69 research outputs found
Effects of T- and P-odd weak nucleon interaction in nuclei: renormalizations due to residual strong interaction, matrix elements between compound states and their correlations with P-violating matrix elements
Manifestations of P-,T-odd weak interaction between nucleons in nucleus are
considered. Renormalization of this interaction due to residual strong
interaction is studied. Mean squared matrix elements of P-,T-odd weak
interaction between compound states are calculated. Correlators between
P-,T-odd and P-odd, T-even weak interaction matrix elements between compound
states are considered and estimates for these quantities are obtained.Comment: Submitted to Phys. Rev. C; 21 pages, REVTEX 3, no figure
NN,N\Delta Couplings and the Quark Model
We examine mass-corrected SU(6) symmetry predictions in the quark model
relating vector, axial-vector and strong NN and N\Delta couplings, and
demonstrate that the experimental N\Delta value is significantly higher than
predicted in each case. Nevertheless the Goldberger-Treiman relation is
satisfied in both sectors. Possible origins of the discrepancy of the quark
model predictions with experiment are discussed.Comment: 22 pg. Latex file, figures available by reques
production in proton-proton scattering close to threshold}
The (958) reaction has been measured at COSY using
the internal beam and the COSY-11 facility. The total cross sections at the
four different excess energies \mbox{
and } have been evaluated to be \mbox{,
, , ~ and },
respectively. In this region of excess energy the (958) cross
sections are much lower compared to those of the and
production.Comment: 11 pages, 3 figure
Constraints on the structure and seasonal variations of Triton's atmosphere from the 5 October 2017 stellar occultation and previous observations
Context. A stellar occultation by Neptune's main satellite, Triton, was observed on 5 October 2017 from Europe, North Africa, and the USA. We derived 90 light curves from this event, 42 of which yielded a central flash detection.
Aims. We aimed at constraining Triton's atmospheric structure and the seasonal variations of its atmospheric pressure since the Voyager 2 epoch (1989). We also derived the shape of the lower atmosphere from central flash analysis.
Methods. We used Abel inversions and direct ray-tracing code to provide the density, pressure, and temperature profiles in the altitude range similar to 8 km to similar to 190 km, corresponding to pressure levels from 9 mu bar down to a few nanobars.
Results. (i) A pressure of 1.18 +/- 0.03 mu bar is found at a reference radius of 1400 km (47 km altitude). (ii) A new analysis of the Voyager 2 radio science occultation shows that this is consistent with an extrapolation of pressure down to the surface pressure obtained in 1989. (iii) A survey of occultations obtained between 1989 and 2017 suggests that an enhancement in surface pressure as reported during the 1990s might be real, but debatable, due to very few high S/N light curves and data accessible for reanalysis. The volatile transport model analysed supports a moderate increase in surface pressure, with a maximum value around 2005-2015 no higher than 23 mu bar. The pressures observed in 1995-1997 and 2017 appear mutually inconsistent with the volatile transport model presented here. (iv) The central flash structure does not show evidence of an atmospheric distortion. We find an upper limit of 0.0011 for the apparent oblateness of the atmosphere near the 8 km altitude.J.M.O. acknowledges financial support from the Portuguese Foundation for Science and Technology (FCT) and the European Social Fund (ESF) through the PhD grant SFRH/BD/131700/2017. The work leading to these results has received funding from the European Research Council under the European Community's H2020 2014-2021 ERC grant Agreement nffi 669416 "Lucky Star". We thank S. Para who supported some travels to observe the 5 October 2017 occultation. T.B. was supported for this research by an appointment to the National Aeronautics and Space Administration (NASA) Post-Doctoral Program at the Ames Research Center administered by Universities Space Research Association (USRA) through a contract with NASA. We acknowledge useful exchanges with Mark Gurwell on the ALMA CO observations. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium).Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. J.L.O., P.S.-S., N.M. and R.D. acknowledge financial support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award to the Instituto de Astrofisica de Andalucia (SEV-2017-0709), they also acknowledge the financial support by the Spanish grant AYA-2017-84637-R and the Proyecto de Excelencia de la Junta de Andalucia J.A. 2012-FQM1776. The research leading to these results has received funding from the European Union's Horizon 2020 Research and Innovation Programme, under Grant Agreement no. 687378, as part of the project "Small Bodies Near and Far" (SBNAF). P.S.-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 "LEO-SBNAF". The work was partially based on observations made at the Laboratorio Nacional de Astrofisica (LNA), Itajuba-MG, Brazil. The following authors acknowledge the respective CNPq grants: F.B.-R. 309578/2017-5; R.V.-M. 304544/2017-5, 401903/2016-8; J.I.B.C. 308150/2016-3 and 305917/2019-6; M.A. 427700/20183, 310683/2017-3, 473002/2013-2. This study was financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior -Brasil (CAPES) -Finance Code 001 and the National Institute of Science and Technology of the e-Universe project (INCT do e-Universo, CNPq grant 465376/2014-2). G.B.R. acknowledges CAPES-FAPERJ/PAPDRJ grant E26/203.173/2016 and CAPES-PRINT/UNESP grant 88887.571156/2020-00, M.A. FAPERJ grant E26/111.488/2013 and A.R.G.Jr. FAPESP grant 2018/11239-8. B.E.M. thanks CNPq 150612/2020-6 and CAPES/Cofecub-394/2016-05 grants. Part of the photometric data used in this study were collected in the frame of the photometric observations with the robotic and remotely controlled telescope at the University of Athens Observatory (UOAO; Gazeas 2016). The 2.3 m Aristarchos telescope is operated on Helmos Observatory by the Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing of the National Observatory of Athens. Observations with the 2.3 m Aristarchos telescope were carried out under OPTICON programme. This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 730890. This material reflects only the authors views and the Commission is not liable for any use that may be made of the information contained therein. The 1.
