IThemba LABS

Somerset East, South Africa

IThemba LABS

Somerset East, South Africa
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Stannard C.,Groote Schuur Hospital | Vernimmen F.,Stellenbosch University | Carrara H.,University of Cape Town | Jones D.,IThemba LABS | And 3 more authors.
Radiotherapy and Oncology | Year: 2013

Background and purpose To evaluate the outcome of malignant salivary gland tumours treated with neutron therapy to assess the potential for other high linear energy transfer (LET) beams. Materials and methods Neutrons at iThemba LABS are produced by the reaction of 66 MeV protons on a beryllium target. A median dose 20.4 Gy, in 12 fractions in 4 weeks or 15 fractions in 5 weeks, was given to 335 patients with 176 irresectable, 104 macroscopically residual and 55 unresected tumours. Results Locoregional control was 60.6% at 5 years and 39.1% at 10 years and DSS was 66.8% and 53.7% at 5 and 10 years respectively. In the univariate analysis T4, >4 cm, high grade, squamous carcinoma, unresected and irresectable tumours, and positive nodes were significantly worse for LRC. In the multivariate analysis tumours >6 cm, squamous carcinoma, irresectable tumours and nodes were significantly worse for LRC. Tumours >6 cm, high grade, squamous carcinoma and nodes were significantly worse for DSS. Neither LRC nor DSS was influenced by age, sex, site, dose, fractionation or for initial or recurrent disease. Conclusions Neutron therapy appears to be the treatment of choice for macroscopically incompletely excised and irresectable salivary gland tumours with improved survival rates. Further improvement may be achieved with other high LET modalities with a superior dose profile, such as carbon ions. © 2013 Elsevier Ireland Ltd. All rights reserved.


Zimmerman W.R.,University of Connecticut | Zimmerman W.R.,Yale University | Destefano N.E.,University of Connecticut | Destefano N.E.,Yale University | And 4 more authors.
Physical Review C - Nuclear Physics | Year: 2011

We measured the 12C(p,p′ )12C* reaction at 25 MeV at the three laboratory angles of 20°, 35°, and 45°. The measured spectra support recent evidence for a new broad 22+ state at 9.6 MeV in 12C, but do not support the claim for such a broad state at 11.1 MeV. © 2011 American Physical Society.


Richter W.A.,IThemba LABS | Richter W.A.,University of the Western Cape | Brown B.A.,Michigan State University | Signoracci A.,Michigan State University | Wiescher M.,University of Notre Dame
Physical Review C - Nuclear Physics | Year: 2011

We present theoretical results for the Al25(p,γ)Si26 resonance-capture rate. The isobaric mass multiplet equation is used to determine the energies and Jπ values of states in Si26 based upon those observed in Mg26 and Al26 together with sd shell calculations for the c coefficients. Three Hamiltonians for the sd shell, USD, USDA and USDB, are used to estimate the theoretical uncertainties in the γ-decay and proton-decay widths that go into the resonance-capture rate. © 2011 American Physical Society.


Comrie A.C.,University of Cape Town | Buffler A.,University of Cape Town | Smit F.D.,IThemba LABS | Wortche H.J.,INCAS
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2015

Three different digital implementations of pulse shape discrimination for pulses from an EJ301 liquid scintillator detector are presented, and illustrated with neutrons and gamma-rays produced by an Am-Be radioisotopic source, a D-T generator and beams produced by cyclotron-accelerated protons of energies 42, 62 and 100 MeV on a Li target. A critical comparison between the three methods is provided. © 2014 Elsevier B.V. All rights reserved.


Richter W.A.,IThemba LABS | Richter W.A.,University of the Western Cape | Brown B.A.,Michigan State University
Physical Review C - Nuclear Physics | Year: 2013

We present results for levels in 30S (the mirror nucleus of 30Si) that are used for the 29P(p,γ) rp reaction rate calculations. The resonance energies used in the reaction rate calculations are based on recent measurements which extend the excitation energy spectrum. The levels are checked against results from the isobaric mass multiplet equation and the binding energies of the T=1 analog states. Where the analog states are not known the levels are calculated with two-body interactions that use the sd-shell interactions USDA and USDB as the charge-independent parts, with a Coulomb, charge-dependent, and charge-asymmetric Hamiltonian added. The γ-decay lifetimes and 29P to 30S spectroscopic factors are also calculated with the same interactions, and together with experimental information on the levels of excited states are used to determine the 29P(p,γ)30S reaction rates. © 2013 American Physical Society.


