41 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "Brookhaven Rhic"  
Results: 1 - 24 next
open access

Coherent beam-beam effects observation and mitigation at the RHIC collider

Description: In polarized proton operation in RHIC coherent beam-beam modes are routinely observed with beam transfer function measurements in the vertical plane. With the existence of coherent modes a larger space is required in the tune diagram than without them and stable conditions can be compromised for operation with high intensity beams as foreseen for future luminosity upgrades. We report on experiments and simulations carried out to understand the existence of coherent modes in the vertical plane a… more
Date: May 20, 2012
Creator: S., White; Fischer, W. & Luo, Y.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Effects of liquid helium bubble formation in a superconducting cavity cryogenic system

Description: We constructed a simple prototype model based on the geometry of the 56 MHz superconducting cavity for RHIC. We studied the formation, in this prototype, of bubbles of liquid helium and their thermal effects on the cavity. We found that due to the low viscosity of the liquid helium, and its small surface tension, no large bubbles formed. The tiny bubbles, generated from most of the area, behaved like light gas travelling in a free space and escaped from the trapping region. The bubbles that wer… more
Date: March 1, 2011
Creator: Chang, X.; Wang, E. & Xin, T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Experimental Study of Synchro-Betatron Coupling Induced By Dipole Modulation

Description: Synchro-betatron coupling in a proton storage ring with electron cooling was studied experimentally by modulating a transverse dipole field close to the synchrotron frequency. The combination of the electron cooling and transverse field modulation on the synchrotron oscillation is equivalent to a dissipative parametric resonant system. The proton bunch was observed to split longitudinally into two pieces, or beamlets, converging toward attractors of the dissipative system. These phenomena might… more
Date: November 4, 2011
Creator: Syphers, M.; Ball, M.; Brabson, B.; Budnick, J.; Caussyn, D. D.; Chao, A. W. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

The RHIC polarized source upgrade

Description: The RHIC polarized H{sup -} ion source is being upgraded to higher intensity (5-10 mA) and polarization for use in the RHIC polarization physics program at enhanced luminosity RHIC operation. The higher beam peak intensity will allow reduction of the transverse beam emittance at injection to AGS to reduce polarization losses in AGS. There is also a planned RHIC luminosity upgrade by using the electron beam lens to compensate the beam-beam interaction at collision points. This upgrade is also es… more
Date: September 27, 2010
Creator: Zelenski, A.; Atoian, G.; Davydenko, V.; Ivanov, A.; Kolmogorov, A.; Ritter, J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

An orbit fit program for localizing errors in RHIC

Description: Many errors in an accelerator are evidenced as transverse kicks to the beam which distort the beam trajectory. Therefore, the information of the errors are imprinted in the distorted orbits, which are different from what would be predicted by the optics model. In this note, we introduce an algorithm for fitting the orbit based on an on-line optics model. By comparing the measured and fitted orbits, we first present results validating the algorithm. We then apply the algorithm and localize the l… more
Date: November 1, 2011
Creator: Liu, C.; Minty, M. & Ptitsyn, V.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Experience With Low-Energy Gold-Gold Operations in RHIC During FY 2010

Description: During Run-10, RHIC operated at several different Au-Au collision energies, as requested mainly by the STAR collaboration in a quest to search for the critical point in the QGP phase diagram. The center-of-mass energies {radical}s{sub NN} are listed in Table 1, together with the respective start and end dates and the duration of the respective run at each energy. While STAR defines 'low energy' as anything below {radical}s{sub NN} = 39 GeV, we focus in the scope of this paper on energies below … more
Date: October 7, 2011
Creator: Montag, C.; Satogata, T.; Ahrens, L. A.; Bai, M.; Beebe-Wang, J.; Blacker, I. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Observation of snake resonances at Relativistic Heavy Ion Collider

Description: The Siberian snakes are powerful tools in preserving polarization in high energy accelerators has been demonstrated at the Brookhaven Relativistic Heavy Ion Collider (RHIC). Equipped with two full Siberian snakes in each ring, polarization is preserved during acceleration from injection to 100 GeV. However, the Siberian snakes also introduce a new set of depolarization resonances, i.e. snake resonances as first discovered by Lee and Tepikian. The intrinsic spin resonances above 100 GeV are abou… more
Date: September 27, 2010
Creator: Bai, M.; Ahrens, L.; Alekseev, I.G.; Alessi, J. & al, et
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Optimizing of the higher order mode dampers in the 56MHz SRF cavity

Description: Earlier, we reported that a 56 MHz cavity was designed for a luminosity upgrade of the RHIC, and presented the requirements for Higher Order Mode (HOM) damping, the design of the HOM dampers, along with measurements and simulations of the HOM dampers. In this report, we describe our optimization of the dampers performance, and the modifications we made to their original design. We also optimized the number of the HOM dampers, and tested different configurations of locations for them.
Date: January 27, 2010
Creator: Wu, Q. & Ben-Zvi, Ilan
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Off-momentum beta-beat correction in the RHIC proton run

