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Nb3Sn quadrupoles in the LHC IR Phase I upgrade

Description: After a number of years of operation at nominal parameters, the LHC will be upgraded to a higher luminosity. This paper discusses the possibility of using a limited number of Nb{sub 3}Sn quadrupoles for hybrid optics layouts for the LHC Phase I luminosity upgrades with both NbTi and Nb{sub 3}Sn quadrupoles. Magnet parameters and issues related to using Nb{sub 3}Sn quadrupoles including aperture, gradient, magnetic length, field quality, operation margin, et cetera are discussed.
Date: June 1, 2008
Creator: Zlobin, A.V.; Johnstone, J.A.; Kashikhin, V.V.; Mokhov, N.V.; Rakhno, I.L.; /Fermilab et al.
Partner: UNT Libraries Government Documents Department

Analysis of optics designs for the LHC IR upgrade

Description: We consider the different options proposed for the LHC IR upgrade. The two main categories: quadrupoles first (as in the baseline design) and dipoles-first have complementary strengths. We analyze the potential of the proposed designs by calculating important performance parameters. We also propose a local scheme for correcting the quadratic chromaticity.
Date: June 1, 2007
Creator: Sen, Tanaji & Johnstone, John
Partner: UNT Libraries Government Documents Department

Nonlinear integrable ion traps

Description: Quadrupole ion traps can be transformed into nonlinear traps with integrable motion by adding special electrostatic potentials. This can be done with both stationary potentials (electrostatic plus a uniform magnetic field) and with time-dependent electric potentials. These potentials are chosen such that the single particle Hamilton-Jacobi equations of motion are separable in some coordinate systems. The electrostatic potentials have several free adjustable parameters allowing for a quadrupole trap to be transformed into, for example, a double-well or a toroidal-well system. The particle motion remains regular, non-chaotic, integrable in quadratures, and stable for a wide range of parameters. We present two examples of how to realize such a system in case of a time-independent (the Penning trap) as well as a time-dependent (the Paul trap) configuration.
Date: October 1, 2011
Creator: Nagaitsev, S.; /Fermilab; Danilov, V. & /SNS Project, Oak Ridge
Partner: UNT Libraries Government Documents Department

Effect of Field Errors in Muon Collider IR Magnets on Beam Dynamics

Description: In order to achieve peak luminosity of a Muon Collider (MC) in the 10{sup 35} cm{sup -2}s{sup -1} range very small values of beta-function at the interaction point (IP) are necessary ({beta}* {le} 1 cm) while the distance from IP to the first quadrupole can not be made shorter than {approx}6 m as dictated by the necessity of detector protection from backgrounds. In the result the beta-function at the final focus quadrupoles can reach 100 km making beam dynamics very sensitive to all kind of errors. In the present report we consider the effects on momentum acceptance and dynamic aperture of multipole field errors in the body of IR dipoles as well as of fringe-fields in both dipoles and quadrupoles in the ase of 1.5 TeV (c.o.m.) MC. Analysis shows these effects to be strong but correctable with dedicated multipole correctors.
Date: May 1, 2012
Creator: Alexahin, Y.; Gianfelice-Wendt, E.; Kapin, V.V. & /Fermilab
Partner: UNT Libraries Government Documents Department

An application for tunes and coupling evaluation from turn-by-turn data at the Fermilab Booster

Description: A console application using the phasing of Turn-by-Turn signals from the different BPMs has been tested at the Fermilab Booster. This technique allows the on-line detection of the beam tunes during the fast Booster ramp in conditions where other algorithms were unsuccessful. The application has been recently expanded to include the computation of the linear coupling coefficients. Algorithm and measurement results are presented. Although improved by the phased sum technique the automatic identification of the tunes is not always successful. This makes the use of the on-line application difficult. Ideas for further improvements are under investigation. Measurements have indicated that the effect of the skew quadrupoles is by a factor 3 weaker than expected from the nominal optics. A calibration of the skew quadrupole circuits using the TBT data is planned.
Date: March 1, 2011
Creator: Marsh, W.; Alexahin, Y.; Gianfelice-Wendt, E. & /Fermilab
Partner: UNT Libraries Government Documents Department

