Search

A novel combination of advanced gas-chromatography and detection systems coupled to a buffer-gas cell was characterized on-line to allow gas-phase chemical studies of accelerator-produced short-lived α -decaying mercury, francium, and astatine isotopes. These were produced in 40Ar- and 48Ca-induced nuclear fusion–evaporation reactions, subsequently isolated in the recoil separators MARS at Texas A&M University, USA, and TASCA at GSI Darmstadt, Germany, before being thermalized in a buffer-gas-stopping cell. From the latter, the nuclear reaction products were extracted into gas-phase chromatographic systems, suitable for registering α -decaying short-lived radionuclides, such as isotopes of superheavy elements. Efficiencies of 21(3)% for 204-209Fr were reached for the extraction into the optimized miniCOMPACT gas-chromatography setup, indicating that this technique enables the identification of isotopes of volatile as well as non-volatile elements. These studies guide the path towards chemical investigations of superheavy elements beyond flerovium, which are out of reach with currently used setups.

Ions with similar charge-to-mass ratios cannot be separated from existing beam profile monitors (BPMs) in nuclear facilities in which low-energy radioactive ions are produced due to nuclear fusion reactions. In this study, we developed a BPM using a microchannel plate and a charge-coupled device to differentiate the beam profiles of alpha-decaying radioactive isotopes from other ions (reaction products) produced in a nuclear reaction. This BPM was employed to optimize the low-energy radioactive francium ion (Fr+) beam developed at the Cyclotron and Radioisotope Center (CYRIC), Tohoku University, for electron permanent electric dipole moment (e-EDM) search experiments using Fr atoms. We demonstrated the performance of the BPM by separating the Fr+ beam from other reaction products produced during the nuclear fusion reaction of an oxygen (18O) beam and gold (197Au) target. However, as the mass of Au is close to that of Fr, separating the ions of these elements using a mass filter is a challenge, and a dominant number of Au+ renders the Fr+ beam profile invisible when using a typical BPM. Therefore, by employing the new BPM, we could successfully observe the Fr+ beam and other ion beams distinctly by measuring the alpha decay of Fr isotopes. This novel technique to monitor the alpha-emitting radioactive beam covers a broad range of lifetimes, for example, from approximately 1 s to 10 min, and can be implemented for other alpha-emitter beams utilized for medical applications., Comment: 7 pages, 8 figures

A computer simulation of the radioactive isotope beam targets used at the Isotope Separation and ACceleration (ISAC) facility of TRIUMF was built, to support target material development. The simulation was constructed using the GEANT4 nuclear transport toolkit, and can simulate the production rate of isotopes from user-defined beam and target characteristics. This GEANT4 simulation produces isotopes using the Liege intra-nuclear cascade, coupled to the ABLAv3 de-excitation code and consists of a primary 480 MeV proton beam impinging upon a production target. The isotopes produced by this interaction are used to calculate in-target production rates. Results from the simulation are presented, alongside an analysis of the release times of a subset of the francium isotopes, 211–214 Fr.

Various isotopes of Ac, Ra, Fr, and Rn were produced by fusion-evaporation reactions using a 48Ca beam. The energetic ions were stopped in and extracted from a helium gas cell. The extracted ions were identified using a multi-reflection time-of-fight mass spectrograph. In all cases, it was observed that the predominant charge state for the extracted ions, including the alkali Fr, was 2+.

The negative- and positive-parity states and electromagnetic transitions for [Formula: see text]Rn and [Formula: see text]Fr nuclei have been studied by using the Interacting Boson–Fermion Approximation (IBFM-1). Based on our calculations, the spin assignments for some states with uncertain spin have been done. Energy spectra, electromagnetic transition probabilities and branching ratios in these isotopes are calculated and compared with available experimental data. The wave functions are analyzed to understand the nuclear structure. In addition, some predictions of levels that have no experimental data are presented such as spin and electromagnetic transitions. Good results were obtained with a decrease in the collectivity properties, especially for the most neutron-deficient isotopes.

We are planning test experiments of fundamental symmetries based on the intrinsic properties of francium. It is expected that the laser cooling and trapping of francium will produce precision measurements. The pilot experiment using rubidium was performed with the goal of francium trapping. The ion beam generated with a francium ion source was investigated using a Wien filter. Each piece of equipment still must be studied in more detail, and the equipment should be upgraded in order to trap radioactive atoms.

