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Importance of high order momentum terms in SLC optics

Description: The evaluation of background levels at the SLC relies, in several cases, on the proper representation of how low momentum electrons propagate through the Arcs and the Final Focus System (FFS). For example, beam - gas bremsstrahlung in the arcs causes electrons of up to 6% energy loss to be transported through to the IP; secondary showers on edges of masks and collimators yield debris with a very wide momentum spectrum. This note is a naive attempt at checking the validity of TRANSPORT and TURTLE calculations, by evaluating the contributions of the momentum terms to increasingly higher order, and checking the mutual consistency of the results produced by the two methods on a beam of wide momentum spread. 8 refs., 4 figs., 1 tab.
Date: July 10, 1985
Creator: Kozanecki, W.
Partner: UNT Libraries Government Documents Department

Progress report on the SLAC Linear Collider

Description: In this paper we report on the status of the SLAC Linear Collider (SLC), the prototype of a new generation of colliding beam accelerators. This novel type of machine holds the potential of extending electron-positron colliding beam studies to center-of-mass (c.m.) energies far in excess of what is economically achievable with colliding beam storage rings. If the technical challenges posed by linear colliders are solvable at a reasonable cost, this new approach would provide an attractive alternative to electron-positron rings, where, because of rapidly rising synchrotron radiation losses, the cost and size of the ring increases with the square of the c.m. energy. In addition to its role as a test vehicle for the linear collider principle, the SLC aims at providing an abundant source of Z/sup 0/ decays to high energy physics experiments. Accordingly, two major detectors, the upgraded Mark II, now installed on the SLC beam line, and the state-of-the-art SLD, currently under construction, are preparing to probe the Standard Model at the Z/sup 0/ pole. The SLC project was originally funded in 1983. Since the completion of construction, we have been commissioning the machine to bring it up to a performance level adequate for starting the high energy physics program. In the remainder of this paper, we will discuss the status, problems and performance of the major subsystems of the SLC. We will conclude with a brief outline of the physics program, and of the planned enhancements to the capabilities of the machine. 26 refs., 7 figs.
Date: November 1, 1987
Creator: Kozanecki, W.
Partner: UNT Libraries Government Documents Department

Where do we stand on the SLC (SLAC Linear Collider)

Description: This paper reviews the current performance of the SLAC Linear Collider, as well as the issues, problems and prospects facing the project. A few of the original accelerator physics results achieved in the last year are described in detail. 36 refs., 12 figs., 1 tab.
Date: February 1, 1989
Creator: Kozanecki, W.
Partner: UNT Libraries Government Documents Department

Interactive beam tuning simulator for the SLC (Stanford Linear Collider) final focus

Description: An interface to the DIMAD beam optics computer program enables the operator to perform in simulation the sequence of magnet adjustments that would be used online for tuning the Stanford Linear Collider Final Focus System. The program accepts any input beam matrix from a disk file and presents a menu of magnet adjustments and scan and display options. The results of a ray trace calculation are presented as profiles or envelope plots on the graphics screen. We give results from studies of the optimization of the beam under various input conditions. 11 refs., 4 figs.
Date: March 1, 1989
Creator: Ford, W.T.; Kozanecki, W.; Lohse, T. & Servranckx, R.V.
Partner: UNT Libraries Government Documents Department

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

Description: 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 plant. 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 speed (/approximately/200 /mu/rad) and the optimum beam spot size (/approximately/2 /mu/m), which when combined yield measurements of the beam emittance consistent with those obtained using conventional profile monitor techniques. 8 refs., 5 figs., 1 tab.
Date: August 1, 1989
Creator: Phinney, N.; Bambade, P.; Kozanecki, W. & Koska, W.
Partner: UNT Libraries Government Documents Department

Beamstrahlung spectra in next generation linear colliders

Description: For the next generation of linear colliders, the energy loss due to beamstrahlung during the collision of the e{sup +}e{sup {minus}} beams is expected to substantially influence the effective center-of-mass energy distributions of the colliding particles. In this paper, we first derive analytical formulae for the electron and photon energy spectra under multiple beamstrahlung processes, and for the e{sup +}e{sup {minus}} and {gamma}{gamma} differential luminosities. We then apply our formalism to various classes of 500 GeV e{sup +}e{sup {minus}} linear collider designs currently under study.
Date: February 1, 1992
Creator: Barklow, T.; Chen, P. & Kozanecki, W.
Partner: UNT Libraries Government Documents Department

