No abstract

Advice was published in 2005 (NRPB 2005 Doc. NRPB 16 1-29) to provide a framework for the protection of on-site personnel who are not involved in mitigating actions in the event of a radiation accident. Such persons could include employees of the site operator, contractors and visitors. Following on from this advice, the HPA has developed additional on-site protection guidance (Watson et al 2007 Report to HSE) (the guidance produced by Watson et al (2007) was written as a commercial contract report for the Health and Safety Executive. Parties who have relevant interest in this guidance, or who wish to comment on it, can request a copy from the HPA). The issues discussed are protection of the unborn child, measures to protect against serious deterministic injury and high individual risk of stochastic effects, implications of off-site and public exposure considerations, and development of on-site neighbouring areas. In each case particular thought is required to ensure that protective measures are efficient and do not lead to any discontinuities in the level of protection offered. Although not formal HPA advice, the new guidance is intended to aid discussions between operators and regulators.

No abstract

No abstract

Detailed comparisons are made of the results of two approaches to the problem of nonlinear refraction at frequencies just below the band edge in semiconductors. The physical origin o f the nonlinear dispersion is taken to be direct saturation of independent, T 2 -broadened band states in the first model discussed. In the second model the refraction associated with a dynamic Burstein-Moss shift of the absorption edge is considered. Both models predict an extremely large nonlinearity, X (3) ≈ 1 e. s. u., of importance in the field of dispersive optical bistability and consistent with experimental observations of bistability, two-beam differential gain and four-wave mixing.