[en] To complete the analysis of the 4-rod split-ring RFQ started with cold model studies, computer simulations have also been made using the MAFIA code. Computations of voltage ad magnetic field distributions were done for both a three and a ten module RFQ for a range of structure dimensions such as, minor to major radius ratio r/R, ring width, tank diameter, and spacing between adjacent rings. Shunt impedance and power densities derived from these computations were then used to optimize the dimensions of a three module split-ring RFQ now under construction. (author). 3 refs., 1 tab., 4 figs

[en] A post accelerator, primarily to provide beams of interest to nuclear astrophysics users, is included in the upgrading and expansion of the radioactive beam facility at TRIUMF. Singly charged ion beams, with A ≤ 30, delivered from the on line mass separator with an energy of 2 keV/u, will be accelerated in a stage linac consisting of an RFQ and a post-stripper drift-tube. As a consequence of the low charge-to-mass ratio of the ions, a low operating frequency for the RFQ is required to achieve adequate transverse focusing. CW operation is specified to preserve beam intensity. Because of its relatively high specific shunt impedance, mechanical stability, and the absence of vane voltage asymmetries in the end regions, the split-ring 4-rod RFQ structure has been chosen. Several cold models have been built to study three different types of split-ring RFQ structures. Specific shunt impedance and longitudinal field have been measured. A comparison of these measurements for various split-ring structures is presented. (author). 8 refs., 6 tabs., 5 figs

[en] This paper describes the ISAC-1 radioactive ion beam facility proposed at TRIUMF. A novel approach for the target/ion source station will allow an incident proton beam intensity of at least 10 μA at 500 MeV. This should give high luminosity for the production of nuclei far from stability with a very large isotopic range. After mass separation the beams can be sent to two different experimental areas. One uses the 60 keV energy beam for experiments such as the neutral atoms trap, parity violation, etc. The second one, mainly dedicated to nuclear astrophysics, will use the 0.2 to 1.5 MeV/u post-accelerated beam. Singly charged ion beams, with A ≤ 30 delivered from the on line mass separator, with an energy of 2 keV/u, will be accelerated in a two stage linac consisting of an RFQ and a post-stripper drift-tube linac up to 1.5 MeV/u. CW operation mode is required to preserve beam intensity. As a consequence of the low charge to mass ratio of the ions a low operating frequency for the RFQ is required to achieve adequate transverse focusing. The main features of this accelerator are: 35 MHz RFQ, stripping at 150 keV/u, and beam energy continuously variable from 0.2 keV/u to 1.5 MeV/u. (author). 5 refs., 1 tab., 2 figs

[en] A radioactive ion beam (RIB) facility is being built at TRIUMF. A novel design for the target/ion source station will allow us to bombard a thick target with TRIUMF's 100 μA, 500 MeV proton beam, producing a variety of very intense beams of nuclei far from stability. After mass separation the beams can be sent to two different experimental areas. One uses the 60 keV energy beam and the second one will use the 0.15 to 1.50 MeV/u post-accelerated beam. Singly charged ion beams, with A≤30 delivered from the on line mass separator, with an energy of 2 keV/u, will be accelerated in a two stage linac consisting of an RFQ and a post-stripper drift-tube linac up to 1.5 MeV/u. CW operation mode is required to preserve beam intensity. As a consequence of the low q/A ions a low operating frequency for the RFQ is required to achieve adequate transverse focusing. The main features of this accelerator are: 35 MHz RFQ, stripping at 150 keV/u, beam energy continuously variable from 0.15 to 1.50 MeV/u and CW operation. (orig.)

[en] The ISAC radioactive ion beams facility being built at TRIUMF requires cw operation of a low frequency RFQ structure. This implies a large structure with adequate cooling while still maintaining mechanical alignment and stability. Our goal is to achieve a thermal stability alignment of +/-0.08 mm along the entire length of the RFQ structure and a dynamic stability of the operating assembled RFQ structure, taking into account deformation due to thermal drifts and vibrations induced by cooling and vacuum pumps, to within +/- 0.025 mm. Cold model studies have been carried out to confirm the RF characteristics of the RFQ design. To confirm the manufacturability of the design to maintain the above tolerances, a prototype section consisting of three RFQ rings is being fabricated and will be tested to full cw power (85 kV between electrodes). The basic design of the structure is different from other RFQ structures in that the RF surfaces have been de-coupled from the mechanical support structure for improved stability. The features of this mechanical design will be discussed and the first results of the RFQ prototype tests will be presented. (author)

[en] A radioactive ion beam (RIB) facility is being built at TRIUMF. A novel design for the target/ion source station will allow us to bombard a thick target with TRIUMF's 100 μA, 500 MeV proton beam, producing a variety of very intense beams of nuclei far from stability. After mass separation the beams can be sent to two different experimental areas. One uses die 60 keV energy beam and the second one will use the 0.15 to 1.50 MeV/u post-accelerated beam. Singly charged ion beams, with A ≤ 30 delivered from the on line mass separator, with an energy of 2 keV/u, will be accelerated in a two stage linac consisting of an RFQ and a post-stripper drift-tube linac up to 1.5 MeV/u. CW operation mode is required to preserve beam intensity. As a consequence of me low q/A ions a low operating frequency for me RFQ is required to achieve adequate transverse focusing. The main features of this accelerator are: 35 MHz RFQ, stripping at 150 keV/u, beam energy continuously variable from 0.15 to 1.50 MeV/u and CW operation. (author)

[en] A new technique, full neutrino momentum reconstruction, is used to set limits on the admixture of heavy neutrinos into the electron neutrino. We measure coincidences between nuclear recoils and positrons from the beta decay of trapped radioactive atoms and deduce the neutrino momentum. A search for peaks in the reconstructed recoil time-of-flight spectrum as a function of positron energy is performed. The admixture upper limits range from 4x10^-3 to 2x10^-2 and are the best direct limits for neutrinos (as opposed to antineutrinos) for the mass region of 0.7 to 3.5 MeV

[en] We have set limits on contributions of scalar interactions to nuclear β decay. A magneto-optical trap provides a localized source of atoms suspended in space, so the low-energy recoiling nuclei can freely escape and be detected in coincidence with the β. This allows reconstruction of the neutrino momentum, and the measurement of the β-ν correlation, in a more direct fashion than previously possible. The β-ν correlation parameter of the 0⁺→0⁺ pure Fermi decay of ³⁸K^m is a-tilde=0.9981±0.0030(+0.0032/-0.0037), consistent with the standard model prediction a-tilde=1

[en] Neutral atoms trapped with modern laser cooling techniques offer the promise of improving several broad classes of weak interaction experiments with radioactive isotopes. For nuclear β decay, demonstrated trap techniques include neutrino momentum measurements from beta-recoil coincidences, along with methods to produce highly polarized samples. These techniques enable experiments to search for non-Standard Model interactions, test whether parity symmetry is maximally violated, search for 2nd-class tensor and other tensor interactions, and search for new sources of time reversal violation. Ongoing efforts at TRIUMF, Berkeley, and Los Alamos are highlighted. Trap experiments involving fundamental symmetries in atomic physics, such as time-reversal violating electric dipole moments and neutral current weak interactions, are briefly mentioned. (orig.)

[en] 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 (96.5(0.8)%) sample of the short-lived β⁺-emitter ³⁷K. The angular distribution of neutrinos from this polarized decay, inferred from the daughter recoil asymmetry, is used to search for a hypothetical V+A current in the weak interaction. We find the ν asymmetry parameter to be B_ν=-0.755+/-0.020(stat)+/-0.013(syst), in agreement with the standard model's purely V-A interaction