[en] We have measured parity nonconserving optical rotation near the 6³P₀ → 6³P₁, 1.28 μm magnetic dipole transition in lead. Electroweak interactions in the lead atom contribute a small E1 amplitude to this transition. The interference between these two amplitudes leads to a peak optical rotation of order 10^-6 radians in our experiment. Our apparatus uses a tunable external cavity InGaAs diode laser and calcite polarizers as a sensitive polarimeter. By alternately placing a tube of heated lead vapor or an empty tube in the optical path, we can effectively subtract spurious background rotations. Measurement of the parity-conserving Faraday rotation is used as a check of the absolute angle calibration. Data have been obtained for a variety of operating conditions including a range of optical depths from 10 to 50. We have measured R, the ratio of the PNC E1 amplitude to the M1 amplitude, to better than 1% statistical accuracy. Possible systematic effects at the 1% level continue to be investigated. Current results will be presented

[en] Parity non-conserving (PNC) optical rotation has been measured in the 6²P_1/2 → 6²P_3/2 1.28 μm M1 transition in atomic Tl with a polarimetry method. PNC is measured as the amplitude of a dispersive lineshape of optical rotation across the transition. The technique is sensitive to ∼ 10^-8 rad. This allows precise measurement of the nuclear spin independent contribution to atomic PNC, and measurements on different hyperfine components of the transition will allow improved measurement of the nuclear spin dependent contributions, including the anapole moment of the nucleus. The study of PNC in this transition in Tl also provides comparison to other PNC work in the 6²P_1/2 → 7²P_1/2 transition in Tl. We will present current results for Tl with comments on systematic errors. We will also discuss prospects for future work in atomic PNC with this method, including studies of isotopically enriched samples of high Z atoms (e.g. Pb) in which we expect measurement of ratios of PNC in different isotopes to be less affected by uncertainties in atomic calculations and more sensitive to electroweak physics

[en] The DIANA project (Dakota Ion Accelerators for Nuclear Astrophysics) is a collaboration between the University of Notre Dame, University of North Carolina, Western Michigan University, and Lawrence Berkeley National Laboratory to build a nuclear astrophysics accelerator facility 1.4 km below ground. DIANA is part of the US proposal DUSEL (Deep Underground Science and Engineering Laboratory) to establish a cross-disciplinary underground laboratory in the former gold mine of Homestake in South Dakota, USA. DIANA would consist of two high-current accelerators, a 30 to 400 kV variable, high-voltage platform, and a second, dynamitron accelerator with a voltage range of 350 kV to 3 MV. As a unique feature, both accelerators are planned to be equipped with either high-current microwave ion sources or multi-charged ECR ion sources producing ions from protons to oxygen. Electrostatic quadrupole transport elements will be incorporated in the dynamitron high voltage column. Compared to current astrophysics facilities, DIANA could increase the available beam densities on target by magnitudes: up to 100 mA on the low energy accelerator and several mA on the high energy accelerator. An integral part of the DIANA project is the development of a high-density super-sonic gas-jet target which can handle these anticipated beam powers. The paper will explain the main components of the DIANA accelerators and their beam transport lines and will discuss related technical challenges

[en] For the on-line production of a ¹⁴O⁺ ion beam, an integrated target--transfer line ion source system is now under development at LBNL. ¹⁴O is produced in the form of CO in a high temperature carbon target using a 20 MeV ³He beam from the LBNL 88'' Cyclotron via the reaction ¹²C(³He,n)¹⁴O. The neutral radioactive CO molecules diffuse through an 8 m room temperature stainless steel line from the target chamber into a cusp ion source. The molecules are dissociated, ionized and extracted at energies of 20 to 30 keV and mass separated with a double focusing bending magnet. The different components of the setup are described. The release and transport efficiency for the CO molecules from the target through the transfer line was measured for various target temperatures. The ion beam transport efficiencies and the off-line ion source efficiencies for Ar, O₂ and CO are presented. Ionization efficiencies of 28% for Ar⁺, 1% for CO, 0.7% for O⁺, 0.33 for C⁺ have been measured