2m Kryoneri telescope is operated by the Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing of the National Observatory of Athens. The Astronomical Observatory of the Autonomous Region of the Aosta Valley (OAVdA) is managed by the Fondazione Clement Fillietroz-ONLUS, which is supported by the Regional Government of the Aosta Valley, the Town Municipality of Nus and the "Unite des Communes valdotaines Mont-Emilius". The 0.81 m Main Telescope at the OAVdA was upgraded thanks to a Shoemaker NEO Grant 2013 from The Planetary Society. D.C. and J.M.C. acknowledge funds from a 2017 'Research and Education' grant from Fondazione CRT-Cassa di Risparmio di Torino. P.M. acknowledges support from the Portuguese Fundacao para a Ciencia e a Tecnologia ref. PTDC/FISAST/29942/2017 through national funds and by FEDER through COMPETE 2020 (ref. POCI010145 FEDER007672). F.J. acknowledges Jean Luc Plouvier for his help. S.J.F. and C.A. would like to thank the UCL student support observers: Helen Dai, Elise Darragh-Ford, Ross Dobson, Max Hipperson, Edward Kerr-Dineen, Isaac Langley, Emese Meder, Roman Gerasimov, Javier Sanjuan, and Manasvee Saraf. We are grateful to the CAHA, OSN and La Hita Observatory staffs. This research is partially based on observations collected at Centro Astronomico HispanoAleman (CAHA) at Calar Alto, operated jointly by Junta de Andalucia and Consejo Superior de Investigaciones Cientificas (IAA-CSIC). This research was also partially based on observation carried out at the Observatorio de Sierra Nevada (OSN) operated by Instituto de Astrofisica de Andalucia (CSIC). This article is also based on observations made with the Liverpool Telescope operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. Partially based on observations made with the Tx40 and Excalibur telescopes at the Observatorio Astrofisico de Javalambre in Teruel, a Spanish Infraestructura Cientifico-Tecnica Singular (ICTS) owned, managed and operated by the Centro de Estudios de Fisica del Cosmos de Aragon (CEFCA). Tx40 and Excalibur are funded with the Fondos de Inversiones de Teruel (FITE). A.R.R. would like to thank Gustavo Roman for the mechanical adaptation of the camera to the telescope to allow for the observation to be recorded. R.H., J.F.R., S.P.H. and A.S.L. have been supported by the Spanish projects AYA2015-65041P and PID2019-109467GB-100 (MINECO/FEDER, UE) and Grupos Gobierno Vasco IT1366-19. Our great thanks to Omar Hila and their collaborators in Atlas Golf Marrakech Observatory for providing access to the T60cm telescope. TRAPPIST is a project funded by the Belgian Fonds (National) de la Recherche Scientifique (F.R.S.-FNRS) under grant PDR T.0120.21. TRAPPIST-North is a project funded by the University of Liege, and performed in collaboration with Cadi Ayyad University of Marrakesh. E.J. is a FNRS Senior Research Associate
A large topographic feature on the surface of the trans-Neptunian object (307261) 2002 MS measured from stellar occultations
This work aims at constraining the size, shape, and geometric albedo of the
dwarf planet candidate 2002 MS4 through the analysis of nine stellar
occultation events. Using multichord detection, we also studied the object's
topography by analyzing the obtained limb and the residuals between observed
chords and the best-fitted ellipse. We predicted and organized the
observational campaigns of nine stellar occultations by 2002 MS4 between 2019
and 2022, resulting in two single-chord events, four double-chord detections,
and three events with three to up to sixty-one positive chords. Using 13
selected chords from the 8 August 2020 event, we determined the global
elliptical limb of 2002 MS4. The best-fitted ellipse, combined with the
object's rotational information from the literature, constrains the object's
size, shape, and albedo. Additionally, we developed a new method to
characterize topography features on the object's limb. The global limb has a
semi-major axis of 412 10 km, a semi-minor axis of 385 17 km, and
the position angle of the minor axis is 121 16. From
this instantaneous limb, we obtained 2002 MS4's geometric albedo and the
projected area-equivalent diameter. Significant deviations from the fitted
ellipse in the northernmost limb are detected from multiple sites highlighting
three distinct topographic features: one 11 km depth depression followed by a
25 km height elevation next to a crater-like depression with an
extension of 322 39 km and 45.1 1.5 km deep. Our results present an
object that is 138 km smaller in diameter than derived from thermal
data, possibly indicating the presence of a so-far unknown satellite. However,
within the error bars, the geometric albedo in the V-band agrees with the
results published in the literature, even with the radiometric-derived albedo
Constraints on the structure and seasonal variations of Tritonâs atmosphere from the 5 October 2017 stellar occultation and previous observationsâ
