10,034 research outputs found
Novel diagnostic for precise measurement of the modulation frequency of Seeded Self-Modulation via Coherent Transition Radiation in AWAKE
We present the set-up and test-measurements of a waveguide-integrated
heterodyne diagnostic for coherent transition radiation (CTR) in the AWAKE
experiment. The goal of the proof-of-principle experiment AWAKE is to
accelerate a witness electron bunch in the plasma wakefield of a long proton
bunch that is transformed by Seeded Self-Modulation (SSM) into a train of
proton micro-bunches. The CTR pulse of the self-modulated proton bunch is
expected to have a frequency in the range of 90-300 GHz and a duration of
300-700 ps. The diagnostic set-up, which is designed to precisely measure the
frequency and shape of this CTR-pulse, consists of two waveguide-integrated
receivers that are able to measure simultaneously. They cover a significant
fraction of the available plasma frequencies: the bandwidth 90-140 GHz as well
as the bandwidth 255-270 GHz or 170-260 GHz in an earlier or a latter version
of the set-up, respectively. The two mixers convert the CTR into a signal in
the range of 5-20 GHz that is measured on a fast oscilloscope, with a high
spectral resolution of 1-3 GHz dominated by the pulse length. In this
contribution, we will describe the measurement principle, the experimental
set-up and a benchmarking of the diagnostic in AWAKE.Comment: Conference proceedings to 3rd European Advanced Accelerator Concepts
Worksho
Entanglement in thermal equilibrium states
We revisist the issue of entanglement of thermal equilibrium states in
composite quantum systems. The possible scenarios are exemplified in bipartite
qubit/qubit and qubit/qutrit systems.Comment: 4 figure
Singular kernels, multiscale decomposition of microstructure, and dislocation models
We consider a model for dislocations in crystals introduced by Koslowski,
Cuiti\~no and Ortiz, which includes elastic interactions via a singular kernel
behaving as the norm of the slip. We obtain a sharp-interface limit
of the model within the framework of -convergence. From an analytical
point of view, our functional is a vector-valued generalization of the one
studied by Alberti, Bouchitt\'e and Seppecher to which their rearrangement
argument no longer applies. Instead we show that the microstructure must be
approximately one-dimensional on most length scales and exploit this property
to derive a sharp lower bound
Precision measurement of gravity with cold atoms in an optical lattice and comparison with a classical gravimeter
We report on a high precision measurement of gravitational acceleration using
ultracold strontium atoms trapped in a vertical optical lattice. Using
amplitude modulation of the lattice intensity, an uncertainty was reached by measuring at the 5 harmonic of the Bloch
oscillation frequency. After a careful analysis of systematic effects, the
value obtained with this microscopic quantum system is consistent with the one
we measured with a classical absolute gravimeter at the same location. This
result is of relevance for the recent interpretation of related experiments as
tests of gravitational redshift and opens the way to new tests of gravity at
micrometer scale.Comment: 4 pages, 4 figure
MacromamÃferos (équidos, bóvidos) de la cueva de Praducelos (Suegos, Luego)
[Resumen] En este trabajo se describen restos -óseos: 1 mandibula,l tibia derecha de Equus Cabalus aff.gallicus, y un fragmento de maxilar y otro de base de cuerna de Bos sp.(o Bison sp.), procedentes de la cueva de Praducelos(Suegos,Lugo).[Abstract] the note describe bone rests:one mandibule and one tibia of Equus Cabalus aff. and a maxilar fragment and horn base of Bos sp.( or Bison sp.),from Praducelos, (Suegos,Lugo,Spain)
- …