The Dirac&ndash, Hartree&ndash, Fock plus many-body perturbation theory (DHF + MBPT) method has been used to calculate hyperfine structure constants for Fr. Calculated hyperfine structure anomaly for hydrogen-like ion is in good agreement with analytical expressions. It has been shown that the ratio of the anomalies for s and p1/2 states is weakly dependent on the principal quantum number. Finally, we estimate Bohr&ndash, Weisskopf corrections for several Fr isotopes. Our results may be used to improve experimental accuracy for the nuclear g factors of short-lived isotopes.

A factory of laser-cooled francium (Fr) atoms is being developed to search for the electric dipole moment (EDM) of the electron. The factory has achieved the production of Fr ions of 9 × 10 5 particles/s and transport with a transmission efficiency of 2%. In pilot experiments, the magneto-optical trapping of rubidium (Rb) has been performed using a new ion-to-atom converter. To achieve the Fr trap, the development and design of each of the factory’s components are in progress.

The CRIS setup at CERN-ISOLDE is a laser spectroscopy experiment dedicated to the high-resolution study of the spin, hyperfine structure and isotope shift of radioactive nuclei with low production rates (a few per second). It combines the Doppler-free resolution of the in-flight collinear geometry with the high detection efficiency of resonant ionisation. A recent commissioning campaign has demonstrated a 1% experimental efficiency, and as low as a 0.001% non-resonant ionisation. The current status of the experiment and its recent achievements with beams of francium isotopes are reported. The first identified systematic effects are discussed. publisher: Elsevier articletitle: The Collinear Resonance Ionization Spectroscopy (CRIS) experimental setup at CERN-ISOLDE journaltitle: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms articlelink: http://dx.doi.org/10.1016/j.nimb.2013.05.088 content_type: article copyright: Copyright © 2013 The Authors. Published by Elsevier B.V. ispartof: Nuclear Instruments & Methods in Physics Research B vol:317 issue:PART B pages:565-569 ispartof: location:Matsue, Japan status: published

The study of weak interactions in atoms started soon after the discovery of parity nonconservation PNC [1]. Its small size remained a challenge, but the Bouchiats [2] recognized that in an appropriate interference experiment the size of the effect of atomic parity noncon servation (APNC) scales faster than Z3, with Z the atomic number. This strong scaling has made possible not only to observe PNC effects in atoms, but to measure weak interaction coupling constants, at very low energies.

The existence of a non-zero electric dipole moment (EDM) implies the violation of time reversal symmetry. As the time-reversal symmetry violation predicted by the Standard Model (SM) for the electron EDM is too small to be observed with current experimental techniques and any a non-zero EDM would indicate new physics beyond the SM. The tiny signal from the electron EDM is enhanced in the heavy atoms such as francium (Fr). We are constructing the laser-cooled Fr factory to search for the electron EDM.

We present a method for measuring the nuclear anapole in a string of francium isotopes. The anapole is a parity non-conserving electromagnetic moment that enables parity-forbidden transitions between ground state hyperfine levels of an atom. The experiment is run by the FrPNC collaboration and relies on a beam of artificially-produced francium from the ISAC facility at TRIUMF.

We report on the status of the FrPNC experiments and summarize our plans for measurements of parity non-conservation (PNC) in a sample of cold francium. The FrPNC collaboration has commissioned a laser cooling apparatus at the TRIUMF accelerator that collects and cools francium atoms for PNC experiments. We have recently demonstrated the robust, high efficiency transfer (50 %) of laser cooled francium atoms to a second laser cooling apparatus, located 0.7 m below the first, where the PNC experiments will be conducted.

The ASACUSA collaboration has developed injection-seeded Ti:sapphire lasers of linewidth Γpl ∼ 6 MHz, pulse energy 50–100 mJ, and output wavelength λ = 726–941 nm. They are being used in two-photon spectroscopy experiments of antiprotonic helium atoms at the Antiproton Decelerator (AD) of CERN. Ti:sapphire lasers of larger linewidth Γpl ∼ 100 MHz but more robust design will also be used in collinear resonance ionization spectroscopy (CRIS) experiments of neutron-deficient francium ions at the ISOLDE facility.