Scenarios for the ATF2 Ultra-Low Betas Proposal

Description: The current ATF2 Ultra-Low beta proposal was designed to achieve 20nm vertical IP beam size without considering the multipolar components of the FD magnets. In this paper we describe different scenarios that avoid the detrimental effect of these multipolar errors to the beam size at the interaction point (IP). The simplest approach consists in modifying the optics, but other solutions are studied as the introduction of super-conducting wigglers to reduce the emittance or the replacement of the normal-conducting focusing quadrupole in the Final Doublet (NC-QF1FF) with a super-conducting quadrupole one (SC-QF1FF). These are fully addressed in the paper.
Date: June 29, 2012
Creator: Marin, Eduardo; /CERN; Tomas, Rogelio; /CERN; Bambade, Philip; /Orsay, LAL et al.
Partner: UNT Libraries Government Documents Department

Coupling Measurements in ATF2 Extraction Line

Description: The purpose of ATF2 is to deliver a beam with stable very small spotsizes as required for future linear colliders such as ILC or CLIC. To achieve that, precise controls of aberrations such as dispersion and coupling are necessary. Theoretically, the complete reconstruction of the beam matrix is possible from the measurements of horizontal, vertical and tilted beam sizes, combining skew quadrupole scans at several wire-scanner positions. Such measurements were performed in the extraction line (EXT) of ATF2 in May 2009. We present analysis results attempting to resolve the 4 x 4 beam matrix. We aimed to reconstruct the full beam matrix using only skew quadrupole scans at different EXT wire-scanner locations, with measurements of horizontal, vertical and two tilted beam size projections. Checking the coherence of the {sigma}{sub 13} reconstruction from the {sigma}{sub 80{sup o}} and the {sigma}{sub 100{sup o}} measurements was essential to perform this analysis. We have shown that reconstruction of the coupling element can not be performed independantly of the 4 x 4 diagonal ones since it leads to unphysical results. A more accurate and automatisable method was find, leading to physical beam matrix reconstruction, compatible with the measurements. Another analysis should be performed based on a larger number of data sets to minimise statistical errors.
Date: June 29, 2012
Creator: Rimbault, Cecile; /Orsay, LAL; Kuroda, Shigeru; /KEK, Tsukuba; Tauchi, Toshiaki; /KEK, Tsukuba et al.
Partner: UNT Libraries Government Documents Department

Variable Permanent Magnet Quadrupole

Description: A permanent magnet quadrupole (PMQ) is one of the candidates for the final focus lens in a linear collider. An over 120 T/m strong variable permanent magnet quadrupole is achieved by the introduction of saturated iron and a 'double ring structure'. A fabricated PMQ achieved 24 T integrated gradient with 20 mm bore diameter, 100 mm magnet diameter and 20 cm pole length. The strength of the PMQ is adjustable in 1.4 T steps, due to its 'double ring structure': the PMQ is split into two nested rings; the outer ring is sliced along the beam line into four parts and is rotated to change the strength. This paper describes the variable PMQ from fabrication to recent adjustments.
Date: May 23, 2007
Creator: Mihara, T.; Iwashita, Y.; U., /Kyoto; Kumada, M.; /NIRS, Chiba; Spencer, C.M. et al.
Partner: UNT Libraries Government Documents Department

Operational aspects of the Main Injector large aperture quadrupole (WQB)

Description: A two-year Large Aperture Quadrupole (WQB) Project was completed in the summer of 2006 at Fermilab. [1] Nine WQBs were designed, fabricated and bench-tested by the Technical Division. Seven of them were installed in the Main Injector and the other two for spares. They perform well. The aperture increase meets the design goal and the perturbation to the lattice is minimal. The machine acceptance in the injection and extraction regions is increased from 40{pi} to 60{pi} mm-mrad. This paper gives a brief report of the operation and performance of these magnets. Details can be found in Ref [2].
Date: June 1, 2007
Creator: Chou, W.; Bartelson, L.; Brown, B.; Capista, D.; Crisp, J.; DiMarco, J. et al.
Partner: UNT Libraries Government Documents Department

