Experimental study of 199Hg spin anti-relaxation coatings

We report on a comparison of spin relaxation rates in a $^{199}$Hg magnetometer using different wall coatings. A compact mercury magnetometer was built for this purpose. Glass cells coated with fluorinated materials show longer spin coherence times than if coated with their hydrogenated homologues. The longest spin relaxation time of the mercury vapor was measured with a fluorinated paraffin wall coating.Comment: 9 pages, 6 figures, submitted to JINS

An Improved Search for the Neutron Electric Dipole Moment

A permanent electric dipole moment of fundamental spin-1/2 particles violates both parity (P) and time re- versal (T) symmetry, and hence, also charge-parity (CP) symmetry since there is no sign of CPT-violation. The search for a neutron electric dipole moment (nEDM) probes CP violation within and beyond the Stan- dard Model. The experiment, set up at the Paul Scherrer Institute (PSI), an improved, upgraded version of the apparatus which provided the current best experimental limit, dn < 2.9E-26 ecm (90% C.L.), by the RAL/Sussex/ILL collaboration: Baker et al., Phys. Rev. Lett. 97, 131801 (2006). In the next two years we aim to improve the sensitivity of the apparatus to sigma(dn) = 2.6E-27 ecm corresponding to an upper limit of dn < 5E-27 ecm (95% C.L.), in case for a null result. In parallel the collaboration works on the design of a new apparatus to further increase the sensitivity to sigma(dn) = 2.6E-28 ecm.Comment: APS Division for particles and fields, Conference Proceedings, Two figure

Testing isotropy of the universe using the Ramsey resonance technique on ultracold neutron spins

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 using 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. An non-zero 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.Comment: proceedings of the PNCMI2010 conferenc

Experimental study of 199Hg spin anti-relaxation coatings

We report on a comparison of spin relaxation rates in a 199Hg magnetometer using different wall coatings. A compact mercury magnetometer was built for this purpose. Glass cells coated with fluorinated materials show longer spin coherence times than if coated with their hydrogenated homologues. The longest spin relaxation time of the mercury vapor was measured with a fluorinated paraffin wall coating

Measurement of the permanent electric dipole moment of the neutron

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 (UCN). Our measurement stands in the long history of EDM experiments probing physics violating time reversal invariance. The salient features of this experiment were the use of a Hg-199 co-magnetometer 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_{\rm n} = (0.0\pm1.1_{\rm stat}\pm0.2_{\rmsys})\times10^{-26}e\,{\rm cm}

A measurement of the neutron to 199Hg magnetic moment ratio

The neutron gyromagnetic ratio has been measured relative to that of the 199Hg atom with an uncertainty of 0.8 ppm. We employed an apparatus where ultracold neutrons and mercury atoms are stored in the same volume and report the result γn/γHg=3.8424574(30)γn/γHg=3.8424574(30)

A measurement of the neutron to 199Hg magnetic moment ratio

The neutron gyromagnetic ratio has been measured relative to that of the 199Hg atom with an uncertainty of 0.8 ppm. We employed an apparatus where ultracold neutrons and mercury atoms are stored in the same volume and report the result γn/γHg=3.8424574(30)

Vertiefte Auswahl von Probenahmeregionen fuer die Umweltprobenbank und oekologische Beratung zu ihrem Betrieb

With the selection of two urban-industrial areas, this report brings to completion a selection of a national network of ecological assessment parks. Herein we have recommended Urban-industrial system Frankfurt am Main and the industrial conurbation of the Saarland. The complete network of ecological assessment parks consists of 11 areas in which the national environmental assessment program can be conducted in a coordinated fashion. We have initiated the process of selecting and characterizing study areas within these parks and the design and implementation of sampling programs for environmental specimen banking within the recommended parks. The study areas are selected and generally small watersheds. Even the urban-industrial system of the Saarland comprises a single drainage system. Within the reported study areas are defined and discussed for Berchtesgaden National Park (NP), Bavarian Forest National Park (NP), Bornhoeved Lakes Region, Schleswig-Holstein Waddensea (NP) and in the Urban-industrial System of the Saarland. In the study sites presampling collections (e.g., spruce, beech, poplar, earthworms, fish, mussels, brown algae) were made as a basis for establishing sampling designs and collection protocols to be used on a continuing bases. (orig./RHM)Zur Vervollstaendigung des Netzes Oekologischer Umweltbeobachtungsgebiete, werden im vorliegenden Bericht die urban-industriellen Systeme Frankfurt/M. und der Ballungsraum des Saarlandes empfohlen. Das vollstaendige Kernnetz der Oekologischen Umweltbeobachtungsgebiete besteht demnach aus 11 Gebieten, in denen in koordinierter Vorgehensweise ein Oekologisches Umweltbeobachtungsprogramm eingerichtet werden kann. Innerhalb der empfohlenen Gebiete ist es notwendig, Kernbereiche (Untersuchungsregionen) auszuwaehlen, in denen langfristige Umweltforschungsprogramme wie auch die Probennahme der Umweltprobenbank durchgefuehrt werden koennen. Hierzu wurde das Konzept der Wassereinzugsgebiete zugrunde gelegt. Im vorliegenden Bericht wird die Auswahl der Untersuchungsregionen fuer die Gebiete NP Berchtesgaden, NP Bayerischer Wald, NP Schleswig-Holsteinisches Wattenmeer, Bornhoeveder Seengebiet und Urban-industrielles System Saarland dargestellt; die Gebiete und die Untersuchungsregionen werden ausfuehrlich diskutiert. Innerhalb dieser Untersuchungsregionen wurden fuer ausgewaehlte Probenarten (Fichte, Buche, Pappel, Regenwurm, Brasse, Miesmuschel, Braunalge) Screening-Versuche als Grundlage fuer langfristige Sampling-Designs konzipiert und durchgefuehrt. (orig./RHM)Available from TIB Hannover: RN 8908(93-035) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Umwelt, Naturschutz und Reaktorsicherheit, Bonn (Germany)DEGerman

MC calculations for the nEDM experiment systematics

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