Thursday, January 29, 2015

Transfer Reactions: A Way To Create Stable Elements Beyond 106?

Even though creating transuranic elements in the lab has been regarded to as a mere “scientific curiosity”, is there a way to create new ones beyond the atomic number 106?

By: Ringo Bones 

 These days, most of the general public is not jumping up and down with excitement when it comes to synthesizing new elements beyond the atomic number 106. But for almost 35 years now, there has been a very promising method of creating “relatively stable” new elements beyond the atomic number 106. 

At the start of the 1980s, nuclear chemists have thus far been frustrated in their attempts to create super heavy elements with atomic numbers greater than 106, although theories predict that some such elements may be relatively stable. Back in 1980, hopes turned to “transfer reactions” in which one nucleus transfers a portion of its nucleons to another nucleus during a collision. Traditionally, it has been believed that colliding nuclei should combine totally to form a compound nucleus, but Prof. Darlene Hoffman and colleagues from Los Alamos Labs in New Mexico observed that partial combinations occur in certain reactions. The transfer mechanism holds out hope for producing some of the super heavy elements. 

Back in 1999, the technique of transfer reactions did manage to generate some excitement – and a brand new element. Via an e-mail announcement back then, scientists at the Joint Institute for Nuclear Research in Dubna, near Moscow reported strong evidence that they have created the heaviest element yet, one with 114 protons and 184 neutrons. In a recently published work back then, a team of nuclear physicists led by Yuri Oganessian and Vladimir Utyonkov smashed a rare isotope, calcium-48 with a plutonium-244 target to make the element 114. The then brand new element lasted an astonishingly long 30 seconds before decaying into another lighter element, far longer than the 280 microseconds of the last new element found – element 113. The relatively long life of element 114 proves that “islands of stability” exist in the super heavy element range. 

Tuesday, January 27, 2015

Do Protons Really Last Forever?

With the lower limit for the lifetime of a proton is described to be 100 billion trillion times longer than the age of the universe, do protons really last forever? 

By: Ringo Bones 

Those Madison Avenue “Mad Men” hired by DeBeers may have been a little way off the mark when they made a bold advertising claim that “A diamond is forever” – well, at least on a human timescale. But in the world of theoretical physicists – which we are also a part of – there is something that may indeed really last forever and could potentially even outlast our own universe. 

Given the current experimental evidence obtained so far, theoretical physicists has reached a current consensus that the lower limit for the lifetime of a proton – which forms part of the atomic nucleus of ordinary baryonic matter – is described to be at least 100 billion trillion times longer than the age of our universe – which current experimental observations pegged it to be about 13.8 billion years old. For almost 40 years, Scientific American magazine has published several articles on various experiments – some of them are even elaborately grandiose in scale – to determine the absolute lifetime of a proton. 

In particle physics, proton decay is a hypothetical form of radioactive decay in which a proton decays into lighter subatomic particles, such as a neutral pion and a positron. As far as particle physics knows, proton decay has yet to be observed and there is currently no experimental evidence that proton decay even occurs.
In the Standard Model, protons – a type of baryon – are theoretically stable because their baryon number is conserved, that is under normal circumstances; however there is that “chiral anomaly”. Therefore protons will not decay into other particles on their own because they are the lightest – and therefore the least energetic – baryon. 

Some theoretical studies beyond the Standard Model, grand unified theories (GUTs) explicitly break the baryon number symmetry, allowing protons to decay via the Higgs Particle, magnetic monopoles or new X-bosons. Proton decay is one of the few observable effects of the various proposed grand unified theories. To date, all attempts to observe a proton’s decay so far have failed, but some theoretical physicists have proposed that the continuously accelerating expansion of our own universe since the Big Bang might affect the apparent stability of the proton – maybe perhaps 100 billion years from now.