Robert Martin Adam

National Research Foundation, South Africa | NRF · SA SKA Radio Telescope

The inner ∼200 pc region of the Galaxy contains a 4 million M ⊙ supermassive black hole (SMBH), significant quantities of molecular gas, and star formation and cosmic-ray energy densities that are roughly two orders of magnitude higher than the corresponding levels in the Galactic disk. At a distance of only 8.2 kpc, the region presents astronomers...

The inner $\sim$200 pc region of the Galaxy contains a 4 million M$_{\odot}$ supermassive black hole (SMBH), significant quantities of molecular gas, and star formation and cosmic ray energy densities that are roughly two orders of magnitude higher than the corresponding levels in the Galactic disk. At a distance of only 8.2 kpc, the region present...

MeerKAT's large number of antennas, spanning 8 km with a densely packed 1 km core, create a powerful instrument for wide-area surveys, with high sensitivity over a wide range of angular scales. The MeerKAT Galaxy Cluster Legacy Survey (MGCLS) is a programme of long-track MeerKAT L-band (900-1670 MHz) observations of 115 galaxy clusters, observed fo...

To cite this article: R. M. Adam (2020): Technology, policy and politics: critical success factors in high-technology infrastructure projects, Social Dynamics, ABSTRACT The article examines critical success factors in high technology projects by comparing the Square Kilometre Array, the Pebble Bed Modular Reactor and the Reactor Conversion Project...

We present the confusion-limited 1.28 GHz MeerKAT DEEP2 image covering one $\approx 68'$ FWHM primary beam area with $7.6''$ FWHM resolution and $0.55 \pm 0.01$ $\mu$Jy/beam rms noise. Its J2000 center position $\alpha=04^h 13^m 26.4^s$, $\delta=-80^\circ 00' 00''$ was selected to minimize artifacts caused by bright sources. We introduce the new 64...

The Galactic Centre contains a supermassive black hole with a mass of 4 million suns within an environment that differs markedly from that of the Galactic disk. While the black hole is essentially quiescent in the broader context of active galactic nuclei, X-ray observations have provided evidence for energetic outbursts from its surroundings. Also...

The Galactic Centre contains a supermassive black hole with a mass of four million Suns¹ within an environment that differs markedly from that of the Galactic disk. Although the black hole is essentially quiescent in the broader context of active galactic nuclei, X-ray observations have provided evidence for energetic outbursts from its surrounding...

New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100x larger than during its dormant state. The X-ray flux...

We study the ground-state and the low-lying excitations of a trapped Bose gas in an isotropic harmonic potential for very small (\(\sim \)3) to very large (\(\sim \)\(10^7\)) particle numbers. We use the two-body correlated basis functions and the shape-dependent van der Waals interaction in our many-body calculations. We present an exhaustive stud...

We investigate the quantum mechanical system of a carbon “test atom” in the proximity of a C60 molecule, both inside and outside the fullerene “cage”. Two sets of bound states are found to exist, a deeply bound set inside the cage and another weakly bound set outside it. Tunnelling between these regions is highly unlikely to happen because of the e...

We employ a hypervirial method within the few-body integro-differential equation approach to investigate cluster-structuring in a variety of hyper-nuclear and mesic-nuclear systems. We use this to investigate the possibility of the existence of the H-dibaryon as a stable subsystem within a larger hypernuclear system. To this end a series of alpha-c...

We study the ground state and the low-lying excitations of interacting Bose gas trapped in an isotropic harmonic potential for very small (N ∼ 3) to very large particle number (N ∼ 107 ). We use the correlated two-body basis function and shape dependent van der Waals interaction in our many-body calculation. We investigate the effect of inteatomic...

The ground-state energy of the double-Λ hypernucleus ΛΛ11Be is calculated within the frame-work of the five-body model ααnΛΛ. The five-body nucleus is described using the Faddeev formalism for the unequal mass clusters involved and the potential harmonics expansion of the corresponding amplitudes. The resulting coupled differential equations depend...

The ground-state energy of the double-I > hypernucleus (I > I >) (11) Be is calculated within the frame-work of the five-body model alpha alpha nI > I >. The five-body nucleus is described using the Faddeev formalism for the unequal mass clusters involved and the potential harmonics expansion of the corresponding amplitudes. The resulting coupled d...

