries in accident causation and with the continued development and regeneration of our urban centres, confined site construction is quickly becoming the norm - an environment which only fuels accident creation within the construction sector. This research aids on-site management that requires direction and assistance in the identification and implementation of key strategies for the management of health and safety, particularly in confined construction site environments.

Thomson spectrometer-microchannel plate assembly calibration for MeV-range positive and negative ions, and neutral atoms

We report on the absolute calibration of a microchannel plate (MCP) detector, used in conjunction with a Thomson parabola spectrometer. The calibration delivers the relation between a registered count numbers in the CCD camera (on which the MCP phosphor screen is imaged) and the number of ions incident on MCP. The particle response of the MCP is evaluated for positive, negative, and neutral particles at energies below 1 MeV. As the response of MCP depends on the energy and the species of the ions, the calibration is fundamental for the correct interpretation of the experimental results. The calibration method and arrangement exploits the unique emission symmetry of a specific source of fast ions and atoms driven by a high power laser.

Supply Chain Management in Confined Site Construction: Strategies to Reduce Delay in the Delivery of Materials to Site

With the increase in construction in dense urban environments, the delays associated with managing the material supply chain to site is called into question. Purpose: The aim of this investigation is to gain the perspective of construction contractors operating in a dense urban environment and the resulting strategies adopted to reduce delays in the delivery of materials to site. Methodology: This is achieved through incorporating a comprehensive literature review on the subject in conjunction with industry interviews with construction professionals in the identification of various management issues and corresponding strategies in the reduction of delays in the delivery of materials to site. Findings: The key issue which emerges is the lack of space for unloading bays while the corresponding key strategy is to schedule deliveries outside peak congestion times. Practical Implication: With confined site construction evident throughout the industry and the noted importance of an effective supply chain, the findings here in further assist on-site management in the daily task of ensuring the effective delivery and off-loading of materials in a complex and hazardous environment. Originality/Value: This research aids on-site management of confined site environments in the coordination of the material supply chain to site.

Confined Site Construction and its Impact on Personnel Productivity

Inner city, confined site construction is quickly becoming the norm within the construction sector. The aim of this paper is to identify and document the effect, if any, that a confined construction site environment has on the productivity of on-site personnel. In order to compile the relevant information and attain appropriate results on the matter in question, a qualitative analytical approach is adopted. This process incorporates multiple cases studies from Ireland, Northern Ireland and USA. From the resulting case studies, a minimum of three individual interviews and focus group seminars are conducted to aid in the collection of the data while also assisting in the confirmation of the factors identified from a critique of the relevant literature. From the resulting case studies and discussions, a list of the key issues pertaining to the on-site productivity of personnel emerged and is documented as follows; 1) Overcrowding of personnel at workstations, 2) Lack of space for the effective movement of personnel on-site, 3) Numerous trades working within the one space on-site. Through identifying the issues highlighted and proactively mitigating or eliminating the factors detailed, on-site management professionals can strive to ensure maximum productivity from the industry’s most important resource – people.

Material Management in Confined Site Construction

The objective of this paper is to identify various managerial issues encountered and resulting strategies adopted, with regards management of materials on confined construction site. This is achieved through classifying the various managerial burdens encountered with the numerous strategies adopted, for the successful management of such confined environments within the realm of materials management.


Through conducting an extensive literature review and detailed interviews, a comprehensive insight into the materials management concerns within a confined construction site environment is envisaged and portrayed. The following are the leading issues highlighted; (1)Lack of adequate storage space, (2)Work place becoming over-crowded, (3)Lack of adequate room for the effective handling of materials and (4)Difficult to transport materials around site. The leading managerial strategies to the management of materials on confined construction sites may be listed in order of importance, as follows; (1)Pre-fabrication and pre-assembly, (2)Providing adequate storage, (3)Space scheduling, (4)Just-In-Time delivery techniques, and (5)Effective design site layout.

Based on the research conducted, it can be concluded, that through effective management of the issues identified along with implementing the various strategies highlighted; successful materials management within a confined construction site environment is attainable.


Innovative Aspect of Paper: An empirical study of three different construction sites in three different countries (Ireland, England and USA) investigating the managerial issues and strategies relating to implementation of materials management in confined construction sites.