[en] For the on-line production of a ¹⁴O⁺ ion beam, an integrated target transfer line ion source system is now under development at LBNL. ¹⁴O is produced in the form of CO in a high temperature carbon target using a 20 MeV ³He beam from the LBNL 88^double-prime Cyclotron via the reaction ¹²C(³He,n)¹⁴O. The neutral radioactive CO molecules diffuse through an 8 m room temperature stainless steel line from the target chamber into a cusp ion source. The molecules are dissociated, ionized and extracted at energies of 20 to 30 keV and mass separated with a double focusing bending magnet. The different components of the setup are described. The release and transport efficiency for the CO molecules from the target through the transfer line was measured for various target temperatures. The ion beam transport efficiencies and the off-line ion source efficiencies for Ar, O₂ and CO are presented. Ionization efficiencies of 28% for Ar⁺, 1% for CO, 0.7% for O⁺, 0.33 for C⁺ have been measured. copyright 1999 American Institute of Physics

[en] For the on-line production of a ¹⁴O⁺ ion beam, an integrated target-transfer line ion source system is now under development at LBNL. ¹⁴O is produced in the form of CO in a high temperature carbon target using a 20 MeV ³He beam from the LBNL 88'' Cyclotron via the reaction ¹²C(³He,n)¹⁴O. The neutral radioactive CO molecules diffuse through an 8 m room temperature stainless steel line from the target chamber into a cusp ion source. The molecules are dissociated, ionized and extracted at energies of 20 to 30 keV and mass separated with a double focusing bending magnet. The different components of the setup are described. The release and transport efficiency for the CO molecules from the target through the transfer line was measured for various target temperatures. The ion beam transport efficiencies and the off-line ion source efficiencies for Ar, O₂ and CO are presented. Ionization efficiencies of 28% for Ar⁺, 1% for CO, 0.7% for O⁺, 0.33 for C⁺ have been measured

[en] The β-ν correlation coefficient, a_βν, is measured in ²¹Na by detecting the time of flight of the recoil nucleus detected in coincidence with the atomic electrons shaken off in β decay. The sample of ²¹Na is confined in a magneto-optic trap. High detection efficiency allows low trap density, which suppresses the photoassociation of molecular sodium, which can cause a large systematic error. Suppressing the fraction of trapped atoms in the excited state by using a dark trap also reduces the photoassociation process, and data taken with this technique are consistent. The main remaining systematic uncertainties come from the measurement of the position and size of the atom trap and the subtraction of background. We find a_βν=0.5502(60), in agreement with the Standard Model prediction of a_βν=0.553(2), and disagreeing with a previous measurement, which was susceptible to an error introduced by the presence of molecular sodium

[en] The charge-state distribution following the β⁺ decay of²¹Na has been measured, showing a larger than expected fraction of the daughter ²¹Ne in positive charge states. No dependence on either the β⁺ or recoil nucleus energy is observed. The data are compared to a simple model based on the sudden approximation. Calculations suggest that a small but important contribution from recoil ionization has significant consequences for precision β decay correlation experiments detecting recoil ions

[en] We have measured the half-life of ¹⁴O, a superallowed (0⁺→0⁺) β decay isotope. The ¹⁴O was produced by the ¹²C(³He,n)¹⁴O reaction using a carbon aerogel target. A low-energy ion beam of ¹⁴O was mass separated and implanted in a thin beryllium foil. The beta particles were counted with plastic scintillator detectors. We find t_1/2=70.696±0.052 s. This result is 1.5σ higher than an average value from six earlier experiments, but agrees more closely with the most recent previous measurement

[en] At the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory we have developed an intense low energy ¹⁴O ion beam. During the last development run, an average beam intensity of 2x10⁷ particles per second (pps) was achieved with a peak intensity of 3x10⁷ pps. The ¹⁴O will be used to measure the shape of the beta decay spectrum of the Garnow-Teller branch as a test of the Conserved Vector Current Hypothesis. The half-life will also be measured and used to determine the Vud element of the Cabibbo-Kobayashi-Maskawa mixing matrix