We calculate the ground-state energy and the collective excitation frequency of trapped bosons at large scattering length interacting via the realistic two-body van der Waals potential. Our many-body method keeps two-body correlations produced by all interacting pairs. When the scattering length is small compared to the trap size and the number of...

A simple method to calculate ground state energies for a typical condensates containing up to A ~ 107 atoms is presented. The method, based on the expansion of the wave function in terms of the Faddeev components, which in turn are expanded in terms of potential harmonics is numerically efficient. We obtain ground state results for condensates of 8...

A two-body correlated basis set is used to develop a many-body theory which is valid for any number of bosons in the trap. The formalism incorporates the van der Waals interaction and two-body correlations in an exact way. The theory has successfully been applied to Bose-Einstein condensates—dilute weakly interacting and also dilute but having a la...

We present a formalism describing the bound state of a large number of bosons and apply it to study nuclei consisting of A α particles. The method has its roots in a few-body approach and is based on the expansion of the many-body Faddeev components in Potential Harmonics, and the subsequent reduction of the Faddeev equation into a two-variable, in...

The description of nuclei as a system of α particles is considered using a two-variable integrodifferential equation describing A-boson systems. The method is based on the assumption that two-body forces are the dominant ones within the system. This allows the expansion of the A-body wave function in Faddeev components which in turn can be expanded...

We present a Faddeev-type coupled integrodifferential equations describing unequal mass A-particle systems. The equations are obtained by assuming an expansion of the A-particle wave function in Faddeev amplitudes which, in turn, are expanded in terms of Potential Harmonics. By projecting the resulting system on rij-space we obtained a system of co...

We use the assumption that the potential for the A-boson system can be written as a sum of pairwise acting forces to decompose the wave function into Faddeev components that fulfill a Faddeev type equation. Expanding these components in terms of potential harmonic (PH) polynomials and projecting on the potential basis for a specific pair of particl...

We present a two-variable integro-differential equation describing bound systems of unequal mass particles. The method is based on an extension of the two-variable integro-differential equations in the D = 3(A − 1)-dimensional space, known as IDEA, describing the bound states of A-body systems. This method has been successfully applied in the past...

We present an integro-differential equation describing systems with large number of bosons. The new equation includes the two-body correlations exactly into account and the kernel has a simple analytic form. The equation has been employed to obtain results for A Î {10,100}{A\in\{10,100\}} 87Rb atoms confined by an externally applied trapping potent...

The two-variable Integrodifferential Equation Approach (IDEA) valid for A nucleons is generalized to describe quantum mechanical systems consisting of A, unequal mass, particles. The method is based on an expansion of the wave function in Faddeev amplitudes for the various particle pairs and a subsequent expansion of them in terms of Potential Harm...

We present a Faddeev-type coupled integrodifferential equations describing unequal mass A-particle systems. The equations are obtained by assuming an expansion of the A-particle wave function in Faddeev amplitudes which, in turn, are expanded in terms of Potential Harmonics. By projecting the resulting system on rij-space we obtained a system of co...

A relaxation method to obtain exact solutions for the two-dimensional integro-differential equations encountered in Few-Body Systems is proposed. The method has been tested by solving the integro-differential equation (IDEA) for three-, four-, and sixteen-bosons with soft and hard core two-body potentials. The results obtained are excellent and com...

The Integrodifferential Equation Approach (IDEA) to many-body quantum mechanical systems involves projecting the Hilbert space onto a basis set of hyperspherical harmonic functions and is exact if higher than two-body correlations are excluded from the dynamics. In the current work the IDEA is extended to systems of unequal masses and this generali...

http://www.ctwatch.org/quarterly/articles/2006/02/high-performance-computing-in-south-africa-computing-in-support-of-african-development/

AIP Conference Proceedings 768(1), 235 (2005) DOI: http://doi.org/10.1063/1.1932920

We present a method based on hyperspherical harmonics to solve the nuclear many-body problem. It is an extension of accurate methods used for studying few-body systems to many bodies and is based on the assumption that nucleons in nuclei interact mainly via pairwise forces. This leads to a two-variable integro-differential equation which is easy to...

