ADVANCED, ENHANCED HEX PROGRAM FOR PIXE

The REX code and subsequent HEX code, originating at Florida State University, have been extensively used for PIXE spectra fitting. In 1989 we produced a renovated HEX package: WITS-HEX, enabling the original Fortran program to be more accessible to the PIXE community. We modernised the user interface by replacing the batch mode of operation with an integrated, menu-driven environment. We added the ability to edit support data files from within the program, provided detailed feedback during the fitting process and enhanced spectral plots using high resolution colour graphics. Our prototype also permitted the inclusion of many more peaks and absorption coefficients into the element library than the original HEX. permitting a more extensive element request list to be used during the fitting operation. We have now completed the second phase of the renewal of HEX. The man-machine interface has been upgraded to conform to the IBM SAA Common User Access (CUA) standard. This eliminated several of the sequential (modal) human-computer dialogues, replacing them with a single parallel system. The support utility used in WITS-HEX to convert the binary format of spectra captured using foreign data acquisition systems has been replaced by code to directly access data in ASCII format. The program is now equipped with context-sensitive help and a tutorial. The polynomial background model has been supplemented by a digital filter model, eliminating the associated instability from the fitting process and other spectral features modelled. The program has been validated by comparing results with those obtained from the former versions: WITs-HEX and HEX. A demonstration version is available on request for evaluation purposes.