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THE RHIC HYDROGEN JET LUMINESCENCE MONITOR.

Description: A hydrogen jet polarimeter was developed for the RHIC accelerator to improve the process of measuring polarization. Particle beams intersecting with gas molecules can produce light by the process known as luminescence. This light can then be focused, collected, and processed giving important information such as size, position, emittance, motion, and other parameters. The RHIC hydrogen jet polarimeter was modified in 2005 with specialized optics, vacuum windows, light transport, and a new camera system making it possible to monitor the luminescence produced by polarized protons intersecting the hydrogen beam. This paper describes the configuration and preliminary measurements taken using the RHIC hydrogen jet polarimeter as a luminescence monitor.
Date: June 25, 2007
Creator: RUSSO,T.; BELLAVIA, S.; GASSNER, D.; THIEBERGER, P.; TRBOJEVIC, D. & TSANG, T.
Partner: UNT Libraries Government Documents Department

Sorting chromatic sextupoles for easily and effectively correcting second order chromaticity in the Relativistic Heavy Ion Collider

Description: Based on the contributions of the chromatic sextupole families to the half-integer resonance driving terms, we discuss how to sort the chromatic sextupoles in the arcs of the Relativistic Heavy Ion Collider (RHIC) to easily and effectively correct the second order chromaticities. We propose a method with 4 knobs corresponding to 4 pairs of chromatic sextupole families to online correct the second order chromaticities. Numerical simulation justifies this method, showing that this method reduces the unbalance in the correction strengths of sextupole families and avoids the reversal of sextupole polarities. Therefore, this method yields larger dynamic apertures for the proposed RHIC 2009 100GeV polarized proton run lattices.
Date: January 2, 2009
Creator: Luo,Y.; Tepikian, S.; Fischer, W.; Robert-Demolaize, G. & Trbojevic, D.
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

A new luminescence beam profile monitor for intense proton and heavy ion beams

Description: A new luminescence beam profile monitor is realized in the polarized hydrogen gas jet target at the Relativistic Heavy Ion Collider (RHIC) facility. In addition to the spin polarization of the proton beam being routinely measured by the hydrogen gas jet, the luminescence produced by beam-hydrogen excitation leads to a strong Balmer series lines emission. A selected hydrogen Balmer line is spectrally filtered and imaged to produce the transverse RHIC proton beam shape with unprecedented details on the RHIC beam profile. Alternatively, when the passage of the high energy RHIC gold ion beam excited only the residual gas molecules in the beam path, sufficient ion beam induced luminescence is produced and the transverse gold ion beam profile is obtained. The measured transverse beam sizes and the calculated emittances provide an independent confirmation of the RHIC beam characteristics and to verify the emittance conservation along the RHIC accelerator. This optical beam diagnostic technique by making use of the beam induced fluorescence from injected or residual gas offers a truly noninvasive particle beam characterization, and provides a visual observation of proton and heavy ion beams. Combined with a longitudinal bunch measurement system, a 3-dimensional spatial particle beam profile can be reconstructed tomographically.
Date: October 1, 2008
Creator: Tsang,T.; Bellavia, S.; Connolly, R.; Gassner, D.; Makdisi, Y.; Russo, T. et al.
Partner: UNT Libraries Government Documents Department

MUON ACCELERATION WITH THE RACETRACK FFAG

Description: Muon acceleration for muon collider or neutrino factory is still in a stage where further improvements are likely as a result of further study. This report presents a design of the racetrack non-scaling Fixed Field Alternating Gradient (NS-FFAG) accelerator to allow fast muon acceleration in small number of turns. The racetrack design is made of four arcs: two arcs at opposite sides have a smaller radius and are made of closely packed combined function magnets, while two additional arcs, with a very large radii, are used for muon extraction, injection, and RF accelerating cavities. The ends of the large radii arcs are geometrically matched at the connections to the arcs with smaller radii. The dispersion and both horizontal and vertical amplitude fictions are matched at the central energy.
Date: June 25, 2007
Creator: TRBOJEVIC,D.; EBERHARD, K. & SESSLER, A.
Partner: UNT Libraries Government Documents Department

SUPERCONDUCTING NON-SCALING FFAG GANTRY FOR CARBON-PROTON CANCER THERAPY

Description: We report on improvements in the non-scaling Fixed Field Alternating Gradient (FFAG) gantry design. As we previously reported, a major challenge of the carbodproton cancer therapy facilities is isocentric gantry design. The weight of the isocentric gantry transport elements in the latest Heidelberg carbon/proton facility is 135 tons. In this report we detail improvements to the previous non-scaling gantry design. We estimate that this non-scaling FFAG gantry would be almost hundred times lighter than traditional heavy ion gantries. Very strong focusing with small dispersion permits passage of different energies of carbon beams through the gantry's fixed magnetic field.
Date: June 25, 2007
Creator: TRBOJEVIC,D.; GUPTA, R.; PARKER, B.; KEIL, E. & SESSLER, A.M.
Partner: UNT Libraries Government Documents Department

OBSERVATION OF EXPERIMENTAL BACKGROUND IN RHIC POLARIZED PROTON RUN 2006.

