The nucleus previously unknown in aluminum-20 was observed for the first time by detecting its disintegrations in flight.
Troisy aluminum-20 emission. Image credit: Xiaodong Xu.
Currently, more than 3,300 nucleids are known, but less than 300 are stable and exist naturally. The others are unstable nucleids that undergo radioactive disintegration.
Current modes of disintegration, such as α disintegration, β-pourade decline, β +disintegration, electron capture, γ radiation and fission, were discovered in the middle of the 20th century.
In recent decades, due to the enormous development of nuclear physics experimental installations and detection technologies, scientists have discovered several exotic disintegration modes in the study of nuclei far from stability, in particular in neutron -deficient nuclei.
In the 1970s, scientists discovered unique proton radioactivity, where nuclei decomposed by emitting a proton.
In the 21st century, radioactivity with two proton was found in the disintegration of certain nuclei extremely deficient in neutron.
In recent years, even rarer disintegration phenomena such as three, four and five proton emissions have been observed.
“Aluminum-20 is the lightest aluminum isotope that has been discovered so far,” said Dr. Xiaodong Xu, a physicist of the Modern Physical Institute of the Chinese Academy of Sciences.
“Located beyond the proton drain line, it has seven less neutrons than stable aluminum isotope.”
Using a flight decrease technique in the Fragments separator of the GSI Helmholtz Center for Heavy Ion Research, physicists measured the angular correlations of aluminum-20 disintegration products.
Thanks to a detailed analysis of the angular correlations, they found that the fundamental state of aluminum-20 first disintegrates by emitting a proton in the intermediate fundamental state of magnesium-19, followed by a subsequent decadence of the fundamental state of magnesium-19 via a simultaneous program with two proton.
Aluminum-20 is the first observed three-proton transmitter where its daughter of decrease in a proton is a radioactive nucleus with two proton.
The researchers also found that the energy of disintegration of the fundamental state of aluminum-20 is significantly smaller than the predictions deducted from ISOSPIN symmetry, indicating a possible ISOSPIN symmetry breaking in aluminum-20 and its partner Mirror Neon-20.
This observation is supported by advanced theoretical calculations which predict that the parity of the spin of the fundamental state of aluminum-20 differs from the parity of the spin of the basic state neon-20.
“This study advances our understanding of the phenomena of proton-emission and gives an overview of the structure and the decrease of nuclei beyond the range of protons,” said Dr. Xu.
The team’s article was published this month in the newspaper Physical examination letters.
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X.-D. Xu and al. 2025. ISOSPIN symmetry disknight disclosed in the disintegration of the issuer to three 20al proton. Phys. Rev. Lett 135, 022502; Doi: 10.1103 / HKMY-YFDK
