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The radioactive decays of166Ho isomers (Iπ=7− and 0−) have been reinvestigated using high-resolution γ-ray detectors in single and coincidence measurements. Nine γ-lines are new, among the fifty-three γ-lines accurately measured belonging to166Hom decay (Iπ=7−); sixteen γ-lines were measured in166Hog decay (Iπ=0−) out of which 3 are new; moreover, γ-γ coincidence experiments using two germanium detectors were performed. A166Er level scheme was built which interprets all γ-lines measured: two new levels are proposed to be fed in the166Hom decay, namely theKIπ=22+ at 785.8 keV and aIπ=4− state at 1572.1 keV; in166Hog decay, theKIπ=022+ state in166Er is confirmed, and a new level is found at 1812.8 keV (Iπ=1+). Spin, parity and Nilsson orbitals assignments of the intrinsic166Er states are discussed.

The {sup 14}C decay of {sup 222}Ra has been reinvestigated, using an 85 MBq activity {sup 230}U source radiochemically separated, a Si barrier detector, and a superconducting magnetic spectrometer. In a 16 days counting run, 210 {sup 14}C events were recorded. The {sup 14}C particles energy value 30.930{plus minus}0.090 MeV was found and an upper limit {ital b}{le}2{times}10{sup {minus}12} was estimated for the {sup 14}C branching ratio to the {sup 208}Pb first excited state; the branching-ratio value to the {sup 208}Pb ground state, thus equal to the total branching ratio, was found to be {ital b}={lambda}{sub {ital c}}/{lambda}{sub {alpha}}=(2.31{plus minus}0.31){times}10{sup {minus}10}.

The decay of radiochemically-separated /sup 228/Ac sources has been reinvestigated using high-resolution coaxial HPGe detectors and ..gamma..-..gamma.. coincidence measurements. Energies and intensities of more than 240 photons were accurately measured, 80 of them for the first time. A /sup 228/Th level scheme, built on the bases of good energy fits and on ..gamma..-..gamma.. coincidence data, involves 58 excited states, of which 17 are new, up to 2159 keV with spin 0less than or equal toIless than or equal to6. Collective properties of low-energy states belonging to K/sup ..pi../ = 0/sup -/,2/sup +/,2/sup -/ bands are discussed in the framework of the Bohr-Mottelson model. Decay modes of a K/sup ..pi../ = 0/sup +/ excited band at 831.82 keV favor strong two octupole phonon K/sup ..pi../ = 0/sup -/ components. The K/sup ..pi../ = 1/sup -/ band is expected to have I = 2 and 3 members at 938.5 and 968.4 keV. Coriolis coupling calculations involving the four K/sup ..pi../ = 0/sup -/, 1/sup -/, 2/sup -/, and 3/sup -/ bands were carried out. Tentative K/sup ..pi../ = 2/sup +/ two-quasiparticle bands at 1638.23 and 1899.99 keV are discussed in terms of Nilsson orbitals.

The decay of radiochemically separated $^{234}\mathrm{Pa}$ (UZ) sources has been reinvestigated by means of single and \ensuremath{\gamma}-\ensuremath{\gamma} coincidence spectrometry using planar and high efficiency coaxial HPGe detectors. Of the 330 \ensuremath{\gamma} rays observed in the 40--2100 keV energy range, of which 140 are new, more than 310 \ensuremath{\gamma} rays are accommodated in an improved $^{234}\mathrm{U}$ level scheme, accounting for 98% of the $^{234}\mathrm{Pa}$ \ensuremath{\beta} decay; of the 77 excited states observed here, 37 had not been previously found in this decay. Within the framework of the collective model of strongly deformed nuclei, couplings between the collective positive parity ${K}^{\ensuremath{\pi}}$${=0}_{1}^{+}$ (g.s. band), ${0}_{2}^{+}$, ${2}_{1}^{+}$, ${0}_{3}^{+}$, and ${2}_{2}^{+}$ bands are estimated from the perturbed transition probabilities and the distortions to the adiabatic energy systematics. The Coriolis interaction weakly coupling the ${K}^{\ensuremath{\pi}}$${=0}^{\mathrm{\ensuremath{-}}}$, ${1}^{\mathrm{\ensuremath{-}}}$, and ${2}^{\mathrm{\ensuremath{-}}}$ octupole bands was evaluated consistently by a fit to the experimental energy levels. Several new levels and a tentative ${K}^{\ensuremath{\pi}}$${=3}^{+}$ band (at 1770 keV) are discussed in terms of Nilsson orbitals assignments.