Francium is one of the best candidates for measurements of atomic parity violation and in the search for permanent electric dipole moments. These fundamental measurements rely on precision studies in atomic spectroscopy and on the development of magneto-optical traps. A radioactive francium production and trapping facility was built and commissioned at INFN's national laboratories in Legnaro, Italy. Here we describe the beamline that is used to transport Fr + ions at a kinetic energy of 3 keV from the production target to the magneto-optical trap. The design principles, construction, diagnostics, and performance are discussed.

A complete set of the Mi (i = 1–5) subshell fluorescence and Coster–Kronig (CK) yields has been generated by interpolation for elements with 67 ⩽ Z ⩽ 92 from the Dirac–Hartree–Slater (DHS) model based values tabulated for a limited number of elements, considering the cutoff/onset of different CK transitions in accordance with the CK transition energies evaluated in the present work. The CK transition energies have been deduced from tabulated values of the Dirac–Hartree–Fock–Slater model based neutral atom binding energies [K. Huang, M. Aoyagi, M.H. Chen, B. Crasemann, H. Mark, At. Data Nucl. Data Tables 18 (1976) 243] and the Li (i = 1–3) subshell CK transition energies [M.H. Chen, B. Crasemann, K. Huang, M. Aoyagi, H. Mark, At. Data Nucl. Data Tables 19 (1977) 97] in order to establish the cutoff/onset of different CK transitions at specific atomic numbers. A second set of the Mi (i = 1–5) subshell fluorescence yields have also been deduced using radiative widths computed from the Dirac–Fock (DF) model based X-ray emission rates, and the total widths reevaluated to incorporate the DF model based radiative widths in place of those based on the DHS model. Further, the CK-corrected (νi) and average fluorescence (ϖM) fields, which are experimentally important, have been evaluated from the generated set of CK yields and two sets of fluorescence yields.

The evaluator presents in this publication spectroscopic data and level schemes from radioactive decay and nuclear reactions for all nuclei with mass number A = 232. Highlights from this evaluation include the discovery of a new isotope of francium, {sup 232}Fr, and the study of its {beta} {sup -} decay to levels in {sup 232}Ra (2004Pe17,1990Me13). Also, it includes the first observation of spontaneous fission in {sup 232}Th and {sup 232}U, as well as the measurement of their respective partial half-lives of 1.2 (4) x 10{sup 21}y (1995Bo18) and 2.6 (5) x 10{sup 15}y (2000Bo46) for this type of decay.

Francium combines a heavy nucleus (Z = 87) with the simple atomic structure of alkalis and is a very promising candidate for precision tests of fundamental symmetries such as atomic parity non-conservation measurements. Fr has no stable isotopes, and the ISAC radioactive beam facility at TRIUMF, equipped with an actinide target, promises to provide record quantities of Fr atoms, up to 1010/s for some isotopes. We discuss our plans for a Fr on-line laser trapping facility at ISAC and experiments with samples of cold Fr atoms. We outline our plans for a measurement of the nuclear anapole moment — a parity non-conserving, time-reversal conserving moment that arises from weak interactions between nucleons — in a chain of Fr isotopes. Its measurement is a unique probe for neutral weak interactions inside the nucleus.

State of the art laser technology and modern spectroscopic methods allow to address issues of fundamental symmetries and fundamental interactions in atoms with high precision experiments. In particular the discrete symmetries Parity (P), Charge Conjugation (C), Time Reversal (T) as well as their combinations CP and CPT are in the center of interest at present. Actual projects are concerned with Parity Violation in atoms, Time Reversal Violation in beta-decays and searches for permanent Electric Dipole Moments (EDMs), and tests of CPT conservation in particle-antiparticle properties, in particular antiprotonic atoms.

The Penning trap mass spectrometer ISOLTRAP has to date been used for the determination of close to 300 masses of radionuclides. A relative mass uncertainty of 10$^{-8}$ can now be reached. Recent highlights were measurements of rp-process nuclides as for instance $^{72-74}$Kr or superallowed $\beta$ emitters like $^{22}$Mg, $^{74}$Rb and $^{34}$Ar. The heaviest nuclides measured so far with ISOLTRAP are neutron-rich radium and francium isotopes. An overview of ISOLTRAP mass measurements and details about the recent experiment on $^{229-232}$Ra and $^{230}$Fr are presented.

