An Improved Neutron Electric Dipole Moment Experiment

A new measurement of the neutron EDM, using Ramsey's method of separated oscillatory fields, is in preparation at the new high intensity source of ultra-cold neutrons (UCN) at the Paul Scherrer Institute, Villigen, Switzerland (PSI). The existence of a non-zero nEDM would violate both parity and time reversal symmetry and, given the CPT theorem, might lead to a discovery of new CP violating mechanisms. Already the current upper limit for the nEDM (|d_n|<2.9E-26 e.cm) constrains some extensions of the Standard Model. The new experiment aims at a two orders of magnitude reduction of the experimental uncertainty, to be achieved mainly by (1) the higher UCN flux provided by the new PSI source, (2) better magnetic field control with improved magnetometry and (3) a double chamber configuration with opposite electric field directions. The first stage of the experiment will use an upgrade of the RAL/Sussex/ILL group's apparatus (which has produced the current best result) moved from Institut Laue-Langevin to PSI. The final accuracy will be achieved in a further step with a new spectrometer, presently in the design phase.Comment: Flavor Physics & CP Violation Conference, Taipei, 200

Complex narrow band-pass filters for QRS detection in contactless magnetocardiograms of small animals

Recently, magnetocardiography (MCG) of small animals was proposed for the investigation of drug safety and for phenotype characterization of genetically modified mice. MCG is a contactless measurement method to provide information very similar to the ECG. In order to cover the wide variation of signal shape and frequency content of the heart signals of small animals, we used a complex narrow-band filter characterized by center frequency and bandwidth as a preprocessor for QRS detection. We applied the method to MCG signals of rabbits, hamsters, guinea pigs and mice. While in human MCGs the preferential center frequency of the bandpass filter is 20 Hz at a bandwidth of 2 Hz, the respective values for rabbits are 40(4) Hz, for guinea pigs 40(4) Hz, for hamsters 100(10) Hz, and for mice 150(30) Hz. The method works stable even in cases where the signal to noise ratio is only 2:1

Characterization of magnetic field noise in the ARIADNE source mass rotor

The Axion Resonant Interaction Detection Experiment (ARIADNE) is a nuclear-magnetic-resonance-based experiment that will search for novel axion-induced spin-dependent interactions between an unpolarized source mass rotor and spin-polarized He-3 nuclei placed nearby. To detect a feeble axion-mediated signal at the subattotesla level, the experiment relies on ultralow magnetic background and noise. We measure and characterize the magnetic field from a prototype tungsten rotor. We show that the field is dominantly caused by a few discrete magnetic dipoles, likely due to impurities in the rotor. This is done via a numerical optimization pipeline which fits for the locations and magnetic moments of each dipole. We find that under the current demagnetization procedure, the magnetic moment of the impurities is bounded at 10(-9) A m(2). We further show that a shielding factor of 10(9) will support ARIADNE&apos;s design sensitivity with the current level of tungsten purity and demagnetization process.11Nscopu