13,028 research outputs found
Recycling Pulsars: spins, masses and ages
Although the first millisecond pulsars (MSPs) were discovered 30 years ago we
still do not understand all details of their formation process. Here, we
present new results from Tauris, Langer & Kramer (2012) on the recycling
scenario leading to radio MSPs with helium or carbon-oxygen white dwarf
companions via evolution of low- and intermediate mass X-ray binaries (LMXBs,
IMXBs). We discuss the location of the spin-up line in the (P,Pdot)-diagram and
estimate the amount of accreted mass needed to obtain a given spin period and
compare with observations. Finally, we constrain the true ages of observed
recycled pulsars via calculated isochrones in the (P,Pdot)-diagram.Comment: Contributed talk, Proceedings of IAUS 291 "Neutron Stars and Pulsars:
Challenges and Opportunities after 80 years", J. van Leeuwen (ed.); 4 pages,
2 figure
Scanning electron microscopy of Rydberg-excited Bose-Einstein condensates
We report on the realization of high resolution electron microscopy of
Rydberg-excited ultracold atomic samples. The implementation of an ultraviolet
laser system allows us to excite the atom, with a single-photon transition, to
Rydberg states. By using the electron microscopy technique during the Rydberg
excitation of the atoms, we observe a giant enhancement in the production of
ions. This is due to -changing collisions, which broaden the Rydberg level
and therefore increase the excitation rate of Rydberg atoms. Our results pave
the way for the high resolution spatial detection of Rydberg atoms in an atomic
sample
Thermodynamic dislocation theory of high-temperature deformation in aluminum and steel
The statistical-thermodynamic dislocation theory developed in previous papers
is used here in an analysis of high-temperature deformation of aluminum and
steel. Using physics-based parameters that we expect theoretically to be
independent of strain rate and temperature, we are able to fit experimental
stress-strain curves for three different strain rates and three different
temperatures for each of these two materials. Our theoretical curves include
yielding transitions at zero strain in agreement with experiment. We find that
thermal softening effects are important even at the lowest temperatures and
smallest strain rates.Comment: 7 pages, 8 figure
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