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Title: Unfolding with Maxed and Gravel.

Version: 00 UMG (Unfolding with MAXED and GRAVEL) is a package of seven programs written for the analysis of data measured with spectrometers that require the use of unfolding techniques. See the developers' website for information on training courses The program MAXED applies the maximum entropy principle to the unfolding problem, and the program GRAVEL uses a modified SAND-II algorithm to do the unfolding. There are two versions of each: MXD_FC33 and GRV_FC33 for "few-channel" unfolding (e.g., Bonner sphere spectrometers) and MXD-MC33 and GRV_MC33 for "multi-channel" unfolding (e.g., NE-213). The program IQU can be used to calculate integral quantities for both MAXED and GRAVEL solution spectra and, in the case of MAXED solutions, it can also be used to calculate the uncertainty in these values as well as the uncertainty in the solution spectrum. The uncertainty calculation is handled in the following way: given a solution spectrum generated by MAXED, the program IQU considers variations in the measured data and in the default spectrum and uses standard methods to do sensitivity analysis and uncertainty propagation. There are two versions: IQU_FC33 for "few channel" unfolding and IQU_MC33 for "multi-channel" unfolding. The program UMGPlot can be used to display the resultsmore » from the unfolding programs MAXED and GRAVEL in graphical form in a quick and easy way.« less
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Report Number(s):
UMG 3.3; 004474IBMPC00
RSICC ID: P00529PC586
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Owner Installation: PHYSICAL TECH. BUNDESANSTALT Contributors: Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany. MAXED is based on the maximum entropy principle. The solution to the unfolding problem is obtained by maximization of the relative entropy (used here in the form due to Skilling, which is a generalization of the usual expression to distributions that are not necessarily normalized) subject to constraints imposed by the measurements. This approach permits the inclusion of prior information in a well defined and mathematically consistent way, and it leads to a solution spectrum that is a non-negative function which can be written in closed form. This last feature permits the use of standard methods for sensitivity analysis and propagation of uncertainties, which are implemented in program IQU. GRAVEL is an iterative unfolding program that was first developed for the HEPRO package. It uses a slight modification of the SAND-II algorithm. KEYWORDS: BONNER SPHERE; NEUTRON; SENSITIVITY ANALYSIS; UNCERTAINTY ANALYSIS; UNFOLDING
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
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Country of Publication:
United States

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