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Multiple error data analysis for RHIC low-energy operations

Description: In FY10, RHIC operated with gold beams at three different energies below its regular injection energy, namely at {radical}s = 5 GeV; 7.7 GeV; and 11.5 GeV: While beam lifetimes of about 10 minutes were achieved at 11.5 GeV and 7.7 GeV; leading to stable collider operation, beam lifetimes during tests at {radical}s = 5 GeV were only of the order of several seconds. Though space charge effects are a major concern in low energy operations due to the 1/{gamma}{sup 2} scaling of the space charge force, these can effectively be ruled out as the main cause of this abysmal performance because of the tiny bunch intensities of approximately 10{sub 8} Au/bunch, compared to 10{sup 9} Au/bunch at the two higher energies. During these 5 GeV tests, large betatron tune spreads were observed, but the extremely short beam lifetime prevented chromaticity measurements. Instead, chromaticities were scanned over a range of 40 units, but to no effect. It was therefore suspected at that time that the large tune spread was caused by higherorder multipole errors in the RHIC magnets.
Date: January 1, 2011
Creator: Montag, C.
Partner: UNT Libraries Government Documents Department

Lattice design for head-on beam-beam compensation at RHIC

Description: Electron lenses for head-on beam-beam compensation will be installed in IP 10 at RHIC. Compensation of the beam-beam effect experienced at IP 8 requires betatron phase advances of {Delta}{psi} = k {center_dot} {pi} between the proton-proton interaction point at IP 8, and the electron lens at IP 10. This paper describes the lattice solutions for both the BLUE and the YELLOW ring to achieve this goal.
Date: March 28, 2011
Creator: Montag, C.
Partner: UNT Libraries Government Documents Department

A LOW GAMMA_T INJECTION LATTICE FOR POLARIZED PROTONS IN RHIC

Description: Polarized protons are injected into the Relativistic Heavy Jon Collider (RHIC) just above transition energy. When installation of a cold partial Siberian snake in the AGS required lowering the injection energy by {Delta}{gamma} = 0.56, the transition energy in RHIC had to be lowered accordingly to ensure proper longitudinal matching. This paper presents lattice modifications implemented to lower the transition energy by {Delta}{gamma}{sub t} = 0.8.
Date: June 25, 2007
Creator: MONTAG,C.
Partner: UNT Libraries Government Documents Department

RHIC progress and future

Description: The talk reviews RHIC performance, including unprecedented manipulations of polarized beams and recent low energy operations. Achievements and limiting factors of RHIC operation are discussed, such as intrabeam scattering, electron cloud, beam-beam effects, magnet vibrations, and the efficiency of novel countermeasures such as bunched beam stochastic cooling, beam scrubbing and chamber coatings. Future upgrade plans and the pertinent R&D program will also be presented.
Date: May 4, 2009
Creator: Montag,C.
Partner: UNT Libraries Government Documents Department

Future BNL plans for a polarized electron-ion collider (eRHIC)

Description: To provide polarized electron-proton collisions of {radical}s = 100 GeV; addition of a 10 GeV electron accelerator to the existing RHIC facility is currently under study. Two design lines are under consideration: a self-polarizing electron ring, and an energy recovery linac. While the latter provides significantly higher luminosities, it is technologically very challenging. We present both design approaches and discuss their advantages and limitations.
Date: July 26, 2009
Creator: Montag,C.
Partner: UNT Libraries Government Documents Department

Vibration control in accelerators

Description: In the vast majority of accelerator applications, ground vibration amplitudes are well below tolerable magnet jitter amplitudes. In these cases, it is necessary and sufficient to design a rigid magnet support structure that does not amplify ground vibration. Since accelerator beam lines are typically installed at an elevation of 1-2m above ground level, special care has to be taken in order to avoid designing a support structure that acts like an inverted pendulum with a low resonance frequency, resulting in untolerable lateral vibration amplitudes of the accelerator components when excited by either ambient ground motion or vibration sources within the accelerator itself, such as cooling water pumps or helium flow in superconducting magnets. In cases where ground motion amplitudes already exceed the required jiter tolerances, for instance in future linear colliders, passive vibration damping or active stabilization may be considered.
Date: January 1, 2011
Creator: Montag, C.
Partner: UNT Libraries Government Documents Department

Ion bunch length effects on the beam-beam interaction in a high luminosity ring-ring electron-ion collider with head-on beam-beam compensation

Description: The luminosity of a ring-ring electron-ion collider is limited by the beam-beam effect on the electrons. Simulation studies have shown that for short ion bunches this limit can be significantly increased by head-on beam-beam compensation via an electron lens. However, due to the large beam-beam parameter experienced by the electrons, together with an ion bunch length comparable to the beta-function at the IP, electrons perform a sizeable fraction of a betatron oscillation period inside both the long ion bunches and the electron lens. Recent results of our simulation studies of this effect will be presented.
Date: May 23, 2010
Creator: Montag, C. & Fischer, W.
Partner: UNT Libraries Government Documents Department

HERA BEAM TAIL SHAPING BY TUNE MODULATION.

