DECAY OF THE SHORT-LIVED RADIOISOTOPES Si$sup 26$, S$sup 30$, Na$sup 26$, AND Al$sup 3$$sup 0$
R > @ ? # hort half lives, previously unobserved or uninvestigated, were produced using the He/sup 3/ beam of the Purdue University cyclotron and neutrons from the reaction Li/sup 7/(d,n)Be/sup 8/ using the deuteron beam of the cyclotron. Bombardment of high purity natural magnesium with 8-Mev He/sup 3/ ions yielded, in addition to decays of known isotopes, a (2.22 surface proces 0.11)-sec activity. Half life studies indicated that this activity was due to the decay of a positron-emitting isotope with a maximum positron kinetic energy greater than 3.5 Mev. The features of the gamma spectrum, with the exception of a weak line at 824 surface proces 15 kev, could be understood in terms of the decay characteristics of known radioisotopes. An internally consistent argument based on the known decay characteristics of reaction products that may be expected from energy considerations, the results of half life studies, experimental gamma spectra, and nuclear systematics, was made to support the conclusion that the (2.22 surface proces 0.1l)-sec half life is that of Si/sup 26/ produced in the reaction is proposed. The Si/sup 26/ --Al/sup 26/ mass difference is 4.96 surface proces 0.08 Mev. He/sup 3/-ion irradiation of high purity natural silicon yielded an activity with a half life of 1.35 surface proces 0.10 sec in addition to activities associated with well-known radioisotopes. A (677 surface proces 10)-kev gamma ray was associated with the 1.35-sec half life. Decomposition of decay-curves constructed from data obtained by observing annihilation radiation as well as positrons with energies in excess of 3.15 Mev also indicated the presence of a 1.35-sec activity. The beta spectrum in coincidence with two annihilation quanta extended to approximately 5.0 Mev, a higher energy than can be accounted for by positrons from the known reaction products. The beta spectrum in coincidence with the (677 surface proces 10)-kev gamma ray had an end-point energy of 4.30 surface proces 0.15 Mev. The assignment of the (1.35 surface proces 0.10)-sec activity to the decay of S/sup 30/, produced in the reaction Si/sup 28/(He/sup 3/,n)S/sup 30/, a nd the proposed decay scheme are supported by arguments formulated from the known characteristics of reaction products, half life studies using both beta and gamma radiation, the features of the experimental beta and gamma spectra, beta-gamma coincidence spectra, nuclear systematics, and nuclear theory. A S/sup 30/-P/sup 30/ mass difference of (6.01 surface proces 0.15)Mev was obtained. The bombardment of high purity natural magnesium targets with fast neutrons from the Li/sup 7/(d,n)Be/sup 8/ reaction (E/sub n/ < 24 Mev) yielded, in addition to activities associated with well-known isotopes, an activity having an experimental half life of 1.03 surface proces 0.06 sec. Scintillation spectrometer measurements showed a (1.82 surface proces 0.03)-Mev gamma ray and a (6.7 surface proces 0.3)-Mev beta group decaying with the 1.03-sec half life. The 6.7-Mev beta group was found to be in coincidence with the 1.82-Mev gamma ray. Assignment of the (1.03 surface proces 0.06)-sec half life to Na/sup 26/, produced in the reaction Mg/sup 26/(n,p)Na/sup 26/, and the proposed decay scheme are supported by internally consistent arguments based on known characteristics of the reaction products and their decay modes, half life studies using both beta and gamma radiation, features of experimental beta and gamma spectra, and nuclear systematics. A Na/sup 26/-Mg/sup 26/ mass difference of 8.5 surface proces 0.3 Mev was derived. High purity natural silicon targets bombarded with the fast neutrons yielded, in addition to well-known radiations, a beta spectrum with an end-point of 5.05 surface proces 0.25 Mev and two gamma rays with energies of 2.26 surface proces 0.03 Mev and 3.52 surface proces 0.03 Mev. These gamma rays and the beta group decayed, within experimental error, with the same half life, 3.27 surface proces 0.20 sec. The assignment of this activity to Al/sup 30/ and the proposed decay scheme are supported by considerations involving the decay schemes of the well-known isotopes produced, half life studies using portions of both the beta and gamma spectra, and nuclear systematics. The result
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-17-026633
- OSTI ID:
- 4720556
- Resource Relation:
- Other Information: Thesis. Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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RESEARCH IN NUCLEAR PHYSICS. Progress Report No. 11
DECAY OF Si$sup 2$$sup 6$
Related Subjects
ALUMINUM 26
ALUMINUM 30
ANNIHILATION
ARGON 34
BETA PARTICLES
CALCIUM
COINCIDENCE METHODS
CYCLOTRONS
DECAY
EMISSION
FAST NEUTRONS
GAMMA RADIATION
HALF-LIFE
HELIUM 3
IONS
IRRADIATION
MAGNESIUM
MAGNESIUM 24
MAGNESIUM 26
MASS
MEASURED VALUES
NEUTRONS
NUCLEAR REACTIONS
PHOSPHORUS 30
POSITRONS
PRODUCTION
PROTONS
RADIOACTIVITY
SCINTILLATIONS
SILICON
SILICON 26
SILICON 28
SILICON 30
SODIUM 26
SPECTRA
SPECTROMETERS
SULFUR
SULFUR 30
TITANIUM 42