COALESCENCE OF PHOTONS IN THE COULOMB FIELD OF NUCLEI (in Russian)
Expressions are deduced for the probability of photon coalescence in the Coulomb field of nuclei. The expressions are obtained for the limiting cases of large and small photon frequencies as compared to the electron mass. Coalescence of photons in the high frequency region is investigated by the dispersion relation method. The low frequency range is investigated by introducing radiative corrections to the Lagrangian function of the electromagnetic field. (auth) The energy dependence of the BETA - gamma directional correlation involving the outermost non-unique first forbidden BETA -ray groups in the decay of Eu/sup 152/, Eu/aup 154/, and Sb/sup /124/ and th e cascade E2 gamma -rays in the daughter nuclei has been measured using a BETA - gamma coincidence spectrometer of the slowfast'' type with a coincidence resolving time of 30-40 nanoseconds. A small shaped field magnetic spectrometer with 5% resolution and transmission is used for BETA -ray momentum selection. The data indicate that these transitions are predominantly governed by the B/sub ij/ matrix element of rank 2. A general method of analysis, applicable to the BETA - gamma directional and circular polarization correlation data, is developed by combining a least squares analysis of the data with the complete theoretical expressions of Kotani for these observables. It is shown that a knowledge of the three observables C(W), epsilon , and P/sub c/ (the for a unique determination of the nuclear parameters. The matrix elements thus obtained from this analysis are given. All the matrix elements are reduced by a factor of 10 to 1000 from the values expected for a perfect overlap of the initial and final state nuclear wave functions, the rank one matrix elements being retarded much more than the rank two, indicating that a selection rule rather than cancellation effect is responsible for the deviation from the tween 360 and approximation in these transitions. The j-selection rule seems to be operative in Sb/sup 124/ while the K-selection rule appears to inhibit the decay of Eu/sup 154/. The selection rule effect in the decay Eu/sup 152/- Gd/sup 152/ is not clear because K is not a good quantum number in this case involving a transition from a deformed to a spherical nucleus. (A.G.W.) Several attempts were made to measure the Zeeman resonance frequencies of the short-lived isotope sodium 21, which would allow the computation of the spin and nuclear magnetic dipole moment of its nucleus. Two distinct approaches to this problem were taken: the optical detection of the change in opacity of a scattering cell containing very metry in the angular distribution of positrons resulting from the beta decay of this nucleus. The first technique was unsuccessful because the signal-to-noise ratio was below unity for the number of sodium 21 atoms that could be produced, in spite of a very sensitive detection system. In the beta-decay experiment an asymmetry was observed in the angular distribution of the positrons eminating from a pumped sample. The magnitude of this asymmetry corresponding to an a'' of 0.008 in the theoretical (1 + a cos ) distribution was not sufficiently large to allow the reliable observation of change when resonant r-f was applied to the sample. This asymmetry is, however, direct evidence of nuclear polarization through optical pumping. The reasons for this low asymmetry coefficient are presented, and it is shown that a suitable optical filter should render either experiment successful. The production and handling of sodium 21 is discussed in detail and considerable information concerning the adherence of sodium to various materials is presented. The theory of optical pumping and the theory of the beta decay of polarized nuclei are considered. Estimates of obtainable signal-to-noise ratios for this type of experiment are developed. (Dissertation Abstr. XXIII, No. 8)
- Research Organization:
- Inst. of Physics and Tech., Academy of Sciences, USSR
- NSA Number:
- NSA-17-021093
- OSTI ID:
- 4719482
- Journal Information:
- Zh. Eksperim. i Teor. Fiz., Vol. Vol: 44; Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- Russian
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