Superheavy hydrogen 5H and spectroscopy of 7He

Data on the spectroscopy of ⁵H and ⁷He from recent experiments with radioactive beams in Dubna and in RIKEN are presented.     

Heavy element research at FLNR (Dubna)

The setting of the experiments is described and the results obtained on the synthesis of the heaviest nuclides in reactions induced by ⁴⁸Ca projectiles are presented. The decay properties of the new nuclei confirm the theoretical predictions about the new nuclear shells and the “islands of stability” of superheavy elements. Briefly, also the results of the first experiments aimed to study the atomic and chemical properties of element 112 are reported.     

Fusion-fission of heavy and superheavy nuclei

The process of fusion-fission of heavy and superheavy nuclei (SHE) with Z=82–122 formed in the reactions with ⁴⁸Ca and ⁵⁸Fe ions at energies near and below the Coulomb barrier has been studied. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR) and at the XTU Tandem accelerator of the National Laboratory of Legnaro (LNL) using the time-of-flight spectrometer of fission fragments CORSET and the neutron multidetector DEMON. As a result of the experiments, mass and energy distributions (MED) of fission fragments; fission, quasifission, and evaporation residue cross sections; and multiplicities of neutrons and γ-quanta and their dependences on the mechanism of formation and decay of compound systems have been studied.     

Behavior of nuclear matter under extreme conditions in fission

The spontaneous fission of ²⁵²Cf has been studied via γ-γ-γ coincidence and γ-γ light charged particle coincidence with Gammasphere. The binary fission yields of correlated Mo?Ba pairs with 0–10 neutron emission have been remeasured. The existence of “hot” fission mode with 8–10 neutron emission seen previously in the Mo?Ba split is confirmed but with lower intensities. By gating on the light charged particles detected in ΔE-E detectors and a γ ray in one partner, the relative yields of correlated pairs in alpha ternary SF with zero to 6n emission are observed for the first time with the distribution peaked at 2.5n. New correlated pairs are identified in ¹⁰Be ternary SF. We observed essentially only cold, On ¹⁰Be and little, if any, hot, xn ¹⁰Be. New γ-γ-γ data with 2.3 times the total events show weak non-Doppler broadened high energy peaks in coincidence with transitions in correlated pairs in ¹⁰Be SF shifted by the same 6,1 to 26 keV from the 2-0 energy in ¹⁰Be as seen earlier.     

Parton structure of heavy mesons with variousJ P in QCD

We calculate the moments of heavy quark-parton distribution in heavy flavored (c, b) mesons with variousJ ^P by means of QCD sum rule approach. The results demonstrate that this method allows to distinguish between the structure functions of hadrons with the same quark content and different spin-parity. In particular the leading effect of heavy quark is less in the case ofP-wave mesons (0⁺, 1⁺). This prediction may be tested in the fragmentation of heavy quark into mesons with variousJ ^P.     

Synthesis and decay properties of superheavy atoms in nuclear reactions induced by stable and radioactive ion beams

This talk consists of two parts. The first one presents the results of investigations performed in 1998-2000 in Dubna on the synthesis of superheavy nuclei in reactions induced by ⁴⁸Ca ions. The radioactive decay properties of the nuclei, indicating a considerable increase in the α-decay and spontaneous fission half-lives of the isotopes of elements 110-116 when approaching the closed neutron shell at N = 184, are given. In the second part the possible ways of advancing into the region of more neutron-rich nuclei, using stable and radioactive ion beams, are discussed. Since so far no intense radioactive ion beams are available, some experiments with stable beams are considered as a test for the suggested ideas. Received: 1 May 2001 / Accepted: 4 December 2001     

Evidence for K mixing in 178Hf

Systematics for the appearance of K-mixing levels for the pumping or spontaneous decay of multi-quasiparticle isomers in Hf isotopes are detailed in this letter. The possible location of such a level in the nuclide ¹⁷⁸Hf is discussed and an experiment is proposed to investigate its existence. This revised version was published online in August 2006 with corrections to the Cover Date.     

Multiplicity of prompt neutrons from spontaneous fission of the isotope 252102

The average number of prompt neutrons, $\text{v}$, emitted in the spontaneous fission of the isotope of element 102 with mass number 252 and a half-life of 2.4 s has been measured to be 4.15±0.30 relative to $\text{v}\text{= 2.69±0.01}$ for spontaneous fission of ²⁴⁴Cm.     

Production of high-purity26Al

²⁶Al is a positron emitting radioisotope of aluminium and has a half-life of 7.16×10⁵y. In addition to annihilation -rays of 511 keV, there are three high energy -rays 1129 (2.4%), 1809 (99.73%) and 2938 (0.27%) keV.²⁶Al is the only radioisotope of aluminium available for radiochemical applications, the half-lives of the other aluminium isotopes are seconds and minutes. The usage of²⁶Al is very important in the investigations of the metabolism of Al in human body (for example in Alzheimer disease studies) or as a tracer in radiochemical studies. But²⁶Al is such a long-lived isotope that the task of producing it in tangible amounts is a very difficult one.