Search results for "Electron optics"
showing 6 items of 6 documents
Theoretical prediction of the electronic properties of silicon fullerenes
1994
Summary form only given. High symmetry silicon clusters present currently intense interest because of the possibility they present properties similar to those displayed by fullerenes. Thermodynamic studies have shown that the buckminsterfullerene structure of Si6o is much more stable than other suggested structures. We present here a detailed investigation of the structure and electronic properties of silicon cluster analogous to fullerenes. We have made use of AMI method to obtain reliable geometrical parameters. The calculated valence effective Hamiltonian (VEH) electronic structures are used to predict ionization potentials, electron affinities, HOMO-LUMO energy gaps and first allowed tr…
Some Advantages of the Gyrotrons with Width Emitters
2020
The main trends in gyrotron development are escalation of the radiated power and increasing the frequency of coherent radiation. For both trends it is beneficial to develop gyrotrons with wide emitters because this allows one to use cryomagnets with smaller inner bore sizes. For analyzing and optimizing the operation of gyrotrons with wide emitters it is proposed to represent such emitters as a superposition of thin rings and analyze the properties of electron beams emitted by each of these rings. The analysis of electron beam properties, for electron optical systems with different emitters is presented. The possibility to reduce velocity spread by anode profiling is discussed. The dynamics…
Collimation for CLIC
2003
The collimation system of the Compact Linear Collider (CLIC) must fulfil a number of conflicting requirements, namely it should (1) remove beam halo to reduce the detector background, (2) provide a minimum distance between collimators and collision point for muon suppression, (3) ensure collimator survival and machine protection against errand beam pulses, (4) not be excessively long, and (5) not amplify incoming trajectory fluctuations via the collimator wake fields. Two optical systems have been designed — the first linear, the second non‐linear —, which promise to meet all these requirements for the design beam energy of 1.5 TeV. We decribe the various design criteria, a preliminary perf…
Performance Studies of Pixel Hybrid Photon Detectors for the LHCb RICH Counters
2006
The Pixel Hybrid Photon Detector is a vacuum tube with a multi-alkali photo cathode, high voltage cross-focused electron optics and an anode consisting of a silicon pixel detector bump-bonded to a readout CMOS electronic chip fully encapsulated in the device. The Pixel HPD fulfils the requirements of the Ring Imaging Cherenkov counters of the LHCb experiment at LHC. The performances of the Pixel HPD will be discussed with reference to laboratory measurements, Cherenkov light imaging in recent beam tests, image distortions due to a magnetic field.
A Mott polarimeter operating at MeV electron beam energies.
2011
We have developed a Mott electron polarimeter for the Mainzer microtron (MAMI) accelerator in Mainz, Germany. At beam energies ranging between 1.0 and 3.5 MeV two double focusing magnet spectrometers collect elastically backscattered electrons from gold targets. In spite of the small spectrometer acceptance, a sufficient statistical efficiency is achieved to provide very fast measurements if beam currents typical for experiments at MAMI are being used. High reproducibility is achieved, demonstrating that the results of asymmetry measurements are independent of the primary beam current in a range from 0.004 to 45 μA at a level of <1% relative variation. Compared to low energy polarimeters of…
Surface magnetism studied by photoelectron spectromicroscopy with high spatial and time resolution
2004
Abstract Photoemission electron microscopy (PEEM) is widely used for the study of magnetic surfaces and thin films. Ferromagnetic and antiferromagnetic microstructures are investigated exploiting magnetic circular and linear dichroism in the soft X-ray range using tuneable synchrotron radiation. Local dichroism spectroscopy gives access to magnetic moments of the elements in compounds or multilayer materials. Beyond these achievements, the method bears a high future potential with respect to an increased lateral resolution via aberration correction of the electron optics and a high time resolution in the 100 ps range for the study of dynamic processes. In addition, photoelectron spin polari…