15,596 research outputs found
Gravitational waves from pulsars with measured braking index
We study the putative emission of gravitational waves (GWs) in particular for
pulsars with measured braking index. We show that the appropriate combination
of both GW emission and magnetic dipole brakes can naturally explain the
measured braking index, when the surface magnetic field and the angle between
the magnetic dipole and rotation axes are time dependent. Then we discuss the
detectability of these very pulsars by aLIGO and the Einstein Telescope. We
call attention to the realistic possibility that aLIGO can detect the GWs
generated by at least some of these pulsars, such as Vela, for example.Comment: 6 pages and 4 figure
Universal R-C crossover in current-voltage characteristics for unshunted array of overdamped Nb-AlO_x-Nb Josephson junctions
We report on some unusual behavior of the measured current-voltage
characteristics (CVC) in artificially prepared two-dimensional unshunted array
of overdamped Nb-AlO_x-Nb Josephson junctions. The obtained nonlinear CVC are
found to exhibit a pronounced (and practically temperature independent)
crossover at some current I_{cr}=\left(\frac{1}{2\beta_C}-1\right)I_C from a
resistance R dominated state with V_R=R\sqrt{I^2-I_C^2} below I_{cr} to a
capacitance C dominated state with V_C=\sqrt{\frac{\hbar}{4eC}} \sqrt{I-I_C}
above I_{cr}. The origin of the observed behavior is discussed within a
single-plaquette approximation assuming the conventional RSJ model with a
finite capacitance and the Ambegaokar-Baratoff relation for the critical
current of the single junction
Manifestation of geometric resonance in current dependence of AC susceptibility for unshunted array of Nb-AlOx-Nb Josephson junctions
A pronounced resonance-like structure has been observed in the current
dependence of AC susceptibility for two-dimensional array of unshunted
Nb-AlOx-Nb Josephson junctions. Using a single-plaquette approximation, we were
able to successfully fit our data assuming that resonance structure is related
to the geometric (inductive) properties of the array.Comment: to appear in Physica C (in press
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