6533b829fe1ef96bd128abbc

RESEARCH PRODUCT

Heavy isotopes of actinium: 229Ac, 230Ac, 231Ac and 232Ac

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Abstract By irradiation of 232Th with 150-MeV bremsstrahlung and with 14-MeV neutrons, three new neutron-rich isotopes of actinium, 230Ac, 231Ac and 232Ac, were produced and identified and the previously reported isotope, 229Ac, was confirmed. The actinium isotopes were chemically isolated by a fast procedure based on elution with α-hydroxyisobutyric acid from cation exchange resins. For 229Ac, a half-life of 62·7 ± 0·5 min and a β-ray energy of 1·14 ± 0·15 MeV were found; 35 γ-rays were observed, the strongest ones with the following energies and relative intensities: 135·3(34), 146·4(35), 164·6(100), 252·2(24), 261·9(39), 317·0(23), 539·9(20), 569·1(91), and 605·2 keV(23). For 230Ac, a half-life of 80 ± 10 sec and γ-rays of 454·4(100) and 508·1 keV (58) were obtained. 231Ac was found to decay with a half-life of 7·5 ± 0·1 min. A total of 22 γ-rays were detected with the strongest ones at 185·6(43), 221·2(49), 240·6(11), 282·3(100), 306·9(77) and 368·8 keV (38). For 232Ac, a half-life of 35 ± 5 sec was obtained.