353 research outputs found

    Geometric-phase-induced false electric dipole moment signals for particles in traps

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    Theories are developed to evaluate Larmor frequency shifts, derived from geometric phases, in experiments to measure electric dipole moments (EDMs) of trapped, atoms, molecules and neutrons. A part of these shifts is proportional to the applied electric field and can be interpreted falsely as an electric dipole moment. A comparison is made between our theoretical predictions for these shifts and some results from our recent experiments, which shows agreement to within the experimental errors of 15 %. The comparison also demonstrates that some trapped particle EDM experiments have reached the sensitivity where stringent precautions are needed to minimise and control such false EDMs. Computer simulations of these processes are also described. They give good agreement with the analytical results and they extend the study by investigating the influence of varying surface reflection laws in the hard walled traps considered. They also explore the possibility to suppress such false EDMs by introducing collisions with buffer gas particles. Some analytic results for frequency shifts proportional to the square of the E-field are also given and there are results for the averaging of the B-field in the absence of an E-field

    An Improved Experimental Limit on the Electric Dipole Moment of the Neutron

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    An experimental search for an electric-dipole moment (EDM) of the neutron has been carried out at the Institut Laue-Langevin (ILL), Grenoble. Spurious signals from magnetic-field fluctuations were reduced to insignificance by the use of a cohabiting atomic-mercury magnetometer. Systematic uncertainties, including geometric-phase-induced false EDMs, have been carefully studied. Two independent approaches to the analysis have been adopted. The overall results may be interpreted as an upper limit on the absolute value of the neutron EDM of |d_n| < 2.9 x 10^{-26} e cm (90% CL).Comment: 5 pages, 2 figures. The published PRL is slightly more terse (e.g. no section headings) than this version, due to space constraints. Note a small correction-to-a-correction led to an adjustment of the final limit from 3.0 to 2.9 E-26 e.cm compared to the first version of this preprin

    Gravitational depolarization of ultracold neutrons: comparison with data

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    We compare the expected effects of so-called gravitationally enhanced depolarization of ultracold neutrons to measurements carried out in a spin-precession chamber exposed to a variety of vertical magnetic-field gradients. In particular, we have investigated the dependence upon these field gradients of spin-depolarization rates and also of shifts in the measured neutron Larmor precession frequency. We find excellent qualitative agreement, with gravitationally enhanced depolarization accounting for several previously unexplained features in the data

    Revised experimental upper limit on the electric dipole moment of the neutron

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    We present for the first time a detailed and comprehensive analysis of the experimental results that set the current world sensitivity limit on the magnitude of the electric dipole moment (EDM) of the neutron. We have extended and enhanced our earlier analysis to include recent developments in the understanding of the effects of gravity in depolarizing ultracold neutrons; an improved calculation of the spectrum of the neutrons; and conservative estimates of other possible systematic errors, which are also shown to be consistent with more recent measurements undertaken with the apparatus. We obtain a net result of dn=−0.21±1.82×10−26  e cm, which may be interpreted as a slightly revised upper limit on the magnitude of the EDM of 3.0×10−26  e cm (90% C.L.) or 3.6×10−26  e cm (95% C.L.)

    Experts' Judgments of Management Journal Quality:An Identity Concerns Model

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    Many lists that purport to gauge the quality of journals in management and organization studies (MOS) are based on the judgments of experts in the field. This article develops an identity concerns model (ICM) that suggests that such judgments are likely to be shaped by the personal and social identities of evaluators. The model was tested in a study in which 168 editorial board members rated 44 MOS journals. In line with the ICM, respondents rated journal quality more highly to the extent that a given journal reflected their personal concerns (associated with having published more articles in that journal) and the concerns of a relevant ingroup (associated with membership of the journal’s editorial board or a particular disciplinary or geographical background). However, judges’ ratings of journals in which they had published were more favorable when those journals had a low-quality reputation, and their ratings of journals that reflected their geographical and disciplinary affiliations were more favorable when those journals had a high-quality reputation. The findings are thus consistent with the view that identity concerns come to the fore in journal ratings when there is either a need to protect against personal identity threat or a meaningful opportunity to promote social identity

    Cognition in stroke rehabilitation and recovery research: Consensus-based core recommendations from the second Stroke Recovery and Rehabilitation Roundtable

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    Cognitive impairment is an important target for rehabilitation as it is common following stroke, is associated with reduced quality of life and interferes with motor and other types of recovery interventions. Cognitive function following stroke was identified as an important, but relatively neglected area during the first Stroke Recovery and Rehabilitation Roundtable (SRRR I), leading to a Cognition Working Group being convened as part of SRRR II. There is currently insufficient evidence to build consensus on specific approaches to cognitive rehabilitation. However, we present recommendations on the integration of cognitive assessments into stroke recovery studies generally and define priorities for ongoing and future research for stroke recovery and rehabilitation. A number of promising interventions are ready to be taken forward to trials to tackle the gap in evidence for cognitive rehabilitation. However, to accelerate progress requires that we coordinate efforts to tackle multiple gaps along the whole translational pathway

    Cognition in Stroke Rehabilitation and Recovery Research: Consensus-Based Core Recommendations From the Second Stroke Recovery and Rehabilitation Roundtable

    Get PDF
    Cognitive impairment is an important target for rehabilitation as it is common following stroke, is associated with reduced quality of life and interferes with motor and other types of recovery interventions. Cognitive function following stroke was identified as an important, but relatively neglected area during the first Stroke Recovery and Rehabilitation Roundtable (SRRR I), leading to a Cognition Working Group being convened as part of SRRR II. There is currently insufficient evidence to build consensus on specific approaches to cognitive rehabilitation. However, we present recommendations on the integration of cognitive assessments into stroke recovery studies generally and define priorities for ongoing and future research for stroke recovery and rehabilitation. A number of promising interventions are ready to be taken forward to trials to tackle the gap in evidence for cognitive rehabilitation. However, to accelerate progress requires that we coordinate efforts to tackle multiple gaps along the whole translational pathway
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