An automated focal point positioning and emittance measurement procedure for the interaction point of the SLC

To achieve maximum luminosity at the SLC, both the electron and positron beams must reach their minimum transverse size within 1 mm of the longitudinal location where the two bunches collide. This paper describes an automated procedure for positioning the focal point of each beam at this collision point. The technique is based on measurements of the beam size utilizing either secondary emission or bremsstrahlung signals from carbon fibers a few microns in diameter. We have achieved simultaneous and reproducible measurements of the angular spread (~ 200 [mu] rad) and of the optimum beam spot size ~ [omega]m), which when combined yield measurements of the beam emittance consistent with those obtained using conventional profile monitor techniques.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28674/1/0000491.pd

Measurement of the Vertical Emittance and beta-Function at the PEP-II Interaction Point Using the BaBar Detector

We present measurements of the effective vertical emittance and IP {beta}-function in the PEP-II asymmetric B Factory at SLAC. These beam parameters are extracted from fits to the longitudinal dependence of the luminosity and the vertical luminous size, measured using e{sup +}e{sup -} {yields} {mu}{sup +}{mu}{sup -} events recorded in the BABAR detector. The results are compared, for different sets of machine conditions, to accelerator-based measurements of the optical functions of the two beams

Microstructures Manufactured in Diamond by Use of Laser Micromachining.

Different microstructures were created on the surface of a polycrystalline diamond plate (obtained by microwave plasma-enhanced chemical vapor deposition-MW PECVD process) by use of a nanosecond pulsed DPSS (diode pumped solid state) laser with a 355 nm wavelength and a galvanometer scanning system. Different average powers (5 to 11 W), scanning speeds (50 to 400 mm/s) and scan line spacings ("hatch spacing") (5 to 20 µm) were applied. The microstructures were then examined using scanning electron microscopy, confocal microscopy and Raman spectroscopy techniques. Microstructures exhibiting excellent geometry were obtained. The precise geometries of the microstructures, exhibiting good perpendicularity, deep channels and smooth surfaces show that the laser microprocessing can be applied in manufacturing diamond microfluidic devices. Raman spectra show small differences depending on the process parameters used. In some cases, the diamond band (at 1332 cm-1) after laser modification of material is only slightly wider and shifted, but with no additional peaks, indicating that the diamond is almost not changed after laser interaction. Some parameters did show that the modification of material had occurred and additional peaks in Raman spectra (typical for low-quality chemical vapor deposition CVD diamond) appeared, indicating the growing disorder of material or manufacturing of the new carbon phase

Maintaining micron-size beams in collision at the interaction point of the Stanford Linear Collider

In order to maintain collisions between two micron-size beams at the interaction point of the SLC, we take advantage of the mutual electromagnetic deflection induced by one beam on the other as they cross with a nonzero relative impact parameter. We determine simultaneously the incoming and outgoing trajectory parameters of each beam on a pulse-by-pulse basis, using beam position monitors located near the IP. Comparing incoming and outgoing angles for a given beam yields the magnitude of the deflection the beam experienced during the collision from which the distance currently separating the two beams can be extracted. A simple proportional control is applied to calculate the change in upstream corrector settings to null out this distance. 3 refs., 6 figs

Machine-Related Backgrounds in the SiD Detector at ILC

With a multi-stage collimation system and magnetic iron spoilers in the tunnel, the background particle fluxes on the ILC detector can be substantially reduced. At the same time, beam-halo interactions with collimators and protective masks in the beam delivery system create fluxes of muons and other secondary particles which can still exceed the tolerable levels for some of the ILC sub-detectors. Results of modeling of such backgrounds in comparison to those from the e+ e- interactions are presented in this paper for the SiD detector.Comment: 29 pages, 34 figures, 7 table

Beam-beam deflection as a beam tuning tool at the SLAC linear collider

To achieve maximum integrated luminosity at the SLAC Linear Collider, a method of noninvasive beam tuning is required. Traditional luminosity monitors based on Bhabha scattering are inadequate because of low instantaneous counting rates. Coherent deflections of one beam by the electromagnetic field of the other are sensitive not only to the relative steering of the two bunches but also to their spot sizes. A brief description of beam-beam deflection theory forms the basis for a discussion of this phenomenon as a tool for single-beam tuning and for luminosity optimization at the interaction point of the SLC.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28771/1/0000603.pd

Comparison of the TESLA, NLC and CLIC Beam Collimation Systems Performance

This note describes studies performed in the framework of the Collimation task Force organized to support work of the International Linear Collider Technical Review Committee aiming in comparison of performance of the post-linac beam collimation systems in TESLA, JLC/NLC and CLIC linear collider designs. Collimation of the beam halo and synchrotron radiation collimation have been compared for all projects using the same computer code and same assumptions. It is shown that though the performance of the presently designed systems differ, and not always correspond to expected performance, achieving required performance in the future collider is feasible. Furthe, post-TRC plans of the Collimation task Force are discussed as well

Closed Orbit Distortion and the Beam-Beam Interaction

We study the applicability of beam-beam deflection techniques as a tuning tool for the SLAC/LBL/LLNL B factory, PEP-II. Assuming that the closed orbits of the two beams are separated vertically at the interaction point by a local orbit bump that is nominally closed, we calculate the residual beam orbit distortions due to the beam-beam interaction. Difference orbit measurements, performed at points conveniently distant from the IP, provide distinct coordinate- or frequency-space signatures that can be used to maintain the beams in collision and perform detailed optical diagnostics at the IP. A proposal to test this method experimentally at the TRISTAN ring is briefly discussed