26,104 research outputs found
SCR Blocking Pulse Gate Amplifier-Patent
Silicon controlled rectifier pulse gate amplifier for blocking false gating caused by negative transient voltage
Quantitative sum rule analysis of low-temperature spectral functions
We analyze QCD and Weinberg-type sum rules in a low-temperature pion gas
using vector and axial-vector spectral functions following from the
model-independent chiral-mixing scheme. Toward this end we employ recently
constructed vacuum spectral functions with ground and first-excited states in
both channels and a universal perturbative continuum; they quantitatively
describe hadronic tau-decay data and satisfy vacuum sum rules. These features
facilitate the implementation of chiral mixing without further assumptions, and
lead to in-medium spectral functions which exhibit a mutual tendency of
compensating resonance and dip structures, suggestive for an approach toward
structureless distributions. In the sum rule analysis, we account for pion mass
corrections, which turn out to be significant. While the Weinberg sum rules
remain satisfied even at high temperatures, the numerical evaluation of the QCD
sum rules for vector and axial-vector channels reveals significant deviations
setting in for temperatures beyond ~140 MeV, suggestive of additional physics
beyond low-energy chiral pion dynamics.Comment: 8 pages, 3 figure
Apparatus for recording oscillation properties of a Penning ionization gauge at very high frequencies
Recording equipment for very high frequency oscillations in Penning ionization gaug
Enhancing the cosmic-ray mass sensitivity of air-shower arrays by combining radio and muon detectors
The muonic and electromagnetic components of air showers are sensitive to the
mass of the primary cosmic particle. The sizes of the components can be
measured with particle detectors on ground, and the electromagnetic component
in addition indirectly via its radio emission in the atmosphere. The
electromagnetic particles do not reach the ground for very inclined showers. On
the contrary, the atmosphere is transparent for the radio emission and its
footprint on ground increases with the zenith angle. Therefore, the radio
technique offers a reliable detection over the full range of zenith angles, and
in particular for inclined showers. In this work, the mass sensitivity of a
combination of the radio emission with the muons is investigated in a case
study for the site of the Pierre Auger Observatory using CORSIKA Monte Carlo
simulations of showers in the EeV energy range. It is shown, that the
radio-muon combination features superior mass separation power in particular
for inclined showers, when compared to established mass observables such as a
combination of muons and electrons or the shower maximum Xmax. Accurate
measurements of the energy-dependent mass composition of ultra-high energy
cosmic rays are essential to understand their still unknown origin. Thus, the
combination of muon and radio detectors can enhance the scientific performance
of future air-shower arrays and offers a promising upgrade option for existing
arrays
Groups and semigroups with a one-counter word problem
We prove that a finitely generated semigroup whose word problem is a one-counter language has a linear growth function. This provides us with a very strong restriction on the structure of such a semigroup, which, in particular, yields an elementary proof of a result of Herbst, that a group with a one-counter word problem is virtually cyclic. We prove also that the word problem of a group is an intersection of finitely many one-counter languages if and only if the group is virtually abelian
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