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Through ( α, 4 n) and ( τ, 3 n) reactions the high-spin states in the two-neutron nucleusGd were populated up to I=21− at 7.2 MeV, including numerous states above the yrast line. TheGd energy spectrum is interpreted in terms of the spherical shell model. Identification of the (ν f i) state gives the ν i single particle energy free of octupole admixtures as 2.1(1) MeV. Eight high-spin states between 1.2 and 3.7 MeV were identified as the couplings of the two valence-particles to theGd octupole phonon, and three above-lying levels are assigned as double-octupole excitations including a 12 state which decays by an E3- E3 stretched cascade. All these octupole levels can be quantitatively predicted from the one-particle x phonon spectrum ofGd. The high-spin states above 3 MeV are four-quasiparticle excitations of π π ν and π ν type and their energies are in good accord with shell model estimates. [ABSTRACT FROM AUTHOR]

From in-beam γ-ray measurements we have established the high-spin states inEu up to 3.5 MeV excitation and I=(15). The highest levels observed are formed by alignment of four nucleons, involving excitation of theSm core. Negative-parity states at about 2 MeV are classified as πh νf × 3 octupole excitations. Quantitative analyses for the octupole multiplet members and for the ν=4 states based on empirical data from neighbouring nuclei are presented. [ABSTRACT FROM AUTHOR]

Levels ofPr populated in the ( p,2 n) reaction were studied using methods of in-beam γ-ray and conversion electron spectroscopy. Many low-lying positive-parity states give evidence of a deformation of β=0.15-0.20. The same conclusion is evident from band structures built on these positive-parity states and on the h negative-parity state. The triaxial rotor-plus-particle model reproduces quite well band structures with β=0.20 and γ= 21°. [ABSTRACT FROM AUTHOR]

From ( p, xn) in-beam γ-ray and electron measurements a T=235(14) ns isomer at 720 keV was identified inEu and the levels populated in its decay have been characterized. The results determine I=9 for the isomeric state, and we assign it as the ( πh j ν f)9 shell model state, analogous to the configuration of the 235 μs isomer inEu. [ABSTRACT FROM AUTHOR]

Multiple coincidence rates have been measured using a detector system consisting of a Ge(Li) spectrometer and eight NaI(Tl) or eight liquid scintillators. Reactions induced by α-particles with energies of 51-55 MeV and 118 MeVC ions are studied. The data are analysed to give the first and second central moments of the distribution of the number of γ-rays feeding individual levels in the final nuclei. When these numbers are compared to spin distributions calculated with the statistical model code GROGI the relative importance of dipole and quadrupole deexcitation modes can be ascertained. In particular, in theTe( α, 4 n)Xe reaction the γ-decay prior to the entry into the ground band is well described as a statistical process proceeding to 50% by dipole and 50% by quadrupole radiation. In theEr( α,4 n)Yb andOs( α,4 n)Pt reactions the relative amount of quadrupole radiation is larger and it seems that the dipole and quadrupole decay takes place via separate cascades. In theDy(C, 7-8 n) reactions the average multiplicity is independent of spin, suggesting that the nucleus forgets the spin of the entry state before the process enters into the ground band. In theYb(C, 8 n)Os reaction, finally, the nucleus definitely retains memory of the entry state during the decay. In this last case the multiplicity measurement is combined with a γ-ray singles measurement to give an average excitation energy prior to the α-decay and the average moment of inertia characterising the decay of the high-spin states. [ABSTRACT FROM AUTHOR]

The high spin level structure of the three-neutron nucleusGd has been investigated by in-beam γ-ray and electron spectroscopy with ( α, xn) reactions. The observed levels are characterized as members of the shell model multiplets νf, νh f, νf×3, νh f×3, and tentatively νf×(3). The energies of the ν f states agree only moderately with those calculated using empirical two-nucleon interactions taken fromGd, which indicates the importance of long range contributions already at N=85. [ABSTRACT FROM AUTHOR]

The level structure ofAu has been studied by observing prompt and delayed γ-rays followingPt( p,n) andPt( p,2 n) reactions. The conversion electron and γ-ray spectra from the decay of the 0.42s (10) and 0.60s (5) isomers at 476 keV and 107.4 keV, respectively, have been measured using the He-jet method. The half-lives of the 6 (278.2 keV, 1.1±0.4 ns), 7 (224.6 keV, 2.6±0.2 ns) and 8 (406.8 keV, 2.9±0.4 ns) members of the πd- vi multiplet have been obtained from the time distributions between cyclotron beam pulses and γ-rays depopulating these levels. A calculation made assuming a pure two-particle configuration for the multiplet predicts very well the B( E2) values for the transitions between the levels of this multiplet but the calculated B( M1) values are not in agreement with experimental results. [ABSTRACT FROM AUTHOR]

