Karl J. Casper

Angular correlation of cascade gamma rays in 94Nb

Abstract The directional correlation and polarization correlation of the 703-871 keV gamma ray cascade following the decay of 20 000 y 94 Nb have been measured. On the basis of these measurements the spin and parity of the 1574 keV level in 94 Mo has been determined as 4 + .

Fabrication methods for lithium drifted surface barrier silicon detectors

Abstract Techniques for the fabrication of lithium surface barrier silicon detectors are presented. All important chemical procedures are described in detail. The detectors made by these techniques exhibit resolutions of 15–30 keV on internal conversion electrons when operated at room temperature.

Energy of the first excited state of Sr86

Abstract The energy of the gamma-ray transition following the beta decay of Rb 86 has been determined. A lithium drifted surface barrier solid state detector was used to measure the K photoelectrons ejected from a tantalum converter by the gamma ray; comparison was made with the internal conversion lines for the 1.063 MeV transition in Bi 207 . The energy of the Sr 86 gamma ray has been found to be 1077.2±0.5 keV.

Analysis of chance coincidences in fast-slow coincidence systems☆

Abstract A complete treatment is given of the various processes which contribute to the chance coincidence rate in a two-fold fast-slow coincidence system and a similar analysis for the three-fold system is carried to second order. The effects of circuit and detector deadtimes are included and methods are suggested for the elimination of all chance-coincidence contributions which do not result exclusively from the finite resolving time of the fast coincidence circuit.

Decay of 5.4 d Pm148

The spin and parity of the 1.46 MeV excited state of Sm148 populated by the decay of 5.4 d Pm148 have been investigated using angular correlation techniques. Both directional correlation and polarization direction correlation measurements have been made on the 910–550 keV cascade. On the basis of these measurements, it has been possible to make an assignment of 1− for the spin and parity of the 1.46 MeV level.

Beta decay of 86Rb

Abstract The beta decay of 86Rb has been measured using lithium drifted surface barrier silicon detectors. Corrections to the spectrum have been made using the measured response function of the detectors. The inner branch has an allowed spectral shape and an endpoint energy of 677 ± 5 keV, and the outer branch has a first forbidden unique spectral shape and an endpoint energy of 1753 ± 4.5 keV.

Angular correlation measurements with multichannel analyzers

Abstract A technique is described which allows the angular correlations of several radiations, each in cascade with one common gamma ray, to be determined simultaneously through the use of a multichannel analyzer. Normalization is provided by simultaneously recording both the singles and coincidence spectra using the subgrouping facilities of the analyzer. A subgroup programmer has been constructed which provides this capability while maintaining identical calibration for the two spectra.

An angular correlation test of time-reversal invariance

Abstract A test of time-reversal invariance in electromagnetic transitions is proposed in which all possible two-gamma angular correlations in a triple cascade are measured. The results can be combined to yield a term proportional to cos η.