Search

The hyperfine structure of short-lived trapped Ra-211,209(+) ions was investigated by means of laser spectroscopy. The hyperfine structure constants A and B of the 6d(2)D(3/2) level were determined. There is a 2.2 standard deviation difference between the theoretical and the more accurate experimental value for the B coefficient of Ra-211(+). These measurements provide a test for the atomic theory required for upcoming experiments on atomic parity violation and atomic clocks. (C) 2011 Elsevier B.V. All rights reserved.

We investigate parity and time-reversal violation in neutron-proton scattering in the optical regime. We calculate the neutron spin rotation and analyzing power in scattering on polarized protons. This allows us to quantify the sensitivity that such experiments should aim for in order to be competitive to present-day measurements of the neutron electric dipole moment in constraining the P- and T-odd two-nucleon interaction. While state-of-the-art techniques fall short by some three orders of magnitude for the neutron-proton case, specific neutron-nucleus experiments look promising, provided certain experimental and theoretical challenges are met.

After reviewing the method of energy-dependent partial-wave analysis of the two-nucleon scattering data, I report on recent work to include the two-pion-exchange interaction [1,2]. The chiral two-pion-exchange component of the long-range nucleon-nucleon interaction is derived from the effective chiral Lagrangian. Its presence and importance is demonstrated in the partial-wave analysis. The values of the chiral coupling constants c(i) (i = 1,3,4) are determined in a fit to the data, and agree well with those obtained previously from pion-nucleon scattering amplitudes.

We re-examine the puzzling π + emission from the weak decay of Λ 4 He and propose an explanation in terms of a three-body decay of the virtual Σ + . Such a resolution of the π + decay puzzle is consistent with the calculated Σ + probability in light Λ hypernuclei as well as the experimentally observed π + energy spectrum and s -wave angular distribution.

The situation in low-energy pion-nucleon scattering is reviewed, using an energy-dependent PWA as a tool. The method and some conclusions of this new PWA of πN scattering data across the Δ(1232) are summarized. In particular, the “inconsistencies” in the low-energy database are addressed, and the state-of-the-art of the NNπ coupling constant and of the πN σ-term is discussed.

At the Kernfysisch Versneller Instituut (KVI) a new facility (TRIμP) is under development. It aims for producing a spectrum of radioactive isotopes in direct, inverse kiematics fusion and evaporation or fragmentation reactions with heavy ion beams from the superconducting cyclotron AGOR. The products will be slowed down and trapped for accurate measurements of fundamental symmetries and interactions in physics. The scientific focus of the local KVI research groups includes precision studies of nuclear β-decays through β-neutrino (recoil nucleus) momentum correlations in weak decays and searches for permanent electric dipole moments in heavy atomic systems. This research programme offers a large potential for discovering new physics or to limit parameters in models beyond standard theory significantly. The scientific approach chosen in TRIμP can be regarded as complementary to such high energy physics. The TRIμP facility in Groningen will be open for users worldwide.