SOFTWARE DEVELOPMENT FOR PROCESSING SOLUTION SCATTERING DATA RECORDED BY MARCCD1

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The improved electronic stability of the MarCCD165 detector has provided an alternative way to record solution scattering data, in addition to using the gas chamber detector data collection system and associated programs developed by EMBL-Hamburg. We felt there is a universal need for a new data processing program for 2D scattering data acquired by both the MarCCD165 and the BL4-2 image-intensified CCD system, another 2D detector. We have developed a data processing program, Marparse, for this purposed during the grant year. This program reads a text file, which has essential parameters for data processing such as direct beam position, radial averaging areas, data file names, and performs radial averaging, scaling to integrated beam intensities, and conversion of detector pixels to momentum transfers. The program also evaluates data statistics upon radial averaging and checks for signal variance as an indicator of radiation damage and/or instrumental instability. It then averages sequentially recorded scattering data according to user specified statistical criteria and performs background subtraction. All these procedures are done in one step within a few minutes by running the program in command line on a Windows PC. Users obtain a log file and resulting1D scattering curves, whose ASCII format is compatible with a number of data analysis program packages, such as Primus developed by EMBL-Hamburg. The object oriented coding of the program, written in C++, allows future implementation of a graphical user interface as well as adaptation to other computational platforms. The specific data format and processing procedures for image-intensified CCD data will be incorporated in Marparse early in 2006.