Tag Archives: Isotope

Newly Discovered Aluminum Isotope: Aluminum-20

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The detection of previously unknown nuclear aluminum-20 was achieved by observing attenuation during its flight.

A three-proton release from aluminum-20. Image credit: Xiaodong Xu.

Currently, more than 3,300 nuclides have been identified, yet fewer than 300 are stable and naturally occurring. The remaining nuclides are unstable and undergo radioactive decay.

By the mid-20th century, researchers had discovered several common decay modes, including α-decay, β+ decay, electron capture, γ-radiation, and nuclear fission.

In the last few decades, advancements in nuclear physics experimental facilities and detection techniques have enabled the discovery of various exotic decay modes, particularly in nuclei that are far from stability, especially neutron-deficient nuclei.

In the 1970s, the phenomenon of single proton radioactivity was identified, where the nucleus was attenuated by releasing a proton.

In the 21st century, the discovery of bipolar radioactivity emerged, attributed to the decay of highly neutron-deficient nuclei.

Recently, even rarer disintegration events have been recorded, including those resulting in three, four, and five products.

“Aluminum-20 is the lightest aluminum isotope ever discovered,” states Dr. Xiaodong Xu, a physicist at the Institute of Modern Physics, Chinese Academy of Sciences.

“It resides across the proton drip line and has seven fewer neutrons compared to stable aluminum isotopes.”

Employing in-flight damping techniques with fragment separators at the GSI Helmholtz Center for Heavy Ion Research, physicists assessed the angular correlation of the damping products of aluminum-20.

Their detailed analysis of these angular correlations revealed that the ground state of aluminum-20 initially decays by releasing one proton into an intermediate ground state of magnesium-19, which subsequently collapses through the simultaneous release of two protons.

Aluminum-20 marks the first observed tripolar emitter, classified as a bipolar radionuclide.

The research also indicated that the damping energy of the aluminum-20 ground state is significantly lower than anticipated based on isospin symmetry, suggesting a potential breaking of isospin symmetry between aluminum-20 and its mirror partner, neon-20.

This conclusion is endorsed by advanced theoretical calculations predicting that the spin parity of the aluminum-20 ground state differs from the spin parity of the neon-20 ground state.

“This research will enhance our understanding of the proton evaporation phenomenon and provide insights into the structural dynamics and collapse of nuclei beyond the proton drip line,” Dr. Xu remarked.

The team’s paper was published this month in the journal Physical Review Letters.

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X.-D. Xu et al. 2025. Isospin symmetry revealed through the attenuation of the three-proton emitter aluminum-20. Phys. Rev. Lett. 135, 022502; doi:10.1103/hkmy-yfdk

Source: www.sci.news

Physicists Unveil Heaviest Known Proton-Luminescent Isotope: Astatine-188

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At the Accelerator Laboratory of the University of Zibaskira in Finland, physicists utilized a gas-filled recoil separator focal plane spectrometer to observe two attenuation events of the newly discovered isotope astatin-188 (188At), which is composed of 85 protons and 103 neutrons.

Kokkonen et al. Report the discovery of the new nucleus 188At, which is the heaviest proton-emitting isotope known to date.

“Proton emission is a rare type of radioactive decay where the nucleus releases protons, moving toward stability,” explained Henna Kokkonen, a doctoral researcher at Zibaskira University.

“This new nucleus is currently the lightest known isotope of astatin, 188At, containing 85 protons and 103 neutrons.”

“Studying this type of exotic nucleus is exceedingly challenging due to its brief lifespan and low production cross-section. Therefore, precise techniques are essential.”

“The nuclei were produced through fusion deposition reactions by irradiating natural silver targets with a 84Sr ion beam,” added Dr. Kare Auranen of Zibaskira University.

“The detection of the new isotopes was made possible using the Ritu Recoil separator’s detector setup.”

In addition to the experimental findings, the physicists expanded theoretical models to interpret the collected data.

According to the team, 188At can be likened to a strong explosion, resembling “the shape of a watermelon.”

“The nuclear properties suggest a shift in the behavior of the binding energy of valence protons,” Kokkonen stated.

“This is attributed to unprecedented interactions with heavy nuclei.”

“Isotopes are rare globally, and this marks the second occasion I’ve had the chance to make history.”

