A novel method for characterising the full spectrum of deuteron ions emitted by laser driven multi-species ion sources is discussed. The procedure is based on using differential filtering over the detector of a Thompson parabola ion spectrometer, which enables discrimination of deuterium ions from heavier ion species with the same charge-to-mass ratio (such as C 6+ , O 8+ , etc.). Commonly used Fuji Image plates were used as detectors in the spectrometer, whose absolute response to deuterium ions over a wide range of energies was calibrated by using slotted CR-39 nuclear track detectors. A typical deuterium ion spectrum diagnosed in a recent experimental campaign is presented, which was produced from a thin deuterated plastic foil target irradiated by a high power laser.

Recent development in laser-based accelerators is finally offering the possibility of building metre-size electron-positron colliders with specifications comparable to those based on conventional acceleration techniques. Electron beams with energies exceeding the GeV have been experimentally demonstrated [1] with the possibility of approaching 100 GeV with the next generation of laser systems [2]. It is thus timely to study the feasibility of generating laser-driven positron beams with similar characteristics. Here we report on the experimental demonstration of table-top, all-optical generation of short (beam duration ~ 30fs), ultra-relativistic and collimated positron beams with peak energies approaching the GeV and divergencies in the mrad range. Plasma-based afterburners [3] to further accelerate these beams will also be discussed. The reported results represent the first experimental step towards the generation of metre-scale all-optical electron-positron colliders. The intrinsic synchronisation of these sources with a high-intensity laser will prove fundamental for the study of highly non-linear photon-lepton interactions and the testing of matter-antimatter symmetry in a highly non-linear regime.

The anaerobic fermentation of waste prawn shell (Nephrops norvegicus) using lactic acid bacteria, in combination with especially selected proteolytic enzyme producing bacteria, has been established as an effective method for breaking down shell waste and isolating the valuable components contained within the shell structure. One of these components is the biopolymer chitin, which has numerous industrial applications and has traditionally been produced by a harsh chemical method which is extremely hazardous, energy consuming and ultimately damaging to the environment as it employs high concentrations of mineral acid and alkali. This qualitative study investigates the potential of prawn shell fermentation to provide a multi-product process, thereby eliminating waste and generating revenue. Fermentations were carried out in a bench-top, stirred tank bioreactor (5-litres). Various components of the fermentation product were analysed. The chitinous residues were characterised by CHN and calcium analysis. The composition of the protein mixture in the fermentation liquor was assessed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Two-dimensional SDS-PAGE followed by mass spectrometry allowed remaining proteins in the liquor to be identified. Carotenoid pigments in the liquor, potentially applicable in animal feed supplements, were investigated for their extractability in various solvents. A fine, white precipitate that is formed in the fermentation broth was also examined. Key results of the study showed that the unique microbial mixture used in the fermentation of prawn shell waste served to achieve the desired objectives i.e. (i) the production of a purified chitin with calcium removal as high as 93.8%; (ii) the production of a pigmented liquor containing peptides, amino acids only a few intact proteins. Sarcoplasmic calcium-binding protein was consistently found as a surviving protein in the fermentation broth. This study demonstrates the use of a biotechnological process as an alternative to the traditional chemical approach used in the manufacture of chitin. Trials have begun to assess the nutritive value of the liquor in lobster farming while biotransformation studies on bioprocessed chitin are ongoing.

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Calibration of three scintillators (EJ232Q, BC422Q and EJ410) in a time-of-flight (TOF) arrangement using a laser drive-neutron source is presented. The three plastic scintillator detectors were calibrated with gamma insensitive bubble detector spectrometers, which were absolutely calibrated over a wide range of neutron energies ranging from sub MeV to 20 MeV. A typical set of data obtained simultaneously by the detectors are shown, measuring the neutron spectrum emitted from a petawatt laser irradiated thin foil.