In 2012 the new collinear resonance ionization spectroscopy (CRIS) experiment at ISOLDE celebrated its first successful campaign on the rare francium isotopes. This work builds on 30 years of research and development that has aimed at combining the high sensitivity of resonance ionization spectroscopy with the high resolution of collinear laser spectroscopy.

A new facility has been constructed at the INFN Legnaro National Laboratory (LNL) for the production of francium isotopes via a fusion-evaporation nuclear reaction and a laser laboratory has been set up for francium trapping. Francium is produced inside a gold target and after diffusion desorbs from its surface as an ion. A secondary beam line delivers the francium ions to the trapping cell where they are neutralized and trapped in a magneto-optical trap (MOT). Details on the production, delivery and neutralization methods are presented. Preliminary results on trapped francium are also shown. Production rate of ≃ 10 6 ions/s and a trap population of about 100 atoms have been achieved.

The radioactive element francium is of great interest in many laboratories because, as an alkali, it is the heaviest atom in which the atomic properties can presently be calculated to better than 1%. The electron-nucleus interactions in heavy atoms are stronger than in lighter alkalis and are more sensitive to weak interaction effects in nuclei, such as anapole moments, electric dipole moments, and other parity‐ violating effects. The ability to trap large numbers of atoms, >lo6, would make possible precision measurements

Neutron-rich thallium, lead, and bismuth isotopes were investigated at the ISOLDE facility. After mass separation and resonant laser ionisation of the produced activity, new spectroscopic data were obtained for 215,218 Bi and 215 Pb. An attempt to reach heavy thallium had to be abandoned because of a strong francium component in the beam that gave rise to a neutron background through (α,n) reactions on the aluminium walls of the experimental chamber.

In order to trap francium atoms in a magneto-optical trap, a beam of singly charged francium ions must be neutralized and reduced to thermal energies. Vacuum requirements prevent the use of a gas-filled charge exchange cell. The simple alternative is to implant the ion beam into a hot catcher foil where the ions neutralize within the foil and then diffuse out. The fraction of ions which neutralize depends upon the work function of the foil and first ionization potential of the ion beam. In order to produce such a neutralizer several suitable materials were tested in a variety of different mechanical designs to determine the most effective and robust system.

Neutral atoms trapped with modern laser cooling techniques offer the promise of improving several broad classes of experiments with radioactive isotopes. In nuclear β decay, neutrino spectroscopy from beta-recoil coincidences, along with highly polarized samples, enable experiments to search for non-Standard Model interactions, test whether parity symmetry is maximally violated, and search for new sources of time reversal violation. Ongoing efforts at TRIUMF, Los Alamos and Berkeley will be highlighted. The traps also offer bright sources for Doppler-free spectroscopy, particularly in high- Z atoms where precision measurements could measure the strength of weak neutral nucleon–nucleon and electron–nucleon interactions. Physics with francium atoms has been vigorously pursued at Stony Brook. Several facilities plan work with radioactive atom traps; concrete plans and efforts at KVI Groningen and Legnaro will be among those summarized. Contributions to the multidisciplinary field of trace analysis will be left up to other presenters.

Collinear laser fluorescence spectroscopy has been performed on the ground and isomeric states of $^{204,206}\mathrm{Fr}$ in order to determine their spins, nuclear moments, and changes in mean-squared charge radii. A new experimental technique has been developed as part of this work which much enhances the data collection rate while maintaining the high resolution. This has permitted the extension of this study to the two isomeric states in each nucleus. The investigation of nuclear $g$ factors and mean-squared charge radii indicates that the neutron-deficient Fr isotopes lie in a transitional region from spherical towards more collective structures.

The difference in isotope production between 1 and 1.4 GeV proton projectiles was investigated at ISOLDE/CERN during the year 1999. As target materials uranium carbide, thorium carbide, lead and lanthanum oxide were used and the ratio of the measured production yields for the two different projectile energies were determined for isotopes of the elements francium, mercury, thallium, xenon, cesium, krypton, rubidium and neon. A comparison of these experimental results with the predictions from a two-step reaction model Monte-Carlo code shows good agreement. (C) 2002 Elsevier Science B.V. All rights reserved.