The radioactive decay of 110Agm+g has been studied extensively using gamma-gamma coincidence and sum-coincidence spectrometers. Levels at 2078.8, 2250.7, 2287.7, 2433.1, 2539.6, 2659.9, 2706, 2793.4, 2842.5 and 2876.8 keV previously proposed on energy sum considerations are proved by these techniques. For the first time the gamma rays of 120.3, 133.4, 341.4 and 356.4 keV are interpreted. The existence of a new level at 2356.2 keV is proposed. An interpretation is suggested for known gamma rays of 120.3, 133.4, 341.4 and 356.4 keV as well as for new transitions of about 648, 714.9, 1465.6 and 1698.5 keV. The spins of a few levels of 110Cd are discussed on the basis of present models.

The decay of228Ac has been reinvestigated by means of high resolution HPGe detectors. Accurate energies and intensities of 242 γ photons were measured, of which 80 were found for the first time.

Le spectre xL du Np accompagnant la desintegration de 241Am a ete soigneusement examine avec des detecteurs HPGe. Les valeurs des energies des raies principales sont en bon accord avec les resultats deduits du travail de Bearden, sauf pour les raies Lα1 et Lβ2,15 qui depassent les valeurs theoriques de 8 et 22 eV respectivement. Les intensites des differentes raies s'accordent bien avec les resultats anterieurs; les raies β9, β10, γ11, γ13, t et s sont caracterisees pour la premiere fois dans le Np (Z = 93). Les rapports de probabilite dans les sous-couches L sont coherents avec les calculs Hartree–Fock–Slater de Scofield. The L x-ray spectrum of Np following α-decay of 241Am was carefully reinvestigated by using HPGe detectors. Energy values of major lines are in good agreement with data deduced from Bearden's work, except for Lα1 and Lβ2,15 which exceed theoretical values by 8 and 22 eV, respectively. Intensities of different components agree well with previous experimental work, and β9, β10, γ11, γ13, t and s lines were found for the first time for Np (Z = 93). L subshell probability ratios are consistent with the Hartree-Fock-Slater calculations of Scofield.

The decay of radiochemically separated /sup 144/Ce source in equilibrium with /sup 144/Pr isomers has been reinvestigated with HPGe detectors. The energies and intensities of 19 ..gamma.. rays were measured, of which three are new. A /sup 144/Nd level scheme allows the incorporation of most of the transitions between 13 excited states. Levels at 2072.8 (2/sup +/), 2368.3 (2/sup +/), 2581.8 (3/sup +/), and 2742.8 (0/sup +/) keV, observed earlier in nuclear reactions, are found to be fed in these decays. A 2675.3 keV (J/sup ..pi../ = 0/sup +/) level seems to be a component of the 2.663 MeV multiplet observed in the (p,t) reaction.

L'etude du rayonnement gamma de l'arsenic 77 a l'aide d'un spectrometre a semiconducteur a permis d'observer des gammas de 87,7 keV (16,1), 162,0 keV (19,1), 238,8 keV (100), 249,5 keV (22,5), 271,1 keV (0,5), 281,9 keV (3,5) et 520,74 keV (24,9). La desintegration de l'arsenic 77 se fait partiellement par l'intermediaire de deux niveaux tres voisins du selenium 77 situes a 238,8 et 249,5 keV.

The energy of the E1 γ-ray following the isomeric transition of 108Agm was carefully measured with a high resolution HPGe detector. A mean value of (79.131±0.003) keV was found at the 2σ confidence level, which could be used for energy calibration.

The decay of radiochemically separated 144Ce source has been reinvestigated with a high resolution HPGe detector. Accurate energy values of three γ lines at 53.395 ± 5, 80.120 ±5 and 131.515 ± 4 keV (eV) can be used for calibrating Ge detectors.