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in creator/contributor: "Calaga, R."

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Transverse Coupling Measurement Using SVD Modes From Beam Histories.

In this report we investigate the measurement of local transverse coupling from turn-by-turn data measured at a large number of beam position monitors. We focus on a direct measurement of coupled lattice functions using the singular value decomposition (SVD) modes and explore the accuracy of this method.

Date: July 5, 2004

Creator: Calaga, R. & Wang, C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

RHIC BPM Performance: Comparison of Run 2003 and 2004.

Identification of malfunctioning beam position monitors (BPMs) play an important role in any orbit or turn-by-turn analysis. Singular value decomposition (SVD) and Fourier transform methods were recently employed to identify malfunctioning BPMs at RHIC. A detailed statistical comparison between the two methods for Run 2003 was in good agreement and proved to be a robust method to identify faulty BPMs. We evaluate detailed BPM performance for different upgrades of BPM low-level software during R… more

Date: July 5, 2004

Creator: Calaga, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

LHC crab-cavity aspects and strategy

The 3rd LHC Crab Cavity workshop (LHC-CC09) took place at CERN in October 2009. It reviewed the current status and identified a clear strategy towards a future crab-cavity implementation. Following the success of crab cavities in KEK-B and the strong potential for luminosity gain and leveling, CERN will pursue crab crossing for the LHC upgrade. We present a summary and outcome of the variousworkshop sessions which have led to the LHC crab-cavity strategy, covering topics like layout, cavity des… more

Date: May 23, 2010

Creator: Calaga, R.; Tomas, R. & Zimmermann, F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Synchro-betatron effects in the presence of large Piwinski angle and crab cavities at the HL-LHC

The reduction of {beta}* at the collision points for the high luminosity LHC (HL-LHC) requires an increment in the crossing angle to maintain the normalized beam separation to suppress the effects of long-range beam-beam interactions. However, an increase in the crossing angle may give rise to synchro-betatron resonances which may negatively affect the beam emittance and lifetime. 6D weak-strong and strong-strong simulations were performed to study the effect of synchro-betatron resonances in t… more

Date: May 20, 2012

Creator: S., White; Calaga, R. & Miyamoto, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Summary of the Mini BNL/LARP/CARE-HHH Workshop on Crab Cavities for the LHC (LHC-CC08)

The first mini-workshop on crab compensation for the LHC luminosity upgrade (LHC-CC08) was held February 24-25, 2008 at the Brookhaven National Laboratory. A total of 35 participants from 3 continents and 15 institutions from around the world participated to discuss the exciting prospect of a crab scheme for the LHC. If realized it will be the first demonstration in hadron colliders. The workshop is organized by joint collaboration of BNL, US-LARP and CARE-HHH. The enormous interest in the subj… more

Date: May 1, 2008

Creator: Ben-Zvi, Ilan; Calaga, R. & Zimmermann, F.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

RHIC BBLR measurements in 2009

Long range beam-beam experiments were conducted during the Run 2009 in the Yellow and the Blue beams of the RHIC accelerator with DC wires. The effects of a long-range interaction with a DC wire on colliding and non-colliding bunches with the aid of beam losses, orbits, tunes were studied. Results from distance scans and an attempt to compensate a long-range interaction with a DC wire is presented. Two DC wires in the vertical plane were installed in the RHIC accelerator in 2006 with the aim of… more

Date: May 23, 2010

Creator: Calaga, R.; Robert-Demolaize, G. & Fischer, W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Summary of the Mini BNL/LARP/CARE-HHH workshop on Crab Cavities for the LHC

N/A

Date: May 1, 2008

Creator: Ben-Zvi, Ilan; Calaga, R. & Zimmermann, F.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Ampere Average Current Photoinjector and Energy Recovery Linac.

High-power Free-Electron Lasers were made possible by advances in superconducting linac operated in an energy-recovery mode. In order to get to much higher power levels, say a fraction of a megawatt average power, many technological barriers are yet to be broken. We describe work on CW, high-current and high-brightness electron beams. This will include a description of a superconducting, laser-photocathode RF gun employing a new secondary-emission multiplying cathode, an accelerator cavity, bot… more

Date: August 17, 2004

Creator: Ben-Zvi, Ilan; Burrill, A. & Calaga, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Fast Compensation of Global Linear Coupling in Rhic Using Ac Dipoles.

