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Ta quadrupole resonanceYasuoka, Hiroshi; Kubo, Tetsuro*; Kishimoto, Yasuki*; Kasinathan, D.*; Schmidt, M.*; Yan, B.*; Zhang, Y.*; To, Hideki*; Felser, C.*; Mackenzie, A. P.*; et al.
Physical Review Letters, 118(23), p.236403_1 - 236403_6, 2017/07
Times Cited Count：26 Percentile：82.44(Physics, Multidisciplinary)The Ta quadrupole resonance (NQR) technique has been utilized to investigate the microscopic magnetic properties of the Weyl semi-metal TaP. We found three zero-field NQR signals associated with the transition between the quadrupole split levels for Ta with 
=7/2 nuclear spin. A quadrupole coupling constant, 
= 19.250 MHz, and an asymmetric parameter of the electric field gradient, 
= 0.423 were extracted, in good agreement with the theoretical calculations. In order to examine the magnetic excitations, the temperature dependence of the spin lattice relaxation rate (1/
) has been measured for the 
-line (
transition). We found that there exist two regimes with quite different relaxation processes. Above 
*
K, a pronounced (
behavior was found which is attributed to the magnetic excitations at the Weyl nodes with temperature dependent orbital hyperfine coupling. Below *, the relaxation is mainly governed by Korringa process with (1/) = constant, while we have to include a 
type dependence in order to reproduce our experimental data. We show that Ta-NQR is a novel probe for the bulk Weyl fermions and their excitations.
I/
I ratios in surface waters of the English Lake DistrictAtarashi-Andoh, Mariko; Schnabel, C.*; Cook, G.*; MacKenzie, A. B.*; Dougans, A.*; Ellam, R. M.*; Freeman, S.*; Maden, C.*; Olive, V.*; Synal, H.-A.*; et al.
Applied Geochemistry, 22(3), p.628 - 636, 2007/03
Times Cited Count：16 Percentile：39.79(Geochemistry & Geophysics)Accelerator Mass Spectrometry (AMS) was used to measure I/I ratios in surface sea, lake and river water samples collected in 2004 and 2005 from the English Lake District and from South west Scotland, areas which are in relatively close proximity to the Sellafield nuclear fuel reprocessing plant in north west England. The I/I ratios in surface water collected from the shore of the Irish Sea were in the range 2.8
10
to 8.210. These ratios are one order of magnitude higher than that of seawater collected from the Irish Sea in 1992, correlating with the increase in I content of the Sellafield liquid effluent discharge over the last decade. The I/I ratios in lakes in the Lake District were in the range 0.710 to 6.410 and decreased exponentially as a function of distance from Sellafield.
Sasao, Eiji; Ota, Kunio; Iwatsuki, Teruki; Niizato, Tadafumi; Arthur, R. C,*; Stenhouse, M. J.*; Zhou, W.*; Metcalfe, R.*; Takase, Hiroyasu; MacKenzie, A. B.*
Geochemistry; Exploration, Environment, Analysis, 6(1), p.5 - 12, 2006/02
The present natural analogue study of the Tono uranium deposit (Tono Natural Analogue Project) was started in 2001 with the main aim of studying a worst case scenario for safety assessment. The project has involved characterising the geology, hydrogeology, geochemistry and microbiology of the deposit and obtaining quantitative information about specific times in the past, as a means for developing, and building confidence in, conceptual and numerical models. Some recent results from site investigations, such as depositional age of the host sedimentary sequence and fault activity, are presented in this paper and in other papers in the series.
