Speaker
Description
In 2014, an accelerator mass spectrometry measurement counted a surprisingly large number of $^{10}$Be atoms in a sample of $^{11}$Be decay products, inferring the $^{11}$Be$\rightarrow^{10}$Be decay branch to be 9(1) ppm. The presence of $^{10}$Be can be interpreted as the first evidence of the never before observed $\beta^-$-delayed proton decay. A measurement of the low-energy charged-particle emission in 2019 appeared to confirm the discovery of this novel decay channel, measuring $^{11}$Be($\beta^-$p) protons with 13(3) ppm intensity and center-of-mass energy 196(20) keV. However, more recent AMS measurements suggest molecular contamination during the sample preparation in the previous measurement resulting in a revised limit of $<$2 ppm for $^{11}$Be$\rightarrow^{10}$Be. Additionally, theoretical studies of $^{11}$Be decay are not unified in their pre- and post-dictions of a $\sim$10 ppm $^{11}$Be($\beta^-$p) branch.
We will present, for the first time, the results of an independent search for $^{11}$Be($\beta^-$p) performed using a fast, fragmented $^{11}$Be beam at the National Superconducting Cyclotron Laboratory (NSCL) and the Gaseous Detector with Germanium Tagging (GADGET) system. GADGET consists of a gaseous proportional detector that is sensitive to low-energy charged-particle emission and the Segmented Germanium Array that provides gamma-ray detection. Leveraging the two detection systems, detector characterization is performed by the well-studied $^{11}$Be($\beta^-\alpha$)$^7$Li decay in situ to construct the anticipated proton signal.
This work has been supported by the U. S. Department of Energy under Award No.: DE-SC0016052
and the U. S. National Science Foundation under Award No.: 1565546 and 1913554.
| Topic | Experiment |
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