Context. A stellar occultation by Neptune's main satellite, Triton, was observed on 5 October 2017 from Europe, North Africa, and the USA. We derived 90 light curves from this event, 42 of which yielded a central flash detection. Aims. We aimed at constraining Triton's atmospheric structure and the seasonal variations of its atmospheric pressure since the Voyager 2 epoch (1989). We also derived the shape of the lower atmosphere from central flash analysis. Methods. We used Abel inversions and direct ray-tracing code to provide the density, pressure, and temperature profiles in the altitude range âŒ8 km to âŒ190 km, corresponding to pressure levels from 9 ÎŒbar down to a few nanobars. Results. (i) A pressure of 1.18 ± 0.03 ÎŒbar is found at a reference radius of 1400 km (47 km altitude). (ii) A new analysis of the Voyager 2 radio science occultation shows that this is consistent with an extrapolation of pressure down to the surface pressure obtained in 1989. (iii) A survey of occultations obtained between 1989 and 2017 suggests that an enhancement in surface pressure as reported during the 1990s might be real, but debatable, due to very few high S/N light curves and data accessible for reanalysis. The volatile transport model analysed supports a moderate increase in surface pressure, with a maximum value around 2005-2015 no higher than 23 ÎŒbar. The pressures observed in 1995-1997 and 2017 appear mutually inconsistent with the volatile transport model presented here. (iv) The central flash structure does not show evidence of an atmospheric distortion. We find an upper limit of 0.0011 for the apparent oblateness of the atmosphere near the 8 km altitude
Ecological half-times of
More than 200 data sets from the literature of measured time series of activity concentrations and transfer factors concerning: (1) soil, green plants, mushrooms, and game in forests and (2) water, particulate matter, and fish in rivers, reservoirs and lakes in Europe have been analyzed. We used a sum of up to 3 exponential functions to evaluate ecological half-times (T).
In fresh water systems we fitted lognormal distributions of T for 137Cs (e.g. in the water of 32 European lakes, T = (0.3*2.2) years and T = (5.7*3.9) years as geometric mean value and standard deviation). Pronounced seasonal variations were observed in suspended matter of Lake Lugano, reflecting the bio-mass cycle of this lake.
In forests, ecological half-times for 137Cs can also be fitted by a lognormal distribution. For Central Europe T 12 years. Extraordinarily high 137Cs activity concentrations were observed recently in wild boar in Germany. For Eastern Europe the physical half-time is dominant and in some components of the ecosystem the activity concentration is still increasing.
Bioverfuegbarkeit von Caesium-Radionukliden in Waldgebieten - Datenerhebung und Modellierung. Verwendungsnachweis und Anlagen 1-4
A model of radiocaesium soil-plant transfer is proposed, combining two separate approaches to describe radionuclide distribution in soil-soil solution system and soil solution-plant system. According to the model radiocaesium concentration in soil solution is determined by abilities of soil to fix and selectively sorb radiocaesium as well as cationic composition of soil solution. Soil solution - plant transfer is determined by Cs concentration in soil solution and also by cationic status of soil solution. It is derived that soil-plant transfer factor should be a linear function of availability parameter A of the soil which is a combination of soil parameters and cationic status of soil solution. The parametrisation is tested against the field data on soil-plant transfer for various forest sites in Germany, Russia, Sweden and Switzerland. Satisfactory agreement has been achieved. A simplified method of the parameterisation based on the application standard argochemical characteristics of soil is presented and experimentally tested. The approach can be used in radioecological GIS to map radiocaesium soil-plant transfer factor. (orig.)Available from TIB Hannover: F00B570 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman
Time-dependency of the
14 years after the nuclear reactor accident in Chernobyl, activity concentrations of lake water are measured as 0.06 mBq/l. 2 mBq/l, and 60 mBq/l in Lake Constance. Lake Lugano and Lake Vorsee. These values can be explained by differences in limnological character of these lakes. To describe and predict the data of lake water contamination we use (1) a simple exponential "transfer function" model for the runoff of activity from contaminated catchments, and assume that runoff water determines lake water contamination. In a second approach (2) lake water residence times and 137Cs uptake by sediments are taken into account together with runoff. With their blind predictions both models describe the 137Cs contamination in lake water of the three lakes quite well. Based on the second approach, a fish model is used to blindly predict the fish contamination in Lake Constance and Lake Vorsee with a deviation smaller than factor 10 from measured values. Attempts to use these models also for a number of other lakes in Europe and in the CIS countries near to the site of Chernobyl are promising with respect to a generalisation of our results to predict 137Cs contamination of freshwater lakes for radiation protection purposes in case of emergency
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