Development of odd-Z-projectile reactions for transactinide element synthesis

Thesis/Dissertation · Thu Jan 01 00:00:00 EST 2004

DOI:https://doi.org/10.2172/843003· OSTI ID:843003

Folden, III, Charles Marvin ^[1]

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1. Univ. of California, Berkeley, CA (United States)

The development of new odd-Z-projectile reactions leading to the production of transactinide elements is described. The cross section of the even-Z-projectile ²⁰⁸Pb(⁶⁴Ni, n)²⁷¹Ds reaction was measured at two new energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. In total, seven decay chains attributable to ²⁷¹Ds were observed. These data, combined with previous results, establish an excitation function for the production of ²⁷¹Ds. The maximum cross section was 20 +15 -11 pb at a center-of-target energy of 311.5 MeV in the laboratory frame.The data from the ²⁷1Ds experiments were used to estimate the optimum beam energy for the new odd-Z-projectile ²⁰⁸Pb(⁶⁵Cu, n)272-111 reaction using the Fusion by Diffusion theory proposed by Swiatecki, Siwek-Wilczynska, and Wilczynski. A cross section for this reaction was measured for the first time, at a center-of-target energy of 321.1 MeV in the laboratory frame. The excitation energy f or compound nuclei formed at the target center was 13.2 MeV. One decay chain was observed, resulting in a measured cross section of 1.7 +3.9 -1.4 pb. This decay chain is in good agreement with previously published data on the decay of 272-111.The new odd-Z-projectile ²⁰⁸Pb(⁵⁵Mn, n)²⁶2Bh reaction was studied at three different projectile energies, and 33 decay chains of ²⁶²Bh were observed. The existence of a previously reported alpha-decaying isomeric state in this nuclide was confirmed. Production of the ground state was preferred at all three beam energies. The maximum cross section was 540 +180 -150 pb at a projectile center-of-target energy of 264.0 MeV. This cross section is much larger than that previously reported for the even-Z-projectile ²⁰⁹Bi(⁵⁴Cr, n)²⁶²Bh reaction, which may be because the 54Cr projectile energies in the latter reaction were too high for optimum production of the 1n product. At the highest projectile energy of 268.0 MeV in the target center, two decay chains from ²⁶¹Bh were observed as a result of the ²⁰⁸Pb(⁵⁵Mn, 2n) reaction. In summary, this work shows that odd-Z-projectile reactions can have cross sections comparable to analogous even-Z-projectile reactions, and that the energy of the maximum cross section for 1n reactions can be estimated simply.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 843003
• Report Number(s): LBNL-56749; R&D Project: NHEAVY; TRN: US0503772
• Resource Relation: Other Information: Doctoral Dissertation, Ph.D., University of California, Berkeley, Berkeley, California, USA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
COMPOUND NUCLEI
CROSS SECTIONS
DECAY
DIFFUSION
EXCITATION
EXCITATION FUNCTIONS
GROUND STATES
ISOTOPES
PRODUCTION
PROJECTILES
SYNTHESIS
TARGETS
TRANSACTINIDE ELEMENTS
heavy elements superheavy elements darmstadtium roentgenium bohrium nuclear reactions nuclear chemistry nuclear physics compound nucleus Fusion by Diffusion