“All experiments pose challenges, and it is rewarding to conduct research that enhances our understanding of the fundamental limits of matter and nuclear structure.”

The authors intend to refine the current uncertainties and half-life of the attenuation energy by further theoretical exploration of charged particle-damped heavy nuclei, observing the evolution of their shapes, and examining additional decay events of 188At.

“Equally intriguing is the study of the collapse of a currently unknown nuclear isotope 189At, which could be a proton-emitting nucleus, an aspect we have yet to explore in future experiments,” they concluded.

Their paper was published in the journal Nature Communications.

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H. Kokkonen et al. 2025. New Proton Emitter 188At signifies unprecedented interactions in heavy nuclei. Nat Commun 16, 4985; doi:10.1038/s41467-025-60259-6

Source: www.sci.news

Scientists create new isotope of plutonium

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The newly discovered isotope plutonium-227 has a half-life of 0.78 seconds, according to a team of Chinese physicists.

Areas 87≤Z≤97 and 112≤N≤136 in the nuclear map show the new isotope plutonium-227 (red star) and 12 nuclides (blue stars) discovered at the Institute of Modern Physics, Chinese Academy of Sciences. Science. Image credit: Huabin Yang.

“The magic numbers of protons and neutrons, such as 2, 8, 20, 28, 50, 82, and 126, are correlated with shell closure,” said Dr. Zaiguo Gan of the Institute of Modern Physics, Chinese Academy of Sciences. . And my colleagues.

“Previous studies have shown that the closure of the 126 neutron shell weakens persistently up to uranium, so it will be interesting to explore whether shell closure weakens in the transuranium region.”

“Through a series of experiments, we discovered that shell closure exists in neptunium isotopes.”

“However, due to the lack of experimental data, the robustness of this closure in plutonium isotopes remains unknown.”

To investigate the unknown plutonium isotope, the authors conducted experiments in the gas-filled reaction separator SHANS (Spectrometer for Heavy Atom and Nuclear Structures).

Using nuclear fusion vaporization reactions, we were able to synthesize plutonium-227, a plutonium isotope that is severely deficient in neutrons.

“Plutonium-227 is the 39th new isotope discovered by the Modern Institute of Physics,” they said.

From the nine decay chains observed, physicists determined the alpha particle energy and half-life of plutonium-227 to be approximately 8,191 keV and 0.78 seconds, respectively.

“These data are in very good agreement with the known plutonium isotope system,” they said.

The researchers now plan to examine more plutonium isotopes to gain a deeper understanding of the evolution of the shell in plutonium.

“The newly discovered plutonium-227 is still seven neutrons away from the magic number 126,” said Dr. Huabin Yang, also of the Institute of Modern Physics, Chinese Academy of Sciences.

“To study the robustness of plutonium’s shell closure, we need to continue research on lighter plutonium isotopes, including plutonium-221 to plutonium-226.”

of the team work appear in the diary Physical Review C.

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HB Yang others. 2024. Alpha decay of the new isotope 227Pu. Physics. Rev.C 110 (4): 044302;doi: 10.1103/PhysRevC.110.044302

Source: www.sci.news

Scientists witness uncommon nuclear decay of potassium isotope

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Physicists are Potassium Decay (KDK) Collaboration. They directly observed for the first time a very rare but important decay pathway from potassium-40 to argon-40. Their results have the potential to improve current understanding of physical processes and increase the accuracy of geological dating.

Decay scheme of potassium 40. Image credit: Stukel other., doi: 10.1103/PhysRevLett.131.052503.

Potassium-40 is a ubiquitous natural isotope whose radioactivity has been used to estimate geological ages over billions of years, to theories of nuclear structure, and to the search for subatomic rare events such as dark matter and neutrinoless double beta decay. influence.

The decay of this long-lived isotope must be precisely known for its use as a global clock and to explain its presence in low-background experiments.

Although potassium-40 has several known decay modes, the electron-capture decay predicted directly into the ground state of argon-40 has never been observed before.

“Some of the nuclei of certain elements radioactively decay into the nuclei of other elements. These decays can be helpful or annoying, depending on the situation,” the KDK physicists said. I am.

“This is especially true for potassium-40, an isotope that normally decays to calcium-40, but about 10% of the time it decays to argon-40.”

