D. Bucurescu

Excited states in {sup 52}Fe and the origin of the yrast trap at I{sup {pi}}=12{sup +}

Excited states in {sup 52}Fe have been studied up to spin 10{h_bar} in the reaction {sup 28}Si+{sup 28}Si at 115 MeV beam energy by using in-beam {gamma}-ray spectroscopy methods at the GASP array. The excitation energy of the yrast 10{sup +} state is 7.381 MeV, almost 0.5 MeV above the well known {beta}{sup +}-decaying yrast 12{sup +} state. Experimental upper limits for the B(E4) transition probabilities from the 12{sup +} isomer to the 8{sub 1}{sup +} and 8{sub 2}{sup +} states have been determined. The mean lifetimes of five excited states have been measured by using the Doppler shift attenuation method. Complete diagonalizations in the pf major shell lead to very good agreement with the experimental level scheme and transition probabilities. The lifetime, log ft value, branching ratios, and B(E4) values are calculated for the 12{sup +} isomer. The positive parity states are also interpreted in terms of a Nilsson projected method. The structure of the yrast levels of {sup 52}Fe is compared with those of its cross conjugate {sup 44}Ti. {copyright} {ital 1998} {ital The American Physical Society}

Conversion electron measurements in the124Laβ-decay. Spin and parity assignments in124Ba

Low-lying energy levels in124Ba have been investigated from124Laβ-decay by using He-jet technique. Spin and parity assignments have been deduced from internal conversion electron measurements. Aβ-vibrational band based on a second 0+ state has been identified. Experimental level energies have been compared with IBFA-2 calculations.

Level structures of 131,129Ce observed in beta decay

Abstract The low-lying levels of the odd-mass nuclei 131 Ce and 129 Ce have been investigated by means of the β + EC decays of 131g+m Pr and 129 Pr, respectively, The Pr nuclei were obtained by bombarding 94,96 Mo targets with a 255 MeV 40 Ca beam. The radioactivities produced in the reactions were transported with a He-jet device and γγt , X γt , e − γt coincidence measurements were performed. Conversion electrons were measured with a magnetic spectrometer and transition multipolarities were deduced. On-line mass separation was used to select the 129 Pr β-decay. The resulting level schemes of 131,129,127 Ce are discussed in connection with level systematics and calculations performed by using the Interacting Boson-Fermion Model (IBFM).

Nuclear structure studies of 125Te with (n,γ), (d,p) and (3He,α) reactions

Abstract Levels in 125 Te were investigated in the range up to 3.3 MeV excitation energy by the (n,γ), (d,p) and ( 3 He,α) reactions. Over 160 levels and about 360 γ-transitions were established, most for the first time. The states below 2.3 MeV with the most complete spectroscopic information were interpreted in terms of the interacting boson-fermion model (IBFM). Unitary treatment of both positive- and negative-parity states is achieved with the same model parameter close to the intermediate case between O(6) and U(5) limits. Excitation energies, electromagnetic transition rates, γ-branchings and spectroscopic factors are discussed in connection with the possible structures. A family of low-spin negative-parity states has been identified and understood by the IBFM proving their antialigned origin.

Study of 121Te with the reaction

Abstract The structure of the 121 Te nucleus has been studied with the 122 Te ( d , t ) reaction at E d =24.0 MeV. About 100 excited states have been observed up to an excitation energy of 2.65 MeV, and for most of them spin and parity values are proposed. A theoretical analysis based on the Interacting Boson–Fermion Model-1 is presented for the whole isotopic chain from 119 Te to 129 Te. The evolution of both positive and negative parity low-lying levels in these nuclei is reasonably well described with an essentially constant boson–fermion interaction. A detailed comparison of the calculations with experimental data is presented for 121 Te. The level scheme up to about 1.5 MeV excitation is reasonably well accounted for. Possible indications of states with “intruder” character are discussed.

Nuclear structure studies of 123Te with (n,γ) and (d,p) reactions

Abstract Levels in 123 Te were investigated in the range up to 3 MeV excitation energy by (n,γ) and (d,p) reactions. Over 120 levels and about 140 γ -transitions were established most of them for the first time. The states below 2 MeV with the most complete spectroscopic information were interpreted in terms of the Interacting Boson–Fermion Model (IBFM). Unified treatment of both positive- and negative-parity states is achieved with constant parameters of the boson-fermion interaction for the whole chain of Te isotopes. Excitation energies, electromagnetic transition rates, γ -branchings and spectroscopic factors are discussed in connection with their possible structure. A family of low-spin negative-parity states has been identified and understood within the IBFM framework, thus proving their antialigned origin.

Low-lying states in the doubly odd nucleus 132Pr from beta decay of 132Nd

Abstract The low-lying level scheme of the odd-odd nucleus 132Pr has been investigated for the first time. The radioactive nuclei were produced by bombarding 96Mo targets with a 225 MeV 40Ca beam. Levels in 132Pr have been populated from the 132Nd β-decay. A new value of its half-life has been measured: T 1 2 = 88 ± 7 s . The activities produced in the reaction have been transported with a He-jet device and γγt, Xγt, e−γt coincidence measurements performed. Internal conversion coefficients have been measured with a magnetic lens spectrometer. The experimental level scheme of 132Pr is compared to theoretical calculations performed with the interacting boson-fermion-fermion model (IBFFM).

Low-lying levels and high-spin band structures in 102Rh

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Evidence for the two-body nature of the E1 transition operator in the sdf-interacting boson model

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