Search

We have measured the non-resonant photoionization cross section of the [7P.sub.3/2] state of francium for 442 nm light to be 20.8 [+ or -] 7.1 Mb. Atoms were irradiated in a magneto-optical trap, and we deduce the photoionization rate from the change in trap lifetime. The result is consistent with a simple extrapolation of known cross sections for other alkali atoms. Key words: photoionization, alkali atoms, magneto-optical trap. Nous mesurons que la section efficace de photo-ionisation hors resonance de l'etat [7P.sub.3/2]] du francium pour une lumiere de 442 nm est de 20.8 [+ or -] 7.11 Mb. Les atomes sont irradies dans un piege magneto-optique et nous deduisons le taux de photo-ionisation a partir du changement du temps de vie du piege. Le resultat est coherent avec la simple extrapolation de sections efficaces connues pour d'autres atomes alcalins. [Traduit par la Redaction] Mots-cles: photo-ionisation, atome alcalin, piege magneto-optique, francium, etat excite., 1. Introduction The near-threshold photoionization of atoms is an important process to consider as a loss mechanism in two-species magnetooptical traps (MOTs) [1]. It is also of indirect importance in [...]

Abstract: A useful tool that can achieve a high level of spin polarization is a circularly polarized far off-resonance dipole force trap (CFORT). This work is the first step in [...]

Motivated by a search for a new physics beyond the standard model, the MTV experiment (Mott Polarimetry for T-Violation Experiment) is intended to achieve the highest precision test of time-reversal symmetry in polarized nuclear beta decay by measuring a triple correlation (the R-correlation). The first physics run of the MTV experiment was performed in 2010 at TRIUMF-ISAC. This paper gives preliminary results and describes the next generation setup, which involves a cylindrical drift chamber.

Copyright of Canadian Journal of Physics is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: A measurement of the neutrino asymmetry is presented which represents the first search for new physics using polarized radioactive atoms initially cooled and confined in a magneto-optical trap. Optical pumping and photoionization techniques are used to generate and measure, in situ, a highly spin-polarized sample of the short-lived -emitter 37K. The angular distribution of neutrinos from this polarized decay, inferred from the daughter recoil asymmetry, is used to search for a hypothetical current in the weak interaction. We find the ν asymmetry parameter to be , in agreement with the standard model''s purely interaction. [Copyright &y& Elsevier]

Hyperfine interactions of Na isotopes in single crystals have been studied using highly nuclear polarized 20,21,26,27,28Na beams provided by ISAC/TRIUMF. The degree of polarization kept in the crystals, the spin-lattice relaxation times, the electric quadrupole coupling constants and the initial distribution of the populations were measured. Such knowledge is indispensable for the application of the hyperfine interactions in the study of precision measurements such as the nuclear structure through nuclear moments and the fundamental symmetries. [ABSTRACT FROM AUTHOR]

Abstract: The electric-quadrupole coupling constant of the ground states of the proton drip line nucleus 20Na (, ) and the neutron-deficient nucleus 21Na (, ) in a hexagonal ZnO single crystal were precisely measured to be and , respectively, using the multi-frequency β-ray detecting nuclear magnetic resonance technique under presence of an electric-quadrupole interaction. An electric-quadrupole coupling constant of 27Na in the ZnO crystal was also measured to be . The electric-quadrupole moments were extracted as and , using the electric-coupling constant of 27Na and the known quadrupole moment of this nucleus as references. The present results are well explained by shell-model calculations in the full sd-shell model space. [Copyright &y& Elsevier]

Abstract: We have measured the isotope shift between 41K and 39K in the 4s1/2 →5p1/2 transition at 405nm using saturation spectroscopy. Our measured isotope shift is 456.1±0.8MHz, implying a residual isotope shift (sum of specific mass shift and field shift) of −52.7±0.8MHz. We deduce a specific mass shift of −40±5MHz, which would imply that the 5p1/2 state has a considerably larger specific mass shift than the 4p1/2 state. We have in addition measured the 5p1/2 hyperfine splitting for 41K. [Copyright &y& Elsevier]

The alignment correlation term in the β-ray angular distribution from nuclear-spin aligned 20Na(Iπ = 2+, T1/2 = 449.7 ms) has been measured for the first time. A large enhancement of the time component d in the main axial vector current was preliminarily obtained and the higher order matrices j2 and j3 were also evaluated. In order to extract very small G-parity violating induced tensor term, the alignment correlation term of the mirror partner 20F have to be measured. [Copyright &y& Elsevier]

Magneto-optical traps provide a cold, compact cloud of radioactive atoms and therefore are an ideal source for use in precision nuclear β decay studies. Optical pumping techniques can add a new dimension to such experiments by efficiently polarizing these samples to ≳99%. Triumf’s experiment E925 is utilizing these techniques to prepare to measure the isospin mixing between the first two Iπ=2+ excited states of 36Ar with the lowest 2+, T=1 isobaric analog state. The spin-polarized 36K β+ decay observables will be measured using Triumf’s neutral atom trap at Isac, Triumf’s isotope separator and accelerator facility. The main purpose is to test isospin mixing models in the s,d-shell needed for determination of the superallowed Fermi strength in 0+ → 0+ decays. [Copyright &y& Elsevier]