Description: In this article, we will review the techniques to measure the off-momentum {beta}-beat and the correction algorithms with the chromatic arc sextupoles in RHIC. We will focus on the measurement and correction of the off-momentum {beta}*-beat at the interaction points. The off-momentum {beta}* is measured with the quadrupole strength change and a high resolution phase lock loop tune meter. The results of off-momentum {beta}* correction performed in a dedicated beam experiment in the 2012 RHIC 250… more
Date: May 20, 2012
Creator: Y., Luo; Bai, M.; Fischer, W.; Marusic, A.; Mernick, K. & White, S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Off-momentum dynamic aperture for lattices in the RHIC heavy ion runs

Description: To reduce transverse emittance growth rates from intrabeam scattering in the RHIC heavy ion runs, a lattice with an increased phase advance in the arc FODO cells was adopted in 2008-2011. During these runs, a large beam loss due to limited off-momentum dynamic aperture was observed during longitudinal RF re-bucketing and with transverse cooling. Based on the beam loss observations in the previous ion runs and the calculated off-momentum apertures, we decided to adopt the lattice used before 200… more
Date: May 20, 2012
Creator: Y., Luo; Bai, M.; Blaskiewicz, M.; Gu, X.; Fischer, W.; Marusic, A. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Analysis and correction of vertical dispersion in RHIC

Description: In the context of preserving the polarization of proton beams, the source of vertical dispersion in RHIC is analyzed. Contributions to dispersion from non-coupling sources and coupling sources are compared. Based on the analysis of sources for dispersion, the right actuator for correcting dispersion is determined and a corresponding algorithm is developed.
Date: September 14, 2011
Creator: Liu, C. & Minty, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Polarization transmission at RHIC, numerical simulations

Description: Typical tracking simulations regarding the transmission of the polarization in the proton-proton collider RHIC are discussed. They participate in general studies aimed at understanding and improving polarization performances during polarized proton-proton runs.
Date: May 20, 2012
Creator: Meot, F.; Bai, M.; Liu, C.; Minty, M. & Ranjbar, V.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Gatling gun: high average polarized current injector for eRHIC

Description: This idea was originally developed in 2001 for, at that time, an ERL-based (and later recirculating-ring) electron-ion collider at JLab. Naturally the same idea is applicable for any gun requiring current exceeding capability of a single cathode. ERL-based eRHIC is one of such cases. This note related to eRHIC was prepared at Duke University in February 2003. In many case photo-injectors can have a limited average current - it is especially true about polarized photo-guns. It is know that e-RHI… more
Date: January 1, 2010
Creator: Litvinenko, V. N.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Conceptual Design of a High Precision Dual Directional Beam Position Monitoring System for Beam Crosstalk Cancellation and Improved Output Pulse Shapes

Description: The Relativistic Heavy Ions Collider (RHIC) would benefit from improved beam position measurements near the interaction points that see both beams, especially as the tolerances become tighter when reducing the beam sizes to obtain increased luminosity. Two limitations of the present beam position monitors (BPMs) would be mitigated if the proposed approach is successful. The small but unavoidable cross-talk between signals from bunches traveling in opposite directions when using conventional BPM… more
Date: April 15, 2012
Creator: Thieberger, P.; Dawson, C.; Fischer, W.; Gassner, D.; Hulsart, R.; Mernick, K. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Re-visit local coupling correction in the interaction regions of RHIC

Description: In this article we will re-visit the local coupling correction in the interaction regions (IRs) of the Relativistic Heavy Ion Collider (RHIC). We will review the measurement data of triplet quadrupole rolls, the local coupling correction strengths in the RHIC control system, and the methods for the local coupling correction with local skew quadrupole correctors. Based on the in-turnnel measurement data of triplet roll errors in 2011, we will analytically calculate and simulate IR-bump method to… more
Date: November 1, 2011
Creator: Luo, Y.; Fischer, W.; Liu, C.; Marusic, A.; Minty, M.; Ptitsyn, V. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Computational challenges for beam-beam simulation for RHIC

Description: In this article we will review the computational challenges in the beam-beam simulation for the polarized proton run of the Relativistic Heavy Ion Collider (RHIC). The difficulties in our multi-particle and million turn tracking to calculate the proton beam lifetime and proton beam emittance growth due to head-on beam-beam interaction and head-on beam-beam compensation are presented and discussed. Solutions to obtain meaningful physics results from these trackings are proposed and tested. In th… more
Date: October 1, 2010
Creator: Luo, Y. & Fischer, W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

High Precision Tune and Coupling Feedback and Beam Transfer Function Measurements in RHIC

