The One Hundred and Fourteenth Chemical Element Nation

Scientists from the US Department of Energy's National Laboratory were able to verify the receipt of the one hundred and fourteenth heavy element, this after about a decade that another research group in Russia claimed the primacy for it. The search for this element has long been an essential part of the expectations of nuclear scientists to find an "island of instability"

Scientists from the US Department of Energy's National Laboratory were able to verify the receipt of the one hundred and fourteenth heavy element, this after about a decade that another research group in Russia claimed the primacy for it. The search for this element has long been an essential part of the expectations of nuclear scientists to find an "island of instability".

Heino Nitsche, head of the radiochemistry and nucleus of heavy elements group at the institute, and professor of chemistry at the University of California, Berkeley, led the group that independently verified the acceptance of the new element. Using a device known as the "Berkeley gas-filled separator", the researchers were able to confirm the reception of two individual nuclei of element 114, each containing 114 protons, but different numbers of neutrons and separate decay paths. "Following the verification of the production of the 114th element, we have removed any doubt as to the validity of the Russian group's claims," ​​notes the lead researcher. "The finding proves that it is indeed possible to produce the most interesting heavy elements in the laboratory." The results of the study were published in the scientific journal Physical Review Letters.

Elements, heavier in weight than the element uranium (atomic number 92, indicating the number of protons in the atomic nucleus), are radioactive and decay in a period of time shorter than the age of the earth; Thus, they cannot be found in nature (despite the fact that you can sometimes find remnants of the elements neptunium and plutonium in uranium lead). Elements up to atomic number 112 have been artificially prepared - those with low atomic numbers in reactors and nuclear explosions, and the highest in particle accelerators - and usually decay very quickly, within a few seconds or fractions of a second.

In the late fifties of the last century, scientists calculated and found that very heavy elements (superheavy) with certain combinations of protons and neutrons, organized in "shells" in the atomic nucleus, should be quite stable, so that in the end an "island of instability" will be obtained in which the length- Their life could reach up to minutes or days - and even, the most optimistic among them believe - millions of years. Early calculations suggested that an element with 114 protons and 184 neutrons might be one of these stable elements. Researchers at the US Department of Energy's National Institute also encouraged the search for the heaviest elements that contain "magic numbers" of nucleons (protons or neutrons as the components of the nucleus).

"People have been dreaming of extremely heavy foundations since the sixties," notes the researcher. "However, it is rare that important findings as claimed by the Russian group regarding the preparation of the 114th element would be unverified for such a long period of time. Scientists have already begun to wonder if indeed heavy elements exist in reality."

In order to create extremely heavy nuclei it is necessary to "shoot" one type of atoms at a target composed of another type; The total number of protons of the fusion of these two types of atoms must be at least equal to the required element. Verification of the results of the Russian group required directing a beam of calcium ions (48Ca, a calcium atom with 20 protons and 28 neutrons in its nucleus) at a target composed of plutonium isotopes (242Pu, which has 94 protons and 148 neutrons). This process was carried out using a cyclotron device - a powerful particle accelerator.

"The treatment of plutonium is notorious for its complexity," says the lead researcher, "and each research group prepares the targets from it in a slightly different way, but extensive experience here at our institute has led to a deep understanding of the process."

While the ejected and target atoms are reacting with each other, many other types of nuclear reaction products are ejected. Since the nuclei of the heaviest elements are rare and short-lived, both groups, both the Russian and the American, used gas-filled separators in which diluted gas and controlled magnetic fields move out the abundance of remnants obtained in the nuclear collisions, so that ideally only fragments with the requested number of nucleons will arrive at the detector.

Using this process, the researchers identified two isotopes: 286114 (114 protons and 172 neutrons) and 287114 (114 protons and 173 neutrons). The first isotope (286114) decayed in about a tenth of a second while emitting alpha particles (a helium nucleus - two protons and two neutrons) - and becoming a "son" nucleus of element 112 - which itself decays to a nucleus with a lower atomic number. The other isotope decays in about the second half, emitting alpha particles to form element 112, which also emits alpha particles afterwards to form element 110, before decaying further into a nucleus with a lower atomic number.

The success of this research group in locating the two isotopes and following their detailed decay paths was based on sophisticated and advanced methods of detection, data collection and analysis. After passing through the separator, the appropriate nuclei reach a detection chamber. If an atom of element 114 is indeed detected, and immediately afterwards an emission of alpha particles is also detected, the particle accelerator beam is immediately turned off, so that further decay events can be recorded without background interference. In addition to such automated methods to increase the collection of information, its analysis was then carried out in a completely independent manner using unique computer programs. "Although the cross sections of the isotopes were much lower than those reported by the Russian researchers - the mode of decay, the lifetimes and the corresponding energies, were all consistent with the previous findings and in fact confirmed their achievement in a decisive way," explains the lead researcher.

"Based on the ideas that were popular in the sixties, we believed that we would indeed reach an island of stability for element 114. More up-to-date theories indicate increased stability of other atomic numbers, such as 120 and 126. Our research will help us determine which of the theories is more correct and how to adjust the models our."

The researcher adds: "During the last twenty years, many stable isotopes have been discovered that are between known isotopes of heavy elements and between the islands of stability - in fact, they can be seen as a springboard to these islands. The remaining question is what is the perimeter of the island - from 114 to 120 or 126, and what is its height above the "sea of ​​instability" that surrounds it."

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