? + ratio and?-delayed?-decay of146Eu

Abstract

The positron decay of 146Eu was investigated, firstly to derive for the allowed transition to the 2046 keV state in 1468m the electron capture to positron decay ratio. The experimental value EC/fl + =43.7(42) is found to be in agreement within the respective error intervals with the ones calculated from the formalism of allowed decay using the recent Q-values of 146Eu. Further on, the y-decay properties of 146Eu have been reinvestigated with emphasis on implied modifications of the hitherto accepted decay scheme: 42 new levels and 33 new 7-transitions were placed in the revised level scheme, 12 of the previously reported levels were deleted. The level distribution of 146Sm is discussed within a statistical model. The indication for a non-statistical fl-strength function is observed.

Structure of the146Sm states from the146Eu decay

“…The summary intensity of all 56 unplaced transitions represents 1.1%. Further, we introduce levels at 3530.5 and 3785.8 keV (in agreement with [4]), the 2879.1 keV level suggested in [6] on the basis of energy differences, and the 2667.2 keV level excited in the (e, 4ny) reaction [-14]. Other 24 levels are introduced on the basis of our coincidence data [7], from which the 3418.92, 3546.13, 3652.2, and 3058.0 keV levels were suggested in [-1, 6] on the energetic basis only.…”

“…(14) 0.040 (2) 1.24 (3) 0.116 (7) 0.340 (12) 0.853 (26) 0.020 (1) 0.798 (24) 0.797 (23) 1.013 (27) 0.157 (14) 1.37 (4) 1.70 (4) 0.758 (20) 0.031 (2) 0.521 (20) 0.173 (6) 2879.12 (12) 2898.29 (4) 2968.80 (8) 2973.82 (6) 3014.59 (4) By use of the 7y-coincidence date I-1-3], 40 excited levels can be established in consistency with our results. The 158.5, 742.65, 753.80, 766.84, 804,67, and 1500.44 keV transitions are placed following from the yy-coincidence results [4]. 11 levels were evidenced independently in the 77-coincidence study [4].…”

“…195 observed transitions are placed in this scheme, 42 transitions cannot be placed unambiguously. 11 levels were evidenced independently in the 77-coincidence study [4]. (14) 0.040 (2) 1.24 (3) 0.116 (7) 0.340 (12) 0.853 (26) 0.020 (1) 0.798 (24) 0.797 (23) 1.013 (27) 0.157 (14) 1.37 (4) 1.70 (4) 0.758 (20) 0.031 (2) 0.521 (20) 0.173 (6) 2879.12 (12) 2898.29 (4) 2968.80 (8) 2973.82 (6) 3014.59 (4) By use of the 7y-coincidence date I-1-3], 40 excited levels can be established in consistency with our results.…”

“…Partly it may be caused also by the existence of non-observed transitions feeding levels with the same energy. ?-coincidence spectra in [2][3][4] is discussed below in connection with the description of the level scheme. A transition is in coincidence with the 747 or 633+634keV transition if Texp>80% or Tcx p > 96%, respectively.…”

“…The most detailed information about excited states of 146Sm up to the 3.8 MeV excitation energy and up to the spin 6 has been obtained from studies of the betadecay of 146Eu (U=4-) [1][2][3][4][5]. The most detailed information about excited states of 146Sm up to the 3.8 MeV excitation energy and up to the spin 6 has been obtained from studies of the betadecay of 146Eu (U=4-) [1][2][3][4][5].…”