Köln 2025 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 17: Structure and Dynamics of Nuclei VI
HK 17.4: Vortrag
Dienstag, 11. März 2025, 16:45–17:00, HS 2 Physik
Search for the Double Alpha Decay of Ra-224 at GSI: Final Sensitivity Estimation — •Heinrich Wilsenach — The Hebrew University of Jerusalem, Jerusalem, Israel
Double alpha decay is a predicted decay mode when the atomic nucleus decays via the simultaneous emission of two α-particles. A recent theoretical publication by Mercier et al. (PRL 127, 012501 (2021)) has renewed interest in this topic, which was first discussed in the late 1970s. The work proposes an experimentally achievable estimate for the branching ratio of about 10−8. In the last 2 years, three experiments have been performed to search for the double alpha decay of trans-lead isotopes: at GSI (2022), at the ISOLDE facility (CERN, 2023), and at MSU (2024).
In this talk, we will focus on the double alpha experiment performed at the FRS Ion Catcher (FRC-IC) to observe the decay of 224Ra. To reduce the random coincidence detection rate, an offline 228Th source was used at FRS-IC to produce a beam of Ra2+ ions. Since the two α-particles are predicted to be emitted in opposite directions with the branching ratio of 10−8, two face-to-face silicon strip detectors were employed to detect all alphas and betas from the known decay transitions in the 224Ra decay chain. A large dataset of 109 224Ra events gives an expected number of signal events of 90 double alpha decays.
The final stage of data analysis is the main focus of this talk. We present the consistent processing of the entire combined dataset and the final evaluation of the detection setup sensitivity.
Keywords: Double alpha decay; Rare decay; Decay spectroscopy