Atomic masses of147m, 148m, 149m Tb,148Dy,150m, 152m Ho derived from decay properties

Abstract

Using nuclear fusion reactions of h~ ions with 112Cd, a~4Sn and 116Sn and subsequent y-ray spectroscopy, the probability ratios of positron emission and electron 6.625(120) and a52mHo, 6.470(80). The present decay-energy data are compared with earlier measurements and the new information obtained for the mass surface around 146Gd is discussed.

Beta-delayed gammas and QEC-values in the decays of150m,152mHo and149Dy

“…The difference can be attributed to our more accurate 7-feeding of the 2401 keV level. In fact, if we compare our (EC+fl+)/fi + ratio without feeding correction with the cited earlier ratios [2,3], perfect agreement is reached.…”

“…If we respect the EC/fl + results only, we may infer that the two QEc-values of [3] e.g. both are too large by 200 keV, or that the present result and the value of [27] correspondingly are too small.…”

“…Using our Q~c-value for 152mHo, 6263 t~+89~-8oJ keV, together with the QEc-Value for 14aTb, 5295(45) keV [27], the energy sum of the circle is -30(96)keV, hence giving a perfect fit. Using the QEc-values, 6470(80)keV of ~52mHo, and 5730(30) keV of 148Tb from the same experiment [3], the corresponding circle sum is + 108 (85) keV, also being close to zero. The QEc-values from the two/?+-endpoint measurements accordingly give a circle sum of -132(128) keV.…”

“…Earlier work has been summarized [6] taking into account the results of the AMCO-7 conference. Q-value measurements in this region of the nuclear chart are also of interest for mass measurements far off stability, because they can tie circles of alpha-and beta-decay energies [3] or long a-decay chains to key-masses [7].…”

Beta-decay energy measurements using total gamma-absorption spectroscopy

“…However this overestimation is rather small, the corresponding error in Q being less than the quoted error bars in the final figures (see Table 1). We can also note that this error is partly [14], Q=6.625(120) [15] Q compensated by another effect of the opposite sign. This effect is connected with the circumstance that in case of e-capture of the total absorption efficiency of X-rays in the spectrometer is significantly lower than that for more energetic (cascade) 7-rays due to absorption of about 50% of the X-rays in the Be-absorber mentioned above and in the vacuum chamber aluminium walls which surrounded the tape with the radioactive source.…”