Culture and Communication

Thermal field emission for low voltage scanning electron microscopy

“…As the electric field is increased so that an increasing amount of the current passes through the barrier there is a significant increase in the energy spread, as can be seen from Fig. 2 (Collier, 1979), by Hewlett-Packard Corporation (Kelly et al, 1981) and by E-Beam Corporation (Livesay, 1984). In this laboratory they have been applied in a scanning Auger microscope which was capable of focusing 110 nA of beam current into spot size of 100 nm at 12 keV beam energy and 125 mm working distance from the final lens (Tuggle et al, 1979).…”

High power laser production of short-lived isotopes for positron emission tomography

“…The importance of figure 2 is that it is needed in order to determine the thickness of the target that generated the highest activity sources. This was carried out using the production of the PET isotope 11 C rather than the more novel 18 F because the cost of doing systematic work using the very The Back/front ratio of 11 C from the (p,n) reactions on 11 B as a function of target thickness. It was found that at the highest pulse energy on target ∼300 J, the 11 C activity maximally was about 6 × 10 6 Bq per shot on each side.…”

“…accelerators, detectors and chemistry since the beginning of modern PET in 1973. PET is a powerful diagnostic/imaging technique requiring the production of short-lived positron emitting isotopes, principally 11 C, 13 N, 15 O and 18 F, by proton irradiation of natural/enriched targets using cyclotrons. The technique requires these isotopes to be administered to the patient in the form of a radiopharmaceutical.…”

“…In a recent article in Science, Ledingham et al [6] have described some preliminary work carried out in order to produce PET isotopes using a high power laser. After an extended programme of research, we report here how to generate the intense, shortlived PET sources, 11 C and 18 F, using the VULCAN petawatt laser beam and also for the first time, the synthesis of 2-[ 18 F]-fluorodeoxy glucose, the 'workhorse' of PET technology from laser-driven 18 F using an enriched water target. In the conclusion to this report the potential for developing this for onsite, easy to shield, compact laser technology for this purpose will also be discussed.…”

Autocreative hierarchy II: dynamics self-organization, emergence and level-changing

“…It is, however, necessary to be somewhat circumspect in insisting that there should be no formally rational link between underlying properties and emergent ones, as in general not all the properties of formal systems are themselves formal (Collier 2002). We will address this issue more extensively in a later section of the paper.…”