New corrector system for the Fermilab booster

Description: We present an ambitious ongoing project to build and install a new corrector system in the Fermilab 8 GeV Booster. The system consists of 48 corrector packages, each containing horizontal and vertical dipoles, normal and skew quadrupoles, and normal and skew sextupoles. Space limitations in the machine have motivated a unique design, which utilizes custom wound coils around a 12 pole laminated core. Each of the 288 discrete multipole elements in the system will have a dedicated power supply, the output current of which is controlled by an individual programmable ramp. This paper describes the physics considerations which drove the design, as well as issues in the control of the system.
Date: June 1, 2007
Creator: Prebys, E.J.; Drennan, C.C.; Harding, D.J.; Kashikhin, V.; Lackey, J.R.; Makarov, A. et al.
Partner: UNT Libraries Government Documents Department

Test results of Fermilab-built quadrupoles for the LHC interaction regions

Description: As part of the US LHC Accelerator Project, Fermilab is nearing the completion of the Q2 optical elements for the LHC interaction region final focus. Each Q2 element (LQXB) consists of two identical high gradient quadrupoles (MQXB) with a dipole orbit corrector (MCBX). This paper summarizes the test results for the LQXB/MQXB program including quench performance, magnetic measurements and alignment, and gives the status of production and delivery of the LQXB magnets to the LHC.
Date: June 1, 2006
Creator: Lamm, M.J.; Bossert, R.; DiMarco, J.; Feher, S.; Hocker, J.A.; Kerby, J. et al.
Partner: UNT Libraries Government Documents Department

Modification and Measurement of the Adjustable Permanent Magnet Quadrupole for the Final Focus in a Linear Collider

Description: An adjustable permanent magnet quadrupole has been developed for the final focus (FF) in a linear collider. Recent activities include a newly fabricated inner ring to demonstrate the strongest field gradient at a smaller bore diameter of 15mm and a magnetic field measurement system with a new rotating coil. The prospects of the R&D will be discussed.
Date: January 18, 2008
Creator: Kuroda, S.; Okugi, T.; Tauchi, T.; /KEK, Tsukuba; Fujisawa, H.; Ichikawa, M. et al.
Partner: UNT Libraries Government Documents Department

Fixing the Closed Orbits in the Debuncher

Description: Without a large number of new trims the best way to fix the closed orbits in the debuncher is to move quads. There are some obvious features in the vertical orbit, Figure 1, that look like they are indeed orbit distortions. The horizontal orbit, Figure 2, also has some systematic features that can be removed by moving a small number of quads. It is likely that removing these orbit distortions will help in improving the aperture. In addition, the second order effects of such large offsets in the closed orbit, like changes in phase advance due to the sextapoles, could improve operations.
Date: April 5, 1991
Creator: Halling, Mike
Partner: UNT Libraries Government Documents Department

Recycler Chromaticities and End Shims for NOvA at Fermilab

Description: In era of NOvA operation, it is planned to slip-stack six on six Booster proton batches in the Recycler ring for a total intensity of 5 x 10{sup 13} protons/cycle. During the slip-stacking, the chromaticities are required to be jumped from (-2,-2) to (-20,-20). However, with the existing 2 families of powered sextupoles in the lattice, the chromaticities can only be adjusted to (-12,-12) from (-2,-2). On the other hand, the presently designed Recycler lattice for Nova replaces the 30 straight section with 8 'D-D half FODO cells'. With the limit of the feasible quad strength, 3 quads in a half-cell were used to obtain the working point under, and the maximum beta-functions in this section cannot be less than 80 m. In this paper, we re-designed the end shims of the permanent magnets in the ring lattice with appropriate quadrupole and sextupole components to meet both chromaticity and tune requirements. We are able to use 2 quads in a half cell in RR30 straight section within feasible quad strength. The maximum beta-functions are also lowered to around 55 m. The dynamic aperture tracking has been done using MAD to simulate the scenario of beam injection into the Recycler ring for Nova.
Date: May 1, 2012
Creator: Xiao, M.
Partner: UNT Libraries Government Documents Department

Preliminary Analysis on Linac Oscillation Data LI05-19 and Wake Field Energy Loss in FACET Commissioning 2012

