Generic guidance on the withdrawal of sheltering, withdrawal of evacuation and evacuation of sheltered populations (displacement) has been developed based on previously unpublished work in the UK and France and on input from stakeholder panels in Germany, Belgium, France and the UK. The guidance is a living document that can be developed further in the future, both in its generic form and also as customised versions in some Member States. The guidance outlines the many factors which influence the withdrawal of emergency countermeasures: official confirmation that any release has stopped; adequacy of monitoring data; radiological criteria; radiological protection advice; availability of resources; social and psychological needs; stakeholder dialogue; and communication strategy. The relative importance placed by decision makers on each of these criteria would vary according to the nature and scale of the accident and also on socio-political, economic and cultural perspectives. In the event of a radiological incident, decision makers will need to be in a position to construct a strategy for managing the withdrawal of emergency countermeasures. For larger scale, longer duration releases involving several nuclides, a management strategy is likely to be complex. The guidance therefore includes a series of checklists which have been developed in conjunction with stakeholders to take into account the main criteria and factors which should be considered.

This paper reports on the status of the PHELIX petawatt laser which is built at the Gesellschaft fuer Schwerionenforschung (GSI) in close collaboration with the Lawrence Livermore National Laboratory (LLNL), and the Commissariat à l'Energie Atomique (CEA) in France. First experiments carried out with the chirped pulse amplification (CPA) front-end will also be briefly reviewed.

We used near-field magneto-photoluminescence scanning microscopy to study structural and optical properties of quantum-dot-like compositional fluctuations in GaAsN and InGaAsN alloys. We show that these fluctuations manifest themselves by the appearance of narrow emission lines (halfwidth 0.5−2 meV) at temperatures below 70K. We estimated the size, density, and nitrogen excess of individual compositional fluctuations (clusters), revealing phaseseparation effects in the distribution of nitrogen in GaAsN and InGaAsN. We found a dramatic difference in the Zeeman splitting of cluster lines between GaAsN and InGaAsN, indicating a strong effect of In on the exciton g-factor.

We report an experimental (infrared reflectance spectroscopy) and theoretical study of the polar optical phonons in hexagonal ternary nitride compounds: AlNm/GaNn (n=2-8, m=4, 8) superlattices (SL) and spontaneously ordered AlxGa1−xN (x=0.08–0.55) alloys. In infrared (IR) reflectivity spectra we revealed two modes having strong LO-TO splitting (20–150 cm−1), and several modes, having a small (1–3 cm−1) LO-TO splitting. All modes have a very high damping parameter ≥20 cm−1. The unusual observation is the negative value of the oscillator strength for the weak IR mode at ∼690 cm−1, suggesting possible lattice instability, consistent with high damping observed. We found from lattice dynamical calculations that weak IR active modes correspond to modes localized at GaN-AlN interfaces. Our analysis has shown that an anomalous mode is induced by the disorder effects and arises due to strong overlapping of the LO-TO phonon branches of the bulk GaN and AlN. In SL samples the anomalous mode corresponds to phonons localized on interface inhomogenities.

We present the results of luminescence studies for free-standing CdZnS/ZnS strained layer multi-quantum wells (MQWs). PL measurements of the CdZnS/ZnS MQW at 1.4 K show intense, sharp excitonic emission in blue-ultraviolet spectral region. The band discontinuity is estimated by an analysis of the luminescence results in terms of a finite-potential well model. A free-standing MQW is assumed. The calculated zero-stress band discontinuity is in extremely good agreement with the value from Harrison’s model.

Lithium ion-implantation was performed on ZnSe layers which were grown on GaAs substrates by MBE. Strong photoluminescence emission due to acceptor-bound excitons was observed from samples implanted with lithium doses of up to 1015cm−2 and annealed under optimized conditions for rapid thermal annealing. Lithium implantation results in low damage to the ZnSe as well as the formation of a shallow acceptor level. Thermal degradation of both implanted and unimplanted epilayers caused by the rapid thermal annealing was inviestigated at various annealing temperatures. We find that, under certain annealing conditions, unimplanted samples show greater thermal degradation than lithium implanted samples. The photoluminescence spectrum of an unimplanted sample annealed at 800°C shows considerable degradation; however, a lithium-implanted sample annealed at the same temperature still shows strong luminescence in the excitonic region.

P-type conduction in bulk ZnSe has been achieved using 1×1016 cm−2 nitrogen (N) ionimplantation followed by a high temperature rapid thermal annealing. Room temperature Hall effect measurements of the sample show that the hole concentration is ∼1×1017 cm−3, and the mobility is ∼30 cm2/V-s. Photoluminescence (PL) measurements were performed to study the optical behavior of the samples, and the results show that the ion implantation damage can be partially repaired by thermal annealing at 900°C or higher. Thermal degradation and recovery of the ion-implantation damage were studied as a function of the annealing temperature.

The enhanced disordering of GaAs/AlGaAs superlattices by diffusion of Zn or Si has been reported by many authors. In the case of Si diffusion, the Si can be introduced during epitaxial growth, by implantation, or by diffusion from a sputtered Si mask. In this paper ion implantation is investigated, and the effect of rapid thermal annealing (RTA), used to minimize Si diffusion while eliminating the implant damage, is compared with furnace annealing (FA). Using low temperature photoluminescence (PL) and SIMS, it is found that no disordering of a GaAs/Al0.5Ga0.5As superlattice takes place for a 2 sec anneal at 900°C, and very minimal partial disordering is observed (reproducibly) for a 10 sec anneal at 970°C. This is in sharp contrast with the FA case (850°C for 30 min), for which significant disordering occurs. The PL spectra show luminescence from both GaAs and GaAs/Al0.5Ga0.5As layers in the case of high-temperature RTA suggesting that recrystallization has occurred without disorder, whereas strong emission is observed after FA which corresponds to a disordered layer of average-composition GaAs/Al0.15Ga0.25As In both cases, PL indicates that annealing of the implant damage has occurred. Thus, damage can be eliminated either with or without disordering the superlattice by using FA or RTA, respectively. This is important for 2-D electron gas structures, for which no broadening of the hetero-interface is desired.

The Fe depth distribution has been measured in semi-insulating (SI) InP implanted with Si as a function of implant temperature and post-implant annealing technique (either furnace annealing or rapid thermal annealing). Depth profiles obtained by secondary ion mass spectrometry and Rutherford backscattering measurements of the damage demonstrate that Fe redistributes into regions of residual damage during thermal processing. These results are interpreted in terms of implantation-related damage effects and the stoichiometry imbalance induced by the Si implantation.

The volatilization of technetium in the course of high-level waste vitrification may be considerable, depending on process variations. A series of experiments has been performed in order to gain more insight into the vaporization behavior of Tc during HLLW vitrification. No losses have been observed during chemical denitration or drying of the solutions on a drum drier at moderate temperatures. However, substantial volatilization (40–60 %) occurred during high temperature processing which applied either liquid feeding or feeding as a dehydrated product into the glass melter. Details of parameters investigated are described, and consequences for technical process application are discussed.