ALPHA-DECAY AND SPONTANEOUS FISSION HALF-LIVES OF SUPER-HEAVY NUCLEI AROUND 270Hs

Transcription

1 ALPHA-DECAY AND SPONTANEOUS FISSION HALF-LIVES OF SUPER-HEAVY NUCLEI AROUND 270Hs C.I. ANGHEL 1,2, I. SILISTEANU 1 1 Department of Theoretical Physics, IFIN_HH, Bucharest - Magurele, Romania, 2 University of Bucharest, Faculty of Physics, Bucharest - Magurele, Romania Contents 1. OUTLINE OF THE HALF-LIFE CALCULATIONS 1.1. α- DECAY (AD). SHELL MODEL RATE THEORY (SMRT) I. Silisteanu and A. I. Budaca, At. Dat. Nucl. Data Tab. (2012) 98. A. I. Budaca and I. Silisteanu, Phys. Rev. C 88, (2013). C. I. Anghel and I. Silisteanu, Phys. Rev. C 95, (2017) SPONTANEOUS FISSION (SF). SF HALF-TIME KARPOV, ZAGREBAEV, PALENZUELA, RUI, GREINER, INT. J. MOD. PHYS. E 21, (2012) RESULTS FOR DECAY PROPERTIES 2.1. α- decay energies and half-lives 2.2. SF half-lives 2.3. Competition α- decay - SF 3. CONCLUSIONS and OUTLOOK

2 ABSTRACT Background: AD and SF are the most important decay processes of SHN. Purpose: To investigate the stability of SHN with Z= and N= as observed in their decay modes and lifetimes. Methods: AD half-lives: - microscopic (shell model) formation amplitude AMFA; - reaction amplitude RA (integrating Eqs. of motion). SF half-lives: - phenomenological method based on LDM-liquid drop model and SF barrier (Muller 2015). Results: A summary of experimental decay data and calculated decay properties is presented. New half-life predictions are made for many unknown nuclei. A systematics of decay properties was proposed for nuclei around (270)Hs.

3 J. H. Hamilton, S. Hofmann, Y. T. Oganessian, Annu. Rev. Nucl. Part. Sci. (2013) 63

4 1. α- DECAY. SHELL MODEL RATE THEORY (SMRT)

5 1.2 Spontaneous Fission KARPOV, ZAGREBAEV, PALENZUELA, RUI, GREINER Int. J. Mod. Phys. E 21, No. 2 (2012) Bf - Muller et al PRC (2015) 91 new even-odd corrections ( extracted from data fit )

6 2. RESULTS FOR DECAY PROPERTIES -value extrapolations J. Dong, W. Zuo and W. Scheid, PRL 107, (2011) calculated measured calculated

7 The Qα energy (experimental - 30 and calculated - 50) as a function of N for the isotopic series of this elements

8 Qα energy as a function of Z and N for the isotopic and isotonic series with Z= and N= (A linear increasing with Z and irregular decreasing with N) N=162 we have minimum energy values; N=164 we have maximum values of energy.

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10 A good accordance of calculated total half-lives with experimental data.

11 Sg: -strong competition AD-SF for N= ;N= A good accord exp-theory for N=159 and N=165. N=160: - competition AD-SF for Z= ;. -for Z=odd, total half-lives greater than for Z=even nuclei; Hs: - competition AD-SF for N= ; - α main decay mode for N= N=162: - α main decay channel for Z= ; - accord exp-theory. Ds: -competition AD-SF for N=158, 159; - For N= α main decay mode; N=164: - competition AD-SF for Z= ;. -α main channel for Z= Experimental and calculated α decay and spontaneous fission and total half-lives for isotopes (first line) and isotones (second line) of the elements around (270)Hs. For isotones we have a good agreement between theory and experiment data. The odd nucleon increases considerably the fission half-life and less the α half-life.

12 The SHN studied in this paper. For each isotope, the mass number, Q alpha energy, total half-lives and branching ratio for alpha and SF are shown. Qα,total half-lives (30 nuclei-exp. Data); Qα,total half-lives (81 nuclei-calculated values). Table with of experimental data is incomplete. For each isotope, mass number, half-lives and branching ratio are shown. The nuclei with Z=108 ± 1, N=162 ± 1 no fission. The nucleus Hs + α =Ds - alpha decay. The nucleus Hs α =Sg - spontaneous fission.

13 Summary and outlook The alpha-decay and Spontaneous Fission half-lives are successfully described by semi-empirical formulas derived from the systematics of decay data and theoretical results (including: shell structure, finite sizes corrections, fine structure, deformation, pairing correlation, resonance scattering). Alpha-decay and spontaneous fission are competitive decay modes for superheavy nuclei around (270)Hs. The agreement between experiment and theoretical predictions good. Half-lives predictions for many unknown nuclei. A major reason of interest in nuclear decay properties is the insight witch these data afford into the structure and dynamics of the SUPERHEAVY ELEMENTS.

14 Thank You For Your Attention!