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S Sanguinetti,
R Calabrese,
L Corradi,
A Dainelli,
A Khanbekyan,
E Mariotti,
C de Mauro,
P Minguzzi,
L Moi, G Stancari,
L Tomassetti,
S Veronesi
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ABSTRACT: An interferometric method is used to improve the accuracy of the 7S-7P transition frequencies of three francium isotopes by 1 order of magnitude. The deduced isotope shifts for 209-211Fr confirm the ISOLDE data. The frequency of the D2 transition of 212Fr--the accepted reference for all Fr isotope shifts--is revised, and a significant difference with the ISOLDE value is found. Our results will be a benchmark for the accuracy of the theory of Fr energy levels, a necessary step to investigate fundamental symmetries.
Optics Letters 05/2009; 34(7):893-5. · 3.40 Impact Factor
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ABSTRACT: We have studied magneto-optical traps (MOTs) for efficient on-line trapping of radioactive atoms. After discussing a model of the trapping process in a vapor cell and its efficiency, we present the results of detailed experimental studies on Rb MOTs. Three spherical cells of different sizes were used. These cells can be easily replaced, while keeping the rest of the apparatus unchanged: atomic sources, vacuum conditions, magnetic field gradients, sizes and power of the laser beams, detection system. By direct comparison, we find that the trapping efficiency only weakly depends on the MOT cell size. It is also found that the trapping efficiency of the MOT with the smallest cell, whose diameter is equal to the diameter of the trapping beams, is about 40% smaller than the efficiency of larger cells. Furthermore, we also demonstrate the importance of two factors: a long coated tube at the entrance of the MOT cell, used instead of a diaphragm; and the passivation with an alkali vapor of the coating on the cell walls, in order to minimize the losses of trappable atoms. These results guided us in the construction of an efficient large-diameter cell, which has been successfully employed for on-line trapping of Fr isotopes at INFN's national laboratories in Legnaro, Italy. Comment: 9 pages, 7 figures, submitted to Eur. Phys. J. D
11/2008;
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S. Sanguinetti,
R Calabrese,
L. Corradi,
A. Dainelli,
A. Khanbekyan,
E. Mariotti,
C. de Mauro,
P. Minguzzi,
L. Moi, G. Stancari,
L. Tomassetti,
S. Veronesi
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ABSTRACT: We present the accurate measurement of the frequency of the $7S-7P$ laser-trapping transition for three francium isotopes. Our approach is based on an interferometric comparison to deduce the unknown laser frequency from a secondary laser frequency-standard. After careful investigation of systematics, with samples of about 100 atoms the final accuracy reaches 8 MHz, an order of magnitude better than the best previous measurement for $^{210}$Fr, and opens the way to improved tests of the theoretical computation of Fr atomic structure.
08/2008;
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C. de Mauro,
R Calabrese,
L. Corradi,
A. Dainelli,
A. Khanbekyan,
E. Mariotti,
P. Minguzzi,
L. Moi,
S. Sanguinetti, G. Stancari,
L. Tomassetti,
S. Veronesi
[show abstract]
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ABSTRACT: We report the first measurement of the diffusion coefficients of francium and rubidium ions implanted in a yttrium foil. We developed a methodology, based on laser spectroscopy, which can be applied to radioactive and stable species, and allows us to directly take record of the diffusion time. Francium isotopes are produced via fusion-evaporation nuclear reaction of a 100 MeV 18-O beam on a Au target at the Tandem XTU accelerator facility in Legnaro, Italy. Francium is ionized at the gold-vacuum interface and Fr+ ions are then transported with a 3 keV electrostatic beamline to a cell for neutralization and capture in a magneto-optical trap (MOT). A Rb+ beam is also available, which follows the same path as Fr+ ions. The accelerated ions are focused and implanted in a 25 um thick yttrium foil for neutralization: after diffusion to the surface, they are released as neutrals, since the Y work function is lower than the alkali ionization energies. The time evolution of the MOT and the vapor fluorescence signals are used to determine diffusion times of Fr and Rb in Y as a function of temperature. Comment: 7 pages, 8 figures
08/2008;
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G. Stancari,
S. N. Atutov,
R. Calabrese,
L. Corradi,
A. Dainelli,
C. de Mauro,
A. Khanbekyan,
E. Mariotti,
P. Minguzzi,
L. Moi,
S. Sanguinetti,
L. Tomassetti,
S. Veronesi
[show abstract]
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ABSTRACT: Francium is one of the best candidates for atomic parity
nonconservation (APNC) and for the search of permanent electric
dipole moments (EDMs). APNC measurements test the weak force
between electrons and nucleons at very low momentum transfers. They
also represent a unique way to detect weak nucleon-nucleon
interactions. EDMs are instead related to the time-reversal
symmetry. Preliminary to these fundamental measurements are
precision studies in atomic spectroscopy and the development of
magneto-optical traps (MOT), which partially compensate for the lack
of stable Fr isotopes. At LNL Legnaro, francium is produced by
fusion of 100-MeV 18O with 197Au in a thick target,
followed by evaporation of neutrons from the compound nucleus.