The effect of antisymmetrization in diquark models of baryons composed of light (u&d) quarks is investigated. The diquark in this study is considered alternately as a point-like and as a composite particle where antisymmetrization is taken into account by means of Generator Coordinate Model operator kernels. The effect on ground state masses and fo...

Models for national systems of innovation generally involve the interaction of a strong science base with local industry. However, in developing countries the term "science base" may be over-optimistic. Instead, at best we have isolated peaks of scientific excellence. Is it possible to optimise this configuration of peaks to support national develo...

The authors show that for the 4He ground state and effective potentials the integrodifferential equation approach (IDEA) produces binding energies which are more accurate than those calculated using a harmonic oscillator shell model basis and requires little numerical effort. This is because the IDEA employs the potential harmonic (PH) basis which...

The authors extend the integro-differential equation approach (IDEA) from few nucleon to closed-shell and closed-subshell nuclei and outline the analytical methods required for the calculation of the density functions, which enter into the integro-differential equations. These contain all the physics for a system of fermions associated with the Pau...

The authors have extended the integrodifferential equation approach (IDEA) to systems of nonidentical particles and thereby calculated binding energies for the hypernuclei Lambda5He (modelled as a five-body (4N) Lambda system) and Lambda Lambda6He (modelled both as a three-body alpha Lambda Lambda system and as a six-body (4N) Lambda Lambda system)...

Inverse scattering methods based on exactly solvable models have been used to determine specific momentum dependent nucleon-nucleon potentials from nucleon-nucleon phase shifts in uncoupled partial waves. The novel method has been applied to the 1S0 channel. The explicit momentum dependencies considered are restricted to those of the well known par...

We demonstrate how the parameterized proton elastic charge form factor may be used to determine the quark-quark interaction assuming a constituent-quark model of the nucleon and non-relativistic kinematics. The relation between the hypercentral component of the three-quark bound-state wave function and the charge density is obtained by using an Abe...

We have recently shown, assuming nonrelativistic kinematics, that the parametrized elastic charge form factor data for an {ital N}-particle system may be used to determine the underlying two-particle interaction. We now extend the validity of our formalism, using the prescription of Mitra and Kumari, to include relativistic kinematics, and apply it...

Just as $^3\roarrow{\rm He}$ can be approximately characterized as a polarized neutron target, polarized \Li6D has been advocated as a good {\em isoscalar} nuclear target for the extraction of the polarized gluon content of the nucleon. The original argument rests upon a presumed ``alpha + deuteron'' picture of \Li6, with the polarization of the nu...

We present a new method, based on the hypervirial operator, for calculating expectation values of many-body Hamiltonians for local velocity-independent potentials. Our approach enables us to calculate the contributions of different components of an interaction [e.g., tensor, one pion exchange part (OPEP)] to the binding energy when all components a...

The correction to the mass for the spurious centre-of-mass motion in a three-quark system is calculated exactly in the nonrelativistic constituent quark model for the Cornell potential. The result is somewhat higher than MIT bag model estimates but similar to that of a soliton bag model and a relativistic oscillator model.

Just as 3--> can be approximately characterized as a polarized neutron target, polarized 6LiD has been advocated as a good isoscalar nuclear target for the extraction of the polarized gluon content of the nucleon. The original argument rests upon a presumed ``alpha + deuteron'' picture of 6Li, with the polarization of the nucleus carried by the pol...

Using inverse-scattering methods we determine a statistical distribution of 1S0 potentials from the experimental phase-shift errors. The propagation of such errors in few-nucleon systems is investigated by calculating the corresponding triton and α-particle binding energies Et and Eα. For this purpose we replace the Reid-soft-core 1S0 potential by...

We show that the removal of Pauli forbidden s-states in the local alpha-alpha potential of Buck et al., by means of successive supersymmetric transformations, leads to a simultaneous removal of groups of ``unphysical'' states of the 3alpha- and 4alpha-systems, but that the remaining states are largely unaffected. Potentials of different strength bu...

This doctoral dissertation looks at the structures of various light nuclei in the Integrodifferential Equation Approach (IDEA). This approach uses a hyperspherical harmonics basis (the PH basis) onto which a Faddeev type many body equation is projected. The resulting Schrodinger wave function is exact for up to two body correlations.