Branching of Transitions in Some Mirror Nuclei

Branching ratios for theβdecay ofNa21

“…1), the adopted branching ratio for the β transition to the first excited state not only affects their data analysis but also helps determine the theoretical prediction for a βν itself, since the axial-vector component of the ground-state branch can only be determined from its ft value, which also depends on the branching ratio. This branching ratio is a key component of their standard-model test, yet the five published values [2][3][4][5][6] are between 25 and 45 years old, are quite inconsistent with one another and range from 2.2(3) to 5.1(2)%. To remedy this problem, we report here a new measurement of the ground-state branching ratio, for which we quote ±0.8% relative precision, five times better than the best precision claimed in any previous measurement.…”

Precise measurements of half-lives and branching ratios for the $ \beta$ β mirror transitions in the decay of 23Mg and 27Si

“…The K130 cyclotron produced a proton beam with an energy of 15 MeV (30 MeV for some runs at the beginning of the experiment). The targets were 23 Na and 27 Al for 23 Mg and 27 Si, respectively, produced by means of (p,n) reactions. After mass separation ( M ∆M = 500), beams of 23 Mg or 27 Si, contaminated only by stable 23 Na and 27 Al, respectively, were transported to the yield station.…”

“…The nuclei 23 Mg and 27 Si were deposited on a mylar tape (50 µm thickness and 1.25 cm width). The tape moved the sample from the collection point to the measurement point (about 12 cm) between a plastic scintillator for the detection of β particles and a germanium detector for γ rays (see Figure 1).…”

“…This paper is dedicated to the mirror decays of 23 Mg and 27 Si. We will focus on measuring very precisely their half-lives and branching ratios.…”

“…We will focus on measuring very precisely their half-lives and branching ratios. Prior to the present work, the half-lives of 23 Mg and 27 Si were known with precisions of 0.27% and 0.36%, respectively, and the branching ratio of 23 Mg with a precision of 0.26%. Only the branching ratio of 27 Si had a very high precision of 0.02%.…”