We describe several methods for efficiently injecting a small number of radioactive atoms into a laser trap. The characteristics of laser traps that make them desirable for physics experiments are discussed and several different experimental directions are described. We describe recent experiments with the alkali element Fr and point to future directions of the neutral atom trapping program.  2002 Elsevier Science B.V. All rights reserved.

The development of thick gold targets for the production of radioactive beams of Fr + is discussed. In order that the Fr + ions, created within the target, be released, the gold must be elevated in temperature to just below its melting point. Several different designs and production processes are compared and contrasted to determine how to create a robust target capable of producing the greatest abundance of Fr + ions.

The alkali element francium has a simple electronic structure, and copious amounts of a wide range of isotopes can be produced in present and future rare isotope facilities. The atomic parity violating weak interaction in Fr is 18 times larger than in Cs, which makes it one of the best candidates to search for the effects of the weak interaction and its isotopic dependence. Atomic trapping methods now offer new ways to study these atoms with precision, and we will discuss some of our recent measurements with trapped Fr atoms. Future measurements of the spin-independent weak interaction can be used to test the standard model, but advances in atomic theory and improved understanding of the neutron distribution in nuclei are needed to make progress. We have made precise hyperfine-anomaly measurements in Fr and have shown that they are sensitive to the radial distribution of the neutron magnetization. Measurements of this type can help to constrain the neutron distributions. Future measurements of the spin-dependent weak interaction should allow extraction of the nuclear anapole moments for a sequence of isotopes, and allow separation of the neutron and proton weak interactions between hadrons.

The magnetic dipole moments and changes in mean-square charge radii of the neutron-rich $^{218m,219,229,231}\text{Fr}$ isotopes were measured with the newly-installed Collinear Resonance Ionization Spectroscopy (CRIS) beam line at ISOLDE, CERN, probing the $7s~^{2}S_{1/2}$ to $8p~^{2}P_{3/2}$ atomic transition. The $\delta\langle r^{2}\rangle^{A,221}$ values for $^{218m,219}\text{Fr}$ and $^{229,231}\text{Fr}$ follow the observed increasing slope of the charge radii beyond $N~=~126$. The charge radii odd-even staggering in this neutron-rich region is discussed, showing that $^{220}\text{Fr}$ has a weakly inverted odd-even staggering while $^{228}\text{Fr}$ has normal staggering. This suggests that both isotopes reside at the borders of a region of inverted staggering, which has been associated with reflection-asymmetric shapes. The $g(^{219}\text{Fr}) = +0.69(1)$ value supports a $\pi 1h_{9/2}$ shell model configuration for the ground state. The $g(^{229,231}\text{Fr})$ values support the tentative $I^{\pi}(^{229,231}\text{Fr}) = (1/2^{+})$ spin, and point to a $\pi s_{1/2}^{-1}$ intruder ground state configuration., Comment: Accepted for publication with Physical Review C

Au and isotopically enriched Pt targets are discussed for the production of radioactive Fr beams. Target foils, serving also as ionizers, have to be heated in order to enhance the diffusion of atoms to the surface for further extraction and injection into the electrostatic transport system.

Discussion and tests of several designs of sources for continuous vacuum deposition of Au.

A formalism developed previously to study the smaller nuclear spin-dependent parity-violating effects using the relativistic mean field theory has been generalized to the case of odd-odd nuclear systems such as Fr-210. Because of the recent success in trapping Fr atoms, parity-violation experiments for Fr seem feasible. The nuclear spin-dependent parameters eta and eta' are calculated using the anapole moment parameters kappa(p) and kappa(n). They are used to calculate the hyperfine transition amplitudes for the 6S-->7S transition in Cs-134 and 7S -->8S in Fr-210. The calculated hyperfine transition amplitudes in Fr are one order of magnitude larger than those in Cs.

