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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

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

Transfer of polarized 3He ions in the AtR beam transfer line

Description: In addition to collisions of electrons with various unpolarized ion species as well as polarized protons, the proposed electron-hadron collider (eRHIC) will facilitate the collisions of electrons with polarized {sup 3}He ions. The AGS is the last acceleration stage, before injection into one of the RHIC's collider ring for final acceleration. The AtR (AGS to RHIC) transfer line will be utilized to transport the polarized {sup 3}He ions from AGS into one of the RHIC's collider rings. Some of the peculiarities of the AtR line's layout (simultaneous horizontal and vertical bends) may degrade the matching of the stable spin direction of the AtR line with that of RHIC's. In this paper we discuss possible simple modifications of the AtR line to accomplish a perfect matching of the stable spin direction of the injected {sup 3}He beam with the stable spin direction at the injection point of RHIC.
Date: May 20, 2012
Creator: N., Tsoupas; MacKay, W.W.; Meot, F.; Roser, T. & Trbojevic, D.
Partner: UNT Libraries Government Documents Department

The AGS with four helical magnets

Description: The idea of using multiple partial helical magnets was applied successfully to the AGS synchrotron, to preserve the proton beam polarization. In this paper we explore in details the idea of using four helical magnets placed symmetrically in the AGS ring. This modification provides many advantages over the present setup of the AGS that uses two partial helical magnets. First, it provides a larger 'spin tune gap' for the placement of the vertical betatron tune of the AGS during acceleration, second, the vertical spin direction during the beam injection and extraction is closer to vertical, third, the symmetric placement of the snakes allows for a better control of the AGS optics, and for reduced values of the beta and eta functions, especially near injection, fourth, the optical properties of the helical magnets also favor the placement of the horizontal betatron tune in the 'spin tune gap', thus eliminating the horizontal spin resonances. In this paper we provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and we compare these results with the present setup of the AGS that uses two partial helical magnets.
Date: February 25, 2010
Creator: Tsoupas, N.; Huang, H.; MacKay, W.W.; Roser, T. & Trbojevic, D.
Partner: UNT Libraries Government Documents Department

A DRAMATICALLY REDUCED SIZE IN THE GANTRY DESIGN FOR THE PROTON-CARBON THERAPY.

Description: Gantries in the proton/carbon cancer therapy machines represent the major cost and are of the largest size. This report explains a new way to the gantry design. The size and cost of the gantries are reduced and their use is simplified by using the fixed magnetic field. The ''new'' gantry is made of a very large momentum acceptance non-scaling Fixed Field Alternating Gradient (FFAG) quarter and half arc beam lines. The gantry is made of combined function magnets with a very strong focusing and small dispersion function. Additional magnets with a fast response are required to allow adjustments of the beam position for different energies at the beginning of the gantry. Additional strong focusing magnets following the gantry have also to be adjustable to provide required spot size and radial scanning above the patients. The fixed field combined function magnets could be made of small permanent magnets for the proton machine, or of the high temperature superconductors or superconductors for the carbon machine, reducing dramatically the size.
Date: June 23, 2006
Creator: TRBOJEVIC, D.; GUPTA, R.; PARKER, B.; KEIL, E. & SESSLER, A.M.
Partner: UNT Libraries Government Documents Department

The Transverse Linac Optics Design in Multi-pass ERL

Description: In this paper, we analyzed the linac optics design requirement for a multi-pass energy recovery linac (ERL) for arbitrary number of linacs. A set of general formula of constrains for the 2-D transverse matrix is derived to ensure design optics acceptance matching throughout the entire accelerating and decelerating process. Meanwhile, the rest free parameters can be adjusted for fulfilling other requirements or optimization purpose. As an example, we design the linac optics for the future MeRHIC (Medium Energy eRHIC) project and show the optimization for small {beta} function.
Date: May 23, 2010
Creator: Hao, Y.; Kewisch, J.; Litvinenko,V.; Pozdeyev, E.; Ptitsyn, V.; Trbojevic, D. et al.
Partner: UNT Libraries Government Documents Department

COMPARISON BETWEEN THE PREDICTIONS AND MEASUREMENTS FOR THE BEAM GAS INTERACTIONS DURING THE LAST GOLD AND PROTON RUNS IN RHIC.

Description: The last gold-gold and polarized proton-proton collision runs were performed at energies of 100 GeV/nucleon. The beam gas interactions in RHIC are very important for the beam lifetime in RHIC. In this report the lifetime predicted by pressure data differences between the beams ON and beams OFF, at the energies of 100 GeV/nucleon. are compared to the predictions for the beam gas interaction and beam lifetimes.
Date: June 2, 2002
Creator: TRBOJEVIC,D.; HSEUH,H.C.; FISCHER,W.; ZHANG,S.Y. & MACKAY,W.W.
Partner: UNT Libraries Government Documents Department