Global linear coupling has been extensively studied in accelerators and several methods have been developed to compensate the coupling coefficient C using skew quadrupole families scans. However, scanning techniques can become very time consuming especially during the commissioning of an energy ramp. In this paper they illustrate a new technique to measure and compensate, in a single machine cycle, global linear coupling from turn-by-turn BPM data without the need of a skew quadrupole scan. The… more

Date: June 26, 2006

Creator: Calaga, R. & Franchi, A. (Gsi), Tomas, R.(Cern)

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Bpm Calibration Independent Lhc Optics Correction

The tight mechanical aperture for the LHC imposes severe constraints on both the beta and dispersion beating. Robust techniques to compensate these errors are critical for operation of high intensity beams in the LHC. We present simulations using realistic errors from magnet measurements and alignment tolerances in the presence of BPM noise. Correction reveals that the use of BPM calibration and model independent observables are key ingredients to accomplish optics correction. Experiments at RH… more

Date: June 25, 2007

Creator: Calaga, R.; Tomas, R.; Giovannozzi, M. & Zimmermann, F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

RHIC BPM SYSTEM MODIFICATIONS AND PERFORMANCE.

The RHIC beam position monitor (BPM) system provides independent average orbit and turn-by-turn (TBT) position measurements. In each ring, there are 162 measurement locations per plane (horizontal and vertical) for a total of 648 BPM planes in the RHIC machine. During 2003 and 2004 shutdowns, BPM processing electronics were moved from the RHIC tunnel to controls alcoves to reduce radiation impact, and the analog signal paths of several dozen modules were modified to eliminate gain-switching rel… more

Date: May 16, 2005

Creator: Satogata, T.; Calaga, R.; Cameron, P. & Al., Et

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Linear and chromatic optics measurements at RHIC

Measurements of chromatic beta-beating were carried out for the first time in the RHIC accelerator during Run 2009. The analysis package developed for the LHC was used to extract the off-momentum optics for injection and top energy. Results from the beam experiments and compassion to the optics model are presented. The primary goal of the RHIC experiments were execute an on-line measurement of the optics using the tools developed for the LHC. Turn-by-turn BPM trajectories (typically 1000 turns)… more

Date: May 23, 2010

Creator: Aiba, M.; Calaga, R.; Aiba, M.; Tomas, R. & Vanbavinkove, G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Global and Local Coupling Compensation Experiments in Rhic Using Ac Dipoles.

Compensation of transverse coupling during the RHIC energy ramp has been proven to be non-trivial and tedious. The lack of accurate knowledge of the coupling sources has initiated several efforts to develop fast techniques using turn-by-turn BPM data to identify and compensate these sources. This paper aims to summarize the beam experiments performed to measure the coupling, matrix and resonance driving terms with the aid of RHIC ac dipoles at injection energy.

Date: June 26, 2006

Creator: Calaga, R. & Franchi, A. (Gsi), Tomas, R.(Cern)

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Procedures and Accuracy Estimates for Beta-Beat Correction in the Lhc.

The LHC aperture imposes a tight tolerance of 20% on the maximum acceptable beta-beat in the machine. An accurate knowledge of the transfer functions for the individually powered insertion quadrupoles and techniques to compensate beta-beat are key prerequisites for successful operation with high intensity beams. They perform realistic simulations to identify quadrupole errors in LHC and explore possible ways of correction to minimize beta-beat below the 20% level.

Date: June 26, 2006

Creator: Tomas, R.; Bruning, O. (Cern); Calaga, R. & Peggs, S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

HOM damping and multipacting analysis of the quarter-wave crab cavity

The quarter-wave crab cavity design has been analyzed further to accommodate LHC requirements. The goal for the design is to provide strong deflecting voltage to the proton bunches at the IP, while keeping the effective length as short as possible. We will evaluate the higher order mode damping with two or four magnetic coupling dampers installed in different configuration. In this paper, we also show possible multipacting locations which are simulated by 2D and 3D codes.

Date: May 20, 2012

Creator: Wu, Q.; Belomestnykh, S.; Ben-Zvi, Ilan & Calaga, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

R-Square Impedances of Erl Ferrite Hom Absorber.

An R&D facility for an Energy Recovery Linac (ERL) intended as part of an electron-cooling project for RHIC is, being constructed at this laboratory. The center piece of the facility is a 5-cell 703.75 MHz super-conducting RF linac. Successful operation will depend on effective HOM damping. It is planned to achieve HOM damping exclusively with ferrite absorbers. The performance of a prototype absorber was measured by transforming it into a resonant cavity and alternatively by a conventional… more

Date: July 10, 2005

Creator: Hahn, H.; Burrill, A.; Calaga, R.; Kayran, D. & Zhao, Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

RHIC OPTICS MEASUREMENTS AT DIFFERENT WORKING POINTS.

