Identifying the full extent of the nuclear landscape, essentially how many isotopes exist, is vital for nuclear physics.
There is a lot left to learn. Beyond the stable nuclei that we find on Earth, there are many unstable nuclei that are formed in stellar events such as supernovae, but which are short-lived. There is a limit to how many protons and neutrons a nucleus can hold – too many and the excess will literally ‘pop out’. These limits are known as the proton and neutron ‘drip lines’.
Although these drip lines can be calculated, getting experiments to agree is another issue. Even finding them experimentally can be a difficult prospect.
A new study by the University of Liverpool, STFC’s Daresbury Laboratory and the University of Jyväskylä has discovered that nuclei can exist in special states that blur the boundaries of existence - behavior of isotopes that are so rare they might only exist momentarily during stellar explosions. Until now, these could have only been predicted through calculations; but the reality was proving to be very different to theory.
Measured half-lives of longest-living states of neutron-deficient Tm, Lu, Ta, Re, and Ir isotopes. Main decay modes are indicated by symbols given in the key. The solid lines connect successive data points from Ref.  for each element. The dashed lines indicate the proton drip line, beyond which proton emission from nuclear ground states is energetically possible (Qp>0). No states are known in nuclei beyond the lightest isotopes shown.
Using spectrometers, the researchers report experimental discovery of an isomer of tantalum with a structure that allows it to live longer than expected before decaying. This multiparticle spin-trap isomer 2,668 keV above the known 9+ state and has a spin 10ℏ higher and negative parity. The 19− isomer also has an 8644(11) keV, 1.4(2)% α-decay branch that populates the
9+ state in 154Lu (lutetium). No proton-decay branch from the isomer was identified, despite the isomer being unbound to proton emission by 3261(14) keV.
That is remarkable stability against proton emission is compared with theoretical predictions.
The University of Liverpool’s Professor Robert Page, who led the research, said, “We usually think of nuclear ground states as being the most stable, but these results show that certain excited states have enhanced stability and could extend the range of observable nuclei far beyond the drip lines.”
Citation: R. J. Carroll, R. D. Page, D. T. Joss1, J. Uusitalo, I. G. Darby1, K. Andgren, B. Cederwall, S. Eeckhaudt, T. Grahn, C. Gray-Jones, P. T. Greenlees, B. Hadinia, P. M. Jones, R. Julin, S. Juutinen, M. Leino, A.-P. Leppänen, M. Nyman, D. O’Donnell, J. Pakarinen, P. Rahkila2, M. Sandzelius, J. Sarén, C. Scholey, D. Seweryniak, and J. Simpson, 'Blurring the Boundaries: Decays of Multiparticle Isomers at the Proton Drip Line', Phys. Rev. Lett. 112, 092501 – Published 4 March 2014 DOI: 10.1103/PhysRevLett.112.092501
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- Part I: Bee Deaths Mystery Solved? Neonicotinoids (Neonics) May Actually Help Bee Health
- Microwave Electron Guns: A Field-Emission Plug-And-Play Solution
- Ancient Buried Canyon In South Tibet Rules Out Tectonic Aneurysm
- Interstellar Is A Dangerous Fantasy Of US Colonialism
- In A Snowstorm, Do You Want Salt Or Vegetable Juice On Your Road?
- The BPA Paradox – Too Many Studies?
- Extraordinary Claims: Review My Paper For $10
- "Way to miss the point of the article, genius. Let me guess, you call yourself a nice guy?..."
- "Seriously? You reveal the final scene of a movie and yet do not provide a spoiler alert in advance..."
- "Well, that is not a great example. If you prefer basketball, you don't watch the NBA at all. ..."
- "Men are better athletes than women. If someone had a choice between watching the NBA and the WNBA..."
- "Why did you find it interesting? It's a rather bland political statement by someone not even in..."
- Investigational drug reduces high potassium levels in chronic kidney disease patients
- Study: Doubling saturated fat in the diet does not increase saturated fat in blood
- Women with serious mental illness less likely to receive cancer screenings
- Only half of patients take their medications as prescribed
- Rare new species of plant: Stachys caroliniana