16 research outputs found
Electric and magnetic field optimization procedure for Penning trap mass spectrometers
Significant systematic errors in high-precision Penning trap mass
spectrometry can result from electric and magnetic field imperfections. An
experimental procedure to minimize these uncertainties is presented for the
on-line Penning trap mass spectrometer ISOLTRAP, located at ISOLDE/CERN. The
deviations from the ideal magnetic and electric fields are probed by measuring
the cyclotron frequency and the reduced cyclotron frequency, respectively, of
stored ions as a function of the time between the ejection of ions from the
preparation trap and their capture in the precision trap, which influences the
energy of their axial motion. The correction parameters are adjusted to
minimize the frequency shifts.Comment: 25 pages, 9 figure
Progress at the WITCH experiment
The WITCH-experiment will measure the energy spectrum of the recoiling daughter ions in -decay to search for non-standard scalar and tensor type interaction. To facilitate this a Penning trap is used to store the radioactive ions. Thus the recoil ions can leave the source without any energy loss and their energy can be probed by the subsequent retardation spectrometer. The experiment is being set up at present at ISOLDE/CERN. The principle and the status of the WITCH-experiment will be presented. (12 refs)
COLETTE: A linear Paul-trap beam cooler for the on-line mass spectrometer MISTRAL
A segmented, radiofrequency quadrupole mass filter COLETTE (Cooler for Emittance Elimination) was designed for cooling continuous radioactive beams for injection into the transmission spectrometer MISTRAL at CERN-ISOLDE. A description of the design of COLETTE is given, along with details of performance including measured emittances of less than 8 pi mm mrad with 20 keV beams from the test bench SIDONIE in Orsay. On-line results with stable and short-lived radionuclide beams from ISOLDE are also presented. (C) 2008 Elsevier B.V. All rights reserved
A highly heterogeneous 3D PWR core benchmark: deterministic and Monte Carlo method comparison
Physical analyses of the LWR potential performances with regards to the fuel utilization require an important part of the work dedicated to the validation of the deterministic models used for theses analyses. Advances in both codes and computer technology give the opportunity to perform the validation of these models on complex 3D core configurations closed to the physical situations encountered (both steady-state and transient configurations). In this paper, we used the Monte Carlo Transport code TRIPOLI-4Âź; to describe a whole 3D large-scale and highly-heterogeneous LWR core. The aim of this study is to validate the deterministic CRONOS2 code to Monte Carlo code TRIPOLI-4Âź; in a relevant PWR core configuration. As a consequence, a 3D pin by pin model with a consistent number of volumes (4.3 millions) and media (around 23,000) is established to precisely characterize the core at equilibrium cycle, namely using a refined burn-up and moderator density maps. The configuration selected for this analysis is a very heterogeneous PWR high conversion core with fissile (MOX fuel) and fertile zones (depleted uranium). Furthermore, a tight pitch lattice is selcted (to increase conversion of 238U in 239Pu) that leads to harder neutron spectrum compared to standard PWR assembly. In these conditions two main subjects will be discussed: the Monte Carlo variance calculation and the assessment of the diffusion operator with two energy groups for the core calculation
Mass measurements of the exotic nuclides (11)Li and (11,12)Be performed with the MISTRAL spectrometer
The mass of the halo nuclide (11)Li has been measured with unprecedented precision with the MISTRAL mass spectrometer at CERN's ISOLDE facility. Its resulting two-neutron separation energy, S(2n) = 378 +/- 5 keV, is 25% higher than the previously accepted value and about an order of magnitude more precise than any of the previous measurements. We also report measurement of the masses of (11)Be and (12)Be. The detailed analysis of these results and their evaluation are presented, along with a discussion concerning mass models. (C) 2009 Elsevier B.V. All rights reserved
Recent results from the Penning trap mass spectrometer ISOLTRAP
In the last few years a number of new scientific highlights have been obtained by ISOLTRAP, the tandem Penning trap mass spectrometer for on-line mass measurements of short-lived radionuclides. The precise determination of nuclear binding energies far from stability includes nuclei that are produced at rates of 100 ions/s and with half-lives below 100 ms. The mass resolving power reaches 10 and the uncertainty of the resulting mass values has been pushed down to . In this article recent ISOLTRAP mass measurements are summarized and the current status of ISOLTRAP is presented
Mass measurements of Cr and the question of shell reincarnation at
Binding energies determined with high accuracy provide smooth derivatives of the mass surface for analysis of shell and pairing effects. Measurements with the Penning trap mass spectrometer ISOLTRAP at CERN-ISOLDE were made for Cr for which an accuracy of was achieved. Analysis of the mass surface for the supposed new shell closure rather indicates a sub-shell closure, but of a different nature than known cases such as Sr