Experimental and theoretical investigations of the decays of /sup 206/Fr and /sup 208/Fr. [100 to 150 MeV]

Technical Report · Mon Jan 01 04:00:00 EST 1979

DOI:https://doi.org/10.2172/5612055· OSTI ID:5612055

Ritchie, B. G.

/sup 206/Fr and /sup 208/Fr were mass separated and observed with large-volume semiconductor detectors in calibrated geometries. Alpha, gamma, and electron singles and gamma-gamma and gamma-electron coincidence data were taken. The alpha decay experiments permitted the determination of the alpha branching ratios for /sup 206/ /sup 208/Fr as well as /sup 205/ /sup 207/Fr. The method used includes the information obtained from the electron capture decay studies of those nuclei. The alpha branching ratios obtained are generally higher than those reported previously. Energies and half-lives are in general agreement with previous measurements. The alpha measurements also revealed the presence of a heretofore unobserved alpha-emitting isomer in /sup 206/Fr. The isomer has a half-life of 0.7 +- 0.1 seconds, and the energy of the associated alpha decay is 6.930 +- 0.005 MeV. Gamma data taken with the alpha measurements suggest that the isomeric level is 531 keV above the /sup 206/Fr ground state, with the associated alpha decay populating a level at 391 keV in the /sup 202/At nucleus. Measured alpha branching ratios were analyzed with the Rasmussen reduced width formalism. All observed francium decays were deduced to be unhindered. This study produced detailed level schemes for /sup 206/Rn and /sup 208/Rn. The gamma and electron data permitted the determination of internal conversion coefficients, multipolarities, spins, and parities. It appears from systematics that two different bands of states above J/sup ..pi../ = 4+ are populated by in-beam studies. The deduced level scheme of /sup 208/Rn was studied in the interacting boson approximation (IBA) with the computer code PHINT. The level scheme is readily explained with this model up to around 2 MeV. Good agreement between theory and experiment was also obtained for /sup 204/Rn and /sup 206/Rn.

• Research Organization: South Carolina Univ., Columbia (USA). Dept. of Physics and Astronomy
• DOE Contract Number: EY-76-C-05-0033
• OSTI ID: 5612055
• Report Number(s): DOE/TIC-11100
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALKALI METAL ISOTOPES
ALPHA DECAY
ALPHA DECAY RADIOISOTOPES
ALPHA SPECTRA
ANGULAR MOMENTUM
BETA DECAY
BETA DECAY RADIOISOTOPES
BRANCHING RATIO
CHARGED-PARTICLE REACTIONS
CONVERSION
CROSS SECTIONS
DATA
DATA FORMS
DECAY
ELECTRON CAPTURE DECAY
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
ENERGY LEVELS
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EVEN-EVEN NUCLEI
EXCITATION FUNCTIONS
EXPERIMENTAL DATA
FRANCIUM 205
FRANCIUM 206
FRANCIUM 207
FRANCIUM 208
FRANCIUM ISOTOPES
FUSION REACTIONS
GRAPHS
HALF-LIFE
HEAVY ION REACTIONS
HEAVY NUCLEI
INFORMATION
INTERNAL CONVERSION
IRIDIUM
ISOTOPES
METALS
MEV RANGE
MEV RANGE 100-1000
MINUTES LIVING RADIOISOTOPES
MULTIPOLARITY
NEON 20 REACTIONS
NUCLEAR REACTIONS
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
PARITY
PARTICLE PROPERTIES
PLATINUM METALS
RADIOISOTOPES
RADON 206
RADON 208
RADON ISOTOPES
REFRACTORY METALS
SPECTRA
SPIN
TRANSITION ELEMENTS