Accession Number : AD0489088

Title :   DETERMINATION OF THE HALF-LIFE OF HF-178M.

Descriptive Note : Master's thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Little, Donald Cubbison, Jr

Report Date : MAY 1966

Pagination or Media Count : 46

Abstract : Coincidence counting techniques were used in the determination of the half-life of Hf-178m. The experimental sample, essentially a mixture of Hf-177 and Hf-178, was irradiated with thermal neutrons to produce Hf-178m and Hf-179m isomers. The isomeric transition of Hf-178m is followed by a cascade of gammas (.427, .326, .214, and .093 mev). The isomeric transition of Hf-179m (approximately 18-second half-life) is followed by a .215 mev gamma. The decay data of Hf-178m was effectively isolated from that of Hf-179m by counting coincidences between any two of three specific Hf-178m gammas (.427, .326, and .214 mev). After being corrected for change coincidence counts, this counting data was processed by a computer program (FRANTIC). By using the least-squares techniques, the FRANTIC program fitted a calculated exponential decay curve to the counting data from a single experiment and also computed the half-life for that data. The average half-life of Hf-178m, derived from seven decay experiments, had a value of 3.94 seconds and an uncertainty of 0.5%. The additional uncertainties due to gain instability and background count-rate were estimated. The half-life of Hf-178m was found to be 3.94 + or - 0.04 seconds, all uncertainties included. (Author)

Descriptors :   (*HAFNIUM, ISOMERIC TRANSITIONS), NEUTRON ACTIVATION, THERMAL NEUTRONS, NEUTRON REACTIONS, RADIOACTIVE ISOTOPES, HALF LIFE, GAMMA EMISSION, COINCIDENCE COUNTING.

Subject Categories : Radioactiv, Radioactive Wastes & Fission Prod
      Nuclear Physics & Elementary Particle Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE