Objective
To check the hypothetic existence of nuclear shell closures at Z = 114 and N = 178 - 184, one of the fundamental predictions of modern nuclear theory, an experiments will be performed, aiming at the production of superheavy nuclides with Z = 110, 112 and 114 (N = 166-167, 170-171 and 174-175, respectively) via the complete fusion reactions of 232Th, 238U and 244Pu targets nuclei and 48Ca projectiles delivered by the FLNR JINR U400 cyclotron. To separate complete fusion reaction products it is planned to use fast (1 - 2 hours) chemistry in the case of 232Th target, and kinematic separator VASSILISSA and the Dubna gas-filled recoil separator in the case of 238U and 244Pu targets.
These experimental set-ups will provide a fast ( 1 microsecond) and efficient (40 - 60 %) separation of evaporation residues and study of the decay properties of new isotopes of superheavy elements. For the 48Ca + 238U, 244Pu reactions, this facilities, together with the possibility to use projectile beams with intensities of up to 1013 pps, provide experimental sensitivity of 1 pb during 10 - 20 days of irradiation and unambiguous identification of new isotopes of superheavy elements on the basis of genetic correlation method.
Proposed experiment 232Th+ 48Ca will result in the observation of the predicted long-lived heaviest isotopes of element 106 -- 268106 and 269106. Synthesis and study of new even-even isotope 268106 (N=162) will allow important conclusions to be made regarding the strength of the N=162 deformed shell, shell corrections, and masses of the even-even nuclides in this region of the Nuclear Chart. These experiments will make it also possible to identify daughter nuclides 264104 and 265104. Cross section measurement of the reaction 232Th( 48Ca,3-4n) will give the estimation of the cross section level for the complete fusion reaction of actinide target nuclides with 48Ca ions.
As a result of the 238U+ 48Ca reaction the new heaviest isotopes of element 112 -- 282112 and 283112 can be synthesized. Comparison of the radioactive properties of these nuclides and known isotope 277112 will be critical test of the existence of the new region of nuclear stability and the strength of spherical shell closures at Z=114 and N=178-184.
The new heaviest isotopes of elements 104-110 can be identified as descendant nuclides, as well. Cross section level of the reactions 238U( 48Ca,3-4n) will lead to the estimation of the yield of superheavy nuclei in the complete fusion reaction 244Pu( 48Ca,3-4n). The reaction 244Pu+ 48Ca will be used for the synthesis and study of the new element 114. The identification of isotopes 288114 or 289114 will be critical and decisive test of the modern macro-microscopic nuclear theory and can means the discovery of the new region of spherical superheavy elements.
Topic(s)
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64220 Darmstadt
Germany