Physics at the Planck scale could be revealed by looking for tiny violations of fundamental symmetries in low energy experiments. In 2008, a sensitive test of the isotropy of the universe has been ...performed with stored ultracold neutrons (UCN), this is the first clock-comparison experiment performed with free neutrons. During several days we monitored the Larmor frequency of neutron spins in a weak magnetic field using the Ramsey resonance technique. A nonzero cosmic axial field, violating rotational symmetry, would induce a daily variation of the precession frequency. Our null result constitutes one of the most stringent tests of Lorentz invariance to date.
The N = 48 Ge-80 nucleus is studied by means of beta-delayed electron-conversion spectroscopy at ALTO. The radioactive Ga-80 beam is produced through the isotope separation on line photofission ...technique and collected on a movable tape for the measurement of gamma and e(-) emission following beta decay. An electric monopole E0 transition, which points to a 639(1) keV intruder 0(2)(+) state, is observed for the first time. This new state is lower than the 2(1)(+) level in Ge-80, and provides evidence of shape coexistence close to one of the most neutron-rich doubly magic nuclei discovered so far, Ni-78. This result is compared with theoretical estimates, helping to explain the role of monopole and quadrupole forces in the weakening of the N = 50 gap at Z = 32. The evolution of intruder 0(2)(+) states towards Ni-78 is discussed.
We report on a laser based 199Hg co-magnetometer deployed in an experiment searching for a permanent electric dipole moment of the neutron. We demonstrate a more than five times increased signal ...to-noise-ratio in a direct comparison measurement with its 204Hg discharge bulb-based predecessor. An improved data model for the extraction of important system parameters such as the degrees of absorption and polarization is derived. Laser- and lamp-based data-sets can be consistently described by the improved model which permits to compare measurements using the two different light sources and to explain the increase in magnetometer performance. The laser-based magnetometer satisfies the magnetic field sensitivity requirements for the next generation nEDM experiments.
The nEDM experiment hosted at the Paul Scherrer Institute is the flagship project at the new ultracold neutron facility. Estimations of systematic effects for the determination of the neutron ...electric dipole moment play an important role in this project. Experimental studies are supported by Monte Carlo simulations using the MCUCN code. Here we briefly present first results on the experimental benchmark of the model, and on the evaluation of the storage time dependence of the centre of mass of UCN in the nEDM precession chamber. Such time dependence calculations will serve as consistency tests for future measurements involving field gradient corrections of the Ramsey resonance frequency. An analytic benchmark of the spin-handling routines will also be shown.
The N=48 super(80) Ge nucleus is studied by means of beta-delayed electron-conversion spectroscopy at ALTO. The radioactive super(80) Ga beam is produced through the isotope separation on line ...photofission technique and collected on a movable tape for the measurement of gamma and e super(-) emission following beta decay. An electric monopole E 0 transition, which points to a 639(1) keV intruder 0(ProQuest: Formulae and/or non-USASCII text omitted) state, is observed for the first time. This new state is lower than the 2(ProQuest: ... denotes formulae and/or non-USASCII text omitted) level in super(80) Ge, and provides evidence of shape coexistence close to one of the most neutron-rich doubly magic nuclei discovered so far, super(78) Ni. This result is compared with theoretical estimates, helping to explain the role of monopole and quadrupole forces in the weakening of the N=50 gap at Z=32. The evolution of intruder ... states towards super(78) Ni is discussed.
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