P.D. Shidling

Production of short lived radioactive beams of radium

Abstract Short lived Ra 212 , 213 , 214 isotopes have been produced at the TRI μ P facility in inverse kinematics via the fusion–evaporation reaction Pb 206 + C 12 at 8 MeV / u . Isotopes are separated from other reaction products online using the TRI μ P magnetic separator. The energetic radium (Ra) isotopes at the exit of the separator were converted into low-energy ions with a thermal ionizer. Ra isotopes have been identified by observing their α decay and half-lifes. An improved half-life of Ra 213 has been measured to be 162.0 ± 1.7 s .

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 predicted enhancement factor of the APV effect in the S-D transition in Ra+ is about 50 times larger than the S-S transition in neutral Cs. 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. A lower bound on the...

Measurement of the Half-Life of the T=1/2 Mirror Decay of Ne-19 and its Implication on Physics Beyond the Standard Model

The 1+/2 -> 1+/2 superallowed mixed mirror decay of Ne-19 to F-19 is excellently suited for high precision studies of the weak interaction. However, there is some disagreement on the value of the half-life. In a new measurement we have determined this quantity to be T-1/2 = 17.2832 +/- 0.0051((stat)) +/- 0.0066((syst)) s, which differs from the previous world average by 3 standard deviations. The impact of this measurement on limits for physics beyond the standard model such as the presence of tensor currents is discussed.

Precision spectroscopy of trapped radioactive radium ions

Atomic parity violation (APV) can be measured in a single Ra+ ion, enabling a precise measurement of the electroweak mixing angle in the Standard Model of particle physics at low momentum transfer. This provides sensitivity to new particles such as extra Z0 bosons or leptoquarks. The Weinberg angle can be measured via a determination of the light shift in the forbidden 72S1/2–62D3/2 transition in a single trapped Ra+. Ultra-narrow transitions in such an ideal system can also be exploited to realize a high stability frequency standard. At the TRIμP facility of KVI, we have succeeded in the production of a series of radioactive short-lived radium isotopes. The radium isotopes produced were stopped and thermalized to Ra+ in a thermal ionizer, mass separated in a Wien filter, cooled in a gas filled radio frequency quadrupole and subsequently trapped as a cloud in a linear Paul trap. Laser spectroscopy in the trapped radium ions has been performed. The results of hyperfine structure, isotope shift, and lifetim...