Search results for "beam"
showing 10 items of 2126 documents
COMMISSIONING OF THE SPEDE SPECTROMETER WITH STABLE BEAMS
2017
The SPectrometer for Electron DEtection (SPEDE) has been constructed for in-beam nuclear structure studies using radioactive ion beams. SPEDE employs a silicon detector for detecting conversion electrons. It is designed to be used in conjunction with the MINIBALL spectrometer at HIE-ISOLDE, CERN. Peer reviewed
Shell structure and shape coexistence in195Pb
1995
Pb-195 was investigated utilizing the reactions Dy-164(S-36, 5n)Pb-195 and Dy-164(S-34, 3n)Pb-195 at beam energies of 170 and 160MeV respectively. Two new dipole bands which feed into the yrast 25/2(+) state, were found in Pb-195. The connection between the bands and the spherical states was established and thus spins and energies of the involved collective states were determined. The deformation is understood as mainly due to excitations of protons across the Z = 82 shell gap. The observed backbends are interpreted as alignment of i(13/2) neutrons.
Normal metal - insulator - superconductor interferometer
2003
Hybrid normal metal - insulator - superconductor microstructures suitable for studying an interference of electrons were fabricated. The structures consist of a superconducting loop connected to a normal metal electrode through a tunnel barrier . An optical interferometer with a beam splitter can be considered as a classical analogue for this system. All measurements were performed at temperatures well below 1 K. The interference can be observed as periodic oscillations of the tunnel current (voltage) through the junction at fixed bias voltage (current) as a function of a perpendicular magnetic field. The magnitude of the oscillations depends on the bias point. It reaches a maximum at energ…
Reference beam dynamics layout for the SC CW heavy ion HELIAC at GSI
2020
Abstract The standalone superconducting continuous wave heavy ion linac HELIAC (HElmholtz LInear ACcelerator) is a common project of GSI Helmholtz Centre for Heavy Ion Research and Helmholtz Institute Mainz (HIM) under key support of Goethe University Frankfurt (IAP) and in collaboration with National Research Nuclear University MEPhI and NRC “Kurchatov Institute” ITEP. In 2017 the first superconducting section of the linac has been successfully commissioned and extensively tested with beam at GSI. The measurements sufficiently present the capability of 216.816 MHz multi-gap Crossbar H-mode (CH) DTL-structures. An acceleration of heavy ions up to the design beam energy and beyond has been r…
Emittance measurements with optical transition radiation at the S-DALINAC
2020
Abstract A new emittance measurement system has been installed at the superconducting, recirculating electron accelerator S-DALINAC. It is based on the quadrupole-scan technique and beam profile measurements with optical transition radiation. A first demonstration of this setup has been conducted as part of the beam-based alignment of an SRF cavity. The corresponding emittance measurement is described here, and the following data evaluation is discussed.
The energy calibration of LEP in the 1993 scan
1995
This report summarizes the procedure for providing the absolute energy calibration of the LEP beams during the energy scan in 1993. The average beam energy around the LEP ring was measured in 25 calibrations with the resonant depolarization technique. The time variation of this average beam energy is well described by a model of the accelerator based on monitored quantities. The absolute calibration of the centre of mass energies of the off-peak points is determined with a precision of 2 parts in 10(5) resulting in a systematic error on the Z-mass of about 1.4 MeV and on the Z-width of about 1.5 MeV.
Non-local stiffness and damping models for shear-deformable beams
2013
This paper presents the dynamics of a non-local Timoshenko beam. The key assumption involves modeling non-local effects as long-range volume forces and moments mutually exerted by non-adjacent beam segments, that contribute to the equilibrium of any beam segment along with the classical local stress resultants. Elastic and viscous long-range volume forces/moments are endowed in the model. They are built as linearly depending on the product of the volumes of the interacting beam segments and on generalized measures of their relative motion, based on the pure deformation modes of the beam. Attenuation functions governing the space decay of the non-local effects are introduced. Numerical resul…
Compact dielectric reflective elements I Half-sphere concentrators of radially emitted light
1994
Optical designs of aspheric internally reflective concentrators of divergent light emitted within a spatial angle of 2n sr are proposed and discussed. Four types of solid transparent element are considered: the divergence angle reducer, the small-spot illuminator, the point focuser, and the collimator. The output beam aperture in all cases is comparable with the light-source external dimensions. Expressions describing the profiles of beam-transforming surfaces and results from experiments with model devices are presented.
Plasmon-driven Bessel beams
2012
We report on subwavelength diffraction-free beams with grazing propagation in metal-dielectric devices. The nondiffracting beams are resonantly transmitted through the nanostructured medium leading to light confinement and wave amplification around the beam axis.
Squeezing induced by spontaneous rotational symmetry breaking
2009
In this communication we study in depth the phenomenon of quadrature squeezing generated via spontaneous rotational symmetry breaking discussed for the first time in [1]. The idea can be put in short as follows. Consider a degenerate optical parametric oscillator (DOPO) tuned to the first family of transverse modes at the signal frequency, and having perfectly spherical mirrors. When pumped above threshold with a Gaussian beam and within a classical description, it is easy to show that a TEM 10 mode with an arbitrary orientation (measured by θ at Fig. 1) emerges at the subharmonic, hence breaking the rotational symmetry of the system in the transverse plane. Quantum effects are then quite i…