Corresponding parts of the spectra obtained on day 20 of the three measurements performed. credit: Physical examination C (2024). DOI: 10.1103/PhysRevC.109.055501
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Corresponding parts of the spectra obtained on day 20 of the three measurements performed. credit: Physical examination C (2024). DOI: 10.1103/PhysRevC.109.055501
The search for the elusive neutrino takes many forms. Detectors consisting of many tons of gallium are used in several experiments because neutrino interactions can occur on the stable gallium-71 (71Ga) nucleus and transforms it into a radioactive isotope of germanium (71Ge) with an 11-day half-life, which can then be observed with traditional radiation detectors.
However, the speed of 71The production of Ge from these interactions was observed to fall short of expectations. This emerges as what is called the “gallium anomaly” – a significant discrepancy that occurs when electron neutrinos bombard gallium and produce 71Ge.
This anomaly cannot be explained by modern theories. As a result, it has been the subject of speculation that this may be a sign that the neutrino can transform into other exotic particles, such as sterile neutrinos, which interact even less with matter than the normal neutrino; if confirmed, it would be a huge discovery.
It has recently been suggested that this anomaly could instead be explained by something more mundane – an incorrectly measured half-life for 71Ge core. This is because the predicted rate of neutrino interactions depends on this half-life.
To test this possible explanation for the gallium anomaly, a team of scientists at the Lawrence Berkeley and Lawrence Livermore National Laboratories determined 71Half-life of Ge with a set of carefully performed measurements, including two performed side-by-side with other long-lived radioactive isotopes with well-known half-lives. The study appears in Physical examination C.
The team was able to determine 71Ge half-life with an accuracy about four times better than any previous measurement. The operation eliminates the incorrect measurement of 71Ge as an explanation for the anomaly, which must therefore have a different origin – possibly in the existence of a fourth type of neutrino, called the sterile neutrino.
“The new half-life obtained by our team confirmed the earlier results, but put it on a much firmer footing, definitively ruling out the possible explanation that the missing neutrinos were instead due to an incorrect 71Ge half-life,” said LLNL scientist and lead author Nick Skielzo. “Therefore, the gallium anomaly remains a true mystery—one that potentially still requires some unexpected new neutrino behavior to be understood.”
Other LLNL study authors include Narek Gharibyan, Ken Gregorich, Brian Sammis, Jennifer Shusterman and Keenan Thomas.
More info:
EB Norman et al, Half-life of Ge71 and the gallium anomaly, Physical examination C (2024). DOI: 10.1103/PhysRevC.109.055501. On arXiv: DOI: 10.48550/arxiv.2401.15286
Log information:
Physical examination C
arXiv
