Le Climat De La Terre. A. Berger. Publisher De Boeck Publisher Universite,Bruxelles (479 pp) ISBN 2 8041 1497 X BF2550     

Alastair G. Dawson 《第四纪科学杂志》1994,9(1):93-93

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Study and suppression of anomalous fast events in inorganic scintillators for dark matter searches     

V. A. Kudryavtsev  N. J. C. Spooner  P. K. Lightfoot  J. W. Roberts  M. J. Lehner  T. Gamble  M. J. Carson  T. B. Lawson  R. Lüscher  J. E. McMillan  B. Morgan  S. M. Paling  M. Robinson  D. R. Tovey  N. J. T. Smith  P. F. Smith  G. J. Alner  S. P. Hart  J. D. Lewin  R. M. Preece  T. J. Sumner  W. G. Jones  J. J. Quenby  B. Ahmed  A. Bewick  D. Davidge  J. V. Dawson  A. S. Howard  I. Ivaniouchenkov  M. K. Joshi  V. Lebedenko  I. Liubarsky  J. C. Barton  G. Gerbier  J. Mallet  L. Mosca  C. Tao 《Astroparticle Physics》2002,17(4):79-408

The status of dark matter searches with inorganic scintillator detectors at Boulby mine is reviewed and the results of tests with a CsI(Tl) crystal are presented. The objectives of the latter experiment were to study anomalous fast events previously observed and to identify ways to remove this background. Clear indications were found that these events were due to surface contamination of crystals by alphas, probably from radon decay. A new array of unencapsulated NaI(Tl) crystals immersed either in liquid paraffin or pure nitrogen atmosphere is under construction at Boulby. Such an approach allows complete control of the surface of the crystals and the ability to remove any surface contamination. First data from the unencapsulated NaI(Tl) do not show the presence of anomalous fast events.  相似文献   

Uncertainty quantification of two-phase flow problems via measure theory and the generalized multiscale finite element method     

M. Presho  S. Mattis  C. Dawson 《Computational Geosciences》2017,21(2):187-204

The problem of multiphase phase flow in heterogeneous subsurface porous media is one involving many uncertainties. In particular, the permeability of the medium is an important aspect of the model that is inherently uncertain. Properly quantifying these uncertainties is essential in order to make reliable probabilistic-based predictions and future decisions. In this work, a measure-theoretic framework is employed to quantify uncertainties in a two-phase subsurface flow model in high-contrast media. Given uncertain saturation data from observation wells, the stochastic inverse problem is solved numerically in order to obtain a probability measure on the space of unknown permeability parameters characterizing the two-phase flow. As solving the stochastic inverse problem requires a number of forward model solves, we also incorporate the use of a conservative version of the generalized multiscale finite element method for added efficiency. The parameter-space probability measure is used in order to make predictions of saturation values where measurements are not available, and to validate the effectiveness of the proposed approach in the context of fine and coarse model solves. A number of numerical examples are offered to illustrate the measure-theoretic methodology for solving the stochastic inverse problem using both fine and coarse solution schemes.  相似文献   

Editorial welcome     

Clint Dawson  Mary F. Wheeler 《Computational Geosciences》2009,13(1):1-1

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Periglacial trimlines and nunataks of the Last Glacial Maximum: the Gap of Dunloe,southwest Ireland     

Alaric C. Rae  Stephan Harrison  Timothy Mighall  Alastair G. Dawson 《第四纪科学杂志》2004,19(1):87-97

