Studies on the low-lying levels in192Pt and192Os populated in192Ir decay

Low-lying levels in¹⁹²Os and¹⁹²Pt are reinvestigated through¹⁹²Ir (73.831d) decay with improved system performance and counting statistics. Experiments show that gamma rays reported in literature with energies 1413, 1237, 1147, 911, 773, 629, 362 and 325 keV are not from the decay of¹⁹²Ir and gamma rays reported with energies 1200, 1056, 920, 904, 784 and 624 keV are resulted from sum-up or pile-up effects of low energy intensive gamma rays. New gamma-gamma coincidence relations are obtained with 105 cm³–110 cm³ germanium detector system. A level at 1384 keV is established in the decay scheme and four newly proposed levels at 1118.31 keV in¹⁹²Os and 1146.95, 1237.35 and 1413.76 keV in¹⁹²Pt are excluded from the decay scheme. Predictions of Interacting Boson Model on level energies andE2 absolute reduced transition probabilities are compared with experimental results.     

Gamma-gamma directional correlation measurements in192Os

E2/M1 mixing ratios of transitions in¹⁹²Os have been determined by the gammagamma directional correlation technique. The results are: δ(484.5 keV)= ?10±1, δ(283.3 keV)= ?3.8± 0.7 and δ(201.3 keV)= ?4.6±1.     

Particle-triaxial rotor calculations for the low-lying states with negative parity in 193Os

It is shown that the particle-triaxial rotor model is able to describe the low-lying levels with negative parity in ¹⁹³Os supporting their doublet structure. At low excitation energy, the model calculations can be used for a clarification of the spin assignments in cases where they are ambiguous. It is of great interest to check the predictions of the model experimentally by new precise spin determination.     

Description of the Pt and Os isotopes in the interacting boson model

Properties of the even-even Pt and Os isotopes are investigated in the framework of the interacting boson approximation, including the neutron-proton degree of freedom. It is shown that the transition between the gamma unstable region of the heavier Pt isotopes towards the more axially symmetric deformed festures of the lighter Os and Pt isotopes can be described very well by the IBA hamiltonian; qualitatively the properties of the transitional region are reproduced by the smooth change of one parameter, χ_ν, which determines the character of the quadrupole-quadrupole interaction. Calculated excitation energies and electromagnetic properties are compared with experiment.     

Nuclear levels in193Os

The previously completely unknown energy levels of¹⁹³Os have been investigated using the reactions¹⁹²Os(d, p)¹⁹³Os and¹⁹²Os(n, γ)¹⁹³Os. The neutron separation energy was measured to be 5583.5±2.0 keV. Most of the states below 500 keV can be qualitatively interpreted in terms of the Nilsson model; however the occurrence of four levels with significantl=1 transfer strength in this energy range is incompatible with that model. The Nilsson orbital systematics of the odd-A Os and W isotopes are compared.     

The low-lying levels of O

The low-lying levels of ¹⁸O with even parity form a rotational band. Longitudinal and transverse cross sections are calculated for all levels up to 7 MeV excitation energy. The deformed state is a system of two protons and two neutrons in the deformed s, d orbitals above the core ¹⁴C. Also matrix elements between spherical states are calculated using an effective charge _n = 0.4 for neutrons and 1.4 for protons. The effective charge is determined by fitting theoretical and experimental quadrupole moments of ¹⁷O in the ground state. The effective charge in the calculation of the matrix elements between deformed states takes into account the ¹⁴C core deformation. As in ref. 11), too low transitions probabilities are found in comparison with experimental data.     

The effects of γ-instability on the muonic X-ray of 192Os

Feasibility studies of the observation of effects arising from the transitional nature of ¹⁹²Os on its muonic X-rays are presented. Muonic K X-ray spectra are calculated, using E2 matrix elements from experiments and from Baranger-Kumar calculations. Experimentally observable energy shifts result from the nuclear γ-unstable nature of ¹⁹²Os.     

Structure of low-lying levels in220Ac

The low-lying level structure of the odd-odd nucleus²²⁰Ac has been observed for the first time following the alpha decay of 0.8 s²²⁴Pa produced by the reaction²⁰⁹Bi (¹⁸O, 3n). Alpha-gamma and alpha-electron coincidence measurements were used in the construction of the²²⁰Ac level scheme. Opposite parity states with energy splittings similar to those in the recent high-spin nuclear study were observed. However, no levels or gamma transitions were observed in common with those of the high-spin work.     