Description: To study CP violation, the HEM-B experiment uses an internal wire target in the transverse halo of the stored HERA proton beam. Operational experience shows that the resulting interaction rates are extremely sensitive to tiny orbit jitter amplitudes. Various methods have been studied to stabilize these interaction rates by increasing diffusion in the transverse proton beam tails without affecting the luminosity at the electron-proton collider experiments ZEUS and H1. Tune modulation was found to be a promising method for this task. Experiments performed in recent years will be reported.
Date: May 19, 2003
Creator: MONTAG,C.
Partner: UNT Libraries Government Documents Department

GROUND MOTION ACTIVITIES AT DESY - AN OVERVIEW.

Description: Ground motion studies have been performed at DESY for more than a decade, covering beam motion in the two-ring e-p collider NEW, luminosity preservation in Linear Colliders, and active stabilization methods. An overview of past and present activities will be given.
Date: September 2, 2002
Creator: MONTAG,C.
Partner: UNT Libraries Government Documents Department

Simple Beam-Optic Simulations and Proposed Mechanical Mitigation for the Triplet Oscillation Problem

Description: The purpose of these simulations is to gain a better understanding of the relative contributions to the beam perturbation from the main horizontal oscillation modes (yawing and rolling) of Q1, Q2, and Q3. For this purpose, a simple beam transport program was implemented with an EXCEL spreadsheet to calculate the horizontal beam envelop through the Q1, Q2, Q3 triplet up to the IP, with the possibility of specifying horizontal displacements of the singlets. For now, the weak focusing properties of D0 and DX have been ignored, but could easily be included in the future if necessary. In a first simulation, quadrupole strengths have been adopted that correspond to {beta}* = 2m at the IP. The parameters used listed in Table 1 were obtained from references [1] and [2].
Date: May 1, 2008
Creator: Thieberger,P.; Montag, C.; Snydstrup, L.; Trbojevic, D. & Tuozzolo, J.
Partner: UNT Libraries Government Documents Department

Summary of the RHIC Retreat 2007

Description: The RHIC Retreat 2007 took place on July 16-17 2007 at the Foxwoods Resort in CT, about 3 weeks after the end of the RHIC Run-7. The goal of the Retreat is traditionally to plan the upcoming run in the light of the results from the previous one, by providing a snapshot of the present understanding of the machine and a forum for free and frank discussion. A particular attention was paid to the challenge of increasing the time at store, and the related issue of system reliability. An interesting Session covered all new developments aimed to improve the machine performance and luminosity. In Section 2 we summarize the results from Run-7 for RHIC and the injectors and discuss the present objectives of the RHIC program and performance. Sections 3-6 are summaries of the Retreat sessions focused on preparation for deuteron gold and polarized protons, respectively, machine availability and new developments.
Date: August 1, 2008
Creator: Pilat,F.; Gardner, C.; Montag, C. & Roser, T.
Partner: UNT Libraries Government Documents Department

Summary of the RHIC Retreat 2008

Description: The main goal of the RHIC Retreat is to review last run's performance and prepare for the next. As always though we also discussed the longer term goals and plans for the facility to put the work in perspective and in the right priority. A straw-man plan for the facility was prepared for the DOE that assumes 30 cryoweek and running 2 species per year. The plan outlines RHIC operations for 2008-2012 and integrates well accelerator and detector upgrades to optimize the physics output with high luminosities. The plans includes guidance from the PAC and has been reviewed by DOE.
Date: August 1, 2008
Creator: Pilat,F.; Brennan, M.; Brown, K.; Fischer, W. & Montag, C.
Partner: UNT Libraries Government Documents Department

TOUSCHEK LIFETIME CALCULATIONS AND SIMULATIONS FOR NSLS-II

Description: The beam lifetime in most medium energy synchrotron radiation sources is limited by the Touschek effect, which describes the momentum transfer from the transverse into the longitudinal direction due to binary collisions between electrons. While an analytical formula exists to calculate the resulting lifetime, the actual momentum acceptance necessary to perform this calculation can only be determined by tracking. This is especially the case in the presence of small vertical apertures at insertion devices. In this case, nonlinear betatron coupling leads to beam losses at these vertical aperture restrictions. In addition, a realistic model of the storage ring is necessary for calculation of equilibrium beam sizes (particularly in the vertical direction) which are important for a self-consistent lifetime calculation.
Date: June 25, 2007
Creator: MONTAG,C.; BENGTSSON, J. & NASH, B.
Partner: UNT Libraries Government Documents Department

Analysis of intensity instability threshold at transition in RHIC.

Description: The beam intensity of ion beams in RHIC is limited by a fast transverse instability at transition, driven by the machine impedance and electron clouds. For gold and deuteron beams we analyze the dependence of the instability threshold on beam and machine parameters from recent operational data and dedicated experiments. We fit the machine impedance to the experimental data.
Date: June 23, 2008
Creator: Fischer,W.; Blaskiewicz, M.; Cameron, P.; Montag, C. & Ptitsyn, V.
Partner: UNT Libraries Government Documents Department