Hasil untuk "physics.acc-ph"

B. Poole, S. Ohkuma

The spectral characteristics of dextran, labeled with fluorescein, depend upon pH. We have loaded the lysosomes of mouse peritoneal macrophages with this fluorescence probe and used it to measure the intralysosomal pH under various conditions. The pH of the medium has no effect on the intralysosomal pH. Weakly basic substances in the medium cause a concentration-dependent increase in the intralysosomal pH. However, the concentration of base necessary to produce a significant change in the intralysosomal pH varies over a wide range for different bases. The active form of the base is the neutral, unprotonated form. Although most of these weak bases cause an increase in the volume of the lysosomes, increase in lysosomal volume itself causes only a minor perturbation of the intralysosomal pH. This was demonstrated in cells whose lysosomes were loaded with sucrose, and in cells vacuolated as a demonstrated in cells whose lysosomes were loaded with sucrose, and in cells vacuolated as a consequence of exposure to concanavalin A. The results of these studies are interpreted in terms of energy-dependent lysosomal acidification and leakage of protons out of the lysosomes in the form of protonated weak bases.

J. Skehel, P. Bayley, E. Brown et al.

Osamu Kamigaito

We discuss the relationship between the zero modes of electromagnetic fields in a cavity resonator and the cavity's topological characteristics. We show that the dimension of the electromagnetic zero-mode space coincides with the dimension of the corresponding homology group of the cavity. Moreover, we prove that the alternating sum of the dimensions of the electromagnetic zero-mode spaces is closely related to the Euler characteristic of the cavity boundary, and hence to the integral of the curvature.

W. Busa, R. Nuccitelli

I. H. Madshus

D. S. Bondar, V. I. Maslov, I. N. Onishchenko

Wakefield acceleration methods are known due to some their advantages. The main of them is the high accelerating gradient up to several teravolts per meter. In the paper another important advantage is concluded to the possibility of using a wakefield accelerator as a source of electrons by means of obtaining self injected bunches and their accelera-tion. The result is the simulation of the process of plasma wakefield excitation by a laser pulse with an energy of tens of mJ and a power of 1-2 TW for obtaining the promising electron source. Homogeneous and Gaussian plasma profiles were investigated and compared to increase the energy of the self-injected bunches. The laser parameters were taken that corresponded to the parameters of the laser setup in the Institute of Plasma Electronics and New Methods of Acceleration of the National Scientific Center "Kharkiv Institute of Physics and Technology". Based on the results of the simulation, the possibility of obtaining relativistic self-injected bunches that can be used for further laser acceler-ation experiments, including dielectric laser acceleration, was demonstrated.

Gudrid Moortgat-Pick, Sabine Riemann, Peter Sievers et al.

Several designs for high-energy Lepton Colliders serving as Higgs factories but extendable to higher energies up to the TeV range are under discussion. The most mature design is the International Linear Collider (ILC), but also the Compact Linear Collider (CLIC) as well as the new concept of a Hybrid Asymmetric Linear Higgs Factory (HALHF) have a large physics potential. The first energy stage with $\sqrt{s}=250$~GeV requires high luminosity and polarized beams and imposes an effort for all positron source designs at high-energy colliders. In the baseline design of the ILC, an undulator-based source is foreseen for the positron source in order to match the physics requirements. In this contribution an overview is given about the undulator-based source, the target tests, the rotating target wheel design, as well as the pulsed solenoid and the new technology development of plasma lenses as optic matching devices.

A. Latina

A large multitude of scientific computing tools is available today. This article gives an overview of available tools and explains the main application fields. In addition basic principles of number representations in computing and the resulting truncation errors are treated. The selection of tools is for those students, who work in the field of accelerator beam dynamics.

K. Ulbrich, V. Šubr

S. Angelos, Yingwei Yang, K. Patel et al.

A. Degen, M. Kosec

Kay Wittenburg

Beam halo measurements imply measurements of beam profiles with a very high dynamic range, both in transverse and longitudinal planes. This lesson gives an overview of high dynamic range instruments for beam halo measurements. In addition, halo definitions and quantifications in view of beam instrumentation are discussed.

M. J. V. Streeter, Z. Najmudin

Laser plasma accelerators capable of generating >10 GeV electron beams may require plasma mirrors to remove undepleted laser energy at the end of each accelerator stage. Near the plasma mirror surface, the electron bunch can interact with the reflected light, resulting in inverse Compton scattering. For realistic conditions, we show that a significant fraction of electrons emit one or more photons, increasing the energy spread of the electron bunch. We provide an analytical expression for calculating this effect, and use it to estimate the minimum drift space required before the plasma mirror to meet given energy spread specifications. Mitigation strategies, necessary to achieve sub-percent energy spread in multi-GeV laser wakefield electron sources, are proposed and explored.

Suvrat Rao, Marcus Brüggen, Jochen Liske

Here we calculate the effects of astrophysical gravitational waves (GWs) on the travel times of proton bunch test masses in circular particle accelerators. We show that a high-precision proton bunch time-tagging detector could turn a circular particle accelerator facility into a GW observatory sensitive to millihertz (mHz) GWs. We comment on sources of noise and the technological feasibility of ultrafast single photon detectors by conducting a case study of the Large Hadron Collider (LHC) at CERN.

O. Pokrovsky, J. Schott

R. Buck, S. Rondinini, A. Covington et al.

A. Aggeli, M. Bell, L. Carrick et al.

Yan-Li Zhao, Zongxi Li, Sanaz Kabehie et al.

O. Vandal, Lynda M Pierini, D. Schnappinger et al.

Ayşegül Kırca, M. Özkan, B. Cemeroǧlu