During the last main phase of glaciation (26–13 ka) an ice‐cap developed in southwest Ireland and ice, from a dispersal centre in the vicinity of Kenmare, flowed north through the Gap of Dunloe in the Macgillycuddy's Reeks. On surrounding hillsides a weathering limit separates ice‐moulded bedrock, on low ground, from frost‐weathered terrain above. Assessment of bedrock dilation joint characteristics, Schmidt hammer R‐value data and clay‐sized mineral contents of basal soil samples, demonstrate significant contrasts in the degree of weathering above and below this limit. The weathering limit declines in altitude along former ice flow‐lines and is confluent with morainic deposits on the eastern side of the Gap. This supports the assertion that the high‐level weathering limit is a periglacial trimline that marks the former maximum upper limit of the body of ice which occupied the Gap of Dunloe during the Last Glacial Maximum (LGM). Reconstruction of the former ice‐surface profile from periglacial trimline limits on the eastern side of the Gap yields a mean estimate for basal shear stress of 106.5 kPa. This value suggests that the ice mass which occupied the Gap of Dunloe at the LGM was warm based and flowed on a bedrock substrate. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Computer simulation of plasmas     

John M. Dawson 《Astrophysics and Space Science》1971,13(2):446-467

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Quaternary environments. M. A. J. Williams,D. L. Dunkerley,P. de Deckker,A. P. Kershaw and T. W. Stokes. Publisher Edward Arnold,London 1993 £16.95     

Alastair G. Dawson 《第四纪科学杂志》1995,10(2):187-187

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Tsunami risk in northwestern Europe: a Holocene example     

D. Long  A.G Dawson  D.E. Smith 《地学学报》1989,1(6):532-537

A thin, regionally extensive, laterally persistent sand layer is present within the Holocene coastal sequences of eastern Scotland, dated to 7000 yr BP. It is proposed that this deposit was caused by a tsunami wave generated by a catastrophic submarine landslide (the Second Storegga Slide) on the Norwegian continental slope. The distribution of this tsunami deposit indicates that the wave penetrated at least 2 km beyond the contemporary coastline and a minimum of 4 m above the contemporary high-water mark. Although the frequency of tsunamis may be low in this region their effects should be considered for very long-term or very sensitive strategic developments at coastal sites.  相似文献   

Collective neutrino-plasma interactions     

V.N. Tsytovich  R. Bingham  J.M. Dawson  H.A. Bethe 《Astroparticle Physics》1998,8(4):297-307

Nonlinear processes describing the interaction of neutrinos with collective plasma oscillations and the excitation of plasma turbulence by a large neutrino flux is discussed. The excitation considered is the inverse processes of neutrino emission by plasma waves first considered by Tsytovich (V.N. Tsytovich, Soviet Fiz. Dokl. 9 (1965) 1114). The process is similar to a beam plasma instability considered as inverse Landau damping in which the usual electromagnetic interactions are important. In the neutrino beam relaxation the weak interaction can play a similar role. We emphasize here the possibility of another process namely the interaction of an intense neutrino flux with a strongly turbulent plasma. The turbulence can also be assumed to be due to the shock produced at the early stages of a type II supernova (SN) explosion. The scattering of the neutrinos in the turbulent plasma is shown to be sufficient for transferring momentum and energy from the neutrino flux to the plasma causing the shock to continue moving outward and eventually creating the blow-off of the mantle of the star producing type II SN.  相似文献   

A comparison of cosmic ray composition measurements at the highest energies     

B.R. Dawson  R. Meyhandan  K.M. Simpson 《Astroparticle Physics》1998,9(4):331-338

In recent years the Fly's Eye and Akeno groups have presented analyses of the cosmic ray mass composition at energies above 10¹⁷ eV. While the analysis of the Fly's Eye group points to a likely change in mass composition from heavy to light at energies above 10¹⁸ eV, the Akeno analysis favours an unchanging composition. However, the two groups base their conclusions on simulations using quite different hadronic models. Here we present a comparison of the experiments using the same hadronic model and find that the agreement between the experiments is much improved. Under this model, both experiments measure a composition rich in iron around 10¹⁷ eV which becomes lighter at higher energies. However, the agreement is not complete, which indicates scope for improvement of the interaction model, or perhaps the need for a re-examination of the experimental results.  相似文献