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Manuscript Title: A program for calculating gamma-gamma directional correlation coefficients and mixing ratios.
Authors: E.S. Macias, W.D. Ruhter, D.C. Camp, R.G. Lanier
Program title: ANGCOR
Catalogue identifier: ABPG_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 11(1976)75
Programming language: Fortran.
Computer: CDC 7600.
Operating system: FLOE.
RAM: 25K words
Word size: 60
Peripherals: disc.
Keywords: Nuclear physics, Spectroscopy, Directional, Correlation, Mixing ratios, Solid-angle corrections, Orientation, Directional distribution, Chi-square, F-coefficient, Clebsch-gordan, Legendre polynomial, Multipolarity, Wigner, 3j-symbol, 6j-symbol, Activity detection, Admixture, Level scheme.
Classification: 17.6, 17.15.

Nature of problem:
Conservation of angular momentum governs the multipolarity of electromagnetic transitions between nuclear excited states. In certain cases a mixture of two multipolarities may occur in a single transition. The amount of mixing, i.e. the mixing ratio, is determined by the structure of the nuclear levels involved. By accurately measuring the directional correlation between two transitions and comparing it with several theoretically expected correlations, the most probable mixing ratio can be determined.

Solution method:
The program has two modes of operation: in the first mode, directional correlation coefficients are determined by least-squares fits to the experimental data with second- and fourth-order Legendre polynomials having only even terms. The coefficients are then corrected for the experimental finite solid angles. For each spin sequence entered, a chi-square value is calculated for 49 possible values of each transition mixing ratio. The printout appears as a 49 by 49 point grid which resembles a contour map. A study of several of these printouts allows the user to qualitatively determine possible spin sequences and mixing ratios. Mode II, the data simulation mode, calculates a set of directional correlation coefficients from spins and mixing ratios entered, corrects for solid angle, and calculates a set of angular correlation data normalized to Ao= 10000. The required inputs are spin assignments for the three levels, mixing ratios of the transitions, and the experimental solid-angle corrections. The second mode allows tests of the program or examination of results for given spin sequences and mixing ratios. An option in both modes magnifies any section of the chi squared grid.

Input must be ten angles or fewer. Correlations are limited to successive gamma-ray cascades.