Francium diffuses inside the hot target (1200 K) and is surface
ionized for injection at 3 keV in an electrostatic beamline.
Typically, we produce 1×106(210Fr ions)/s for a
primary flux of 1.5×1012particles/s. We have studied
Fr yields as a function of primary beam energy, intensity, and
target temperature. Information on the efficiency of bulk
diffusion, surface desorption and ionization is deduced. The beam
then enters a Dryfilm-coated cell, where it is neutralized on a
heated yttrium plate. The escape time of neutral Fr (diffusion +
desorption) is approximately 20 s at 950 K, as measured with a
dedicated setup. In the MOT, we use 6 orthogonal Ti:sapphire laser
beams for the main pumping transition and 6 beams from a stabilized
diode repumper. Fluorescence from trapped atoms is observed with a
cooled CCD camera, in order to reach noise levels from stray
light equivalent to approximately 50 atoms. Systematic tests are
being done to improve the trapping efficiency. We plan to further
develop Fr traps at LNL; in parallel, we will study APNC and EDM
techniques and systematics with stable alkalis at Pisa, Siena, and
Ferrara.
The European Physical Journal Special Topics 10/2007; 150(1):389-392. · 1.56 Impact Factor
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Stefano Sanguinetti,
S. N. Atutov,
R. Calabrese,
L. Corradi,
A. Dainelli,
A. Khanbekyan,
E. Mariotti,
C. de Mauro,
P. Minguzzi,
L. Moi, G. Stancari,
L. Tomassetti,
S. Veronesi
[show abstract]
[hide abstract]
ABSTRACT: We present the Trap-rad experiment, which in the long term aims to an atomic parity violation (APV) measurement in francium
isotopes. We describe the present status of the experiment, the francium production and the magneto-optical trap (MOT). Some
details are given about our new CCD detection system. We explore then the possibility to perform APV measurements with francium.
The low Trap-rad francium production rates should allow to perform preliminary tests. With higher rates attainable in other
accelerator facilities, it should be possible to begin a francium APV experiment.
12/2006: pages 185-187;
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S N Atutov,
V Biancalana,
A Burchianti,
R Calabrese,
L Corradi,
A Dainelli,
V Guidi,
B Mali,
C Marinelli,
E Mariotti,
L Moi,
E Scansani, G Stancari,
L Tomassetti,
S Veronesi
[show abstract]
[hide abstract]
ABSTRACT: Experiments aimed at laser cooling and trapping of radioactive atoms are nowadays operational at several laboratories. They open up a bridge between atomic and nuclear physics, allowing new precise spectroscopic measurements and detailed analysis of nuclear decay processes. A magneto-optical trap (MOT) for francium atoms is almost operational at the INFN Legnaro laboratories; its characterization and optimization are under way. Measurements of francium production rate as a function of target temperature, primary beam intensity and energy have been carried out. Preliminary tests with other stable alkali atoms, aimed at an improvement of the MOT collection efficiency, are reported.
Physica Scripta 07/2006; 2003(T105):15. · 1.20 Impact Factor
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ABSTRACT: A facility for the production of radioactive francium is operating at the laboratories of the Istituto Nazionale di Fisica Nucleare (INFN) in Legnaro, Italy. The goal is to collect a cold sample of radioactive atoms in a magneto-optical trap for studies in atomic, nuclear, and particle physics. Production of francium is achieved via the fusion-evaporation reaction <sup>197</sup> Au (<sup>18</sup> O ,kn)<sup>215-k</sup> Fr generated by a ∼100- MeV <sup>18</sup> O <sup>6+</sup> beam on a thick gold target. The production target is heated to ∼1200 K and kept at a potential of +3 kV to enhance Fr diffusion and surface desorption. Average production rates are 0.7×10<sup>6</sup> ions / s for <sup>210</sup> Fr with a primary beam flux of 10<sup>12</sup> particles / s , with peaks of 2×10<sup>6</sup> ions / s . Details are given on the design and construction of the production targets and on the measurements that characterize their performance.