“This decay pathway involves a process called electron capture, which provides information about the nuclear structure.”

“Potassium-40 has a very long half-life, so it can even determine the age of geological objects on billion-year time scales.”

“Due to its long half-life, it is difficult to find another way for potassium-40 to break down.”

In a new study, researchers measured a rare decay branch of potassium-40 at Oak Ridge National Laboratory's Holyfield Radioactive Ion Beam Facility.

“Quantifying the decay rate of potassium-40 and its decay branches is difficult because it requires measuring the parent nucleus and a sufficient number of rare progeny nuclei,” the researchers said.

“We studied a subset of potassium-40 that decays to argon-40 by electron capture, which accounts for about 10% of all potassium-40 decays.”

“Although most potassium-40 electron-capture decays emit characteristic gamma rays that form the background of most experiments, a small subset of these decays occur without gamma ray emission.”

“This happens when potassium-40 captures an electron that goes directly to the ground state of argon-40.”

“We have directly measured this decay for the first time. This result indicates that other decay rates may also need to be reevaluated.”

“The rare decay branch we identified and measured provides unique experimental evidence for so-called forbidden beta decay, with implications for predictions of nuclear structure and for potassium-based geological and solar system age estimates. It removes years of uncertainty.”

“This discovery also improves our assessment of the background that exists in experiments that explore new physics beyond the Standard Model.”

The results are published in two papers (paper #1 and paper #2) in the diary physical review letter and diary Physical Review C.

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M. Stukel other. (KDK collaboration). 2024. 40,000 rare collapses with implications for fundamental physics and geochronology. Physics.pastor rhett 131 (5): 052503; doi: 10.1103/PhysRevLett.131.052503

L. Harias other. (KDK collaboration). 2024. Evidence of ground state electron capture at 40K. Physics. Rev.C 108 (1): 014327; doi: 10.1103/PhysRevC.108.014327

Source: www.sci.news

Nuclear Physicist Investigates Tantalum Decay in 180m Isotope

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Tantalum-180m (180mTa) is a rare isotope of tantalum whose decay has never been observed, and whose lifetime is expected to be about a million times longer than the age of the universe.

Modified Majorana module in assembly glovebox with germanium detector crystal and tantalum sample installed. Image credit: Majorana Collaboration.

Tantalum, a chemical element with symbol Ta and atomic number 73, is a rare, hard, blue-gray, shiny transition metal with excellent corrosion resistance.

It has multiple stable isotopes: 2 stable radioisotopes and 35 artificial radioisotopes.

Tantalum-180, the least abundant isotope, occurs naturally in a long-lived excited state.

In an excited state, the protons or neutrons in the nucleus have a higher energy level than normal.

Although energetically possible, radioactive decay of this excited state in tantalum-180m has never been observed before.

Nuclear physicists from the Majorana collaboration are currently conducting experiments aimed at measuring this decay, which is expected to have a lifetime about a million times longer than the age of the universe.

For the experiment, they Majorana Demonstrator At Sanford Underground Research Facility.

Additionally, a significantly larger amount of tantalum samples were introduced compared to tantalum samples previously used in similar studies.

Over the course of a year, they collected data using a series of high-purity germanium detectors with exceptional energy resolution.

They also developed analytical methods specifically tailored to detect multiple expected decay signatures.

As a result of these combined efforts, we were able to establish unprecedented limits that fall within the range of 10.18 up to 1019 Year.

This level of sensitivity represents the first example in which half-life values ​​predicted from nuclear theory have become achievable.

Although the collapse process has not yet been observed, these advances have significantly enhanced existing limits by one to two orders of magnitude.

Additionally, this advance allowed the Majorana team to ignore certain parameter ranges associated with various potential dark matter particles.

“With a new limit of up to 1.5*1019 “This is the most sensitive search for a single β and electron capture decay achieved to date,” the authors said.

“Across all channels, you can exclude attenuation with T1/2<0.29*10.”18For years. ”

of result appear in the diary physical review letter.

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IJ Arnquist other. (Majorana collaboration).Constraints on collapse 180mTa. Physics.pastor rhett 131 (15): 152501; doi: 10.1103/PhysRevLett.131.152501

Source: www.sci.news