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Manuscript Title: A program to compute the two-step excitation of mesospheric sodium atoms for the Polychromatic Laser Guide Star Project.
Authors: Véronique Bellanger, Arnaud Courcelle, Alain Petit
Program title: BEACON
Catalogue identifier: ADSX_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 162(2004)143
Programming language: FORTRAN 77.
Operating system: Windows, Linux.
RAM: 1 MWord
Word size: 32 bits
Keywords: Polychromatic Laser Guide Star, Mesospheric sodium atoms, Density-matrix formalism.
PACS: 32.10.Fn, 32.80.-t, 32.50.+d.
Classification: 2.5, 15.

Nature of problem:
Resolution of the Bloch equations in the case of two-step laser excitation of sodium atoms.

Solution method:
The program BEACON calculates the evolution of level population versus time using the density matrix formalism. The number of photons emitted from the 3P3/2, 4D5/2 and 4P3/2 levels are calculated using the branching ratios and the level lifetimes.

Restrictions:
Since the backscatter emission is calculated after the excitation process, excitation with laser pulse duration longer than the 4D5/2 level lifetime cannot be rigorously treated. Particularly, cw laser excitation cannot be calculated with this code.

Running time:
12 hours.