Review of Scientific Instruments 04/2006; · 1.37 Impact Factor
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L Corradi,
B R Behera,
E Fioretto,
A Gadea,
A Latina,
A M Stefanini,
S Szilner,
M Trotta,
Y Wu,
S Beghini,
G Montagnoli,
F Scarlassara,
R N Sagaidak,
S N Atutov,
B Mai, G Stancari,
L Tomassetti,
E Mariotti,
A Khanbekyan,
S Veronesi
[show abstract]
[hide abstract]
ABSTRACT: Excitation functions for 208−211 Fr isotopes produced in the 18 O + 197 Au fusion-evaporation reaction have been measured at E lab = 75–130 MeV via characteristic α decays by means of an electrostatic deflector and a semiconductor detector. Data have been compared with calculations giving barrier-passing (capture) cross sections and probabilities of the compound nucleus decay into different channels according to the standard statistical model.
Physical Review C 01/2005; · 3.31 Impact Factor
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S. N. Atutov,
Valerio Biancalana,
A. Burchianti,
R. Calabrese,
L. Corradi,
A. Dainelli,
V. Guidi,
B. Mai,
C. Marinelli,
E. Mariotti,
L. Moi,
E. Scansani, G. Stancari,
L. Tomassetti,
S. Veronesi
[show abstract]
[hide abstract]
ABSTRACT: Laser cooling and trapping techniques made possible during the last two decades important achievements in the atomic physics and quantum mechanics fields. These same techniques can be usefully applied to radioactive atoms by opening new fields of investigations. Nuclear processes can be studied with the atomic physics tools. We focused our attention on Francium radioactive atoms. A magneto-optical trap has been set up at the INFN Legnaro laboratories. Preliminary tests with other stable alkali atoms aimed at an improvement of the MOT collection efficiency are reported. Fast and efficient trap loading of rubidium has been obtained through the light-induced atomic desorption from an organic coating. A larger number of sodium atoms, as compared to monochromatic trapping laser, has been trapped by using a broad-band laser.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
11/2003;
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S. N. Atutov,
V. Biancalana,
A. Burchianti,
R. Calabrese,
L. Corradi,
A. Dainelli,
V. Guidi,
B. Mai,
C. Marinelli,
E. Mariotti,
L. Moi,
A. Rossi,
E. Scansani, G. Stancari,
L. Tomassetti,
S. Veronesi
[show abstract]
[hide abstract]
ABSTRACT: Laser cooling and trapping of radioactive atoms represent the new frontier in atomic physics and a new powerful tool in nuclear physics. We are setting up at the INFN-Legnaro National Laboratories a laser cooling facility that has as a first goal the realization of a 210Fr magneto-optical trap. The general outline of the experiment and the improvements of the final trap efficiency are discussed. Some preliminary results are presented.
Hyperfine Interactions 02/2003; 146-147(1):83-89. · 0.21 Impact Factor
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[show abstract]
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ABSTRACT: We describe the production of francium beams from the fusion–evaporation reaction generated by a ∼100 MeV beam on a thick gold target. The physics of the production process is discussed, together with estimates of expected production rates. The production target is heated to and kept at a potential of to enhance Fr diffusion and surface desorption, and to accelerate surface-ionized ions. Details are given on its design and construction. The performance of the target is measured as a function of primary beam energy and flux, target temperature and extraction voltage. Average production rates are for 210Fr with a primary beam flux of , with peaks of . From these measurements, information on the efficiency of the release processes is inferred.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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[show abstract]
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ABSTRACT: 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.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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G Stancari,
£ S N Atutov,
R Calabrese,
V Guidi,
B Mai,
L Tomassetti,
P Minguzzi,
S Sanguinetti,
V Biancalana,
A Burchianti,
A Khanbekyan,
C Marinelli,
E Mariotti,
L Moi,
S Veronesi
[show abstract]
[hide abstract]
ABSTRACT: The goal of our experiment is to collect alkali atoms in a magneto-optical trap (MOT) for high-precision spec-troscopy and for the study of parity violation in atomic sys-tems. We are focusing on francium isotopes, which are particularly suitable for these purposes. The production of francium is achieved by sending a 100-MeV 18 O beam from the Tandem-XTU accelerator on a thick gold target. The extraction of Fr · is enhanced by heating the target to 1200 K and by biasing it at ·3 kV. The ions are transported to the magneto-optical trap (MOT) through an 8-m electro-static beam line. The diagnostic systems for monitoring the beam intensity (10 5 ionss) are based on silicon surface-barrier detectors sensitive to the α particles from Fr de-cays. Beams of stable Rb · can also be used for optimizing the transport and trapping processes. At injection into the MOT cell, the beam is neutralized and released in atomic form by a heated yttrium foil. Details on Fr production, transport and neutralization are presented.