Lawrie E.A.,iThemba LABS | Shirinda O.,iThemba LABS | Shirinda O.,University of the Western Cape
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2010

The conditions for reaching degeneracy in chiral partner bands built on two-quasiparticle configurations are examined using the two-quasiparticle-plus-triaxial-rotor model. It is shown that in order for degeneracy to occur it is not sufficient to have an aplanar orientation of the total angular momentum, but the angular momenta of the two valence particles need to be completely aligned along the short and long nuclear axes. Such perfect alignment seems impossible to reach with realistic parameters within this model. These results suggest that two-quasiparticle chiral bands may be formed in suitable nuclei, but perfect degeneracy between the partner bands is unlikely to be found. © 2010 Elsevier B.V. All rights reserved.


Richter W.A.,IThemba LABS | Richter W.A.,University of the Western Cape | Brown B.A.,Michigan State University
Physical Review C - Nuclear Physics | Year: 2012

We present results for levels in 36K (the mirror of nucleus 36Ar) that are used in rp reaction rate calculations. The levels are also determined from the isobaric mass multiplet equation and the binding energies of the T=1 analog states as a check on the assignment of spins and parity. Where the analog states are not known, the levels are calculated with two-body interactions that use the sd-shell interactions USDA and USDB as the charge-independent parts, with a Coulomb, charge-dependent, and charge-asymmetric Hamiltonian added. The γ-decay lifetimes and 35Al to 36K spectroscopic factors are calculated with the same interactions, and together with experimental information on the levels of excited states, are used to determine the 35Ar(p,γ)36K reaction rates. © 2012 American Physical Society.


Khenfouch M.,University Sidi Mohammed Ben Abdellah | Baitoul M.,University Sidi Mohammed Ben Abdellah | Maaza M.,IThemba LABS
Optical Materials | Year: 2012

The importance of the white photoluminescence (Pl) with multiple emissions for lighting applications also the attractive optoelectronic properties of graphene and nanostructured zinc oxide (ZnO) are universally known. In this work we present an intense Uv visible blue to red luminescence obtained from our synthesized few layered graphene-zinc oxide (FLG-ZnO) based nanostructures prepared via a sol-gel method using ZnO precursors and a FLG solution. Significant blue-green, yellow-orange moreover, red emissions, from FLG-ZnO deposited on a normal glass substrate, generate a clear white luminescence by their recombination and across the entire visible spectrum. While, to investigate the nanostructure of this system, its interaction and the underlying mechanisms of the broadband photoluminescence, UV-VIS spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) system and photoluminescence spectroscopy (Pl) were used. © 2012 Elsevier B.V. All rights reserved.


Brown B.A.,Michigan State University | Richter W.A.,IThemba LABS | Richter W.A.,University of the Western Cape | Wrede C.,Michigan State University
Physical Review C - Nuclear Physics | Year: 2014

The thermonuclear rate of the reaction P30(p,γ)S31 is important for interpreting nova nucleosynthesis in the A≥30 region. Estimates based on shell-model calculations are complicated by high level density and the presence of negative-parity states in the resonance region near the proton-emission threshold. We present results for the first time of calculations in a full 1 ω model space for the negative-parity states. Spectroscopic factors and proton-decay widths are calculated for input into the reaction rate. Available experimental data are used in conjunction with the calculations to obtain an estimate for the reaction rate. We show that the reaction rate will be uncertain to within about an order of magnitude until the position and decay widths of several of the key states in the region of 6.0 to 6.6 MeV are experimentally determined. © 2014 American Physical Society.


Bossu F.,IThemba LABS
Nuclear Physics A | Year: 2014

ALICE is designed to study ultra-relativistic heavy-ion collisions, where a phase transition to the Quark Gluon Plasma (QGP) is expected. In ALICE, the ϒ{hooked} production can be measured in the di-muon decay channel with the forward muon spectrometer (2.5

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