STUDY OF $gamma$-RAY EMISSION IN THE DECAY OF $sup 228$Ac USING COINCIDENCE TECHNIQUES. (in French)
Journal Article
·
· Compt. Rend., Ser. B 273: No. 12, 509-12(20 Sep 1971).
OSTI ID:4706945
- Research Organization:
- Univ., Nice
- NSA Number:
- NSA-26-014130
- OSTI ID:
- 4706945
- Journal Information:
- Compt. Rend., Ser. B 273: No. 12, 509-12(20 Sep 1971)., Other Information: Orig. Receipt Date: 31-DEC-72
- Country of Publication:
- France
- Language:
- French
Similar Records
EXCITED LEVELS OF $sup 228$Th DEDUCED FROM THE OBSERVATION OF $gamma$-- $gamma$ COINCIDENCES IN THE DECAY OF $sup 228$Ac.
Most theoretical approaches used in nuclear astrophysics to model the nucleosynthesis of heavy elements incorporate the so-called statistical model in order to describe the excitation and decay properties of atomic nuclei. One of the basic assumptions of this model is the validity of the Brink–Axel hypothesis and the related concept of so-called photon strength functions to describe γ-ray transition probabilities. We present a novel experimental approach that allows for the first time to experimentally determine the photon strength function simultaneously in two independent ways by a unique combination of quasi-monochromatic photon beams and a newly implemented γ–γ coincidence setup. This technique does not assume a priori the validity of the Brink–Axel hypothesis and sets a benchmark in terms of the detection sensitivity for measuring decay properties of photo-excited states below the neutron separation energy. The data for the spherical off-shell nucleus 128Te were obtained for γ-ray beam-energy settings between 3 MeV and 9 MeV in steps of 130 keV for the lower beam energies and in steps of up to 280 keV for the highest beam settings. We present a quantitative analysis on the consistency of the derived photon strength function with the Brink–Axel hypothesis. The data clearly demonstrate a discrepancy of up to a factor of two between the photon strength functions extracted from the photoabsorption and photon emission process, respectively. In addition, we observe that the photon strength functions are not independent of the excitation energy, as usually assumed. Thus, we conclude, that the Brink–Axel hypothesis is not strictly fulfilled in the excitation-energy region below the neutron separation threshold (Sn = 8.78 MeV) for the studied case of 128Te.
$gamma$ RAYS EMITTED IN THE DECAY OF $sup 228$Ac $Yields$ $sup 228$Th.
Journal Article
·
Fri Jan 01 00:00:00 EST 1971
· Compt. Rend., Ser. B 273: No. 13, 568-71(27 Sep 1971).
·
OSTI ID:4706945
Most theoretical approaches used in nuclear astrophysics to model the nucleosynthesis of heavy elements incorporate the so-called statistical model in order to describe the excitation and decay properties of atomic nuclei. One of the basic assumptions of this model is the validity of the Brink–Axel hypothesis and the related concept of so-called photon strength functions to describe γ-ray transition probabilities. We present a novel experimental approach that allows for the first time to experimentally determine the photon strength function simultaneously in two independent ways by a unique combination of quasi-monochromatic photon beams and a newly implemented γ–γ coincidence setup. This technique does not assume a priori the validity of the Brink–Axel hypothesis and sets a benchmark in terms of the detection sensitivity for measuring decay properties of photo-excited states below the neutron separation energy. The data for the spherical off-shell nucleus 128Te were obtained for γ-ray beam-energy settings between 3 MeV and 9 MeV in steps of 130 keV for the lower beam energies and in steps of up to 280 keV for the highest beam settings. We present a quantitative analysis on the consistency of the derived photon strength function with the Brink–Axel hypothesis. The data clearly demonstrate a discrepancy of up to a factor of two between the photon strength functions extracted from the photoabsorption and photon emission process, respectively. In addition, we observe that the photon strength functions are not independent of the excitation energy, as usually assumed. Thus, we conclude, that the Brink–Axel hypothesis is not strictly fulfilled in the excitation-energy region below the neutron separation threshold (Sn = 8.78 MeV) for the studied case of 128Te.
Journal Article
·
Tue Jan 01 00:00:00 EST 2019
· Physics Letters B
·
OSTI ID:4706945
+10 more
$gamma$ RAYS EMITTED IN THE DECAY OF $sup 228$Ac $Yields$ $sup 228$Th.
Journal Article
·
Fri Jan 01 00:00:00 EST 1971
· Compt. Rend., Ser. B 273: No. 18, 801-4(3 Nov 1971).
·
OSTI ID:4706945
Related Subjects
N36520* -Physics (Nuclear)-Nuclear Properties & Reactions
A >= 90-Radioactive Decay
N36530 -Physics (Nuclear)-Nuclear Properties & Reactions
A >= 90-Energy Levels & Transitions
ACTINIUM 228
COINCIDENCE METHODS
DECAY
DIAGRAMS
ENERGY LEVELS
GAMMA SPECTRA
KEV RANGE 100-1000
ACTINIUM ISOTOPES Ac-228/beta decay of
$gamma$- $gamma$ coincidence spectra from
(E)
THORIUM ISOTOPES Th-228/energy-level scheme from actinium-228 decay
(E)
A >= 90-Radioactive Decay
N36530 -Physics (Nuclear)-Nuclear Properties & Reactions
A >= 90-Energy Levels & Transitions
ACTINIUM 228
COINCIDENCE METHODS
DECAY
DIAGRAMS
ENERGY LEVELS
GAMMA SPECTRA
KEV RANGE 100-1000
ACTINIUM ISOTOPES Ac-228/beta decay of
$gamma$- $gamma$ coincidence spectra from
(E)
THORIUM ISOTOPES Th-228/energy-level scheme from actinium-228 decay
(E)