Carbon radioactivity of 221Fr and 221Ra and the hindered decay of exotic odd-A emitters

New measurement of exotic decay of 225Ac by 14C emission

“…Moreover, an important motivation for a renewed study of this decay is the disagreement existing between our 1993 experiment [3] , which gave a branching ratio B( 14 C/α)=(6.0±1.3)x10 -12 , and the upper limit obtained in 1986 by the Berkeley group, B< 4.0x10 -13 [5]. Clearly, a confirmation of the latter result and a disproval of ours would imply a considerably higher hindrance, HF > 15, therefore perfectly on line with other results on odd-A exotic emitters [2]. We therefore prepared a new, strong 225 Ac source to be used in two independent experiments: ian high efficiency but low energy resolution experiment to remeasure the integrated decay rate of the 225 Ac→ 14 C+ 211 Bi decay.…”

“…A further improvement was that particle identification was here achieved on the basis of extraction of the couples (R r , S) in three different points along the particle trajectories instead of only one like in previous experiment. From the known source intensity and irradiation time, the branching ratio for 14 C decay of 225 Ac comes out to be B=(4.5±1.4)10 -12 and the corresponding partial half life T 1/2 =(1.9±0.6)10 17 s. This result was obtained by subtracting from the 14 tracks, 2 due to the known 14 C decay of 221 Fr [2] present in equilibrium within the source. The quoted error is determined from statistics (about 30%), from 221 Fr background subtraction (2.5%) , from detection efficiency (5%) and from source activity (5%).…”

“…The situation was summarized in Ref. [2] in the case of hindrance factors for 14 C emitters. This quantity, borrowed from α decay, measures the degree according to which an odd-A transition is slower in comparison with an even-even one having the same barrier penetrability.…”

Spontaneous heavy cluster emission rates using microscopic potentials

“…3, and Fig. 4 the experimental data for logarithmic half lives [4,[12][13][14][15][16][17][18][19] have been plotted against the mass numbers of parent nuclei along with the results of the present calculations for zero angular momentum of the fragments. In all the figures, the open circles depict the experimental data while the continuous line with solid circle represents the present calculations (MSAFM).…”

Cluster radioactivity in 294,296Og

“…have been performed in this region [3,4] from which various clusters like 20 O, 22,24−26 Ne, 28−30 Mg and 32,34 Si have been experimentally observed [5][6][7]. These experimental findings have opened diverseness of clusters in light or medium mass region as well as in superheavy region.…”