We report on the production, deceleration and detection of a SrF molecular beam. The molecules are captured from a supersonic expansion and are decelerated in the X 2 Σ + (v = 0, N = 1) state. We demonstrate the removal of up to 40% of the kinetic energy with a 2 meter long modular traveling-wave decelerator. Our results demonstrate a crucial step towards the preparation of ultracold gases of heavy diatomic molecules for precision spectroscopy.
A new test of Lorentz invariance in the weak interactions has been made by searching for variations in the decay rate of spin-polarized 20 Na nuclei. This test is unique to Gamow-Teller transitions, as was shown in the framework of a recently developed theory that assumes a Lorentz symmetry breaking background field of tensor nature. The nuclear spins were polarized in the up and down direction, putting a limit on the amplitude of sidereal variations of the form jðÀ up À À down Þj=ðÀ up þ À down Þ < 3  10 À3 . This measurement shows a possible route toward a more detailed testing of Lorentz symmetry in weak interactions.Lorentz invariance means that physical laws are independent of boosts and rotations. It is at the basis of all known interactions. In the weak sector relatively few tests of Lorentz invariance have been made, even though the understanding of the weak interactions has been crucial in developing the standard model. In this work we consider a new test that exploits the spin degrees of freedom in decay, searching for a dependence of the nuclear lifetime on the orientation of the nucleus. Recent theoretical work [1] enables relating the present test to other possible Lorentz symmetry tests in the weak interactions and put them in the overall framework developed by Kostelecký and coworkers [2]. Tests whether in neutral-meson [3] or neutrino [4] oscillations the combination of charge conjugation, parity and time reversal is conserved and tests of relativity exploiting the beta-decay endpoint spectrum [5] also concern the weak domain, however, they differ in nature.We write the relative variation in the -decay rate À asHere, À 0 is the standard model decay rate, with the velocity vector of the particle in units of the speed of light. The nuclear polarization of the parent nucleus is hĨi=I. A is the -asymmetry parameter in the standard model that violates parity. Other parameters in the decay of spin-polarized nuclei [1] are not relevant for this work. Lorentz invariance violation (LIV) appears in Eq. (1) with magnitudes 1
Single electron transfer and ionization in collisions of N 5+ and Ne 8+ with ground state Na(3s) and laser excited Na * (3p) are investigated both experimentally and theoretically at collision energies from 1 to 10 keV/amu, which includes the classical orbital velocity of the valence electron. State-selective partial cross sections are obtained using recoil-ion momentum spectroscopy in combination with a magneto-optically cooled Na atom target. A strong dependence of the cross sections on the collision energy is observed. In general, both the relative magnitude and the energy dependence are found to be in good agreement with classical-trajectory Monte Carlo calculations.
A radioactive beam of 20Na is stopped in a gas cell filled with Ne gas. The
stopped particles are polarized by optical pumping. The degree of polarization
that can be achieved is studied. A maximum polarization of 50% was found. The
dynamic processes in the cell are described with a phenomenological model.Comment: 16 pages, 6 figure
We present a systematic experimental and theoretical study of angular differential cross sections of singleelectron transfer in collisions of N 5+ , O 6+ , and Ne 8+ with ground-state Na(3s) in the collision energy range from 1 to 8 keV/amu. Experiments were performed using recoil-ion momentum spectroscopy in combination with a magneto-optically cooled Na atom target. The results are compared with three-body classical-trajectory Monte Carlo theory. Experimental and theoretical angular differential cross sections for capture into highly excited states show an oscillatory structure which is linked to the number of times the active electron crosses the potential energy saddle, i.e., oscillates between the two nuclear centers during the collision process.
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