No abstract

Flash photolysis of K-, Rb-, and Cs-in tetrahydrofuran (THF) produces the corresponding ion-pairs ( K + , e,-), (Rb+, es-), and (Cs', e,-), followed by the regeneration of the parent metal anion, M u . In mixed-metal solutions containing Na and M where M is K, Rb, or Cs, photolysis of Na-also forms the ( M + , e,-) ion-pair and M-, but with the latter then reforming Na-on an extended time scale. Similar results were obtained in dimethoxyethane (DME) at 213 K, but in this case with the initial formation of a loose ion-pair, (M+, e,-),,,,,.

In order to detect and locate buried landmines for peacekeeping, the Canadian Department of National Defence (DND), under the Improved Landmine Detection Project, is developing a vehicle-mounted, two-phase mine detection system. The first phase constitutes a suite of detectors used to indicate the possibility of a mine at a particular location (to _+30 cm in accuracy). In the second phase a Thermal Neutron Activation (TNA) system is used to confirm the presence of explosives via detection of the 10.83 MeV gamma-ray associated with nitrogen decay. The TNA system developed for this uses a 100 p~g 252Cf neutron source surrounded by four 3"x3" NaI(T1) detectors. Combining the use of state-of-the art radiation transport codes for design, judicious choice of specialized shielding materials and development of high-rate, fast-pulse processing electronics, has led to a system which can; (i) confirm the presence of all surface-or lightly-buried anti-tank mines in a few seconds to a minute (depending on mass of explosive), (ii) confirm the presence of anti-tank mines down to 20 cm depth in less than 5 minutes, (iii) confirm the presence of large (>100 g nitrogen) anti-personnel mines in less than five minutes, (iv) operate in adverse climatic conditions. These results have been verified in field trials and the system is due to be fielded in 1999.

No abstract

A simple and inexpensive microcomputer data-acquisition system is described for the investigation of the absorption of infrared photons using a photoacoustic detector. The system produces a graphic display of the results during an experiment and permits the operator to correct procedural errors.