[en] We report on a collinear laser spectroscopy measurement of the nuclear charge radius of ³⁹Ca (I=3/2), yielding δ(r²)^40,39 = -0.127(16) fm². Within the experimental accuracy, the N=20 neutron shell closure has no influence on the charge radii of the calcium isotopes. (author)

No abstract available

No abstract available

[en] The nuclear levels density parameters are the essential tools for investigating nuclear structure. The level densities are important for many aspects of fundamental and applied nuclear physics. The level densities represent a very important ingredient in statistical model calculations of nuclear reaction cross sections, which are needed in many applications from astrophysical calculations (determining thermonuclear rates for nucleosynthesis) to fission or fusion reactor designs. The purpose of this article is to determine the energy dependence of the effective moment of inertia at low excitation energies. A number of nuclei from ²⁰F to ³⁹Ca have been investigated

[en] High-precision Penning trap mass measurements on the stable nuclide Al²⁷ as well as on the short-lived radionuclides Al²⁶ and Ca^38,39 have been performed by use of radiofrequency excitation with time-separated oscillatory fields, i.e. Ramsey's method, recently extended to Penning trap mass measurements of radioactive isotopes. A comparison with the conventional method of a single continuous excitation demonstrates the advantage of up to ten times shorter measurements. The new mass values of Al^26,27 are compared to literature values and clarify conflicting data in this mass region. In addition, the resulting mass values of the superallowed β-emitter Ca³⁸ as well as of the ground state of the β-emitter Al^26m confirm previous measurements. (authors)

[en] The half-lives of ³⁸Ca and ³⁹Ca have been measured at ISOLDE of CERN. The REXTRAP facility was used to prepare ultra-clean samples of radioactive nuclei for precision decay spectroscopy. ³⁸Ca is one of the T_z=-1,0⁺ →0⁺β -emitting nuclides used to determine the vector coupling constant of the weak interaction and the V_ud quark-mixing matrix element. The result obtained, T_1/2=443.8(19) ms, is four times more precise than the average of previous measurements. For ³⁹Ca, a half-life of T_1/2=860.7(10) ms is obtained, a result in agreement with the average value from the literature. (orig.)

[en] We investigate p3/2 strengths in ⁴¹Sc and ⁴⁰Sc, and use the results to estimate proton widths in ⁴⁰Sc, and hence reaction rates for ³⁹Ca(p_,γ)

[en] Photoneutron angular distributions were measured for the reaction ⁴⁰Ca(γ,N₀)³⁹Ca in the giant resonance region. There is no detailed agreement with the theoretical predictions of Marangoni and Saruis (1970). (P.J.S.)

[en] Allowed β⁺ decay branches from ²⁵Al, ³⁷K, ³⁸K and ³⁹Ca have been sought by observation of delayed γ-radiation. The precision of previously known branches has been increased and improved limits obtained for unobserved branches. (Auth.)

[en] Recently it has been shown that pseudospin symmetry has its origins in a relativistic symmetry of the Dirac Hamiltonian. Using this symmetry we relate single-nucleon relativistic magnetic moments of states in a pseudospin doublet to the relativistic magnetic dipole transitions between the states in the doublet, and we relate single-nucleon relativistic Gamow-Teller transitions within states in the doublet. We apply these relationships to the Gamow-Teller transitions from ³⁹Ca to its mirror nucleus ³⁹K. copyright 1999 The American Physical Society