Description: The beam-gas has affected STAR background in RHIC proton Run 2005, but not in Run 2006. With higher beam intensity in Run 2008, the beam-gas effect at STAR may be of concern. The ratio of ZDC background and coincident rate seems to be useful in proton runs in evaluating the experimental background.
Date: June 25, 2007
Creator: ZHANG,S. & TRBOJEVIC, D.
Partner: UNT Libraries Government Documents Department

IBS suppression lattice in RHIC: theory and experimental verification

Description: Intra-beam scattering (IBS) is the limiting factor of the luminosity lifetime for Relativistic Heavy Ion Collider (RHIC) operation with heavy ions. Over the last few years the process of IBS was carefully studied in RHIC with dedicated IBS measurements and their comparison with the theoretical models. A new lattice was recently designed and implemented in RHIC to suppress transverse IBS growth, which lowered the average arc dispersion by about 20% [1]. This lattice became operational during RHIC Run-8. We review the IBS suppression mechanism, IBS measurements before and after the lattice change, and comparisons with predictions.
Date: August 25, 2008
Creator: Fedotov,A.V.; Bai, M.; Bruno, D.; Cameron, P.; Connolly, R.; Cupolo, J. et al.
Partner: UNT Libraries Government Documents Department

ACCELERATION OF ELECTRONS WITH THE RACETRACK NON-SCALING FFAG FOR E-RHIC

Description: The future relativistic electron hadron collider: e-RHIC requires acceleration of electrons to 10 GeV. In the case that the super conducting linac is selected for acceleration, an energy recovery scheme is required. We propose to study a possibility of using the non-scaling Fixed-Field Gradient-Accelerator (NS-FFAG) for different energies. The beam will be accelerated by the superconducting linac at the top of the sine function, brought back to the front of the linac by the non-scaling FFAG and repeating this few times until the total energy of 20 GeV is reached. After collisions the beam is brought back by the non-scaling FFAG and decelerated (on the lower RF phase) in the same sequence but in the reverse order. Conventional and non-conventional beam dynamic issues will be discussed, like the transit time matching effect and the time of flight adjustments.
Date: June 25, 2007
Creator: TRBOJEVIC,D.; BLASKIEWICZ, M.; LITVINENKO, V.; PTITSYN, V. & ROSER, T.
Partner: UNT Libraries Government Documents Department

BEAM-BASED SEXTUPOLE POLARITY VERIFICATION IN THE RHIC

Description: This article presents a beam-based method to check RHIC arc sextupole polarities using local horizontal orbit three-bumps at injection energy. We use 11 bumps in each arc, each covering two SFs (focusing sextupoles) and one SD (defocusing sextupole). If there are no wrong sextupole polarities, the tune shifts from bump to bump and the tune shift patterns from arc to arc should be similar. Wrong sextupole polarities can be easily identified from mismatched signs or amplitudes of tune shifts from bump to bump and/or from arc to arc. Tune shifts in both planes during this study were tracked with a high-resolution base-band tunemeter (BBQ) system. This method was successfully used to the sextupole polarity check in RHIC Blue and Yellow rings in the RHIC 2006 and 2007 runs.
Date: June 25, 2007
Creator: LUO,Y.; SATOGATA, T.; CAMERON, P.; DELLAPENNA, A. & TRBOJEVIC, D.
Partner: UNT Libraries Government Documents Department

ELECTRON CLOUD OBSERVATIONS AND CURES IN RHIC.

Description: Since 2081 MIC has experienced electron cloud effects, which have limited the beam intensity. These include dynamic pressure rises - including pressure instabilities, tune shifts: electrons, a reduction of the stability threshold for bunches crossing the transition energy, and possibly slow emittance growth. We summarize the main observations in operation and dedicated experiments, as well as countermeasures including baking, NEG coated warm beam pipes, solenoids, bunch patterns, anti-grazing rings, pre-pumped cold beam pipes, and scrubbing.
Date: March 1, 2007
Creator: FISCHER,W.; BLASKIEWICZ, M.; HUAN, H.; HSEUH, H.C.; PTITSYN, V.; ROSER, T. et al.
Partner: UNT Libraries Government Documents Department

Dynamic aperture evaluation of the proposed lattices for the RHIC 2009 polarized proton run

Description: In the article we evaluate the dynamic apertures of the proposed lattices for the coming Relativistic Heavy Ion Collider (RHIC) 2009 polarized proton (pp) 100 GeV and 250 GeV runs. One goal of this study is to find out the appropriate {beta}* for the coming 2009 pp runs. Another goal is to study the effect of second order chromaticity correction in the RHIC pp runs.
Date: January 2, 2009
Creator: Luo,Y.; Bai, M.; Beebe-Wang, J.; Fischer, W.; Montag, C.; Robert-Demolaize, G. et al.
Partner: UNT Libraries Government Documents Department

Experience with IBS-suppression lattice in RHIC

Description: An intra-beam scattering (IBS) is the limiting factor of the luminosity lifetime for RHIC operating with heavy ions. In order to suppress the IBS we designed and implemented new lattice with higher betatron tunes. This lattice had been developed during last three years and had been used for gold ions in yellow ring of the RHIC during d-Au part of the RHIC Run-8. The use of this lattice allowed both significant increases in the luminosity lifetime and the luminosity levels via reduction of beta-stars in the IPS. In this paper we report on the development, the tests and the performance of IBS-suppression lattice in RHIC, including the resulting increases in the peak and the average luminosity. We also report on our plans for future steps with the IBS suppression.
Date: June 23, 2008
Creator: Litvinenko,V.N.; Luo, Y.; Ptitsyn, V.; Satogata, T.; Tepikian, S.; Bai, M. et al.
Partner: UNT Libraries Government Documents Department