36 research outputs found
Phonon-mediated anisotropic superconductivity in the Y and Lu nickel borocarbides
We present scanning tunneling spectroscopy and microscopy measurements at low
temperatures in the borocarbide materials RNi2B2C (R=Y, Lu). The characteristic
strong coupling structure due to the pairing interaction is unambiguously
resolved in the superconducting density of states. It is located at the
superconducting gap plus the energy corresponding to a phonon mode identified
in previous neutron scattering experiments. These measurements also show that
this mode is coupled to the electrons through a highly anisotropic
electron-phonon interaction originated by a nesting feature of the Fermi
surface. Our experiments, from which we can extract a large electron-phonon
coupling parameter lambda (between 0.5 and 0.8), demonstrate that this
anisotropic electron-phonon coupling has an essential contribution to the
pairing interaction. The tunneling spectra show an anisotropic s-wave
superconducting gap function.Comment: 5 pages, 3 figure
Recommended from our members
Fast fall-time ion beam in neutron generators
Ion beam with a fast fall time is useful in building neutron generators for the application of detecting hidden, gamma-shielded SNM using differential die-away (DDA) technique. Typically a fall time of less than 1 {micro}s can't be achieved by just turning off the power to the ion source due to the slow decay of plasma density (partly determined by the fall time of the RF power in the circuit). In this paper, we discuss the method of using an array of mini-apertures (instead of one large aperture beam) such that gating the beamlets can be done with low voltage and a small gap. This geometry minimizes the problem of voltage breakdown as well as reducing the time of flight to produce fast gating. We have designed and fabricated an array of 16 apertures (4 x 4) for a beam extraction experiment. Using a gating voltage of 1400 V and a gap distance of 1 mm, the fall time of extracted ion beam pulses is less than 1 {micro}s at various beam energies ranging between 400 eV to 800 eV. Usually merging an array of beamlets suffers the loss of beam brightness, i.e., emittance growth, but that is not an important issue for neutron source applications
The price of pain and the value of suffering
Estimating the financial value of pain informs issues as diverse as the market price of analgesics, the cost-effectiveness of clinical treatments, compensation for injury, and the response to public hazards. Such valuations are assumed to reflect a stable trade-off between relief of discomfort and money. Here, using an auction-based health-market experiment, we show that the price people pay for relief of pain is strongly determined by the local context of the market, that is, by recent intensities of pain or immediately disposable income (but not overall wealth). The absence of a stable valuation metric suggests that the dynamic behavior of health markets is not predictable from the static behavior of individuals. We conclude that the results follow the dynamics of habit-formation models of economic theory, and thus, this study provides the first scientific basis for this type of preference modeling
Supra National, National and Local Dimensions of Voter Turnout in European Parliament Elections
We argue that the decision to vote in European Parliamentary (EP) elections lies at the intersection of three political dimensions: one related to the attitude of citizens towards the European Union, one to the characteristics of the national political system, and the third associated with socio-economic variables observed by voters at the local level. This paper investigates this intersection by analyzing the last four EP elections in the EU-14, for 164 regions. We test a multilevel model. The results indicate a significant role of compulsory voting, domestic political cleavages, labor market conditions and trust in the EU. No evidence is found that GDP per capita affects turnout. Finally, the oldest segment of population seems more prone to vote than the youngest