Atomic parity violation in a single trapped radium ion

Atomic parity violation (APV) experiments are sensitive probes of the electroweak interaction at low energy. These experiments are competitive with and complementary to high-energy collider experiments. The APV signal is strongly enhanced in heavy atoms and it is measurable by exciting suppressed (M1, E2) transitions. The status of APV experiments and theory are reviewed as well as the prospects of an APV experiment using one single trapped Ra+ ion. The predicted enhancement factor of the APV effect in Ra+ is about 50 times larger than in Cs atoms. However, certain spectroscopic information on Ra+ needed to constrain the required atomic many-body theory, was lacking. Using the AGOR cyclotron and the TRIμP facility at KVI in Groningen, short-lived 212 - 214Ra+ ions were produced and trapped. First ever excited-state laser spectroscopy was performed on the trapped ions. These measurements provide a benchmark for the atomic theory required to extract the electroweak mixing angle to sub-1% accuracy and are an important step towards an APV experiment in a single trapped Ra+ ion

Large area isotopic silicon targets for astrophysical reaction rate studies in Si-26

For measurements of stellar reaction rates of proton rich nuclei involving resonance levels just above threshold, targets of Si-28 were used in studies of the Si-21(He-4, He-6)Si-26 reaction using the Research Center for Nuclear Physics (RCNP) Ring Cyclotron at Osaka University. Resonance structure observed in Si-26 above the 5.5 MeV proton threshold identified levels populated in the astrophysically important reaction Al-26(p,gamma) Si-26 and help to determine the yield of Al-26 gamma-rays seen in Novae. A few isolated states were also observed above the 9.2 MeV alpha threshold in the (He-4, He-6) reaction which can be used to improve the present stellar rate calculations. We describe here the involved preparation of large area Si-28 metal targets used for these experiments produced by the method of electron beam evaporation. The parting agent used was betaine. To obtain the 0.7 Mg/cm(2) Si-28 target thickness needed for the experiment, several mounted layers were assembled together by stacking. This formidable approach therefore required many foils. Two targets stacks of 0.7 Mg/cm(2) and 0.5 mg/cm(2) Si-28 were delivered to Osaka for the run. Published by Elsevier B.V

Phased plan for the implementation of the time-resolving magnetic recoil spectrometer on the National Ignition Facility (NIF)

The time-resolving magnetic recoil spectrometer (MRSt) is a transformative diagnostic that will be used to measure the time-resolved neutron spectrum from an inertial confinement fusion implosion at the National Ignition Facility (NIF). It uses a CD foil on the outside of the hohlraum to convert fusion neutrons to recoil deuterons. An ion-optical system positioned outside the NIF target chamber energy-disperses and focuses forward-scattered deuterons. A pulse-dilation drift tube (PDDT) subsequently dilates, un-skews, and detects the signal. While the foil and ion-optical system have been designed, the PDDT requires more development before it can be implemented. Therefore, a phased plan is presented that first uses the foil and ion-optical systems with detectors that can be implemented immediately—namely CR-39 and hDISC streak cameras. These detectors will allow the MRSt to be commissioned in an intermediate stage and begin collecting data on a reduced timescale, while the PDDT is developed in parallel. A CR-39 detector will be used in phase 1 for the measurement of the time-integrated neutron spectra with excellent energy-resolution, necessary for the energy calibration of the system. Streak cameras will be used in phase 2 for measurement of the time-resolved spectrum with limited spectral coverage, which is sufficient to diagnose the time-resolved ion temperature. Simulations are presented that predict the performance of the streak camera detector, indicating that it will achieve excellent burn history measurements at current yields, and good time-resolved ion-temperature measurements at yields above 3 × 1017. The PDDT will be used for optimal efficiency and resolution in phase 3. </jats:p

Search for isovector giant monopole resonances via the Sn-124(He-3,tn) reaction

The (He-3,t) reaction on Sn-124 at E(He-3)=199 MeV and the subsequent decay by neutron emission at backward angles were studied in an attempt to distinguish isovector monopole strength (spin-flip and non-spin-flip) at excitation energies above 25 MeV from the nonresonant continuum. The present approach is based on the assumption that a large fraction of the contributions to the continuum result from quasifree processes and breakup-pickup processes which leave the nucleus in low-lying excited states below the threshold for neutron emission. It was found, however, that even at high "apparent" excitation energies (above 30 MeV) the branching ratio for decay by neutrons was as high as similar to 50%, indicating that a large part of the nonresonant continuum may not be due to quasifree processes involving valence neutrons only. No evidence for monopole strength at high excitation energies was found, although the experiment had sufficient sensitivity and accuracy to detect isovector monopole strength based on theoretical predictions calculated in the framework of normal-mode collective excitations and the distorted-wave Born approximation

TRI mu P - A radioactive isotope trapping facility at KVI

TRImuP, a new research facility to produce and trap rare and short-lived isotopes for high precision physics experiments is under design and construction at KVI. This facility makes use of the existing super-conducting cyclotron and the infrastructure of the laboratory. To be able to study a large variety of heavy ions a new dual function magnetic separator has been developed. Details of the separator and the status of the project will be presented