LONG-LIVED PHOTON-ECHO IN A LAF3-PR3- POLARIZATION PROPERTIES, INFLUENCE OF A WEAK MAGNETIC-FIELD, AND A PROBLEM OF LOCAL DATA ERASURE( CRYSTAL )

A number of problems relating to a long-lived photon echo (LPE) are an alyzed within the framework of a unified mathematical formalism. Polar ization properties of LPE are investigated, both experimentally and th eoretically, for the resonant transition H-3(4)-P-3(0) (the wavelength is 4777 angstrom) in a LaF3:Pr3+ crystal at the temperature of 2.2 K. The influence of a weak magnetic field on the LPE intensity is also i nvestigated. A tenfold increase of the LPE intensity in a permanent ma gnetic field with a field strength no higher than 150 G is revealed an d theoretically explained. A number of physical parameters of the stud ied crystal are determined by theoretical analysis. Specifically, the constants of cross relaxation involving one and three fluorine nuclei are found to be about 10(6) and 10(3) - 10(4) s-1, respectively, and t he electric-dipole moment of the H-3(4)-P-3(0) transition is estimated as (5 - 1) x 10(-22) CGSE. A problem of local data erasure is investi gated. Optimum conditions for solution of this problem are determined.