High Spatial Resolution Fast-Neutron Imaging Detectors for Pulsed Fast-Neutron Transmission Spectroscopy

Two generations of a novel detector for high-resolution transmission imaging and spectrometry of fast-neutrons are presented. These devices are based on a hydrogenous fiber scintillator screen and single- or multiple-gated intensified camera systems (ICCD). This detector is designed for energy-selective neutron radiography with nanosecond-pulsed broad-energy (1 - 10 MeV) neutron beams. Utilizing the Time-of-Flight (TOF) method, such a detector is capable of simultaneously capturing several images, each at a different neutron energy (TOF). In addition, a gamma-ray image can also be simultaneously registered, allowing combined neutron/gamma inspection of objects. This permits combining the sensitivity of the fast-neutron resonance method to low-Z elements with that of gamma radiography to high-Z materials.Comment: Also published in JINST: http://www.iop.org/EJ/abstract/1748-0221/4/05/P0501

Operation and control of a dilution refrigerator for spin conversion measurements with neutrons

We describe the cryogenic and operational aspects of an experiment comprising a dilution refrigerator with a 12-sample container, automatic sample change, automatic refill of cryogenic fluids and a watch-dog alarm system. Thermometry for the range 10 mK to 300 K is described including computer read-out and computerized temperature control.Nous présentons les aspects cryogéniques et opérationnels d'un ensemble expérimental consistant en un cryostat à dilution équipé d'un porte-échantillon multiple, échange-échantillon automatique, alimentation automatisée en cryofluides et un système d'alarme passive. La thermométrie entre 10 mK et 300 K est décrite ainsi que la lecture et le contrôle de la température à l'aide d'un miniordinateur

Improving Access to Livestock Markets for Sustainable Rangeland Management

Productivity of rangelands in Kenya is affected by increasing crop farming especially in more fertile range areas. Among the key factors driving the encroachment of crops on rangelands are the changing opportunities brought about by markets. We hypothesize that the existing market inefficiencies characterizing livestock markets, especially the price disincentives that livestock producers face, are major risks rangelands face. To analyze the effect of livestock market conditions on rangeland management, we draw on household survey and economic modeling tools. We find that traders’ rent seeking behavior and high transport costs act as disincentives to livestock producers’ participation in livestock markets and influence their decisions in seeking alternative rangeland uses to sustain livelihoods. However, improved livestock market access enhances livestock producers’ livelihoods and the stewardship of the ecosystems thus reducing pastoralists’ vulnerability to ecological climate variability associated with rangelands