We present the result of an experiment to measure the electric dipole moment (EDM) of the neutron at the Paul Scherrer Institute using Ramsey's method of separated oscillating magnetic fields with ultracold neutrons. Our measurement stands in the long history of EDM experiments probing physics violating timereversal invariance. The salient features of this experiment were the use of a 199 Hg comagnetometer and an array of optically pumped cesium vapor magnetometers to cancel and correct for magnetic-field changes. The statistical analysis was performed on blinded datasets by two separate groups, while the estimation of systematic effects profited from an unprecedented knowledge of the magnetic field. The measured value of the neutron EDM is d n ¼ ð0.0 AE 1.1 stat AE 0.2 sys Þ × 10 −26 e:cm.

The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation γ-ray spectrometer. AGATA is based on the technique of γ-ray energy tracking in electrically segmented high-purity germanium crystals. This technique requires the accurate determination of the energy, time and position of every interaction as a γ ray deposits its energy within the detector volume. Reconstruction of the full interaction path results in a detector with very high efficiency and excellent spectral response. The realisation of γ-ray tracking and AGATA is a result of many technical advances. These include the development of encapsulated highly segmented germanium detectors assembled in a triple cluster detector cryostat, an electronics system with fast digital sampling and a data acquisition system to process the data at a high rate. The full characterisation of the crystals was measured and compared with detector-response simulations. This enabled pulse-shape analysis algorithms, to extract energy, time and position, to be employed. In addition, tracking algorithms for event reconstruction were developed. The first phase of AGATA is now complete and operational in its first physics campaign. In the future AGATA will be moved between laboratories in Europe and operated in a series of campaigns to take advantage of the different beams and facilities available to maximise its science output. The paper reviews all the achievements made in the AGATA project including all the necessary infrastructure to operate and support the spectrometer

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.

International audienceThe measurement of the neutron electric dipole moment (nEDM) constrains the contribution of CP-violating terms within both the Standard Model and its extensions. The experiment uses ultracold neutrons (UCN) stored in vacuum at room temperature. This technique provided the last (and best) limit by the RAL/Sussex/ILL collaboration in 2006: dn < 2:9 × 10-26 e cm (90% C.L.). We aim to improve the experimental sensitivity by a factor of 5 within 2-3 years, using an upgrade of the same apparatus. We will take advantage of the increased ultracold neutron density at the Paul Scherrer Institute (PSI) and of a new concept including both, external magnetometers and a cohabiting magnetometer. In parallel, a next generation apparatus with two UCN storage chambers and an elaborate magnetic field control is being designed aiming to achieve another order of magnitude increase in sensitivity, allowing us to put a limit as tight as dn < 5 × 10-28 e cm (95% C.L.), if not establishing a finite value

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