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.     

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 of 45Sc

The spins and electromagnetic properties of levels up to 1800 keV in ⁴⁵Sc were studied by means of inelastic proton scattering. Results are discussed with reference to the excited-core model.     

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.     

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.     

Properties of low-lying 9He state

The spectrum of ⁹He was studied by means of the ⁸He(d,p)⁹He reaction at a lab energy of 25 MeV/n and small center of mass (c.m.) angles. Energy and angular correlations were obtained for the ⁹He decay products by complete kinematical reconstruction. The data analysis was done in the assumption of a direct one-neutron transfer reaction mechanism. The ⁹He structure was analysed in the framework of a simple single-particle model. The lowest resonant state of ⁹He is found at about 2 MeV with a width of ∼2MeV and is identified as 1/2^-. The observed angular correlation pattern is uniquely explained by the interference of the 1/2^- resonance with a virtual state 1/2⁺ (a limit on the scattering length is obtained as a > -20fm), and with a 5/2⁺ resonance at energy ≥4.2MeV.     

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.     

Fluctuation properties of spacings of low-lying nuclear levels

Fluctuation properties have been analyzed for a large collection of low-lying nuclear energy levels, with emphasis on the nearest-neighbor spacing distributions. The levels are combined in several ways to search for effects due to mass, spin, and shape. A strong mass dependence appears to be present, and there are suggestions of effects due to spin and deformation.     

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....     

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.     

The multi-configuration Dirac-Fock calculation of the low-lying levels of Sm

The excitation energies and hyper-fine structure constants of the low-lying levels of Sm atom are calculated using the multi-configuration Dirac-Fock (MCDF) method. The results show that the excitation energies of the ground state multiplets can be calculated accurately using a small orbital set but the higher levels need larger orbital sets. Similar inference can also be drawn from the discrepancy between the calculated values of the hyper-fine constants and the experimental data. A sequence of MCDF calculation demonstrates the effect of the MCDF potential on the orbitals. Among the rare earth atoms Sm is a promising candidate for discrete symmetry violation experiments in atoms. This makes accurate theoretical calculations necessary since parameters in particle physics can be derived by combining the experimental results with the theoretical results. And these could be a probe for the physics beyond the standard model. Received 10 October 2000 and Received in final form 23 January 2001     

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.     

Energy systematics of low-lying Nilsson levels in odd-mass einsteinium isotopes

The decay of odd-mass mendelevium isotopes ( A = 247-255) has been studied by means of α-γ spectroscopy. Strong evidence for a small α branch in the decay of ²⁵³Md was found. γ lines in coincidence with α-decays of ^{247, 249, 251, 253}Md have been observed for the first time. Levels in the einsteinium daughter nuclei were assigned on the basis of α-γ coincidence measurements. An energy systematics of the 7/2^-[514] Nilsson level could be established, showing a correlation with the deformation parameter β₂ of the corresponding nuclei. The results are compared with theoretical predictions     

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.     

Excitation cross sections of low-lying levels of the tungsten atom

The excitation of transitions from low-lying levels of the tungsten atom by a beam of slow electrons with an energy of 50 eV is studied. The results obtained are used to calculate the total excitation cross sections of the WI energy levels taking into account the branching ratios.     

Lifetimes of low-lying levels in 18F

Mean lifetimes of levels in ¹⁸F have been measured using the Doppler-shift attenuation method and the inverse reaction ³He(¹⁶O, p)¹⁸F. Targets of ³He implanted into Al, Nb, and Au foils were employed in the measurements. The Doppler-broadened lineshapes observed at 0° to the beam were analyzed to obtain the following lifetime values: 0.971 ± 0.030, 0.605 ± 0.029 and 0.435 ± 0.041 ps for the 1.70(1⁺), 2.52(2⁺) and 3.36(3⁺)MeV members of the K^π = 1⁺ rotational band, 5.12 ± 0.56, 0.403 ± 0.018 and 1.91 ± 0.17 ps for the 2.10(2^?), 3.13(1^?) and 3.79(3^?) MeV members of the K^π = 0^? bands, and 〈1.2, 2.7^+4.1_?2.7 and 20 ± 2 fs for the 3.06(2⁺, T = 1), 3.72(1⁺) and 3.84(2⁺) MeV states, respectively.     

Structure of low-lying levels in91Rb and93Rb

Life-times of low-lying levels in ₃₇ ⁹¹ Rb₅₄ and ₃₇ ⁹³ Rb₅₆ have been determined fromβ ^??γ coincidence measurements at the fission-product separator JOSEF. Values oft _1/2=17.0(8) ns and 2.0(2) ns have been obtained for the levels at 1,134 keV in⁹¹Rb and 267 keV in⁹³Rb, respectively, and upper limits could be deduced for several other states. Calculations in the frame of IBFM/PTQM have been performed for⁹¹Rb, the results of which allow an interpretation of the low-lying levels of this nucleus. For the 1,134 keV level the configuration [πg _9/2?2⁺] 7/2⁺ is suggested which lies close to or even below the 9/2 ₁ ⁺ level. The calculated half-life of 14 ns for the 1,134 keV level reproduces well the experimental value. The half-life of the 267 keV level in⁹³Rb favours the assignment ofI ^π=1/2^? to this state over the alternative 3/2^?.     

Properties of the low-lying positive-parity states in Be and C

Excitation energies and electromagnetic form factors of the low-lying positive-parity states have been calculated in⁹Be and ¹³C on the basis of a particle-core coupling model. The results are compared with recent electron scattering experiments and photon data. The first excited levels in the two nuclei show a large contribution from the spin term of the electromagnetic interaction at low-momentum transfer q² < 0.6 fm⁻².