Search results for "ISOTOPES"
showing 10 items of 1216 documents
Spectroscopy of very neutron-deficient 187,189Bi isotopes
2003
Shape coexistence is well known to occur in nuclei, in particular near closed shells [1], where particle-hole excitations across the shell gap can create deformed intruder states. In the neutron-deficient lead isotopes (Z = 82), deformed structures appear at low excitation energy. The isotope 188Pb [2] shows for example a triple shape coexistence with oblate and prolate excited 0+ states that compete with the spherical ground state. The study of the odd-proton single-particle excitations in Bi isotopes allows to obtain information on the orbitals involved in the different shapes observed in this mass region.
Development of quadrupole collectivity in the neutron-rich Ni, Zn, Ge, and Se isotopes
2003
An experiment was performed to study the collective properties of neutron-rich Ni, Zn, Ge, and Se isotopes. Of particular interest is the vicinity of the N = 50 and Z = 28 shell closures. For most neutron-rich nuclei in this region of the chart of nuclei the B(E2) values of the transitions from the ground to the first excited 2+ states are unknown. This information would give valuable insight into the changes in nuclear structure when going to more neutron-rich nuclei.
Direct determination of the mass of28Si as a contribution to a new definition of the kilogram
1993
The mass of 28Si has been determined to be m(28Si) = 27.976 926 57(30) u by comparing the cyclotron frequencies of the singly charged ions 12C+, 12C+3 and 28Si+ in a Penning trap mass spectrometer. The experimental technique and the setup are described. The obtained accuracy as well as possible improvements are discussed. Our measurements are related to current efforts to base the kilogram on atomic properties by using an almost perfect single crystal of silicon.
Mass measurements on unstable Sn and Sr isotopes with the ISOLTRAP mass spectrometer
2001
Direct mass measurements have been performed on the isotopes 76,77,80,81Sr and 129,130,131,132Sn by means of the Penning trap mass spectrometer ISOLTRAP at ISOLDE/CERN. In the case of 76Sr the mass was measured for the first time and an accuracy of about 30 keV was reached (Fig. 1). The masses of the tin isotopes are known for a long time from Q β measurements.
Experimental studies of the NaRb ground-state potential up to thev″=76level
2002
Laser induced fluorescence spectra of the C {sup 1}{sigma}{sup +}-X {sup 1}{sigma}{sup +} system of {sup 23}Na{sup 85}Rb and {sup 23}Na{sup 87}Rb have allowed vibrational levels of the electronic ground state up to v{sup ''}=76, spanning 99.85% of the potential well to be observed. The ground-state term values have been fitted to a Dunham polynomial expansion, and also to a direct modified Lennard-Jones (MLJ) potential. The analytical MLJ construction allowed us to match previous measured term values for v{sup ''}{<=}30 with long-range behavior of the potential through the intermediate internuclear distance region covered by the present investigation.
LiquidHe4andHe3at negative pressure
1992
The critical pressures {ital P}{sub {ital c}} at which liquid {sup 4}He and {sup 3}He each become macroscopically unstable are determined from two kinds of microscopic calculations that reproduce the equation of state. The behavior of the sound velocity {ital c} around this critical pressure is analyzed, and the critical exponent in {ital c}{proportional to}({ital P}{minus}{ital P}{sub {ital c}}){sup {nu}} is found to be {nu}=1/4. A comparison with empirical analysis is also done.
Monte Carlo calculation of dose rate distributions around 192Ir wires.
1997
Monte Carlo calculations of absolute dose rate in liquid water are presented in the form of away-along tables for 1 and 5 cm 192 Ir wires of 0.3 mm diameter. Simulated absolute dose rate values can be used as benchmark data to verify the calculation results of treatment planning systems or directly as input data for treatment planning. Best fit value of attenuation coefficient suitable for use in Sievert-integrals-type calculations has been derived based on Monte Carlo calculation results. For the treatment planning systems that are based on TG43 formalism we have also calculated the required dosimetry parameters.
Precision Measurement ofLi11Moments: Influence of Halo Neutrons on theLi9Core
2008
The electric quadrupole moment and the magnetic moment of the 11Li halo nucleus have been measured with more than an order of magnitude higher precision than before, |Q| = 33.3(5) mb and mu = +3.6712(3)muN, revealing a 8.8(1.5)% increase of the quadrupole moment relative to that of 9Li. This result is compared to various models that aim at describing the halo properties. In the shell model an increased quadrupole moment points to a significant occupation of the 1d orbits, whereas in a simple halo picture this can be explained by relating the quadrupole moments of the proton distribution to the charge radii. Advanced models so far fail to reproduce simultaneously the trends observed in the r…
New information on 12C states from the decays of 12N and 12B
2003
Abstract The properties of states in 12 C above the 3α-threshold are of high current interest for nuclear astrophysics and for the nuclear many-body problem in general. We have initiated a series of experiments aimed at elucidating this region by using the β-decays of 12 N and 12 B. By applying the ISOL method for producing these radioactive isotopes, in combination with modern segmented charged particle detectors, our approach has significant advantages over previous studies of this region.
In-source laser spectroscopy of75,77,78Cu: Direct evidence for a change in the quasiparticle energy sequence in75,77Cu and an absence of longer-lived…
2011
This paper describes measurements on the isotopes (75,77,78)Cu by the technique of in-source laser spectroscopy, at the ISOLDE facility, CERN. The role of this technique is briefly discussed in the ...