Time-resolved studies on contracting muscle using small-angle X-ray diffraction. I. Design of data collection system

Abstract

Small-angle X-ray diffraction offers a unique method for the study of muscle structure at a molecular level. Structural changes in muscle during contraction can be studied with a 10 ms time resolution with the use of a powerful X-ray generator and electronic detectors. A data-collection system is described which is based on a linear position-sensitive detector capable of synchronizing data from 32 different phases of a muscle contraction cycle and storing it in different subgroups of a multichannel analyzer memory. On completion of an experiment with a muscle the complete data set is transferred via a fast link to a PDP 11/10 computer for processing and storage. A promising approach to the automated analysis of equatorial data is to assume that the pattern is a sum of a polynomial background and Gaussian peaks. A χ2-minimization procedure, which optimizes the parameters used to describe the pattern, gives excellent agreement between experimental data and the proposed model. Finally a detector system is proposed which would allow collection of data at high rates expected from a camera set on a storage ring.