A brief review of the Francium trapping experiments at the INFN-LNL facility is presented in the wide context of Atomic Parity-Nonconservation (APNC), which, as long as acquiring more precise and new spectroscopic data on the Francium isotopes, is the ultimate goal of the experiment. Due to its instability, Francium atoms must be produced continuously by a nuclear fusion–evaporation reaction into a heated Gold target hit by a beam of accelerated oxygen ions. Francium is then extracted in the ionic form and guided by an electrostatic line to the actual science chamber, where the ions are neutralized. Atoms are then cooled down and trapped in a Magneto-Optical Trap (MOT) to ensure both the availability of a sufficiently populated and stable atomic sample and to eliminate the Doppler broadening which would affect the precision of the measurements. A review of the recent improvements to the experimental apparatus and to the detection techniques that led to a sensitivity better than five atoms is presented. The final part of this paper deals with a summary of the recent results obtained by our collaboration and a short outlook for the immediate future.

The masses of Fr222,224,226-233 and Ra233,234 have been determined with the Penning-trap mass spectrometer ISOLTRAP at the ISOLDE facility at CERN, including the previously unknown mass and half-life of Fr233. We study the evolution of the odd-even staggering of binding energies along the francium and radium isotopic chains and of its lowest-order estimator, Δ3(N). An enhancement of the staggering of Δ3(N) is observed towards neutron number N=146, which points to contributions beyond pairing correlations. These contributions are investigated in the Hartree-Fock and Hartree-Fock-Bogoliubov approaches, emphasizing the connections to the single-particle level density and nuclear deformation. © 2014 American Physical Society. ispartof: Physical Review C, Nuclear Physics vol:90 issue:2 status: published

Collective $P$- and $T$-odd moments produced by parity and time invariance violating forces in reflection asymmetric nuclei are considered. The enhanced collective Schiff, electric dipole, and octupole moments appear due to the mixing of rotational levels of opposite parity. These moments can exceed single-particle moments by more than 2 orders of magnitude. The enhancement is due to the collective nature of the intrinsic moments and the small energy separation between members of parity doublets. In turn these nuclear moments induce enhanced $T$- and $P$-odd effects in atoms and molecules. A simple estimate is given and a detailed theoretical treatment of the collective $T$-, $P$-odd electric moments in reflection asymmetric, odd-mass nuclei is presented. In the present work we improve on the simple liquid drop model by evaluating the Strutinsky shell correction and include corrections due to pairing. Calculations are performed for octupole deformed long-lived odd-mass isotopes of Rn, Fr, Ra, Ac, and Pa and the corresponding atoms. Experiments with such atoms may improve substantially the limits on time reversal violation.

The difficult problem of quickly slowing and cooling nuclear reaction products so that they can be injected into a laser trap has been solved by several groups and there are now strong efforts to work with the trapped atoms. The atoms are confined in the trap to a small spatial volume of the order of 1 mm3, but more importantly, they are also confined in velocity, which makes them an ideal sample for spectroscopic measurements with other lasers. We have recently trapped radioactive francium and have embarked on a program to further study the francium atom as a prelude to a test of the Standard Model analogous to previous work with Cs. Our sample of 3 min 210Fr now contains over 20 000 atoms, and is readily visible with an ordinary TV camera. We work on-line with the accelerator, and continuously load the trap to replace losses due to decay and collisions with background gas. We have maintained a sample of Fr atoms in the trap for over 10 hours, with occasional adjustment of the trapping laser frequency to account for drifts. The proposed test of the Standard Model will require accurate calculation of its atomic properties. We are currently testing these calculations by measuring other predicted quantities.

In our clinical investigations focussing on improved therapeutic treatment of specific tumors we have concentrated on a targeted therapy approach utilizing designed radiolabeled monoclonal antibodies as the cytotoxic reagent. The physical characteristics of the alpha particle emitting radionuclide bismuth-213 including the short half-life of 45.6 min, has shown promise for the treatment of specific cancers such as leukemias and lymphomas or micrometastatic carcinomas. In an effort to increase the cytocidal effect of the HuM195, a humanized monoclonal antibody carrier to the CD33 antigen expressed on leukemia cells, our focus is directed toward an “internal” nano-generator composed of Ac-225 radionuclide, the parent of the bismuth-213. The actinium-225 radionuclide decays through several short-lived, alpha emitting daughters including francium-221, astatine-217 and bismuth-213. In order to study the biodistribution and the pharmacokinetics of the individual daughter nuclide, francium-221, the cyclotron production and separation of cesium radionuclides, specifically cesium-132, from a natural xenon gas target was undertaken. The choice of cesium as an analogue for francium was predicated upon both elements being in Group 1A alkali metals and cesium radionuclide possesses a sufficient half-life to allow biodistribution studies to be performed. The preliminary experimental results of this investigation are presented.