Description: In this note, preliminary analysis on linac ocsillation data in FACET linac LI05-09 plus LI11-19 is presented. Several quadrupoles are identified to possibly have different strength, compared with their designed strength in the MAD optics model. The beam energy loss due to longitudinal wake fields in the S-band linac is also analytically calculated, also by LITRACK numerical simulations.
Date: July 23, 2012
Creator: Sun, Yipeng
Partner: UNT Libraries Government Documents Department

Linear Collider Accelerator Physics Issues Regarding Alignment

Description: The next generation of linear colliders will require more stringent alignment tolerances than those for the SLC with regard to the accelerating structures, quadrupoles, and beam position monitors. New techniques must be developed to achieve these tolerances. A combination of mechanical-electrical and beam-based methods will likely be needed.
Date: August 12, 2005
Creator: Seeman, J. T.
Partner: UNT Libraries Government Documents Department

Survey and Alignment of SLAC's B Factory

Description: The survey and alignment of SLAC's B-factory injector and high energy ring will be complete in March 1997. Modern digital electronic surveying tools are contributing to new, efficient alignment procedures. A laser tracker was used to fiducialize almost 300 quadrupole magnets. Digital levels were used to pre-set base plate elevations. Theodolites with very accurate co-axial distance meters were used for everything from layout to 3D magnet positioning to network surveys, all in free stationing mode. A number of procedures and measurement results are outlined.
Date: September 8, 2011
Creator: Pietryka, Matthew J. & Gaydosh, Michael L.
Partner: UNT Libraries Government Documents Department

A Second-Order Achromat Design Based on FODO Cell

Description: Two dipole doglegs are widely used to translate the beam axis horizontally or vertically. Quadrupoles are placed between the two consecutive dipoles to match first order dispersion and provide betatron focusing. Similarly a four dipole chicane is usually employed to form a bypass region, where the beam axis is transversely shifted first, then translated back to the original axis. In order to generate an isochronous section, quadrupoles are again needed to tune the first order transfer matrix element R{sub 56} equaling zero. Usually sextupoles are needed to correct second order dispersion in the bending plane, for both the dogleg optics and the chicane (with quad) optics. In this paper, an alternative optics design is introduced, which is based on a simple FODO cell and does not need sextupoles assistance to form a second-order achromat. It may provide a similar function of either a dogleg or a bypass, by using 2 or 4 of such combined supercells.
Date: August 19, 2011
Creator: Sun, Yipeng
Partner: UNT Libraries Government Documents Department

Study of 2-in1 large-aperture Nb3Sn IR quadrupoles for the LHC luminosity upgrade

Description: Double-aperture Nb{sub 3}Sn quadrupoles with asymmetric coils and with cold and warm iron yokes were studied for the dipole-first upgrade scenario of the LHC Interaction Regions (IR). This paper describes the magnet design concepts and discusses their performance parameters, including field gradient and field quality limitations.
Date: June 1, 2006
Creator: Kashikhin, V. V. & Zlobin, A. V.
Partner: UNT Libraries Government Documents Department

An Improved Design for a Super-B Interaction Region

Description: We present an improved design for a Super-B interaction region. The new design attempts to minimize the bending of the two colliding beams which results from shared magnetic elements near the Interaction Point (IP). The total crossing angle at the IP is increased from 34 mrad to 50 mrad and the distance from the IP to the first quadrupole is increased. Although the two beams still travel through this shared magnet, these changes allow for a new magnetic field design with a septum which gives the magnet two magnetic centers. This greatly reduces the beam bending from this shared quadrupole and thereby reduces the radiative bhabha background for the detector as well as any beam emittance growth from the bending. We describe the new design for the interaction region.
Date: July 25, 2008
Creator: Sullivan, M.K.; Seeman, J.; Wienands, U.; /SLAC; Bettoni, S.; /CERN et al.
Partner: UNT Libraries Government Documents Department

