Observation of new spontaneous fission activities from elements 100 to 105

Thesis/Dissertation · Fri Jan 01 00:00:00 EST 1982

OSTI ID:5138723

Somerville, L P

Several new Spontaneous Fission (SF) activities have been found. Their half-lives and production cross sections in several reactions have been measured by collecting and transporting recoils at known speed past mica track detectors. No definite identification could be made for any of the new SF activities; however, half-lives and possible assignments to element-104 isotopes consistent with several cross bombardments include /sup 257/Rf(3.8s, 14% SF), /sup 258/Rf(13 ms), /sup 259/Rf(approx.3s, 8% SF), /sup 260/Rf(approx.20 ms), and /sup 262/Rf(approx.50 ms). The 80-ms SF activity claimed by the Dubna group for the discovery of element 104 (/sup 260/104) was not observed. A difficulty exists in the interpretation that /sup 260/Rf is a approx.20-ms SF activity: in order to be correct, for example, the SF activities with half-lives between 14 and 24 ms produced in the reactions 109- to 119-MeV /sup 18/O + /sup 248/Cm, 88- to 100-MeV /sup 15/N + /sup 249/Bk, and 96-MeV /sup 18/O + /sup 249/Cf must be other nuclides due to their large production cross sections, or the cross sections for production of /sup 268/Rf must be enhanced by unknown mechanisms. Based on calculated total production cross sections a possible approx.1% electron-capture branch in /sup 258/Lr(4.5 s) to the SF emitter /sup 258/No(1.2 ms) and an upper limit of 0.05% for SF branching in /sup 254/No(55 s) were determined. Other measured half-lives from unknown nuclides produced in respective reactions include approx. 1.6 s (/sup 18/O + /sup 248/Cm), indications of a approx.47-s SF activity (75-MeV /sup 12/C + /sup 249/Cf), and two or more SF activities with 3 s less than or equal to T/sub (1/2)/ less than or equal to 60 s (/sup 18/O + /sup 249/Bk).

• Research Organization: California Univ., Berkeley (USA)
• OSTI ID: 5138723
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ELEMENT 104
SPONTANEOUS FISSION
NOBELIUM 254
NOBELIUM 258
TRANS 104 ELEMENTS
BERKELIUM 249 TARGET
CALIFORNIUM 249 TARGET
CURIUM 248 TARGET
EXPERIMENTAL DATA
HALF-LIFE
MEV RANGE 10-100
MEV RANGE 100-1000
OXYGEN 18 REACTIONS
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
CHARGED-PARTICLE REACTIONS
DATA
DECAY
ELEMENTS
ENERGY RANGE
EVEN-EVEN NUCLEI
FISSION
HEAVY ION REACTIONS
HEAVY NUCLEI
INFORMATION
ISOTOPES
MEV RANGE
NOBELIUM ISOTOPES
NUCLEAR REACTIONS
NUCLEI
NUMERICAL DATA
RADIOISOTOPES
SECONDS LIVING RADIOISOTOPES
TARGETS
TRANSPLUTONIUM ELEMENTS
TRANSURANIUM ELEMENTS
652026* - Nuclear Properties & Reactions
A=220 & above
Experimental- Spontaneous & Induced Fission- (-1987)