Beamstrahlung spectra in next generation linear colliders. Revision

Description: For the next generation of linear colliders, the energy loss due to beamstrahlung during the collision of the e{sup +}e{sup {minus}} beams is expected to substantially influence the effective center-of-mass energy distribution of the colliding particles. In this paper, we first derive analytical formulae for the electron and photon energy spectra under multiple beamstrahlung processes, and for the e{sup +}e{sup {minus}} and {gamma}{gamma} differential luminosities. We then apply our formulation to various classes of 500 GeV e{sup +}e{sup {minus}} linear collider designs currently under study.
Date: April 1, 1992
Creator: Barklow, T.; Chen, P. & Kozanecki, W.
Partner: UNT Libraries Government Documents Department

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

Description: 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.
Date: May 17, 2005
Creator: Thompson, J.M.; Roodman, A.; /SLAC; Kozanecki, W. & /DAPNIA, Saclay
Partner: UNT Libraries Government Documents Department

Characterization of the PEP-II Colliding-Beam Phase Space by the Boost Method

Description: We present a novel approach to characterize the colliding-beam phase space at the interaction point of the energy-asymmetric PEP-II B-Factory. The method exploits the fact that the transverse-boost distribution of e{sup +}e{sup -} {yields} {mu}{sup +}{mu}{sup -} events reconstructed in the BABAR detector reflects that of the colliding electrons and positrons. The mean boost direction, when combined with the measured orientation of the luminous ellipsoid, determines the e{sup +}-e{sup -} crossing angles. The average angular spread of the transverse boost vector provides an accurate measure of the angular divergence of the incoming high-energy beam, confirming the presence of a sizeable dynamic-{beta} effect. The longitudinal and transverse dependence of the boost angular spread also allow to extract from the continuously-monitored distributions detailed information about the emittances and IP {beta}-functions of both beams during high-luminosity operation.
Date: July 19, 2006
Creator: Weaver, M.; /SLAC; Kozanecki, W.; /DAPNIA, Saclay; Viaud, B. & U., /Montreal
Partner: UNT Libraries Government Documents Department

Modeling Lost-Particle Backgrounds in PEP-II Using LPTURTLE

Description: Background studies during the design, construction, commissioning, operation and improvement of BaBar and PEP-II have been greatly influenced by results from a program referred to as LPTURTLE (Lost Particle TURTLE) which was originally conceived for the purpose of studying gas background for SLC. This venerable program is still in use today. We describe its use, capabilities and improvements and refer to current results now being applied to BaBar.
Date: May 17, 2005
Creator: Fieguth, T.; /SLAC; Barlow, R.; U., /Manchester; Kozanecki, W. & /DAPNIA, Saclay
Partner: UNT Libraries Government Documents Department

Experimental Characterization of PEP-II Luminosity And Beam-Beam Performance

Description: The beam-beam performance of the PEP-II B-Factory has been studied by simultaneously measuring the instantaneous luminosity, the horizontal and vertical e{sup +} and e{sup -} beam sizes in the two rings, and the spatial extent of the luminous region as extracted from BaBar dilepton data. These quantities, as well as ring tunes, beam lifetimes and other collider parameters are recorded regularly as a function of the two beam currents, both parasitically during routine physics running and in a few dedicated accelerator physics experiments. They are used to quantify and improve the PEP-II beam-beam performance.
Date: May 9, 2005
Creator: Kozanecki, W.; Baak, M. A.; Seeman, J.; Sullivan, M. K. & Wienands, U.
Partner: UNT Libraries Government Documents Department

Experimental Study of Crossing-Angle and Parasitic Effects at the PEP-II e+e- Collider

Description: In a series of dedicated accelerator experiments, we measure the dependence of the PEP-II luminosity performance on small horizontal crossing angles and on the horizontal separation at the first parasitic crossing. The experiment is carried out by varying the IP angle of one of the beams in two different bunch patterns, one with and one without parasitic crossings. The measurements show satisfactory agreement with three-dimensional beam-beam simulations.
Date: October 7, 2005
Creator: Kozanecki, W.; Narsky, Ilya V.; Cai, Y.; Seeman, J. T. & Sullivan, M.
Partner: UNT Libraries Government Documents Department

Beam-Beam deflection as a beam tuning tool at the SLAC Linear Collider

Description: 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. 13 refs., 5 figs.
Date: April 1, 1989
Creator: Koska, W.; Bambade, P.; Kozanecki, W.; Phinney, N. & Wagner, S.R.
Partner: UNT Libraries Government Documents Department

