Thermo-optical tuning of whispering gallery modes in Er:Yb co-doped phosphate glass microspheres

We demonstrate an all-optical, thermally assisted technique for broad-range tuning of whispering gallery modes in microsphere resonators fabricated from an Er:Yb co-doped phosphate glass (IOG-2). The microspheres are pumped at 978 nm and the heat generated by absorption of the pump expands the cavity, thereby altering the cavity size and refractive index. We demonstrate a significant nonlinear tuning range of greater than 700 GHz of both C- and L-band cavity emissions via pumping through a tapered optical fibre. Finally, we show that large linear tuning up to ∼488 GHz is achievable if the microsphere is alternatively heated by coupling laser light into its support stem.     

A Diffusion Approximation for a Markovian Queue with Reneging

Consider a single-server queue with a Poisson arrival process and exponential processing times in which each customer independently reneges after an exponentially distributed amount of time. We establish that this system can be approximated by either a reflected Ornstein–Uhlenbeck process or a reflected affine diffusion when the arrival rate exceeds or is close to the processing rate and the reneging rate is close to 0. We further compare the quality of the steady-state distribution approximations suggested by each diffusion.     

Kaon production in\bar pp interactions at c.m. energies from 200 to 900 GeV

A detailed analysis ofK _s ⁰ production in \(\bar pp\) |<2.5 the average transverse momentum is found to be 0.53±0.07 GeV/c at 200 GeV and 0.62±0.08 GeV/c at 900 GeV, which is an increase with respect to data at c.m. energies below 60 GeV. TheK _s ⁰ production cross sections in inelastic collisions are 29±4 mb at 200 GeV and 63±6 mb at 900 GeV, showing an increase compared to lower energy data. The central kaon density is found to increase as a logarithmic function of energy. At 900 GeV, where statistics are sufficient to allow one to draw conclusions, the average transverse momentum is higher in events with large charged multiplicity than in events with low multiplicity.     

The search for organically bonded iron in New Zealand brown coals

Brown coal from two areas in New Zealand was treated with acids (HF and HCl) to remove the clays. Iron was then introduced into the “cleaned” coal by ion exchange. Mössbauer spectra of the untreated coal, the low temperature ash of the coal, “cleaned” coal and ion-exchanged coal were analysed. From these spectra we conclude that a pair of lines with QS～1 mm s^?1 and IS～0.45 mm s^?1 is probably due to organically bonded iron.     

Studies on Rare-Earth/Iron and Actinide/Iron Multilayers

Hyperfine Interactions - Multilayers of Ce/Fe and U/Fe were fabricated by sputtering and studied by X-ray diffraction and reflectivity, Mössbauer spectroscopy and polarised neutron...     

The drawing behavior of linear polyethylene: Effect of electron irradiation on drawing and subsequent mechanical behavior of drawn products

Isotropic monofilaments of linear polyethylene were subjected to electron irradiation in different atmospheres at a range of dose levels. It was found that the gel content remained very small up to a dose of about 2.5 Mrad (the gel point), and thereafter increased with irradiation dose in a manner similar to that found by other workers. Drawing of the irradiated filaments was very dependent on dose level, and high draw ratios of 30:1 could not be obtained above the gel point. Although irradiation of the spun monofilaments increased the initial tensile modulus of the drawn material to a small extent, neither the tensile strength nor the shear strength of the monofilaments (the latter measured with a pull-out adhesion technique) was significantly affected. On the other hand, the tensile strain at failure decreased dramatically as the irradiation dose was increased. The results are discussed in terms of our present state of knowledge regarding the structure and properties of highly drawn linear polyethylene, taking into consideration the cross-linking produced by the irradiation.