Unrecognized Backscattering in Low Energy Beta Spectroscopy

We present studies on electron backscattering from the surface of plastic scintillator beta detectors. By using a setup of two detectors coaxial with a strong external magnetic field - one detector serving as primary detector, the other as veto-detector to detect backscattering - we investigate amount and spectrum of unrecognized backscattering, i.e. events where only one detector recorded a trigger signal. The implications are important for low energy particle physics experiments.Comment: 5 pages, 8 figures; v2: published NIM A versio

The Niger Food Crisis: Causes and Implications for Research and Development from an Integrated Agricultural Economics Perspective

During the 2004 food crisis in Niger, the weakness of the main production system, millet, to produce enough food to sustain short term crises, has been revealed. Questions arise how the Nigerian smallholder systems can be assisted by research and development policies to intensify production and improve food security. The paper assesses technical options according to their economic sustainability. A sequence of models is applied: On plot level, production functions of inter cropping systems were estimated to determine yields and their variability of the major crops. These data were fed in a nonlinear program to test the inn ovations, first at stable prices, then at declining prices that were obtained from an interregional trade model. The latter was shocked by the excess obtained from the innovations' surpluses. Results show that due to risk aversion and price volatility of output markets, farmers adopt intensive innovations less than expected. Instead, they switch to low-input techniques. Recommendations derived from the study are that research has to develop low-risk technologies to intensify Nigerian millet systems, and that domestic market policies have to stabilize prices in order to reduce market risks and set incentives for intensification. Price stabilization has to be done in a market-conform way, through buying and selling of millet, but not through price fixing or subsidizing.Food security, Niger, small scale farming, risk management, Food Security and Poverty, Research and Development/Tech Change/Emerging Technologies, O13, Q01, Q12, Q16,

Vector mesons in qqˉqˉq\bar q\bar q systems

A new selection rule is described for the vector mesons in the decuplet representations of flavor SU(3)Comment: 7 pages and 1 figur