BEAM DECOHERENCE DUE TO COMBINATION OF WAKE FORCE AND NONLINEARITY IN SP-RING-8 STORAGE RING

Abstract To understand particle behavior from a beam injection state to equilibrium state determined by radiation effects, we have performed a simple experiment to observe the beam decoherence, i.e., temporal variation of the damping of beam coherent motion generated by a single horizontal kicker. We found that the beam decoherence much depends on chromaticities, the sign of amplitudedependent tune shift and beam current. This suggests that short-range wake force and nonlinearity of ring parameters play important roles in the observed phenomena. Simulations with transverse wake fields show good agreements with the measurements

AMPLITUDE DEPENDENT BETATRON OSCILLATION CENTER SHIFT BY NON-LINEARITY AND BEAM INSTABILITY INTERLOCK

Abstract As a result of the even symmetry of the Sextupole field, it creates the horizontal shift of the averaged position of horizontal and vertical betatron oscillation and the amount of the shift depends on its oscillation amplitude. This shift can be observed with usual slow orbit beam position monitor. At the SPring-8 storage ring, this shift is used to detect the excitation of the betatron oscillation for the interlock system for the protection of the vacuum components from strong radiation of insertion devices. AMPLITUDE DEPENDENT BETATRON OSCILLATION CENTER SHIFT The transverse beam instability drives a horizontal or vertical betatron oscillation, and if this occurs in light sources, the strong synchrotron radiation from insertion devices also oscillates as the beam and cause heat damages on beam pipe components if the radiation continuously hit them. The even symmetry of the sextupole field produces the horizontal shift of the time averaged horizontal position if the horizontal and vertical betatron oscillation exists. Here we call it an amplitude dependent betatron oscillation center shift (ADCS). The ADCS on the sextupole strength can be derived by a canonical perturbation theory as the first order effect by sextupole field [1] as where the symbols with overline are the time averaged values, J z and φ z ( z = x, y ) are the action and the phase, respectively, and related to the position and beta function β z s The sextupole strength is expressed as for the magnetic field

Light emission from a scanning tunneling microscope: Fully retarded calculation

The light emission rate from a scanning tunneling microscope (STM) scanning a noble metal surface is calculated taking retardation effects into account. As in our previous, non-retarded theory [Johansson, Monreal, and Apell, Phys. Rev. B 42, 9210 (1990)], the STM tip is modeled by a sphere, and the dielectric properties of tip and sample are described by experimentally measured dielectric functions. The calculations are based on exact diffraction theory through the vector equivalent of the Kirchoff integral. The present results are qualitatively similar to those of the non-retarded calculations. The light emission spectra have pronounced resonance peaks due to the formation of a tip-induced plasmon mode localized to the cavity between the tip and the sample. At a quantitative level, the effects of retardation are rather small as long as the sample material is Au or Cu, and the tip consists of W or Ir. However, for Ag samples, in which the resistive losses are smaller, the inclusion of retardation effects in the calculation leads to larger changes: the resonance energy decreases by 0.2-0.3 eV, and the resonance broadens. These changes improve the agreement with experiment. For a Ag sample and an Ir tip, the quantum efficiency is $\approx$ 10$^{-4}$ emitted photons in the visible frequency range per tunneling electron. A study of the energy dissipation into the tip and sample shows that in total about 1 % of the electrons undergo inelastic processes while tunneling.Comment: 16 pages, 10 figures (1 ps, 9 tex, automatically included); To appear in Phys. Rev. B (15 October 1998

Identificação de procedências e progênies de Pinus maximinoi com potencial produtivo para madeira.

O objetivo desse trabalho foi estimar variabilidade genética de dois ensaios de P. maximonoi para identificação de matrizes com potencial produtivo para madeira na região de Ventania-PR. O delineamento experimento foi de blocos completos ao acaso, com 63 progênies área 1 e 77 progênies na área 2 procedentes de oito procedências, nove repetições, seis plantas por parcela, espaçamento de 3 x 3 metros. Os caracteres avaliados foram: diâmetro a 1,30 m do solo (DAP, cm), altura total (ALT, m) e volume (VOL, m3.tree-1). As estimativas dos parâmetros genéticos e o ganho na seleção foram estimados com base no método REML/BLUP. Diferenças significativas (p<0,01) foram observadas entre procedências nos dois locais. Houve diferenças significativas entre progênies para os caracteres ALT, DAP e VOL somente para as procedentes de Dulce N. de Colpan (Honduras) e San Jerônimo de Oaxaca (Guatemala) na área 1 e Tapiquil (Honduras) e Valle de Ageles (Honduras) (DAP e VOL) na área 2. Na análise entre procedências os baixos coeficientes de variação genética, herdabilidade aditivos e herdabilidade média de progênies mostram baixo controle genético para os caracteres. As procedências de P. maximinoi apresentaram bom crescimento e desempenho em volume na região de Ventania-PR. As procedências de P. maximinoi devem ser consideradas para plantios comerciais e o estabelecimento de áreas de produção de sementes para essa espécie. Dentre as procedências testadas, San Jeronimo (México) teve as maiores taxas de incremento em volume.Made available in DSpace on 2019-01-07T23:51:04Z (GMT). No. of bitstreams: 1 2018ValderesSFIdentificacao.pdf: 1103838 bytes, checksum: b047a27c9b9f1a8c590d3aafdfbee19f (MD5) Previous issue date: 2019-01-07bitstream/item/189847/1/2018-Valderes-SF-Identificacao.pd