A study of the low-lying levels in 61Ni

Electromagnetic decay properties for seventeen states in ⁶¹Ni have been examined by means of the ⁵⁸Fe(α,nγ)⁶¹Ni reaction with E_α = 8 MeV and the ⁶⁰Ni(d, pγ)⁶¹Ni reaction at E_d = 6 MeV. Mean lifetimes were obtained with the Doppler-shift attenuation method. Spins, parities, and mixing ratios were determined from angular correlation studies and linear polarization measurements. The combined results permit new J^π assignments of $\text{7}\text{2}{}^{\mathrm{?}}\text{,}\text{5}\text{2}{}^{\mathrm{?}}\text{,}\text{7}\text{2}{}^{\mathrm{?}}\text{,}\text{and}\text{9}\text{2}{}^{\mathrm{+}}$ for the levels at 1016, 1611, 2020 and 2123 keV, respectively. Experimental results, including transition strengths, are compared to shell model predictions.     

Properties of the low-lying levels in the transitional Ir and Au nuclei

We try to determine to what extent an “axial prolate rotor +1 or 2 quasiparticle model” succeeds in describing the transitional odd and odd-odd Ir and Au nuclei. The relative location of the excited states, as well as the properties of the ground and isomeric states, particularly the magnetic and spectroscopic quadrupole moments, is compared to the predictions of the model.     

Decay properties of low-lying levels in100Rh

Zeitschrift für Physik A Hadrons and nuclei - Low-lying levels of100Rh have been investigated with the reaction100Ru(p, nγ)100Rh in the proton energy range 4.4 MeV≦E p≦6 MeV....     

In-beam study of low-lying levels in the149Sm nucleus

The¹⁴⁶Nd(α,n) reaction combined with conventional in-beam spectroscopic methods has been used to study low-lying levels in¹⁴⁹Sm. Several new levels andγ-ray transitions have been placed to the¹⁴⁹Sm level scheme. Main features of levels below 1 MeV in¹⁴⁹Sm have been reproduced in a quasiparticle-rotor model calculation.     

The low-lying levels in229Pa and parity doublets

The nucleus ²²⁹ Pa was studied using the reactions ²³¹ Pa(p,t) and ²³⁰ Th(p,2nγ). A level scheme based on particle and conversion-electron-gamma spectroscopy data is suggested.     

Nuclear levels and spectroscopy of191Os

Thirty-nine states, all except two of which are new, have been observed up to 1535 keV in¹⁹¹Os using the reactions¹⁹⁰Os(d,p)¹⁹¹Os,¹⁹²Os(d, t)¹⁹¹Os with 12 MeV deuterons and magnetic analysis with photographic emulsions of the outgoing particles, and¹⁹⁰Os(n, γ)¹⁹¹Os with thermal neutrons and three modes of gamma detection in the energy range from 40 keV to ～6 MeV. The neutron separation energy was determined as 5758.5±2.0 keV in agreement with the value of the (d, p) reaction. TheQ value for the (d, t) reaction was determined as ?1265±15 keV. Spins and parities are assigned for most of the states below 800 keV. The states below 463 keV are shown to be qualitatively but not quantitatively consistent with the expectations of the Nilsson model. Nilsson systematics of the 1/2^?: ¦510¦ and 3/2^? ¦512¦ orbitals in odd-A Os isotopes with increasing neutron number can be understood in terms of decreasing deformation. Anomalously large (d, p) and (d, t) cross sections populating 5/2^? and 3/2^? states at 134 and 142 keV, respectively, are explained as a tendency to restore the cross sections expected for a spherical nucleus. Evidence for triaxiality in¹⁹¹Os is observed in the form of a 5/2^? state at 273 keV which appears to be a rotational state built on the 9/2^? ground state.     

Properties of low-lying levels of39K

The spins and electromagnetic properties of low-lying levels in³⁹K with excitation energy ≦4.127 MeV were studied with the³⁹K(p, p′γ)³⁹K and the³⁶Ar(α, pγ)³⁹K reactions. Experimental results are discussed in terms of shell model calculations with a modified effective surface delta interaction.     

Properties of low-lying levels of59Co

Levels up to 3,016 keV in⁵⁹Co were studied using the⁵⁹Co (p, p′y) and⁵⁶Fe (α, py) reactions. Level energies, branching ratios, mean lifetimes and spins were obtained for a number of levels.     

Properties of low-lying levels of41K

The atomic nucleus⁴¹K was studied with emphysis on the experimental derivation of electromagnetic properties and spin values of low-lying levels with energies ≦3,282 keV. Energy levels, decay properties and mean lifetimes were measured with (p, p′ γ) and (p, p′) reactions at incident proton energies of about 6 MeV. Spin values were deduced from a comparison of results obtained from a Hauser-Feshbach analysis of (p, p′) and (p, p′ γ) reactions and measured transition strengths derived from mixing ratios, lifetimes and decay properties. Experimental results are discussed in terms of shell model calculations with a modified effective surface delta interaction.