The gamma decay of the low-lying energy levels ( E<4MeV) inAl has been studied through theMg( p, γ)Al reaction using seven resonances in the proton energy range E+200−1700 keV. Ge(Li) detectors and isotopically separated targets have been used. Energies and branching ratios of several excited states have been measured. The Q-value of the reaction was determined to be 2271.3±0.8 keV. Lifetimes, investigated by the Doppler-shift attenuation method and γ-ray angular distributions have been determined using the E+823, 1201, 1490 and 1660 keV resonances of theMg( p, γ)Al reaction. [ABSTRACT FROM AUTHOR]

Angular distribution measurements of gamma-rays from theNe( p, γ)Na reaction on the E=897, 1006, 1091 and 1278 keV resonances have been made. Spin and parity assignments for several bound states are presented together with multipole mixing ratios for transitions from resonance and bound states. The level at 6617 keV (7/2) is proposed to be a member of the rotational band based on the Nilsson orbit 5( K=5/2). [ABSTRACT FROM AUTHOR]

The gamma decays of 19Ne( p, γ)Na resonances in the range of E=400−1300 keV have been investigated by means of a 38 cm Ge(Li) detector. Branching ratios of the resonances and bound states were determined. Gamma-ray energy measurements yield the energies of 19 bound states and the value of 8794.0±1.5 keV for Q. The existence of the 3913 keV doublet state was studied through the ( p, γ) reaction. No evidence for such a doublet was found. [ABSTRACT FROM AUTHOR]

The level scheme ofPr has been studied from the decay ofCe. The intensities and energies of gamma rays have been determined with a X-ray Ge(Li) detector. The K-shell internal conversion coefficients for γ-rays have been measured with the K X-ray/γ-ray ratio method using NaI(Tl)-X-ray Ge(Li) coincidence techniques. [ABSTRACT FROM AUTHOR]

Levels ofCd have been investigated via theZr(O,4n)Cd reaction by employing the NORD-BALL array of 17 Compton- suppressed Ge detectors. The yrast band has been observed up to I=28 ħ and 14.2 MeV excitation energy with band crossing at ħω=0.35 MeV. At least three side bands have been constructed. The negative parity bands experience band crossings at ħω ≈ 0.45 MeV. [ABSTRACT FROM AUTHOR]

Measurements of γ-rays from mass analyzed nuclear recoils produced in thePd +Fe reaction at 245MeV have allowed us to characterize the decay of a 35 μs isomer inLu. The rates of E2 transitions de-exciting isomeric levels in proton-rich N=82, 83 isotones are discussed. [ABSTRACT FROM AUTHOR]

Gamma-ray measurements following mass analysis ofPd+245 MeVFe reaction products have characterized a 15 μs isomeric decay inYb and elucidated the systematics of proton-rich N=83 nuclei. [ABSTRACT FROM AUTHOR]

With theRu(Ni,2pn) reaction we producedYb and studied its decay after online mass separation by γ-spectroscopic techniques. The decay populates the four positive parity single proton levels in the N=82 daughter nucleusTm and establishes I=1/2 for the so far unknownTm low spin isomer. Using BCS theory proton single particle energies forTm were extracted from the observed excitation energies. [ABSTRACT FROM AUTHOR]

In-beam studies with (α,4n) and (He, 3n) reactions have located a second 10 state closely above the 10 isomers inGd andSm. The data characterize theSm 10 isomer as the νh excitation in contrast toGd where the 10 isomer is of πh character. [ABSTRACT FROM AUTHOR]

Levels of the N=83 nucleusGd have been investigated by in-beam γ-ray and conversion-electron spectroscopy using theSm(He,3n) and Sm(α,n) reactions. We have observed 16 new low-and medium-spin levels inGd. In addition to the previously known 13/2 level we have located the 11/2, 9/2, 7/2, 3/2 and (1/2) members of the vf×3 septuplet. [ABSTRACT FROM AUTHOR]

A 53.3 keV E2 transition de-exciting the 60 ns isomer inDy has been identified in γγ-coincidence measurements, which locates that isomer at E=5088 keV. The half life of the 11 level at 3161 keV was measured to be T=4.3±0.9 ns. [ABSTRACT FROM AUTHOR]

Through (p,2n) in-beam γ and e measurements the excitation of the 235 μs 9 isomer inEu has been determined to be 666.3 keV. High spin members of the πd νf and πg νf particle hole multiplets populated in the isomeric decay were located. [ABSTRACT FROM AUTHOR]

Three yrast isomers inDy, at 6.03 MeV (I=49/2, T/=15(3) ns), 4.90 MeV (41/2, 5.5(1.0) ns), and at 2.96 MeV(27/2, 1.3(6) ns) have been located throughGd(α,5n) andCe(O, 3n) measurements. Shell model configurations are suggested for them. [ABSTRACT FROM AUTHOR]