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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 synchrotron radiation from electrons at the IR is reduced as they arrive straight to the collision while ions and protons come with 10 mrad crossing angle using the crab cavities.
Date: May 23, 2010
Creator: Trbojevic, D.; Beebe-Wang, J.; Tsoupas, N.; Chang, X.; Kayran, D.; Ptitsyn, V. et al.
Partner: UNT Libraries Government Documents Department

Muon acceleration with RLA and non-scaling FFAG ARCS

Description: Recirculating Linear Accelerators (RLA) are the most likely means to achieve the rapid acceleration of short-lived muons to multi-GeV energies required for Neutrino Factories and TeV energies required for Muon Colliders. In this paper, we present a novel return-arc optics design based on a Non Scaling Fixed Field Alternating Gradient (NS-FFAG) lattice that allows 5 and 9 GeV/c muons of both charges to be transported in the same string of magnets. The return arcs are made up of super cells with each super cell consisting of three triplets. By employing combined function magnets with dipole, quadrupole, sextupole and octupole magnetic field components, each super cell is designed to be achromatic and to have zero initial and final periodic orbit offsets for both 5 and 9 GeV/c muon momenta. This solution would reduce the number of arcs by a factor of 2, simplifying the overall design.
Date: May 23, 2010
Creator: Morozov, V.S.; Trbojevic, D. & Bogacz, A.
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

Update on the Innovative Carbon/Proton Non-Scaling FFAG Isocentric gantries for Cancer Therapy

Description: There is a dramatic increase in numbers of proton/carbon cancer therapy facilities in recent years due to a clear advantage with respect to the other radiation therapy treatments. Cost of the ion cancer therapy is still to high for most of the hospitals and a dominating part comes from the delivery systems. We had previously presented design of the carbon and proton isocentric gantries using the principle of the non-scaling alternating gradient fixed field magnets (NS-FFAG), where a size and weight of the magnets should be dramatically reduced. The weight of the transport elements of the carbon isocentric gantry is estimated to be 1.5 tons compared to the 130 tons a weight of the Heidelberg gantry. The similar claim of 500 kg comes for the transport elements of the proton permanent magnet gantry. We present an update on these designs.
Date: May 23, 2010
Creator: Trbojevic, D.
Partner: UNT Libraries Government Documents Department

Dynamic aperture calculation for the RHIC 2010 100 GeV Au-Au run lattices

Description: In this note we summarize the dynamic aperture calculation with the 2010 RHIC 100 GeV Au-Au run lattices. This study was initiated to understand the observed large beam decay in the Yellow ring after rf re-bucketing in the beginning of this run. The off-line linear lattice models and the interaction region non-linearity models are used. The large beam decay in the Yellow ring after re-bucketing was eventually eliminated by lowering the Yellow tunes to 0.21 from 0.235 with {beta}* = 0.7m lattice. In this note we only focus on the numeric simulation instead of the beam experiments.
Date: August 1, 2010
Creator: Luo, Y.; Brown, K.; Fischer, W.; Ptitsyn, V.; Roser, T.; Schoefer, V. et al.
Partner: UNT Libraries Government Documents Department

Beam lifetime and emittance growth in RHIC under normal operating conditions with the hydrogen gas jet, the cluster-jet and pellet targets

Description: The inelastic scattering of the beam and the residual gas molecules in RHIC could represent one of the limitations on the beam life time and emittance growth. This report covers the dominant central nuclear collisions influence on the beam lifetime and transverse emittance growth. The cross sections for the beam-gas electron radiative captures are an order of magnitude smaller. The capture cross sections include the radiative and non-radiative capture, and the capture from the electron-positron pair creation from the 'vacuum capture'.
Date: September 1, 2010
Creator: Trbojevic, D.
Partner: UNT Libraries Government Documents Department

Improvement of the high voltage properties of the Fermilab electrostatic septa

Description: In the Fermilab Tevatron Switchyard proton beam splits ae initiated by a wire array electrostatic septum. At 1 TeV energy, and with fields limited to 50 kV/cm, an electrostatic septum more than 20 meters in length is required to produce the required angular separation between the beams for the Proton and Neutrino/Meson lines. New techniques have been investigated that will allow reliable operation at fields above 75 kV/cm with resultant beam line economy. Changes in construction and conditioning procedures have been studied using a short sample of an electrostatic septum. 14 refs., 5 figs.
Date: June 1, 1985
Creator: Trbojevic, D.; Crawford, C.; Childress, S. & Tinsley, D.
Partner: UNT Libraries Government Documents Department

