ACTA POLYTECHNICA SCANDINAVICA PHYSICS INCLUDING NUCLEONICS SERIES No. 22 Gamma-Gamma Directional Correlations of Ce140

摘要

The excited levels in Ce140 have been investigated by studying the decay of La140. Intensities have been determined from gamma-ray spectra and the results are 328 keV (19 %), 435 keV (0.4 %), 490 keV (44 %), 635 keV (<1 %), 753 keV (5 %), 818 keV (22 %), 874 keV (5 %), 927 keV (9.5 %), 1120 keV (1 %), 1597 keV (100 %), 1680 keV (1 %, 2355 keV (0.5 %), 2530 keV (4 %), 2900 keV (0.15 %) and 3100 keV (<1 %). Weak peaks were found at 120 keV, 135 keV, 178 keV, 240 keV and 270 keV, the intensities were less than 2 %.nFrom the results of gamma-ray, coincidence and sum spectra a level scheme for Ce140 is proposed.nAngular correlation measurements of eight cascades were carried out and they gave the following spin sequences:1597 keV, 2*;1902 keV. 0+;2090 keV, 4+;2350 keV, 1+ or 2+;2410 keV, 3+;2530 keV, 2+;3280 keV, 2 or 4 and 3390 keV, 0 or 2.