Article (Published Version) http://sro.sussex.ac.uk Alterev, I, Harris, Philip, Shiers, David and et al, (2009) Neutron to mirror-neutron oscillations in the presence of mirror magnetic fields. Physical Review D, 80 (3). 032003. ISSN 1550-7998 This version is available from Sussex Research Online: http://sro.sussex.ac.uk/16039/ This document is made available in accordance with publisher policies and may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the URL above for details on accessing the published version. Copyright and reuse:Sussex Research Online is a digital repository of the research output of the University.Copyright and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable, the material made available in SRO has been checked for eligibility before being made available.Copies of full text items generally can be reproduced, displayed or performed and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way.Neutron to mirror-neutron oscillations in the presence of mirror magnetic fields We performed ultracold neutron storage measurements to search for additional losses due to neutron (n) to mirror-neutron (n 0 ) oscillations as a function of an applied magnetic field B. In the presence of a mirror magnetic field B 0 , ultracold neutron losses would be maximal for B % B 0 . We did not observe any indication for nn 0 oscillations and placed a lower limit on the oscillation time of nn 0 > 12:0sat 95% C.L. for any B 0 between 0 and 12:5 T.

We present a theoretical study of the spectra produced by optical/radio-frequency double resonance devices, in which resonant linearly polarized light is used in the optical pumping and detection processes. We extend previous work by presenting algebraic results which are valid for atomic states with arbitrary angular momenta, arbitrary rf intensities, and arbitrary geometries. The only restriction made is the assumption of low light intensity. The results are discussed in view of their use in optical magnetometers.

A clock comparison experiment, analyzing the ratio of spin precession frequencies of stored ultracold neutrons and 199 Hg atoms is reported. No daily variation of this ratio could be found, from which is set an upper limit on the Lorentz invariance violating cosmic anisotropy field b ⊥ < 2 × 10 −20 eV (95% C.L.). This is the first limit for the free neutron. This result is also interpreted as a direct limit on the gravitational dipole moment of the neutron |gn| < 0.3 eV/c 2 m from a spin-dependent interaction with the Sun. Analyzing the gravitational interaction with the Earth, based on previous data, yields a more stringent limit |gn| < 3 × 10 −4 eV/c 2 m.PACS numbers: 14.20. Dh, 11.30.Er, 11.30.Cp, Lorentz symmetry is a fundamental hypothesis of our current understanding of physics and is central to the foundations of the Standard Model of particle physics (SM). However, the SM is widely believed to be only the low energy limit of some more fundamental theory, a theory which will probably violate more symmetries than the SM, in order to accomodate some features of the universe currently lacking in the SM, e.g., the baryon asymmetry. A SM extension including Lorentz and CPT violating terms has been presented in [1]. It provides a parametrisation of effects suitable to be tested by low energy precision experiments. In particular, clock comparison experiments [2, 3] have proven to be particularly sensitive to spin-dependent effects arising from a so-called cosmic spin anisotropy fieldb filling the whole universe. This Letter reports on a search for such an exotic field via its coupling to free neutrons.In the presence of a fieldb, the two spin states of the neutron will encounter an extra contribution to the energy splitting corresponding to the potential V = σ ·b where σ are the Pauli matrices. Thus, if a neutron is subjected to both a static magnetic field B and the new field b, its spin will precess at the modified Larmor frequency f n , which to first order inb is given byWe searched for a sidereal modulation (at a period of 23.934 hours) of the neutron Larmor frequency induced by b ⊥ , the component ofb orthogonal to the Earth's rotation axis. The experiment is also sensitive to a possible influence of the Sun on the spin precession dynamics, leading to a solar modulation (at a period of 24 h) of the Larmor frequency, as proposed in [4]. Such an effect could arise from a non-standard spin-dependent component of gravity [5,6] or from another long-range spindependent force [7,8]. In particular, a non-zero neutron gravitational dipole moment g n would induce a coupling through (see also [9])where G is Newton's constant, and for the mass M and

We have performed a comparison of laser (LsOPM) and lamp (LpOPM) pumped cesium vapor magnetometers. Although the LsOPM operated 50% above its shot-noise limit we found an intrinsic sensitivity of 15 fT/\sqrt{Hz} and 25 fT/\sqrt{Hz} for the LsOPM and LpOPM respectively. Two modes of operation, viz.,the phase-stabilized and the self-oscillating mode were investigated and found to yield a similar performance. We have compared the performance of the LsOPM and the LpOPM directly by simultaneous measurements of field fluctuations of a 2 microtesla magnetic field inside a multilayer magnetic shield and have used one of the magnetometers for an active field stabilization. In the stabilized mode we found a gradient instability of 25 fT within an integration time of 100 s, which represents an upper limit of the long-term stability of the magnetometers.Comment: 11 pages, 13 figures, 1 tabl