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

Description: 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.
Date: May 1, 1991
Creator: Rouse, F.; Gromme, T.; Kozanecki, W. & Phinney, N.
Partner: UNT Libraries Government Documents Department

Alignment of the SLC Final Focus system using beam orbits

Description: Beam based alignment is being routinely applied in the SLC Final Focus and has proved to be a very useful tool for determining the quality of the zeroth order orbit as defined by various beam line elements. Given the stringent requirement on the beam quality at the interaction point, a well aligned beam line is essential in that it minimizes the confusion which would otherwise arise in the higher order optics, the demand called on the correctors which also serve as optical knobs, and the problem associated with the background radiation. In the SLC final focus we have been relying on an interplay between the field survey and the orbit analysis to achieve this purpose. Mechanical alignment generally provides coordinate information of various beam line elements and offset values inferred from these data and the model of the beam line. Beam based alignment is done mainly by recording the beam orbit under controlled experiment where optical elements or orbit conditions are varied. Due to the complexity of the beamline layout and special power supply configuration in the SLC Final Focus, the latter method is useful only when coupled with off-line analysis which disentangles the data taken at each measurement. In this report we describe the techniques used and the underlying principle, the procedure as applied in the Final Focus, the outcome of this exercise and some problems encountered. 6 figs.
Date: August 1, 1991
Creator: Chao, Y.; LeDiberder, F.; Burchat, P.; Kozanecki, W. & Toge, N.
Partner: UNT Libraries Government Documents Department

Beam-Beam Diagnostics from Closed-Orbit Distortion

Description: The authors study the applicability of beam-beam deflection techniques as a tuning tool for asymmetric B factories, focusing on PEP-II as an example. 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, they calculate the residual beam orbit distortions due to the beam-beam interaction. Difference orbit measurements, performed at points conveniently distant from the interaction point (IP), provide distinct 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. Because of their two-ring structure, asymmetric B factories are likely to require more diagnostics and feedback mechanisms than single-ring colliders in order to guarantee head-on collisions. In addition to the traditional techniques, however, the independence of the two beams allows one to envisage other kinds of beam diagnostics. In this article they investigate one such possibility, by looking at the closed orbit distortion produced by the beam-beam interaction when the beams do not collide exactly head-on. They base this investigation on an analytic model and strong-strong multiparticle simulations. Although the discussion uses the PEP-II design as an example, the conclusion is that this technique is quite a promising diagnostics tool for asymmetric colliders in general.
Date: July 1, 1992
Creator: Furman, M.; Chin, Y.-H.; Eden, J.; Kozanecki, W.; Tennyson, J. & Ziemann, V.
Partner: UNT Libraries Government Documents Department

Simulations and Experiments of Beam-Beam Effects in e+e- Storage Rings

Description: Over the past decade, extensive simulations of beam-beam effects in e{sup +}e{sup -} colliders, based on the particle-in-cell method, were developed to explain many complex experimental observations. Recently, such simulations were used to predict the future luminosity performance of e{sup +}e{sup -} colliders. Some predictions have been proven to be correct in the existing accelerators. In this paper, many effects such as the beam-beam limit, crossing angle, parasitic collisions, betatron spectrum, and the beam-beam lifetime, will be directly compared between simulations and experiments.
Date: May 16, 2005
Creator: Cai, Y.; Seeman, J.; /SLAC; Kozanecki, W.; /DAPNIA, Saclay; Ohmi, K. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the Luminous-Region Profile at the PEP-II IP, And Application to e^\pm Bunch-Length Determination

Description: The three-dimensional luminosity distribution at the interaction point (IP) of the SLAC B-Factory is measured continuously, using e{sup +}e{sup -} {yields} e{sup +}e{sup -}, {mu}{sup +}{mu}{sup -} events reconstructed online in the BABAR detector. The centroid of the transverse luminosity profile provides a very precise and reliable monitor of medium- and long-term orbit drifts at the IP. The longitudinal centroid is sensitive to variations in the relative RF phase of the colliding beams, both over time and differentially along the bunch train. The measured horizontal r.m.s. width of the distribution is consistent with a sizeable dynamic-{beta} effect; it is also useful as a benchmark of strong-strong beam-beam simulations. The longitudinal luminosity distribution depends on the e{sup {+-}} bunch lengths and vertical IP {beta}-functions, which can be different in the high- and low-energy rings. Using independent estimates of the {beta}functions, we analyze the longitudinal shape of the luminosity distribution in the presence of controlled variations in accelerating RF voltage and/or beam current, to extract measurements of the e{sup +} and e{sup -} bunch lengths.
Date: February 10, 2006
Creator: Viaud, B. F.; Kozanecki, W.; Narsky, I. V.; O'Grady, C. & Perazzo, A.
Partner: UNT Libraries Government Documents Department