Virtual Accelerator for Accelerator Optics Improvement

Description: Through determination of all quadrupole strengths and sextupole feed-downs by fitting quantities derivable from precision orbit measurement, one can establish a virtual accelerator that matches the real accelerator optics. These quantities (the phase advances, the Green's functions, and the coupling ellipses tilt angles and axis ratios) are obtained by analyzing turn-by-turn Beam Position Monitor (BPM) data with a model-independent analysis (MIA). Instead of trying to identify magnet errors, a limited number of quadrupoles are chosen for optimized strength adjustment to improve the virtual accelerator optics and then applied to the real accelerator accordingly. These processes have been successfully applied to PEP-II rings for beta beating fixes, phase and working tune adjustments, and coupling reduction to improve PEP-II luminosity.
Date: September 30, 2005
Creator: Yan, Y.T.; Cai, Y.; Decker, F-J.; Ecklund, S.; Irwin, J.; Seeman, J. et al.
Partner: UNT Libraries Government Documents Department

DAFNE Setup And Operation With the Crab-Waist Collision Scheme

Description: In the second half of 2007 a major upgrade has been implemented on the Frascati DA{Phi}NE collider in order to test the novel idea of Crab-Waist collisions. New vacuum chambers and permanent quadrupole magnets have been designed, built and installed to realize the new configuration. At the same time the performances of relevant hardware components, such as fast injection kickers and shielded bellows have been improved relying on new design concepts. The collider has been successfully commissioned in this new configuration. The paper describes several experimental results about linear and non-linear optics setup and optimization, damping of beam-beam instabilities and discusses the obtained luminosity performances. DA{Phi}NE [1] is the Frascati lepton collider working at the c m. energy of the {Phi} meson resonance (1020). It came in operation in 2001 and till summer 2007 provided luminosity, in sequence, to three different experiments which logged a total integrated luminosity of {approx} 4.4 fb{sup -1}. During these years the collider reached its best performances in terms of luminosity and background (L{sub peak} = 1.6 x 10{sup 32} cm{sup -2}s{sup -1} L{sub day} {approx} 10 pb{sup -1}) by means of several successive upgrades, relying on the experience gathered during the collider operations and implemented exploiting the shutdowns required for the experiment change over [2, 3, 4].
Date: October 21, 2011
Creator: Milardi, C.; Alesini, D.; Biagini, M.E.; Biscari, C.; Boni, R.; Boscolo, M. et al.
Partner: UNT Libraries Government Documents Department

Emittance Correction in the 2006 ILC Bunch Compressor

Description: A recent study [1] has indicated substantial potential emittance growth in the ILC bunch compressor due to quad misalignments, BPM misalignments, and pitches in the RF cavities. Table 1 summarizes several results from [1]. In this simulation, quad misalignments and cavity pitches are Gaussian distributed and are considered with respect to the nominal survey line; BPM misalignments are also Gaussian-distributed but are considered with respect to the quadrupole axis. It is assumed that the BPM offsets with respect to the quads are found in a previous quad-shunting BBA step which is not simulated. In this study we seek to repeat the studies documented above, and additionally to perform a study in which additional dispersion bumps are used to further reduce the projected emittance.
Date: March 5, 2007
Creator: Tenenbaum, P.
Partner: UNT Libraries Government Documents Department

Studies of a gas-filled helical muon beam cooling channel

Description: A helical cooling channel (HCC) can quickly reduce the six dimensional phase space of muon beams for muon colliders, neutrino factories, and intense muon sources. The HCC is composed of solenoidal, helical dipole, and helical quadrupole magnetic fields to provide the focusing and dispersion needed for emittance exchange as the beam follows an equilibrium helical orbit through a continuous homogeneous absorber. The beam dynamics of a gas-filled helical muon beam cooling channel is studied by using Monte Carlo simulations. The results verify the cooling theory [1] of the helical magnet. The cooling performance has been improved by correcting chromatic aberration and the non-linear effects caused by the ionization energy loss process. With these improvements, a simulated cooling channel of 160 meters length has achieved a reduction of 6-dimensional (6D) phase space by a factor of 50,000.
Date: June 1, 2006
Creator: Yonehara, K.; /Fermilab; Derbenev, Y.; Lab, /Jefferson; Johnson, R.P.; Roberts, T.J. et al.
Partner: UNT Libraries Government Documents Department