New program system for four-circle diffractometer

A New Form of Diffractometer

A simple diffractometer is described, in which monochromatic light is focused on a pinhole, rendered parallel, and passed through a film of red cells or other objects the size of which is sought. The diffraction patterns are photographed on special plates, and the positions of the first minimum and of the first maximum are subsequently found by the use of a simplified microphotometer. The metho...

A six-circle diffractometer system for synchrotron X-ray studies of surfaces and thin film growth by molecular beam epitaxy

A new ultrahigh vacuum (UHV) surface diffractometer system equipped with molecular beam epitaxy (MBE) capabilities has been developed. It has a versatile 6-circle configuration for defining the diffraction geometry, and a three-axis translation stage for controlling the sample position. Rugged mechanical components are employed in the design to allow accurate diffraction measurements. Sample co...

A two-circle powder diffractometer for synchrotron radiation on Station 2.3 at the SRS

On Embedding Circle-bundles in Four-manifolds

In this paper, we demonstrate an obstruction to finding certain splittings of four-manifolds along sufficiently twisted circle bundles over Riemann surfaces, arising from Seiberg-Witten theory. These obstructions are used to show a non-splitting result for algebraic surfaces of general type.

FOUR NEW RECORDS FOR THE MOSS FLORA OF IRAN

Following 4 species of Mosses are reported from Hezar Masjed mountains (north of Khorasan province) as new records to Iran: Pottia lanceolata, Grimmia alpicola, Bryum badium & Ovthotrichum schimperi.The descriptions, collecting localities (habitats) and distribution of each species in the world along with their figures are given.