A = 8 Recoil Spectroscopy with the Beta Decay Paul Trap

The A = 8 system is a rich playground for probing science ranging from testing the nature of the weak interaction to understanding the physics of the Sun. Through careful study of the β-delayed α-particles following the decays of ⁸Li and ⁸B, the triple coincidence measurement of β-α-α can be used to determine the β-ν angular correlation coefficient a_βν in these Gamow-Teller decays to place constraints on possible Tensor currents in the weak interaction. Additionally, an α-α coincidence measurement enables a determination of the of the ⁸B neutrino energy spectrum. An ideal tool to study the charged particles emitted during the β-decay process are linear Paul traps. These traps suspend a cloud of radioactive ions in a high vacuum environment using static and RF electric fields, confining the cloud to a region of ~1mm³ for extended periods of time, free from interactions with a substrate, and enabling a backing free measurement of the emitted radiation following β-decay. At ANL’s ATLAS facility, the Beta-decay Paul Trap (BPT) is dedicated to studying the β-delayed α emission of ⁸Li and ⁸B. The open geometry of the BPT allows for close packing of four 64x64 mm, 1 mm thick, 32-fold segmented DSSD Si detectors, backed by four plastic scintillators, providing ~25% solid angle coverage.



We will present an overview of the A=8 program with the BPT, including measurements of a_βν in ⁸Li and ⁸B and a determination of the neutrino spectrum following β-decay of ⁸B. In particular, we will highlight the recent results from a high-statistics measurement of the ⁸B dataset to determine a_βν and new constraints on C_T and C’_T in the decay of mirror systems.