Simulation of PEP-II Accelerator Backgrounds Using TURTLE

Description: We present studies of accelerator-induced backgrounds in the BaBar detector at the SLAC B-Factory, carried out using LPTURTLE, a modified version of the DECAY TURTLE simulation package. Lost-particle backgrounds in PEP-II are dominated by a combination of beam-gas bremstrahlung, beam-gas Coulomb scattering, radiative-Bhabha events and beam-beam blow-up. The radiation damage and detector occupancy caused by the associated electromagnetic shower debris can limit the usable luminosity. In order to understand and mitigate such backgrounds, we have performed a full program of beam-gas and luminosity-background simulations, that include the effects of the detector solenoidal field, detailed modeling of limiting apertures in both collider rings, and optimization of the betatron collimation scheme in the presence of large transverse tails.
Date: February 15, 2006
Creator: Barlow, R. J.; Fieguth, T.; Kozanecki, W.; Majewski, S. A.; Roudeau, P. & Stocchi, A.
Partner: UNT Libraries Government Documents Department

Operational experience with optical matching in the SLC Final Focus System

Description: In the SLC Final Focus System, all components of transverse phase-space and the couplings between them must be controlled to minimize the beam size at the interaction point. After summarizing the experimental algorithm and the on-line tuning programs, we present a consistent set of measurements and describe our present understanding of the various contributions to this beam size. 17 refs., 9 figs.
Date: January 1, 1989
Creator: Bambade, P.; Burchat, P.; Burke, D.; Ford, W.; Hawkes, C.; Koska, W. et al.
Partner: UNT Libraries Government Documents Department

Measurement of. nu. p. --> nu. p and anti. nu. p. -->. anti. nu. p elastic scattering. [Differential cross sections, systematic errors, coupling-constant constraints, form factors]

Description: There were 217 (66) events of the process ..nu..p..--> nu..p (anti ..nu..p..-->..anti..nu..p) with an estimated background of 82 (28). The neutral to charged current ratios are sigma(..nu..p..--> nu..p)/sigma(..nu..n..--> mu../sup -/p) = 0.11 +- 0.02 and sigma(anti ..nu..p ..-->.. anti ..nu..p)/sigma (anti ..nu..p ..-->.. ..mu../sup +/n) = 0.19 +- 0.05 for 0.40 < q/sup 2/ < 0.90 (GeV/c)/sup 2/ where -q/sup 2/ is the square of the four momentum transfer to the proton. These yield sigma(anti ..nu..p ..-->.. anti ..nu..p)(..nu..p..--> nu..p) = 0.53 +- 0.17. The errors quoted are statistical; systematic uncertainties are less than 20%. This value of the cross section ratio establishes at a level of approximately 2 1/2 standard deviations that the neutral current is neither pure V, A, T or any mixture of S and P. The present measurements place significant restrictions on the neutral current coupling constants, element of/sub L/(u), element of/sub L/(d), element of/sub R/(u), element of/sub R/(d). The allowed domains are presented including a discussion of the effect of systematic errors. 27 references
Date: January 1, 1978
Creator: Williams, H.H.; Entenberg, A.; Kozanecki, W.; Horstkotte, J.; Mann, A.K.; Rubbia, C. et al.
Partner: UNT Libraries Government Documents Department

Beam-beam diagnostics from closed-orbit distortion

Description: We study the applicability of beam-beam deflection techniques as a tuning tool for asymmetric B factories, focusing on PEP-II as an example. 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 interaction point (IP), provide distinct 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.
Date: July 1, 1992
Creator: Furman, M.; Chin, Y. H.; Eden, J.; Kozanecki, W.; Tennyson, J. & Ziemann, V.
Partner: UNT Libraries Government Documents Department

Closed orbit distortion and the beam-beam interaction

Description: 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.
Date: June 1, 1992
Creator: Furman, M.; Chin, Y. H.; Eden, J.; Kozanecki, W.; Tennyson, J. & Ziemann, V.
Partner: UNT Libraries Government Documents Department

Closed Orbit Distortion and the Beam-Beam Interaction

Description: 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.
Date: February 23, 2007
Creator: Furman, M.; Chin, Y.; Eden, J.; /LBL, Berkeley; Kozanecki, W.; /DAPNIA, Saclay /SLAC et al.
Partner: UNT Libraries Government Documents Department