Large-area Si(Li) orthogonal-strip detectors
Segmented lithium drifted silicon detectors are being developed for use in large Compton cameras and for medical imaging. We have successfully fabricated 3.5 mm thick crossed-strip detectors with active areas of 40 /spl times/ 40 mm/sup 2/ with a 2 mm strip pitch. These detectors utilize new contact technology consisting of a boron implanted p-type contact and an amorphous silicon (/spl alpha/-Si) n-type contact. Good energy resolution and excellent strip separation was obtained from both contacts at relatively high operating temperatures. An energy resolution of 2.1 keV FWHM at 122 keV was obtained for the /spl alpha/-Si strip at temperature up to 200 K and for the B strip at temperature up to 240 K. Measurements of the charge sharing between the strips were also performed. When the detector was flood illuminated with 60 keV gamma-rays, a small signal deficit was observed for events in which the signal was shared between two adjacent strips. The amount of deficit depended on the contact type, strip geometry and the operating temperature.
Considerations for the next Compton telescope mission
A high resolution Compton telescope has been identified by the Gamma Ray Astronomy Program Working Group (GRAPWG) as the highest priority major mission in gamma ray astrophysics following GLAST. This mission should provide 25–100 times improved sensitivity, relative to CGRO and INTEGRAL, for MeV gamma ray lines. It must have good performance for narrow and broad lines and for discrete and diffuse emissions. Several instrumental approaches are being pursued to achieve these goals. We discuss issues relating to this mission including alternative detector concepts, instrumental configurations, and background reduction techniques. We have pursued the development of position-sensitive solid-state detectors (Ge, Si) for a high spectral resolution Compton telescope mission. A ∼1 m2 germanium Compton telescope of position-sensitive germanium detectors was the basis for one of the GRAPWG concepts. Preliminary Monte Carlo estimates for the sensitivities of this instrument are encouraging. However, there are technic...
France in the Middle Ages 987-1460 : from Hugh Capet to Joan of Arc
Translatora s Note. Foreword. List of Illustrations. List of Genealogical Tables. Part I: The Inheritance: . 1. The Empire. 2. The Frankish People. 3. The Principalities. 4. Disturbances. Part II: Lordship:. 5. The Village. 6. The Castle. 7. The Church. 8. King and Lord. Part III: Origins of State and Nation:. 9. The Great Age of Progress. 10. Louis VII. 11. Philip Augustus. 12. The South. 13. The Thirteenth Century. 14. The Fourteenth Century. 15. The Maid of Orleans. Epilogue. Chronology. Bibliography. Index.