Magnetic measurements of the correction and adjustment magnets of the main ring

Description: Correction magnets correct the field imperfections and alignment errors of the main quadrupole and bend magnets. For reducing and controlling chromaticity there are 186 sextupoles and 78 octupoles, while for suppressing various resonances there are 12 normal and 18 skew sextupoles and 24 normal and 19 skew quadrupoles. Beam positions are individually controlled by 108 horizontal and 108 skew dipoles. This report includes results of the all Main Ring correction and adjustment magnet harmonic measurements. The measurement principle and basic equations are described.
Date: July 1, 1986
Creator: Trbojevic, D.
Partner: UNT Libraries Government Documents Department

A transitionless lattice for the Fermilab Main Injector

Description: Medium energy (1 to 30 GeV) accelerators are often confronted with transition crossing during acceleration. A lattice without transition is presented, which is a design for the Fermilab Main Injector. The main properties of this lattice are that the {gamma}{sub t} is an imaginary number, the maxima of the dispersion function are small, and two long-straight section with zero dispersion. 7 refs., 5 figs.
Date: May 1, 1991
Creator: Ng, K.Y.; Trbojevic, D. (Fermi National Accelerator Lab., Batavia, IL (USA)) & Lee, S.Y. (Indiana Univ., Bloomington, IN (USA). Dept. of Physics)
Partner: UNT Libraries Government Documents Department

Design of the D0 overpass dispersion correction

Description: The existing D0 overpass induces a vertical dispersion wave around the Main ring with dispersion amplitudes of around 1.6 to 1.8 m. There are two major reasons to eliminate or reduce vertical dispersion induced by the D0 overpass: to lower the beam momentum dependence on vertical positions which had not existed before the overpass; and to raise the Tevatron luminosity by eliminating the dispersion mismatch between the main Ring and Tevatron. 20 figs., 1 tab.
Date: October 7, 1987
Creator: Trbojevic, D.
Partner: UNT Libraries Government Documents Department

Examination of the stability of the advanced imaginary. gamma. sub t lattice

Description: An advanced imaginary -{gamma}{sub t} lattice for the Fermilab Main Injector is examined for its response to quadrupole field errors, quadrupole misalignment errors, as well as its dynamical aperture. We find that the lattice is tunable except near an integer tune. The misalignment sensitivity factors are acceptable and can be lowered if the low-beta triplet quadrupoles are specially aligned. The dynamical aperture is very large provided that a family of harmonic sextupoles is installed. 6 refs., 4 figs.
Date: May 1, 1991
Creator: Ng, K.Y.; Trbojevic, D. (Fermi National Accelerator Lab., Batavia, IL (USA)) & Lee, S.Y. (Indiana Univ., Bloomington, IN (USA). Dept. of Physics)
Partner: UNT Libraries Government Documents Department

Modification of the horizontal dispersion in the Fermilab Main Ring with additional quadrupoles

Description: In the normal Main Ring lattice, the horizontal dispersion includes a dispersion wave'' which peaks at 6.2 meters because the horizontal dispersion of the arcs is not matched into the straight sections. Six additional small quadrupoles have been installed, one in each sector, and powered at low energies (up to 30 GeV) in order to reduce the amplitude of the dispersion wave. The maxima of the dispersion function were thereby reduced to less than 4.7 meters, thus improving the momentum acceptance of the Main Ring. Measurements of the modified dispersion function agree well with the expected values. 3 refs., 5 figs.
Date: May 1, 1991
Creator: Trbojevic, D.; Kourbanis, I. & Ankenbrandt, C.
Partner: UNT Libraries Government Documents Department

Design and multiparticle simulation of the half integer slow extraction system for the Main Injector

Description: One of the roles of the new Main Injector ring, in the second phase of the Fermilab upgrade, is to deliver all year around the slow extracted 120 GeV test beams. The half-integer slow extraction system design and results from a Monte-Carlo simulation of fast spill are presented. The simulation was performed with a computer tracking program based on the TEVLAT program with a large number of particles (up to 1000). Particle tracking included the systematic errors produced by the magnetic multipoles within the dipoles and quadrupoles as well as random multipole errors.
Date: May 1, 1991
Creator: Trbojevic, D. & Harrison, M.
Partner: UNT Libraries Government Documents Department

