TRIGA-SPEC: A setup for mass spectrometry and laser spectroscopy at the research reactor TRIGA Mainz

The research reactor TRIGA Mainz is an ideal facility to provide neutron-rich nuclides with production rates sufficiently large for mass spectrometric and laser spectroscopic studies. Within the TRIGA-SPEC project, a Penning trap as well as a beam line for collinear laser spectroscopy are being installed. Several new developments will ensure high sensitivity of the trap setup enabling mass measurements even on a single ion. Besides neutron-rich fission products produced in the reactor, also heavy nuclides such as 235-U or 252-Cf can be investigated for the first time with an off-line ion source. The data provided by the mass measurements will be of interest for astrophysical calculations on the rapid neutron-capture process as well as for tests of mass models in the heavy-mass region. The laser spectroscopic measurements will yield model-independent information on nuclear ground-state properties such as nuclear moments and charge radii of neutron-rich nuclei of refractory elements far from stability. This publication describes the experimental setup as well as its present status.Comment: 20 pages, 17 figure

Dual Chamber Laser Ion Source at Lisol

A new type of the gas cell for the resonance ionization laser ion source at the Leuven Isotope Separator On Line (LISOL) has been developed and tested at off-line and on-line conditions. Two-step selective laser ionization is applied to produce purified beams of radioactive isotopes. The selectivity of the ion source has been increased by more than one order of magnitude by separation of the stopping and laser ionization regions. This allows to use electrical fields for further ion purification.Comment: 14 figure

High-sensitivity study of levels in Al-30 following beta decay of Mg-30

gamma-ray and fast-timing spectroscopy were used to study levels in Al-30 populated following the beta(-) decay of Mg-30. Five new transitions and three new levels were located in Al-30. A search was made to identify the third 1(+) state expected at an excitation energy of similar to 2.5 MeV. Two new levels were found, at 3163.9 and 3362.5 keV, that are firm candidates for this state. Using the advanced time-delayed (ATD) beta gamma gamma (t) method we have measured the lifetime of the 243.8-keV state to be T-1/2 = 15(4) ps, which implies that the 243.8-keV transition is mainly of M1 character. Its fast B(M1; 2(+) -> 3(+)) value of 0.10(3) W.u. is in very good agreement with the USD shell-model prediction of 0.090 W.u. The 1801.5-keV level is the only level observed in this study that could be a candidate for the second excited 2(+) state.Peer reviewe

Prospects of ion-mobility measurements in superheavy element research

The element specific electron configuration of ions directly reflects the two quantum mechanical observables 〈r2〉 and rmax, which denote the r2 expectation value of the electron density and the principle maximum of the wave function of the outermost electron orbital, respectively. Thus, the determination of these observables may present a new access to element identification of single superheavy nuclides. In this paper, we discuss how these observables are related to ionic radii deduced from ion-mobility data using the most simple hard sphere model and semi-empirical (n,6,4) model potentials for the interaction of heavy ions with noble gases. A concept for a high resolution ion-mobility spectrometer is presented. Optimum extraction efficiency of the ions will be achieved by decoupling the ion motion from the electric field drift by the friction force of the suitably shaped gas flow at the exit nozzle

Prospects of ion-mobility measurements in superheavy element research

The element specific electron configuration of ions directly reflects the two quantum mechanical observables 〈r2〉 and rmax, which denote the r2 expectation value of the electron density and the principle maximum of the wave function of the outermost electron orbital, respectively. Thus, the determination of these observables may present a new access to element identification of single superheavy nuclides. In this paper, we discuss how these observables are related to ionic radii deduced from ion-mobility data using the most simple hard sphere model and semi-empirical (n,6,4) model potentials for the interaction of heavy ions with noble gases. A concept for a high resolution ion-mobility spectrometer is presented. Optimum extraction efficiency of the ions will be achieved by decoupling the ion motion from the electric field drift by the friction force of the suitably shaped gas flow at the exit nozzle.status: publishe

Production and properties of the heaviest elements

This article reviews the following topics which were discussed at the 375th Wilhelm and Else Heraeus-Seminar Workshop on the Atomic Properties of the Heaviest Elements held from September 25–27, 2006 at the Abtei Frauenwörth im Chiemsee, Germany: (i) the recent progress in the production of the heaviest elements, the investigation of their nuclear structure, and prospects for direct mass measurements in Penning traps. (ii) Recent studies of their chemical properties with the aid of volatile species and single-atom aqueous-phase chemistry; (iii) the current status and future prospects for the investigation of atomic and ionic properties such as optical spectroscopy in gas cells and ion traps, including fully relativistic calculations of the atomic level structure with predictions for the element nobelium; and (iv) ionic charge radii measurements in buffer gas filled drift cells, and ion chemical reactions in the gas phase

Low-field mobilities of rare-earth metals

In this paper, a dedicated ion mobility spectrometer for heavy element research will be presented. Like most advanced mobility spectrometers, the presented apparatus is equipped with a mass spectrometer for isotope-selective detection. In addition, the sample atoms are ionized by exploiting the element-selective laser resonance ionization techniques. First systematic studies at various lanthanide elements have shown that their low-field mobilities in argon are quite similar. The only exception is the element gadolinium, which exhibited an 8% lower reduced mobility of 1.692(24) cm2/V s. This anomaly is assumed to be a direct consequence of occupying the d- instead of an f-orbital in singly charged gadolinium, which in turn has a significant impact on the gadolinium-argon interaction potential

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

Low-field mobilities of rare-earth metals

In this paper, a dedicated ion mobility spectrometer for heavy element research will be presented. Like most advanced mobility spectrometers, the presented apparatus is equipped with a mass spectrometer for isotope-selective detection. In addition, the sample atoms are ionized by exploiting the element-selective laser resonance ionization techniques. First systematic studies at various lanthanide elements have shown that their low-field mobilities in argon are quite similar. The only exception is the element gadolinium, which exhibited an 8% lower reduced mobility of 1.692(24) cm2/V s. This anomaly is assumed to be a direct consequence of occupying the d- instead of an f-orbital in singly charged gadolinium, which in turn has a significant impact on the gadolinium-argon interaction potential.status: publishe