The Composition of the Interstellar Medium towards the Lockman Hole. HI, UV and X-ray observations

The Lockman Hole is well known as the region with the lowest neutral atomic hydrogen colum density on the entire sky. We present an analysis of the soft X-ray background radiation towards the Lockman Hole using ROSAT all-sky survey data. This data is correlated with the Leiden/Dwingeloo survey (Galactic HI 21cm-line emission) in order to model the soft X-ray background by using radiative transfer calculations for four ROSAT energy bands simultaneously. It turns out, that an important gas fraction, ranging between 20-50%,of the X-ray absorbing material is not entirely traced by the HI but is in the form of ionized hydrogen. Far-ultraviolet absorption line measurements by FUSE are consistent with this finding and support an ionized hydrogen component towards the Lockman Hole.Comment: 11 pages, 11 figures, Accepted for Publication in Astronomy & Astrophysics, For full resolution images, see http://www.astro.uni-bonn.de/~mkappes/pub/ms3506.pd

Futures for farmers: hedging participation and the Mexican corn scheme

Administered commodity price schemes in developing countries have proved ineffective in raising farmers' incomes and price stabilisation through futures markets is increasingly advocated as the alternative policy objective. A potential difficulty is that farmers tend not to hedge extensively, even in developed countries where access to futures markets is long established. Explanations for this reticence are examined here with context provided by the Mexican hedging programme, which incorporates financial incentives to spur adoption. Applying representative data for corn to a well-known analysis of the hedging decision suggests that limited participation may reflect rational calculation rather than farmer 'inertia'. A policy implication is that permanent access subsidies are difficult to justify from the national perspective.

Measurement of Carbon Disulfide Anion Diffusion in a TPC

A Negative Ion Time Projection Chamber was used to measure the field dependence of lateral and longitudinal diffusion for CS$_2$ anions drifting in mixtures of CS$_2$ and Ar at 40 Torr. Ion drift velocities and limits on the capture distance for electrons as a function of field and gas mixture are also reported.Comment: 10 pages, 5 figures, LaTeX using elsart.cl

Radiation effects on silicon Fourth quarterly progress report, Sep. 25 - Dec. 31, 1965

Radiation effects in silicon solar cell

Probing the structure of the cold dark matter halo with ancient mica

Mica can store (for >1 Gy) etchable tracks caused by atoms recoiling from WIMPs. Ancient mica is a directional detector despite the complex motions it makes with respect to the WIMP "wind". We can exploit the properties of directionality and long integration time to probe for structure in the dark matter halo of our galaxy. We compute a sample of possible signals in mica for a plausible model of halo structure.Comment: 7 pages, 2 figure