Description: Precision measurement and control of the betatron tunes and betatron coupling in the Relativistic Heavy Ion Collider (RHIC) are required for establishing and maintaining both good operating conditions and, particularly during the ramp to high beam energies, high proton beam polarization. While the proof-of-principle for simultaneous tune and coupling feedback was successfully demonstrated earlier, routine application of these systems has only become possible recently. Following numerous modific… more
Date: May 23, 2010
Creator: Minty, M.; Curcio, A.; Dawson, C.; Degen, C.; Luo, Y.; Marr, G. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

STATUS OF THE RHIC HEAD-ON BEAM-BEAM COMPENSATION PROJECT

Description: In polarized proton operation the luminosity of RHIC is limited by the head-on beam-beam effect, and methods that mitigate the effect will result in higher peak and average luminosities. Two electron lenses, one for each ring, are being constructed to partially compensate the head-on beam-beam effect in the two rings. An electron lens consists of a low energy electron beam that creates the same amplitude dependent transverse kick as the proton beam. We discuss design considerations and present … more
Date: May 23, 2010
Creator: Fischer, W.; Luo, Y.; Pikin, A.; Beebe, E.; Bruno, D.; Gassner, D. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Low-energy run of Fermilab Electron Cooler's beam generation system

Description: As a part of a feasibility study of using the Fermilab Electron Cooler for a low-energy Relativistic Heavy Ion Collider (RHIC) run at Brookhaven National Laboratory (BNL), the cooler operation at 1.6 MeV electron beam energy was tested in a short beam line configuration. The main result of the study is that the cooler beam generation system is suitable for BNL needs. In a striking difference with running 4.3 MeV beam, no unprovoked beam recirculation interruptions were observed.
Date: August 1, 2010
Creator: Prost, Lionel; Shemyakin, Alexander; Fedotov, Alexei & Kewisch, Jorg
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Experience with split transition lattices at RHIC

Description: During the acceleration process, heavy ion beams in RHIC cross the transition energy. When RHIC was colliding deuterons and gold ions during Run-8, lattices with different integer tunes were used for the two rings. This resulted in the two rings crossing transition at different times, which proved beneficial for the 'Yellow' ring, the RF system of which is slaved to the 'Blue' ring. For the symmetric gold-gold run in FY2010, lattices with different transition energies but equal tunes were imple… more
Date: May 23, 2010
Creator: Montag, C.; Tepikian, S.; Blaskiewicz, M. & Brennan, J. M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

RHIC electron lens beam transport system design considerations

Description: To apply head-on beam-beam compensation for RHIC, two electron lenses are designed and will be installed at IP10. Electron beam transport system is one of important subsystem, which is used to transport electron beam from electron gun side to collector side. This system should be able to change beam size inside superconducting magnet and control beam position with 5 mm in horizontal and vertical plane. Some other design considerations for this beam transport system are also reported in this pap… more
Date: October 1, 2010
Creator: Gu, X.; Pikin, A.; Okamura, M.; Fischer, W.; Luo, Y.; Gupta, R. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Measurements of Fast Transition Instability in RHIC

Description: A fast transition instability presents a limiting factor for ion beam intensity in RHIC. Several pieces of evidence show that electron clouds play an important role in establishing the threshold of this instability. In RHIC Runs8 the measurements of the instability, using a button BPM, were done in order to observe details of the instability development on the scale over hundreds and thousands turns. The paper presents and discusses the results of those measurements in time and frequency domain… more
Date: May 23, 2010
Creator: Ptitsyn, V.; Blaskiewicz, M.; Fischer, W.; Lee, R. & Zhang, S. Y.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

RHIC Performance During the FY10 200 GeV Au+Au Heavy Ion Run

Description: Since the last successful RHIC Au+Au run in 2007 (Run-7), the RHIC experiments have made numerous detector improvements and upgrades. In order to benefit from the enhanced detector capabilities and to increase the yield of rare events in the acquired heavy ion data a significant increase in luminosity is essential. In Run-7 RHIC achieved an average store luminosity of <L> = 12 x 10{sup 26} cm{sup -2} s{sup -1} by operating with 103 bunches (out of 111 possible), and by squeezing to {beta}… more
Date: May 23, 2010
Creator: Brown, K. A.; Ahrens, L.; Bai, M.; Beebe-Wang, J.; Blaskiewicz, M.; Brennan, J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Lattice design for the ERL electron ion collider in RHIC

Description: We present electron ion collider lattice design for the Relativistic Heavy Ion Collider (eRHIC) where the electrons have multi-passes through recirculating linacs (ERL) and arcs placed in the existing RHIC tunnel. The present RHIC interaction regions (IR's), where the electron ion collisions will occur, are modified to allow for the large luminosity. Staging of eRHIC will bring the electron energy from 4 up to 20 (30) GeV as the superconducting cavities are built and installed sequentially. The… more
Date: May 23, 2010
Creator: Trbojevic, D.; Beebe-Wang, J.; Tsoupas, N.; Chang, X.; Kayran, D.; Ptitsyn, V. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
Back to Top of Screen