Hard Scattering Based Luminosity Measurement at Hadron Colliders

A strategy to determine the luminosity at Hadron Colliders is discussed using the simultaneous W-boson and Z-boson event counts. The emphasis of the study will be on the uncertainty induced by the parton density functions. Understanding this source of uncertainties is crucial for a reliable luminosity determination using the W-boson and Z-boson events. As an example we will use the D0 run 1 results to extract the luminosity using the vector boson events and compare the result with the traditional method. Subsequently we will look at the implications for the top cross section uncertainties using the extracted luminosity.Comment: 15 pages, 2 (colored) figure

Bone loss and human adaptation to lunar gravity

Long-duration space missions and establishment of permanently manned bases on the Moon and Mars are currently being planned. The weightless environment of space and the low-gravity environments of the Moon and Mars pose an unknown challenge to human habitability and survivability. Of particular concern in the medical research community today is the effect of less than Earth gravity on the human skeleton, since the limits, if any, of human endurance in low-gravity environments are unknown. This paper provides theoretical predictions on bone loss and skeletal adaptation to lunar and other nonterrestrial-gravity environments based upon the experimentally derived relationship, density approximately (mass x gravity)(exp 1/8). The predictions are compared to skeletal changes reported during bed rest, immobilization, certrifugation, and spaceflight. Countermeasures to reduce bone losses in fractional gravity are also discussed

Momentum-resolved electron-phonon interaction in lead determined by neutron resonance spin-echo spectroscopy

Neutron resonance spin-echo spectroscopy was used to monitor the temperature evolution of the linewidths of transverse acoustic phonons in lead across the superconducting transition temperature, $T_c$, over an extended range of the Brillouin zone. For phonons with energies below the superconducting energy gap, a linewidth reduction of maximum amplitude $\sim 6 \mu$eV was observed below $T_c$. The electron-phonon contribution to the phonon lifetime extracted from these data is in satisfactory overall agreement with {\it ab-initio} lattice-dynamical calculations, but significant deviations are found