The ability to study rare isotopes with techniques such as mass spectrometry and laser spectroscopy is often prevented by low production rates and large isobaric contamination. This has necessitated the development of novel beam cleaning techniques that can efficiently isolate the isotope of interest. The Collinear Resonance Ionization Spectroscopy (CRIS) experiment at ISOLDE, achieves this by resonantly ionizing a bunched atom beam in a region of ultra high vacuum. This method is motivated by the need to measure the hyperfine structure and isotope shift at the extremes of isospin where typical production rates drop to 1 atom/s. The technique also offers the ability to purify an ion beam and even select long-lived isomeric states (>1 ms) from the ground state, which can be subsequently studied by decay spectroscopy or mass spectrometry experiments. This paper will report on the successful commissioning of the CRIS beam line and the recent laser spectroscopy results and laser assisted nuclear decay spectroscopy on the neutron deficient francium isotopes. ispartof: pages:131-137 ispartof: Hyperfine Interactions vol:227 issue:1 pages:131-137 ispartof: the 9th International Workshop on Application of Lasers and Storage Devices in Atomic Nuclei Research “Recent Achievements and Future Prospects” (LASER 2013) location:Poznan, Poland date:13 May - 16 May 2013 status: published

Very neutron deficient francium isotopes have been produced in fusion evaporation reactions using ${}^{60}$Ni ions on ${}^{141}$Pr targets. The gas-filled recoil separator RITU was employed to collect the fusion products and to separate them from the scattered beam. The activities were implanted into a position sensitive silicon detector after passing through a gas-counter system. The isotopes were identified using spatial and time correlations between the implants and the decays. Two $\ensuremath{\alpha}$-particle activities, with ${E}_{\ensuremath{\alpha}}=7613(15)$ keV and ${T}_{1/2}$ $=$ (${15}_{\ensuremath{-}5}^{+12}$) ms and ${E}_{\ensuremath{\alpha}}=7684(15)$ keV and ${T}_{1/2}$ $=$ (${16}_{\ensuremath{-}5}^{+13}$) ms were identified in the new isotope ${}^{198}$Fr. In addition, the half-life and $\ensuremath{\alpha}$-particle energy of ${}^{199}$Fr were measured with improved precision. The measured decay properties deduced for ${}^{199}$Fr and ${}^{198}$Fr suggest that there is an onset of ground-state deformation at $N=112$ in the Fr isotopes.

Decay properties of the very neutron-deficient isotopes ${}^{197\char21{}199}$Fr were studied at the velocity filter Separator for Heavy Ion reaction Products (SHIP) at GSI in Darmstadt. The isotopes were produced in the $2n\char21{}4n$ evaporation channels of the fusion-evaporation reaction ${}^{60}$Ni+${}^{141}$Pr $\ensuremath{\rightarrow}$ ${}^{201}$Fr*. Improved $\ensuremath{\alpha}$-decay properties of ${}^{199}$Fr were determined and the possible existence of two $\ensuremath{\alpha}$-decaying states in this nucleus is discussed. For the isotope ${}^{198}$Fr a broad $\ensuremath{\alpha}$-decay energy distribution was detected in the range of $(7470\char21{}7930)$ keV and two $\ensuremath{\alpha}$-decaying states were observed with half-lives of 1.1(7) and 15(3) ms. The new isotope ${}^{197}$Fr was identified based on the observation of one $\ensuremath{\alpha}$-decay chain yielding ${E}_{\ensuremath{\alpha}}=7728(15)$ keV and ${T}_{1/2}=0.{6}_{\ensuremath{-}0.3}^{+3.0}$ ms. The systematics of reduced $\ensuremath{\alpha}$-decay widths are presented for neutron-deficient francium, radon, and astatine isotopes.