A study of betatron and momentum collimators in RHIC

Description: The Relativistic Heavy Ion Collider (RHIC) has two interaction regions where {beta}* = 1--2m, with large detectors PHENIX and STAR. The transverse and longitudinal emittances are expected to double in size between one to two hours due to intra-beam scattering which may lead to transverse beam loss. Primary betatron collimators are positioned in the ring to allow efficient removal of particles with large betatron amplitudes. The authors have investigated distributions and losses coming from the out-scattered particles from the primary collimators, as well as the best positions for the secondary momentum and betatron collimators.
Date: July 1, 1997
Creator: Trbojevic, D.; Stevens, A.J.; Harrison, M.A.; Dell, F. & Peggs, S.
Partner: UNT Libraries Government Documents Department

Measurements of the betatron functions and phases in RHIC

Description: The Relativistic Heavy Ion Collider (RHIC) consists of two rings with six fold symmetry. The six interaction regions (IR)s are connected with twelve FODO cells. RHIC quadrupoles in the interaction regions have independent tuning capability. The betatron functions will be measured by a three methods. First, tunable IR quadrupoles will be adjusted to measure betatron functions at those locations through the change in tune. Second, sinusoidal coherent dipole oscillations will be used to measure the betatron phases and functions (as performed in LEP). Third, a correction dipole kick technique will be used (as at Fermilab). special attention will be given to the betatron squeeze procedure by which the two large experiments PHENIX and STAR will achieve minimum betatron functions between 1 and 2 m.
Date: August 1, 1998
Creator: Trbojevic, D.; Kewisch, J.; Peggs, S.; Satogata, T.; Tepikian, S. & Goddere, G.
Partner: UNT Libraries Government Documents Department

MEASUREMENTS OF THE BETATRON FUNCTIONS IN RHIC.

Description: The Relativistic Heavy Ion Collider (RHIC) provides collisions of the fully stripped gold ions for four experiments. This report shows results from measurements of the betatron functions within the Interaction Regions (IR) as well as in the arcs in both ''blue'' and ''yellow'' rings. A single quadrupole excitation or the beam position monitors' RMS. values at injection are used to obtain the betatron amplitude function.
Date: June 18, 2001
Creator: TRBOJEVIC,D.; AHRENS,L.; BAI,M.; PTITSYN,V.; SATOGATA,T. & VAN ZEIJTS,J.
Partner: UNT Libraries Government Documents Department

BEAM LIFETIME DEPENDENCE ON THE BEAM-GAS INTERACTIONS IN RHIC.

Description: In the Relativistic Heavy ion Collider (RHIC) much larger background signals were occurring at BRAMS, one of the four experiments. This was especially pronounced at the time when vacuum conditions deteriorated due to the beam ionization profile monitor replacements. Recording the beam intensities during the store provided the beam lifetime. Predictions from the beam gas interactions to the above measured values are compared The ionization gauges simultaneously recorded the vacuum pressure data.
Date: June 18, 2001
Creator: TRBOJEVIC,D.; HSUEH,H.C.; MACKAY,W.; DREES,A. & FLILLER,R.
Partner: UNT Libraries Government Documents Department

MEASUREMENTS OF THE BETATRON FUNCTIONS IN RHIC.

Description: The Relativistic Heavy Ion Collider (RI-UC) provides collisions of the fully stripped gold ions for four experiments. This report shows results from measurements of the betatron functions within the Interaction Regions (IR) as well as in the arcs in both ''blue'' and ''yellow'' rings. A single quadrupole excitation or the beam position monitors' RMS. values at injection are used to obtain the betatron amplitude function.
Date: June 18, 2001
Creator: TRBOJEVIC,D.; AHRENS,L.; BAI,M.; PTITSYN,V.; SATOGATA,T. & VAN ZEIJTS,J.
Partner: UNT Libraries Government Documents Department

BEAM LIFETIME DEPENDENCE ON THE BEAM-GAS INTERACTIONS IN RHIC.

Description: In the Relativistic Heavy ion Collider (RHIC) much larger background signals were occurring at BRAMS, one of the four experiments. This was especially pronounced at the time when vacuum conditions deteriorated due to the beam ionization profile monitor replacements. Recording the beam intensities during the store provided the beam lifetime. Predictions from the beam gas interactions to the above measured values are compared The ionization gauges simultaneously recorded the vacuum pressure data.
Date: June 18, 2001
Creator: TRBOJEVIC,D.; HSUEH,H.C.; MACKAY,W.; DREES,A. & FLILLER,R.
Partner: UNT Libraries Government Documents Department

RHIC susceptibility to variations in systematic magnetic harmonic errors

Description: Results of a study to determine the sensitivity of tune to uncertainties of the systematic magnetic harmonic errors in the 8 cm dipoles of RHIC are reported. Tolerances specified to the manufacturer for tooling and fabrication can result in systematic harmonics different from the expected values. Limits on the range of systematic harmonics have been established from magnet calculations, and the impact on tune from such harmonics has been established.
Date: August 1, 1994
Creator: Dell, G. F.; Peggs, S.; Pilat, F.; Satogata, T.; Tepikian, S.; Trbojevic, D. et al.
Partner: UNT Libraries Government Documents Department