Collinear laser spectroscopy at ionic beams of argon and chlorine

Metastable ions of argon and chlorine were accelerated to form a beam which was led antiparallel to dye-laser beam. When the laser beam was tuned to transitions from the metastables to higher states and the accelerating voltage was set to compensate for the remaining shift, fluorescence from the ions could be detected. Scanning the voltage excitation spectra of the ions could be obtained which allowed to determine the isotope shift of the lines the laser excited.     

Collinear laser spectroscopy techniques at JYFL

Over the last 15 years, a collinear laser spectroscopy programme has been developed at the University of Jyväskylä Accelerator Laboratory (JYFL), Finland. Continuous technique development and exploitation has taken place to address physics cases inaccessible elsewhere. In particular, the use of ion beams from the IGISOL and the pioneering application of cooled and bunched beams to laser spectroscopy. Many of these advances have additionally now been exported to facilities worldwide.     

Collinear laser spectroscopy on108g, 108m In using an ion source with bunched beam release

The hyperfine structure and isotope shift of^108gIn and^108mIn have been investigated by means of collinear fast-beam laser spectroscopy in the resonance line atλ=451 nm. The indium isotopes were prepared at the GSI on-line mass separator following a fusion evaporation reaction. For the first time, a FEBIAD ion source with bunched release of indium was used. Magnetic dipole moments, electric quadrupole moments and isotope shifts were determined. The present results lead us to assign the spinI=2 to the¹⁰⁸In (T _1/2=40 min) state. Spins and moments are discussed in the framework of thejj-coupling model.     

First results from laser spectroscopy on bunched radioactive beams from the JYFL ion-beam cooler

A new RFQ ion-beam cooler and buncher, installed after the mass-separating magnet of the ion guide isotope separator, IGISOL, JYFL, has dramatically increased the scope of on-line laser spectroscopy at this facility. The device, operated in a bunching mode, has permitted new measurements on short-lived radionuclei in the Ti, Zr and Hf chains at a sensitivity two orders of magnitude greater than that previously achieved. The device has also opened new prospects for laser-based nuclear spectroscopy at the facility, particularly collinear resonance ionisation spectroscopy. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: pc@mags.ph.man.ac.uk     

Collinear laser spectroscopy at the new IGISOL 4 facility

In 2011 the collinear laser spectroscopy programme at the University of Jyväskylä Accelerator Laboratory (JYFL), Finland, will move to the new IGISOL 4 facility. With its own dedicated cyclotron, this new laboratory will offer unparalleled access to beam time for both technique development and exploitation. Production of sub-millisecond states is available, including elements of a refractory nature.     

Collinear laser ion beam spectroscopy

Collinear Laser Ion Beam Spectroscopy (CLIBS) investigates hyperfine structures (hfs) and isotope shifts (IS) in spectral lines and is well suited for the study of nuclear moments of short-lived isotopes. It is fast, highly selective, highly sensitive and allows many experimental alternatives. The high accuracy makes it also an interesting tool for atomic physics. A basic experimental setup is described. Results for nuclear moments and radii in Sm, Eu, Gd show that the accuracy of hfs and IS data is much better than the resulting moments. We discuss the hfs-anomaly and its dependence on atomic quantum numbers (L, S, J) and show that its determination is possible without the knowledge of the nuclear magnetic moments. A hfs-anomaly in respect of the nuclear quadrupole moment was not found. IS-measurements are used to determine permanent and fluctuating nuclear deformation. The standard interpretation is inconsistent in the case of Eu. Modifications of the theory are suggested. Crossed second order (CSO) effects affect the IS values. We show that CSO-effects may help to determine the field effect of the IS experimentally.     

Collinear fast atomic-beam laser spectroscopy at riken garis/igisol

We have constructed a fast atomic-beam collinear laser spectroscopy system connected to the on-line isotope separator facility GARIS/IGISOL at RIKEN. This system is potentially powerful in studying refractory elements. To test the system, an off-line collinear experiment was made on stable Hf isotopes produced by means of laser ablation technique. For production of radioactive Hf isotopes, the use of the inverse kinematics of a fusion reaction,⁹Be(¹⁶⁶Er,xn)^175-x Hf, was investigated. The radioactive isotope¹⁶⁹Hf was successfully extracted from GARIS/IGISOL and accelerated up to 30 keV.     

Radioactive beams at TRIUMF: Present and future studies

In 1985, a high intensity, accelerated radioactive beam facility (ISAC) of the ISOL type, devoted mainly to studies in nuclear astrophysics, was proposed for installation. A report on the present status of radioactive beam research using the successfully operating TISOL is given, together with a summary of the future plans of these programs including an upgrade of TISOL to accommodate >10 A and a revised ISAC proposal.     

Collinear laser spectroscopy of neutron-rich Cs isotopes at an on-line mass separator

High-resolution laser spectroscopy was carried out in fast atomic beams of ^{133,137,138,139}Cs, yielding hyperfine structure and isotope shift in the 455.5 nm resonance line. Nuclear moments and changes of mean-square radii are derived from the results.     

