Dubna: Berkeley's worthy rival (2)

In the race to hunt for the last superheavy elements in the periodic table, Russia's Institute of Nuclear Research in Russia, Russia is worthy of being a rival to the National Laboratory of the University of California, Berkeley, USA.

>>>Dubna: Berkeley's worthy opponent

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Element 104 was created in 1964, in Dubna, when firing Ne bullets (A = 22, Z = 10) into Pu beer nuclei (A = 242, Z = 94). In this case, some unidentified neutron emitted, and therefore the nuclear mass 104 has not been accurately determined. But in return, by chemical methods, the Dubna group can confirm: the newly created nuclear atoms are eka-hafnium, which means that the new element must be in cell 104 of the reconstituted weekly table. element.

Livermore scientists in Dubna.

The Berkley group also synthesized 104 nuclei, but slower, in 1969. But, through the alpha spectrum of the 102 nuclei, they first identified masses 257, 258 and 259 of new nuclei 104.

The above situation led to a prolonged twinning of the elemental invention 104 and it was not until 1992 that the IUPAC / IUPAP authority resolved it with the decision: i / The patent for the 104 element split for both parties. ii / Do not take any Russian or American names, just name the famous British senior scientist Rutherford to give element 104, ie the official name of 104 is Rutherfordium , the symbol Rf .

The story of element 105 is almost the same.

In 1968, the first 105 nuclei were synthesized by FLNR scientists in Dubna. By firing Ne (22,10) beams into Am beer (243.95), new 105 nuclei are formed and recorded, and their mass has not been accurately determined.

Two years later, 1970, they again synthesized 105 nuclei. And in addition to alpha decay, they discovered both the self-fission phenomenon with a half-life of 2.2 seconds, and found the chemical properties of the This new nuclear atom is similar to Niobium nuclear atoms; ie newly created nuclei must be in the corresponding element 105 of the Mendeleev periodic table. The following year, 1971, the Dubna group upgraded their equipment, repeated their old experiment and correctly identified: the 105 nucleus was formed with the mass number A = 260 .

Berkeley scientists were also a bit slower, and it was announced at the end of April 1970 that the 105 nuclei were synthesized with a mass of A = 260 in the reaction between bullet N (15.7) and Cf beer ( 249.98). They also claimed to measure the alpha energy emitted from this nucleus, but did not coincide with the data obtained by Dubna before.

The evolution of the competition between the world's top two nuclear science centers, which have been awarded the right to invent element 105, also occurred drastically and prolonged. It was not until 1992 that the IUPAC / IUPAP expert groups came to the conclusion that the results from the two JINR and LBNL laboratories complement each other and that the invention patent was common to both.

Again, with element 105 'judges' reconcile! However, the FLNR Science Center in Dubna is still satisfied because it won the great honor: Dubnium Gold name with the symbol Db attached to element 105! The city of Dubna, the real place of birth of the superheavy elements 102, 104 and 105, as well as other elements in the process of being appraised by the competent authorities of IUPAC / IUPAP.

Opponents turn into partners

Famous physicist GN Flerov.

With the elements 104 ( Rutherfordium ) and 105 ( Dubnium ), two senior opponents, Dubna and Berkeley, finally accepted the ruling of the 'referee' IUPAC / IUPAP divided the patent rights.

Going on the path of global reconciliation, entering the new 21st century, the two competitors tightened their hands and turned into partners.

From the early years of the century, Livermore Lawrence Laboratory (LLNL) sent a research project through Dubna as a guest of the Nuclear Reaction Laboratory (FLNL) and conducted experiments with the host. hunt for super-heavy elements at the end of the periodic table of elements, 114 and 116. They take advantage of each other's advantages. Dubna has a powerful U-400 accelerator, an experienced chemical laboratory, etc., and Livermore is exclusive in its beer with Curium or Californium super pure, extremely rare, only made by method. artificial.

On FLNR 's accelerators , they jointly conducted experiments to explore elements 114 and 116. They successfully synthesized nuclei 114 with a mass of A = 287 via the reaction:

Ca (48,20) + Pu (242,94) → X (287,114) + 3n

And collect nuclei 116 with A = 291 via reaction:

Ca (48.20) + Cm (245.96) → X (291,114) + 2n

Recently, the mixed expert group of IUPAC / IUPAP has entered, analyzed and appraised the results of the combined Dubna-Livermore experiment since 2004. And June 1, 2011 has just launched Official conclusion: The authors of the Dubna-Livermore experiment meet copyright criteria for inventing new superheavy elements 114 and 116. And the aforementioned authors are invited to propose names for the elements. 114 and 116 approved by the IUPAC General Assembly.

According to Deputy General Director of JINR, Dubna researcher Dubna wanted the element 114 to be named flerovium to commemorate physicist Georgy Flerov, the late director of FLNR, while element 116 was named moscovium to honor the Moscow Region where Dubna city - the birthplace of many super heavy elements.

So the "marriage" of the two former rivals was fruitful. The expectation of a complete outcome with the official IUPAC decision on names and symbols of 114 and 116 is probably just a matter of time.

Fate of trio 113, 115 and 118?

Now, the more exciting and exciting suspicion is probably shifting to the code set of 113, 115 and 118 with the temporary symbols Uut , Uup and Uuo .

International research group Dubna-Livermore in recent years has actively hunted on the super heavy elements and in turn published the results.

February 1, 2004 International scientific team Dubna-Livermore published the results of the first experiment to synthesize a number of 115 and 113 nuclei when shooting at Americium Am beer with a bunch of Calcium Ca particles on Dubna accelerators. :

Ca (48,20) + Am (243,95) → Uup (288 / 287,115) → Uut (384 / 283,113)

In support of their claims, they conducted additional chemical experiments in June 2004 and December 2005 and proved to have accumulated the following ' great-grandchildren ' of Dubnium Db (268,105). successive alpha decay from 115 'and 113' knots'.

Next, on October 9, 2006, Dubna-Livermore researchers reported the results of the experiment to synthesize about 3-4 nuclei 118 when performing a synthesis experiment on the new Uuo nuclei (294,118). The beam of Ca ions (48,20) of the accelerator at FLNR with Cf beer (249.98) brought from the US.

The results of the study have been reaped by the leading researchers, on the most modern equipment and materials. However, until now the latest products, new elements 113, 115 and 118 have not yet passed through the strict eyes of experts in the Joint Working Party of the Association. International Chemistry and Application (IUPAC). Recently, in this year, the above committee still recommends: The results obtained on the elements 113, 115 and 118 mentioned above (and other research results of German scientists at GSI and Japan in RIKEN) still has not met the criteria to recognize patent rights for its authors.

The road to the end of the periodic table of chemical elements must have many interesting and difficult things.