Raising the acceptance of the AP2-line

Description: The 120 GeV Main Ring proton beam collides with the target at the end of the AP-1 line and creates antiprotons and other secondary particles. The AP-2 line transfers the negative particles from the target to the Debuncher. To provide a bigger antiproton stack size in the Accumulator, both the Debuncher as well as the AP-2 line acceptance have to be raised. This is a proposal for the improvement of the AP-2 line acceptance. The first part of the memo presents an acceptance examination of the existing AP-2 line by computer simulation, while the second presents a short proposal for aperture corrections. The computer program TURTLE was used to trace antiprotons through the AP-2 line without taking into account other negative charged particles. Betatron functions were obtained from the output of the SYNCH computer program. The SYNCH program was also used to check the dispersion match between the AP-2 line and the Debuncher. 3 refs., 6 figs., 5 tabs.
Date: April 5, 1989
Creator: Trbojevic, D.
Partner: UNT Libraries Government Documents Department

Argon and argon-oxygen glow discharge cleaning of the Main Ring beam pipe

Description: This report presents the experimental results from the argon and argon-oxygen gas mixture glow discharge in the Main Ring beam pipe and is a follow-up to the proposal for vacuum improvements of the Main Ring magnets and straight sections and the warm Tevatron straight sections. Glow discharge was used in the experiment in order to clean the vacuum system instead of bakeout which could only be performed with great difficulty or not at all. It is a relatively simple and very effective method. The glow discharge occurs under specific gas pressures (10--120 mTorr) and current flows (10/sup /minus/5/ /minus/ 10/sup /minus/1/ A) through gas excitation and formation of plasma conditions. Deexcitation of the gas molecules produces visible light. Several mechanisms have been proposed to explain the glow discharge cleaning process. Ions can sputter adsorbed molecules or atoms at the cathode surface and even produce lattice damage extending several monolayers below the surface. The glow discharge has already been extensively used for vacuum improvements in accelerators. 9 refs.
Date: February 15, 1989
Creator: Trbojevic, D. & Pastore, N.
Partner: UNT Libraries Government Documents Department

Design and multiparticle simulation of the half integer slow extraction system for the Main Injector

Description: One of the roles of the new Main Injector ring, in the second phase of the Fermilab upgrade, is to deliver all year around the slow extracted 120 GeV test beams. The half-integer slow extraction system design and results from a Monte-Carlo simulation of fast spill are presented. The simulation was performed with a computer tracking program based on the TEVLAT program with a large number of particles (up to 1000). Particle tracking included the systematic errors produced by the magnetic multipoles within the dipoles and quadrupoles as well as random multipole errors.
Date: May 1, 1991
Creator: Trbojevic, D. & Harrison, M.
Partner: UNT Libraries Government Documents Department

RHIC chromatic correction system

Description: The chromaticity correction system, including the nonlinear correction, for the Relativistic Heavy Ion Collider (RHIC) is presented. Expected multipoles in the superconducting magnets have shown that the octupole and decapole might be large enough to reduce the momentum aperture and introduce undesirable nonlinear chromatic behavior of the machine. Simulations of these conditions have been performed with the accelerator physics tracking code TEAPOT. The chromatic dependence curves were obtained by the least square fitting. A correction to the first and the second order terms were applied by using two sextupole and two octupole circuits. The decapole correction system has been applied to correct for the third order dependence on momentum. The long term tracking studies at injection did not include the decapole correction. The studies showed that the octupole correction system significantly improves the dynamical aperture at the injection. The decapole system would not be necessary at commissioning of the machine but the correction magnets will be available. At the top energy, as to be expected, the low beta quadrupoles are the dominant source of the nonlinear momentum dependence.
Date: December 31, 1993
Creator: Trbojevic, D.; Wei, J.; Tepikian, S.; Peggs, S.; Dell, F. & Satogata, T.
Partner: UNT Libraries Government Documents Department

Decoupling correction system in RHIC

Description: A global linear decoupling in the Relativistic Heavy Ion Collider (RHIC) is going to be performed with the three families of skew quadrupoles. The operating horizontal and vertical betatron tunes in the RHIC will be separated by one unit v{sub x}=28.19 and v{sub y}=29.18. The linear coupling is corrected by minimizing the tune splitting Dn-the off diagonal matrix m. The skew quadrupole correction system is located close to the each of the six interaction regions. A detail study of the system is presented by the use of the TEAPOT accelerator physics code.
Date: December 31, 1993
Creator: Trbojevic, D.; Tepikian, S. & Peggs, S.
Partner: UNT Libraries Government Documents Department