94 research outputs found
Performance of a PADC personal neutron dosemeter at simulated and real workplace fields of the nuclear industry
In the framework of the EVIDOS (Evaluation of Individual Dosimetry in Mixed Neutron and Photon Radiation Fields) project, funded by the EC, measurements with PADC personal neutron dosemeters were carried out at several workplace fields of the nuclear industry and at simulated workplace fields. The measured personal neutron dose equivalents of the PADC personal neutron dosemeter are compared with values that were assessed within the EVIDOS project by other partners. The detection limits for different spectra types are given. In cases were the neutron dose was too low to be measured by the PADC personal neutron dosemeter, the response is estimated by convoluting the responses to monoenergetic neutrons with the dose energy distribution measured within EVIDOS. The advantages and limitations of the PADC personal neutron dosemeter are discusse
Progress report of the CR-39 neutron personal monitoring service at PSI
At the Paul Scherrer Institute a personal neutron dosimetry system based on chemically etched CR-39 detectors and automatic track counting is in routine use since the beginning of 1998. The quality of the CR-39 detectors has always been a crucial aspect to maintain a trustable personal neutron dosimetry system. This paper summarises the 7 y experience in routine use. The effect of detector material defects which could lead to false positive neutron doses is described. The potentiality of improving the background statistics by extending the pre-etch time is investigated and involves as a drawback a quite lower sensitivity to thermal neutrons. Furthermore, the impact of small changes in the production process of the detectors on the response to fast and thermal neutrons is shown. For the personal dosimetry at CERN, a new dosimetry concept was launched by combining a CR-39 neutron dosemeter with a Direct-Ion Storage (DIS) dosemeter for photon and beta radiation. The usage period of the CR-39 dosemeters is prolonged now from 3 months up to 12 months. In this context, the long-term behaviour over 1 y of the background track density and the response to Am-Be are describe
Present status of the personal neutron dosemeter based on direct ion storage
In this paper the present status of the Direct Ion Storage Neutron (DIS-N) prototype dosemeter (RADOS) is described. The separation of neutron from photon dose equivalent has been improved by adding tin shieldings. The neutron energy response has been changed by additional plastic covers containing 40% B4C in order to reduce the over-response to thermal neutrons. The responses of the dosemeters were determined for standard photon and neutron fields (monoenergetic neutrons, neutron sources and simulated workplace fields). Irradiations in real workplaces were also performed. The dependence of the neutron response on the angle of incidence was measured for different neutron source
Performance of a personal neutron dosemeter based on direct ion storage at workplace fields in the nuclear industry
In the framework of the EVIDOS project, funded by the EC, measurements were carried out using dosemeters, based on ionisation chambers with direct ion storage (DIS-N), at several workplace fields, namely, at a fuel processing plant, a boiling and a pressurised water reactor, and near transport and storage casks. The measurements and results obtained with the DIS-N in these workplaces, which are representative for the nuclear industry, are described in this study. Different dosemeter configurations of converter and shielding materials were considered. The results are compared with values for personal dose equivalent which were assessed within the EVIDOS project by other partners. The advantages and limitations of the DIS-N dosemeter are discusse
Genome-wide association study for 13 udder traits from linear type classification in cattle
Udder conformation traits are known to correlate with the incidence of clinical mastitis and the length of productive life. The results of a genome-wide association study based on imputed high-density genotypes of 1,637 -Brown Swiss sires and de-regressed breeding values for 13 udder traits are presented here. For seven traits significant signals could be observed in five regions on BTA3, BTA5, BTA6, BTA17, and BTA25. For fore udder length and teats diameter significant SNPs were found in a known region around 90 Mb on BTA6. For the trait rear udder height significant SNPs are positioned in the coding region of the SNX29gene. Several significant SNPs around 62 Mb on BTA17 are associated with the traits rear udder width, frontteat placement and rear teat placement. The function of potential candidate genes and the influence of substructure will be addressed as next steps
Critical behavior of gravitating sphalerons
We examine the gravitational collapse of sphaleron type configurations in
Einstein--Yang--Mills--Higgs theory. Working in spherical symmetry, we
investigate the critical behavior in this model. We provide evidence that for
various initial configurations, there can be three different critical
transitions between possible endstates with different critical solutions
sitting on the threshold between these outcomes. In addition, we show that
within the dispersive and black hole regimes, there are new possible endstates,
namely a stable, regular sphaleron and a stable, hairy black hole.Comment: Latex, 14 pages, 8 figure
Electronic neutron personal dosemeters: their performance in mixed radiation fields in nuclear power plants
This work describes spectral distributions of neutrons obtained as function of energy and direction at four workplace fields at the Krümmel reactor in Germany. Values of personal dose equivalent Hp(10) and effective dose E are determined for different directions of a person's orientation in these fields and readings of personal neutron dosemeters—especially electronic dosemeters—are discussed with respect to Hp(10) and
Pulsation of Spherically Symmetric Systems in General Relativity
The pulsation equations for spherically symmetric black hole and soliton
solutions are brought into a standard form. The formulae apply to a large class
of field theoretical matter models and can easily be worked out for specific
examples. The close relation to the energy principle in terms of the second
variation of the Schwarzschild mass is also established. The use of the general
expressions is illustrated for the Einstein-Yang-Mills and the Einstein-Skyrme
system.Comment: 21 pages, latex, no figure
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