We report a new precision half-life measurement of , performed using the -counting station of the University of Notre Dame's Nuclear Science Laboratory. The measured half-life of s resulting from this work will help resolve the longstanding discrepancy between two earlier sets of high-precision half-life measurements.
DOI:https://doi.org/10.1103/PhysRevC.99.015501
©2019 American Physical Society
All previous half-life measurements along with the Birge-ratio-inflated weighted average depicted by the dashed red lines. The color and shape of each data point indicate the fitting method used in the analysis; red squares indicate least-squares, while blue circles indicate maximum likelihood. See Sec. 4. for more details.
Reuse & PermissionsThe half-life, resulting from summing the cycles from each run individually, is shown as a function of the other fitting parameters; initial activity (top) and background (bottom). The color of each data point corresponds to the PMT bias used for that run, while the shape corresponds to the discriminator threshold voltage. The shaded region signifies the confidence interval resulting from the fit of 100 artificial data sets mimicking the experimental results.
Reuse & PermissionsHalf-life results when data taken with identical systematic settings are combined. Data points along with their uncertainties indicate the result from the sum fit, while the underlaid gray region signifies confidence intervals from artificially created data.
Reuse & PermissionsThe top panel shows a summed decay curve of all cycles with the Eq. (1) fitted result shown as the red line. In the bottom panel are the residuals of the fit divided by the square root of the number of ions in a given bin , shown as blue circles, along with a five-point moving average shown as a red solid line.
Reuse & PermissionsThe top panel shows a summed -decay curve of all cycles with the Eq. (2) fitted result shown in red (solid). The fit includes the influence of the less abundant as a contaminant in orange (high-density dashing), the background in green (low-density dashing), and in purple (high-density dashing). In the bottom panel are the residuals of the fit divided by the square root of the number of ions in a given bin , shown as blue circles, along with a five-point moving average shown as the red solid line.
Reuse & PermissionsFitted half-lives for the summed data set as a function of the time removed at the beginning of the sample. The top panel gives results when fit without a contaminant using Eq. (1), while the bottom panel shows results using Eq. (2) which includes the influence of . Up to ten half-lives were removed.
Reuse & Permissionsmetric as defined by [29] for Monte Carlo generated data shown in yellow. This results from 250 calculations of 968 cycles mimicking the experimental data. The experimental result without consideration of a contaminant, 16.9, is given by the red dashed line. This represents the nonconsistent nature of the data in Fig. 6 with a sample absent of contamination, while the addition of to the decay rate reduces the value to as shown by the blue line with denser dashing.
Reuse & PermissionsResults from fitting subgroups of runs depending on the systematic settings used. The groupings are indicated by shape and color, indicating discriminator threshold voltage and PMT bias respectively. Equation (2) is used for these fits, where the contamination ratio is floated. The top panel gives the half-life resulting from the fit while the bottom panel shows the contamination ratio.
Reuse & Permissions
