Search for a fine structure in theC14decay ofRa

Abstract

The ' C decay of Ra has been reinvestigated, using an 85 MBq activity ' U source radiochemically separated, a Si barrier detector, and a superconducting magnetic spectrometer. In a 16 days counting run, 210 ' C events were recorded. The ' C particles energy value 30.930+0.090 MeV was found and an upper limit b~2X10 ' was estimated for the ' C branching ratio to the 'Pb first excited state; the branching-ratio value to the 'Pb ground state, thus equal to the total branching ratio, was found to be b =A, , /A. =(2.31+0.31)X 10

Microscopic description of cluster radioactivity in actinide nuclei

“…This discovery represented a milestone in the description of nuclear radioactivity as it bridged the gap between the α emission radioactivity and the standard fission reaction. Since then, cluster radioactivity (CR) has been found in twelve eveneven isotopes [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] and seven odd-even isotopes (see, e.g., references in Refs. [22,23]) in the actinide region.…”

4 Track Detectors and Soleno applied for Cluster Radioactivities

“…On the other hand, in spite of their historical importance for the discovery of the 14 C radioactivity and of the fine structure, the chemically separated sources [30] present a dramatic drawback. When they are strong, they contain much material causing finite thickness and noticeable inhomogeneity.…”

“…Intense sources are needed to compensate for the low branching ratio 14 C/a of (10" lo -10" 12 ). Two main types of sources have been used so far: 1) chemically separated and deposited sources [30], and 2) ion-implanted sources [21]. Examples from the first category are two members of the decay chain of 231 Pa: 227 Ac (T = 21.77 y) and 227 Th(T = 18.72 d), which generate 223 Ra(7 = 11.43 d).…”

“…Such an investigation should be done with good statistics and energy resolution. Three experiments were successively performed [29,30,31] using thin and intense sources of 223 Ra, 222 Ra, and 224 Ra, and a single Si surface barrier detector (of 450 mm 2 ) in the focal plane of SOLENO. A large solid angle of about 200 msr was obtained in these experiments.…”

“…With this unique instrument it was possible to discover the fine structure in cluster decay [29][30][31]21] discussed by Martin Greiner and Werner Scheid [32]. An Enge split-pole magnetic spectrometer, with a gas filled detector in its focal plane, has been used at Argonne [33,34] to confirm the mass number of the emitted 14 C fragment from 223 Ra.…”