Working point scans at RHIC were performed during 2004 to determine the effect on lifetime and luminosity. Linear optics were measured for different working point tunes by exciting coherent oscillations with the aid of RHIC AC dipoles. Two methods are currently used to measure the beta functions and phases advances: a conventional fitting technique, and an alternate method based on singular value decomposition (SVD). This paper focuses on the effect of working point on the measurement of linear… more

Date: July 5, 2004

Creator: Calaga, R.; Bai, M.; Peggs, S.; Roser, T. & Satogata, T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Measurement and Optimization of Local Coupling From RHIC BPM Data.

Global coupling in RHIC is routinely corrected by using three skew quadrupole families to minimize the tune split ({Delta}Q{sub min}). In this paper we propose to re-optimize transverse coupling by minimizing the resonance driving terms (RDT's) and the coupling matrix (|{bar C}|/{gamma}{sup 2}) in two steps: (1) Identify locations with coupling sources by inspection of the driving terms and the C-matrix around the ring and minimize the discontinuities and (2) Find the best configuration of the … more

Date: May 16, 2005

Creator: Calaga, R.; Abeytunge, S.; Bai, M.; Fischer, W. & Al., Et

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

HOM identification by bead pulling in the Brookhaven ERL cavity

Several past measurements of the Brookhaven ERL at superconducting temperature produced a long list of higher order modes (HOMs). The Niobium 5-cell cavity is terminated with HOM ferrite dampers that successfully reduce the Q-factors to tolerable levels. However, a number of undamped resonances with Q {ge} 10{sup 6} were found at 4 K and their mode identification remained as a goal for this paper. The approach taken here consists in taking different S{sub 21} measurements on a copper cavity rep… more

Date: June 25, 2012

Creator: Hahn, H.; Calaga, R.; Jain, P.; Johnson, E. C. & Xu, W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Small Angle Crab Compensation for Lhc Ir Upgrade

A small angle (< 1 mrad) crab scheme is an attractive option for the LHC luminosity upgrade to recover the geometric luminosity loss from the finite crossing angle [I]. The luminosity loss increases steeply to unacceptable levels as the IP beta function is reduced below its nominal value (see Fig. 1 in Ref. [2]). The crab compensation in the LHC can be accomplished using only two sets of deflecting RF cavities, placed in collision-free straight sections of the LHC to nullify the effective cr… more

Date: June 25, 2007

Creator: Calaga, R.; Dorda, U.; Ohmi, D.; Oide, K.; Tomas, R. & Zimmermann, F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Transverse Beam Transfer Functions of Colliding Beams in Rhic

We use transverse beam transfer functions to measure tune distributions of colliding beams in RHIC. The tune has a distribution due to the beam-beam interaction, nonlinear magnetic fields -- particularly in the interaction region magnets, and non-zero chromaticity in conjunction with momentum spread. The measured tune distributions are compared with calculations.

Date: June 25, 2007

Creator: Fischer, W.; Blaskiewicz, M.; Calaga, R.; Cameron, P.; Herr, W. & Pieloni, T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Measurement and Correction of Third Resonance Driving Term in the RHIC

To further improve the luminosity in polarized proton operation of the Relativistic Heavy Ion Collider, correction of the horizontal two-third resonance at store is desirable. The long-lasting coherent beam oscillations, produced by the AC dipole, are used to measure 3Q,'s resonance driving term h{sub 30000} through the analysis of turn-by-turn beam position data with the algorithm outlined by J. Bengtsson. The resonance driving term h30000 can be compensated with the 12 arc chromatic sextupole… more

Date: June 25, 2007

Creator: Luo, Y.; Bai, M.; Bengtsson, J.; Calaga, R.; Fischer, W. & AL., ET

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Optics for High Brightness and High Current Erl Project at Bnl.

An energy recovery linac (ERL), under development at Brookhaven National Laboratory [1,2], will push ERLs further towards high current and high brightness beams. This R&D ERL will operate in two modes: a high current mode and a high charge mode. In this paper we present a lattice of the machine and PARMELA simulations from the cathode to the beam dump. We discuss the design considerations and present main parameters for various modes of operation.

Date: May 16, 2005

Creator: Kayran, D.; Ben-Zvi, Ilan; Calaga, R.; Chang, X. Y. & Al., Et

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

LHC beam-beam compensation studies at RHIC

Long-range and head-on beam-beam effects are expected to limit the LHC performance with design parameters. To mitigate long-range effects current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. To reduce the head-on beam-beam effect electron … more

Date: May 4, 2009

Creator: Fischer, W.; Abreu, N.; Calaga, R.; Robert-Demolaize, G.; Luo, Y. & Montag, C.

Item Type: Article

Partner: UNT Libraries Government Documents Department