Development of the collinear laser beam line at TRIUMF

Several commercially available medicaments containing ferrous fumarate (FeC₄H₂O₄) and ferrous sulfate (FeSO₄), as a source of ferrous iron, were studied using a high velocity resolution Mössbauer spectroscopy. A comparison of the ⁵⁷Fe hyperfine parameters revealed small variations for the main components in both medicaments indicating some differences in the ferrous fumarates and ferrous sulfates. It was also found that all spectra contained additional minor components probably related to ferrous and ferric impurities or to partially modified main components.     

High-resolution laser spectroscopy in fast beams

A method of obtaining narrow absorption lines is proposed, based on a simple property of accelerated beams, which would yield a resolution of a few megahertz at optical frequencies. Important linewidth contributions and systematic shifts are estimated. Applications to optical and mass spectroscopy are discussed, with emphasis on investigations of short-lived isotopes.     

Segmented linear radiofrequency quadrupole/laser ion source project at TRIUMF

Reactions such as ²⁵Al(p,γ)²⁶Si are the key to understand the production of ^26g Al and ^26m Al in our galaxy. Experimental results could provide important constraints on nova nucleosynthesis and modelling where ²⁶Al is believed to be produced. To achieve such measurements, high-intensity and high-purity radioactive beams are required. However, production targets at ISOL-type facilities such as ISAC at TRIUMF produce high-intensity alkali beams by surface ionization on hot transfer tubes hampering the measurement of isotopes of interest. To overcome this issue, an ion source combining a segmented linear radiofrequency quadrupole (RFQ) to a laser ion source is being built. Its main function is to suppress alkali impurities whilst allowing for fast-release of short-lived isotopes. The beam production method, the RFQ/laser ion source and the removal of alkali contaminants are discussed in this paper.     

Accelerator plans at TRIUMF

A recently completed Project Definition Study has proposed a network of accelerators to take the existing 500 MeV 150 μA proton beam at TRIUMF to 30 GeV. This facility would be capable of providing beams of kaons, antiprotons and other hadrons of intensities 100 times greater than those presently available. In addition, large numbers of low energy muons should be available and this facility is potentially the most powerful muon source planned for the future. The proposed facilities are described and the potential for future muon beams reported.     

TRIUMF resonant ionization laser ion source

The range of isotopes available at the TRIUMF Isotope Separator Accelerator (ISAC) facility has been greatly enhanced by adding a Resonance Ionization Laser Ion Source (RILIS). A large wavelength range is accessible with the fundamental, second and third harmonic generation of titanium-sapphire laser light. In addition a dedicated laser is available for non-resonant laser ionization. The first on-line beam ⁶²Ga was delivered in Dec. 2004. In general RILIS improves the intensity, purity and emittance of ion beams. ⁶²Ga and ²⁶Al and Be beams have been delivered so far on-line. This work was financed by TRIUMF which is federally funded via a contribution agreement through the National Research Council of Canada.     

Muon facilities at TRIUMF

TRIUMF provides its user community with a wide variety of muon beams for use in μSR and fundamental particle studies. The existing muon channels and their characteristics are described along with a proposed superconducting solenoid to be constructed in 1987.     

IR diode laser spectroscopy in molecular beams

A molecular beam spectrometer for recording cold-jet spectra is described. Modulation of the molecular beam is provided by a mechanical chopper. Some results on CO, C₃H₆ and CF₃Cl are presented.     

Collinear diffraction of divergent optical beams

Two variants of anisotropic collinear diffraction of light on a sinusoidal diffraction grating are studied theoretically with forth and back light scattering relative to the direction of the incident beam. For both variants, two-dimensional transfer functions are calculated and their modification with optical wavelength and diffraction grating period is analyzed. The dependence of integral diffraction efficiency and filter passband on optical beam divergence is examined.     

Collinear laser spectroscopy on unstable isotopes—A tool of nuclear physics

Atomic hyperfine structures and isotope shifts yield basic information about nuclear ground-state spins, moments and mean square charge radii. Recently, the collinear-beam laser experiments at ISOLDE have considerably enlarged the range of elements for which these studies can be extended into regions far from β-stability. The essential features of these experiments are outlined, and examples of the results on the rare-earth and radium isotopic chains are given. Finally, further improvements in sensitivity using non-optical detection are discussed.     

In-beam gamma-ray spectroscopy with exotic beams at the NSCL

Projectile fragmentation provides radioactive beams at intermediate velocities (v/c = 0.3-0.5) by physical means of fragment separation. With the development of position-sensitive photon detectors it has become possible to measure the energies and directions of photons emitted in-flight from such fast-moving exotic beams. This allows the reconstruction of the photons' energies emitted from an exotic projectile with high accuracy. It can be advantageous to employ photon detection in experiments with exotic beams since photons can traverse matter easily and their attenuation can be calculated. Experiments with standard luminosities can be carried out at intermediate beam energies with thick secondary targets (order of g/cm²) and very low incident beam rates (order of particle/s or less). Experimental success in this field is strongly correlated with the development of photon detectors such as position-sensitive scintillation detectors or segmented germanium detectors. In-beam gamma-ray spectroscopy of fast exotic beams has been successfully used at all projectile fragmentation facilities in intermediate-energy heavy-ion inelastic scattering experiments, knockout reactions and fragmentation reactions. Here, we focus on experimental results for neutron-rich exotic nuclei in the π(sd )-shell. Measurements and detector developments carried out at the NSCL at Michigan State University during the last four years are discussed. Received: 1 May 2001 / Accepted: 4 December 2001