The techniques of laser cooling and trapping now make it possible to observe large samples of stable atoms in a small volume at low temperature. This capability was recently extended to radioactive isotopes. This opens up new opportunities for the investigation of fundamental symmetries through measurements using radioactive atoms. In this paper we will discuss several fundamental measurements in atomic systems and how the ability to trap radioactive atoms will play an important role in improving the precision of such measurements. Measurements of the effects of the weak interaction are of particular note since they are becoming quite precise. In particular, we will describe in detail the system developed at Stony Brook to trap radioactive alkali atoms and measure weak interaction effects in francium isotopes.

Third-order many-body perturbation theory is used to obtainE1 transition amplitudes for ions of the lithium and sodium isoelectronic sequences and for the neutral alkali-metal atoms potassium, rubidium, cesium, and francium. Complete angular reductions of the first-, second-, and third-order amplitudes are given. Tables of transition energies and rates are given for the 2p1/2→ 2s1/2, 2p3/2→ 2s1/2, 3s1/2→ 2p1/2, and 3s1/2→ 2p3/2transitions in the lithium isoelectronic sequence and for the corresponding 3p1/2→ 3s1/2, 3p3/2→ 3s1/2, 4s1/2→ 3p1/2, and 4s1/2→ 3p3/2transitions in the sodium sequence. For neutral alkali atoms, amplitudes ofnp1/2→ ns1/2,np3/2→ ns1/2, (n+ 1)s1/2→ np1/2, and (n+ 1)s1/2→ np3/2transitions are evaluated, wherenis the principal quantum number of the valence electron in the atomic ground state. Semi-empirical corrections for the omitted fourth- and higher-order terms in perturbation theory are given for the neutral alkali-metal atoms. Comparisons with previous high-precision calculations and with experiment are made.

Electric dipole moments constitute a competitive method to search for new physics, being particularly sensitive to new CP-violating phases. Given the experimental and theoretical progress in this field and more generally in particle physics, the necessity for more reliable bounds than the ones usually employed emerges. We therefore propose an improved extraction of the electric dipole moment of the electron and the relevant coefficient of the electron-nucleon coupling, taking into account theoretical uncertainties and possible cancellations, to be used in model-dependent analyses. Specifically, we obtain at 95% C.L. |d_e, 8 pages, 2 tables, 4 figures. v2: Extended discussion of the EDM of Tl, corrected value for the nuclear magnetic moment of Hg (implying small shifts in the obtained numerical values) and further minor changes

An experimental program is under way to capture neutral francium atoms in a magneto-optic trap. Production and transport of the radioactive Fr atoms near to the trapping region have been tested, with a steady state of 107 atoms. If one hundred atoms are captured from the Maxwell-Boltzmann distribution into a magneto-optic trap, this will be a sufficient number for spectroscopy of the unknown excited states. These measurements would then open the path to investigations of parity-violating transitions in francium.

An emission channelling study has been performed on α-emitting Fr implants in Fe. The implantation dose was kept below 10 11 atoms cm 2 to assure single cascade conditions. Low dose was possible as the experiment was done on line, and data was recorded with a position sensitive detector. The study revealed 45% of francium in substitutional sites at room temperature and 57% in substitutional sites at 120 K. No evidence for vacancy trapping was found, suggesting a small trapping radius for Fr in Fe.

Neutron-deficient astatine and francium nuclei were produced in the reaction ${}^{30}\mathrm{Si}+{}^{181}\mathrm{Ta}\ensuremath{\rightarrow}{}^{211}{\mathrm{Fr}}^{*}$ at 152 MeV. The evaporation residues from this very fissile system were selected with the HERCULES-II detector system and residue-gated $\ensuremath{\gamma}$ rays were measured with Gammasphere. Excited states were observed for the first time in $^{205,207}\mathrm{Fr}$, as well as sequences of low-energy transitions between high-spin states in $^{204}\mathrm{At}$ and $^{206}\mathrm{Fr}$. These latter structures have properties similar to those associated with magnetic rotation (shears bands) in lead nuclei. Comparisons with established shears bands are presented and prospects for the magnetic-rotation phenomenon near the predicted $N=120$ ``magic'' number are explored.