THE RADIOACTIVITY OF TERBIUM-158 AND TERBIUM-157
Dysprosium enriched to 0.9% in the mass number 158 was bombarded in the Battelle Reactor for a period of three weeks with an average flux of 5 x lO/sup 12/ neutrons/cm/sup 2/sec. A chemical separation of the resulting activity was performed and a terbium fraction was obtained. After an elapse of 27 months, during which interval the Tb/sup 160/ - tially present in the chemical fraction had disappeared, an examination of the gamma spectrum of the terbium cheraical fraction showed gamma rays at energies of 79.7, higher than 950 kev was observed. A weak gamma ray at an energy of 99.5 kev was also observed. The K x ray emitted by the chemical fraction was identified as that of gadolinium by a comparison with the K x rays emitted by Gd/sup 153/ and Dy/sup 159/. In order to make a mass assignment to the activity in the terbium chemical fraction, two samples of gadolinium enriched in the mass numbers 158 and 157, respectively, were bombarded with 6-Mev protons, and the gamma spectra of the terbium cheraical fraction Gd/ sup 158/ + p and Gd/sup 157/ + p were compared. The gamma spectra of these three activities are found to be the same except for the very intense K x-ray peak observed with the chemical fraction. As a further check, the intensity ratios of the 950 and 182.7-kev photopeaks in the Gdsup 158/ + p and Gd/sup 157/ + p were calculated from a knowledge of the isotopic composition of the enriched gadolinium samples and compared with the experimental values for these intensity ratios. The agreement between the calculated value of 2.7 and the experimental values of 3.1 and 3.6 respectively for the intensity ratios of the 950 and 182.7- kev gamma rays was taken as a confirraation of the assignment of the activity in the terbiura cheraical fraction to Tb/sup 158/. A comparison of these two gamma spectra also indicated that there are no gamma rays that could be associated with a long-lived Tb/sup 157/ activity. An examination of the lowenergy portion of the gamma spectrum of the chemical fraction also showed an intense L x-ray peak at 6 kev. Unscrambling of the gamma ray spectrum was carried out and after applying corrections for crystal efficiency, internal conversion, and escape of iodine x ray, the following ratios were obtained for the transition probabilities for the activity in the terbium chemical fraction: L x ray:. K ray:79.7 kev gamma :99.5-kev gamma :182.7-kev gamma :770-kev gamma :. 950-kev gamma =99:100:5.6:0.89:0.59:0.85:3.4. Acomparison of the K x-ray intensity of the terbium chemical fraction with that of the Gd/sup 158/ + p activity showed that the K x ray was 120 times as intense in the chemical fraction. The preponderance of the K x-ray intensity in the chemical fraction is ascribed to Tb/sup 157/ activity. Coincidence studies were carried out on the gamma spectrum of the Tb/ sup 158/ activity. An energy level diagram for the decay of Tb/sup 158/ was arrived at. In the decay of Tb/sup 158/, 87% of the decays are found to be due to electron capture and the rest due to beta emission. Tb/sup 157/ is found to decay by L and K capture without the emission of any gamma rays. No positron decay was observed in the case of Tb/sup 158/.
- Research Organization:
- Ohio State Univ., Columbus
- NSA Number:
- NSA-16-024814
- OSTI ID:
- 4828878
- Journal Information:
- Dissertation Abstr., Journal Name: Dissertation Abstr. Vol. Vol: 22
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
Similar Records
DECAY OF $sup 157$Tb
Tb$sup 150$: A NEW TERBIUM ISOTOPE
Related Subjects
BETA PARTICLES
CAPTURE
COINCIDENCE METHODS
DECAY
DYSPROSIUM
ELECTRONS
ENERGY
ENERGY LEVELS
ENERGY RANGE
GADOLINIUM
GADOLINIUM 157
GADOLINIUM 158
GAMMA RADIATION
IRRADIATION
NEUTRON BEAMS
NUMERICALS
PHYSICS
POSITRONS
PROTONS
RADIOACTIVITY
REACTORS
SEPARATION PROCESSES
SPECTRA
TERBIUM 157
TERBIUM 158
TRANSIENTS
X RADIATION