[en] A nuclear polarimeter based on the low energy analyzing power of the ⁶Li(p, ³He)α reaction has been developed and tested for proton energies below E_p=300 keV. The polarimeter uses a ⁶LiF target evaporated on a water cooled tantalum backing. The target is observed at backwards angles by four silicon surface barrier detectors. The energy dependence of the analyzing power under 130^o for the ⁶Li(p, ³He)α reaction has been determined down to 200 keV. Spin rotation has been observed via a magnetic field incorporated in a Wien filter demonstrating that the polarimeter is operational. (Author) (7 refs., 7 figs.)

[en] In this thesis the experimental study of the reactions ²⁶Al(p,γ) ²⁷Si and ²⁶Al(p,p'γ) ²⁶Al is described. From the measured excitation functions the Q-value and the resonance properties for these reactions were determined. Furthermore the Coulomb excitation of ²⁶Al is considered. The results were used for the calculation of the stellar rates of the reaction ²⁶Al(p,γ) ²⁷Si. In this connection the MgAl cyclus is considered for cold and hot stars. (HSI)

[en] Present plans at TRIUMF for a radioactive beams facility include an upgrade of the TISOL facility to enable the use of a 10μA proton beam and a linear accelerator coupled to the TISOL-2 isotope separator allowing the acceleration of ions with a charge-to-mass ratio of q/A ≥ 1/30 to energies of up to 1.5 MeV/u. The facility (ISAC-1) would use largely the present TRIUMF building structure with some minor extensions. The scientific program at the ISAC-1 facility is predominantly aimed at measuring astrophysically important cross sections of radioactive isotopes, as e.g. ⁷Be(p,γ)⁸B, ¹⁹Ne(p,γ)²⁰Na and others. The status of the facility as well as some aspects of proposed experimental set-ups necessary for these kinds of measurements will be discussed

[en] Some aspects are presented how the cross section and the stellar reaction rate of ¹²C(α,γ)¹⁶O is derived. A few results from the recoil separator DRAGON are discussed, in addition

[en] In some cases stellar reaction rates can be determined by observing the β-delayed particle emission of states relevant to nucleosynthesis. The βα-decay spectrum of ¹⁶N, e.g., permits the determination of the α+¹²C reduced width of the E_x = 7.12 MeV sub-threshold state of ¹⁶O. This state, in turn, dominates the low-energy p-wave capture amplitude of the astrophysically important reaction ¹²C(α,γ)¹⁶O. The α-spectrum following the decay of ¹⁶N has been measured with the help of the TRIUMF isotope separator TISOL. The data obtained, which include 10⁶ α-¹²C coincidences, show that the main α-peak is accompanied by a lower-energy interference structure, as predicted by several authors. The spectrum obtained has been fitted in a K- and R-matrix parametrization. Details of the fits are reported. In addition, an outlook of other reactions important to nucleosynthesis accessible by β-delayed particle emission is given

[en] TRIUMF is finalizing the construction of a new radioactive beam facility of the ISOL type, named ISAC. Some beams of radioisotopes at low energy, up to 60 keV, are already available (since November 1998) while beams with energies up to 1.5 MeV/u will be available by the end of year 2000. In parallel to the ongoing development of the accelerated beam, more unstable beams will become operational on the low energy facility. With further energy upgrades anticipated in the next five-year plan, Canada is positioning itself as a leader in the next generation of radioactive beam facilities. After a general description of the facilities being built, a review of the initial scientific program will follow as well as an outlook onto the upcoming five year plan of TRIUMF. (author)

[en] The ¹²C(α,γ)¹⁶O reaction is of considerable importance in the evolution of massive stars, as its rate, relative to the triple α process, determines the relative abundances of ¹²C and ¹⁶O at the end of helium burning. Due to the presence of subthreshold resonances, the precise determination of this cross section at the relevant energy of E_cm=300 keV is extremely difficult. The Β-delayed α-spectrum of ¹⁶N allows an improved determination of the El part of this cross section by constraining the reduced α-width of the 1^- subthreshold state. This spectrum has recently been remeasured with high statistics down to E_cm=800 keV at the TRIUMF isotope separator, TISOL. The results of extensive R-matrix fits incorporating this new data will be presented

[en] A nuclear polarimeter based on the low energy analyzing power of the ⁶Li(p, ³He)α reaction has been developed and tested for proton energies below E_p = 300 keV. The polarimeter uses a ⁶LiF target evaporated on a water-cooled tantalum backing. The target is observed at backward angles by four silicon surface barrier detectors. The energy dependence of the analyzing power under 130deg for the ⁶Li(p, ³He)α reaction has been determined down to 200 keV. Spin rotation has been observed via a magnetic field incorporated in a Wien filter demonstrating that the polarimeter is operational. (orig.)

[en] The TRIUMF optically pumped polarized H^- ion source has been installed in a 300 keV high voltage platform connected by a 45 m beam transport line to the cyclotron. Several different extraction electrode systems have been tested in the electron cyclotron resonance (ECR) ion source generating the initial section of the source demonstrate that the beam transport depends strongly on the degree of space charge compensation. H^-currents of up to 8 μA at a neutralizer Na thickness of 5 x 10¹³ atoms cm^-2 have been transported into the 300 keV beam line. A polarized H^- beam has been accelerated in the cyclotron and a proton polarization of up to 50% has been achieved. The installation of a superconducting solenoid for further improving the source performance is planned for this summer

[en] Targets with up to 1.4x10¹⁶²⁶Al atoms have been fabricated. The artificial production of the ²⁶Al nuclei via the reaction ²⁶Mg(p, n)²⁶Al was carried out at the cyclotrons in Juelich and Muenchen. The experimental procedures in the fabrication of these targets as well as some test measurements are described. (orig.)