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Description: This is a report to demonstrate use of Non-Scaling Fixed-Field Alternating-Gradient (FFAG) accelerators [1] in acceleration of partially stripped ions of Uranium-238 for Rare Isotopes Production. This example assumes a beam final energy of 500 MeV/u with an average beam output current of 1 {micro}A-particle and a beam average power of 120 kWatt.
Date: June 26, 2006
Partner: UNT Libraries Government Documents Department

Experimental background due to particle induced gas desorption in RHIC

Description: Beam-gas collision created experimental background, i.e., singles, has affected heavy ion and polarized proton operations in Relativistic Heavy Ion Collider at Brookhaven National Laboratory. The gas molecules in interaction region are mainly caused by the electron induced gas desorption. and the electrons are produced from the beam induced electron multipacting, or called electron cloud. The background has a dependence on the usual electron cloud related parameters, such as the bunch intensity, bunch spacing, and the solenoid field. With the RHIC upgrade plan, the experimental background may become a luminosity limiting factor. Mitigations are discussed.
Date: August 10, 2008
Creator: Zhang,S.Y. & Trbojevic, D.
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

A standard FODO lattice with adjustable momentum compaction

Description: An existing lattice made of identical FODO cells can be modified to have adjustable momentum compaction. The modified lattice consists of repeating superperiods of four FODO cells where every two cells have different horizontal phase advance. In existing FODO cell rings an additional quad bus is required for every two consecutive cells. This allows tuning of the momentum compaction or {gamma}{sub t} could be an imaginary number. A drawback of this modification is relatively large values of the dispersion function (two or three times larger than in the regular FODO cell design).
Date: July 1, 1997
Creator: Trbojevic, D. & Courant, E.
Partner: UNT Libraries Government Documents Department


Description: This report presents an attempt of the lattice design with a fixed field alternating gradient (FFAG) magnets without the usual opposite bends. It should allow particle acceleration through a small aperture. An example was made for the muon beam acceleration in an energy range 10-20 GeV with distributed RF cavities. The dispersion function for the central energy of 15 GeV has maximum value of the order of 7 cm. The lattice is composed of a combined function elements and sextupoles. We present the magnet configuration, orbit, chromaticities, tunes, and betatron function dependence on momentum (energies) during acceleration. For the lattice design we used SYNCH an MAD programs. For these large momentum offsets {delta}p/p = +-33% we found discrepancies between analytical and codes' results. This will be corrected in the new versions of codes (MAD-X). Because of uncertainties of the programs MAD and SYNCH some details of the presented results might not be correct.
Date: June 2, 2002
Partner: UNT Libraries Government Documents Department

Preparing accelerator systems for the RHIC sextant commissioning

Description: The Relativistic Heavy Ion Collider (RHIC) construction is progressing steadily towards completion in 1999 when beams will circulate in both collider rings. One of the major tests of the RHIC project was the commissioning of the first sextant with gold ion beams in early 1997. This is a report on preparation of the RHIC accelerator systems for the first sextant test. It includes beam position monitors, timing, injection correction through the magnetic septum and kickers, current transformers, flags and the ionization beam profile monitors, beam loss monitors, beam and quench permit link system, power supply controls, and the configuration database system. The software and hardware development and coordination of the different systems before commissioning were regularly checked during bi-weekly, and (later) weekly, progress report meetings.
Date: July 1, 1997
Creator: Trbojevic, D.; Pilat, F. & Ahrens, L.
Partner: UNT Libraries Government Documents Department

A possible synchrotron light beam profile monitor in RHIC

Description: This report examines the possibility of observing transverse beam profiles by using synchrotron light emission from the 100 GeV/nucleon heavy-ion gold beam in the Relativistic Heavy Ion Collider (RHIC). Synchrotron radiation experiences a shift towards higher photon energy when the magnetic field at the end of a dipole varies rapidly over a short distance. Synchrotron light signals from high energy (larger than 400 GeV) proton beams have already been routinely used to observe the transverse beam profiles at the SPS in CERN and at the TEVATRON at Fermilab. Because of the modest relativistic factor of the fully stripped stored gold ions in RHIC this push towards higher critical energy is not large enough to place the synchrotron light within the visible region of the spectrum. The critical wavelength remains within the infrared region. A 77 K cooled infrared array detector with 160 elements, made of PbSe (Lead Salt) could be used for beam profile detection. It would cover the wavelength range between 1 and 6 microns, with maximum sensitivity at a wavelength of 4.5 microns.
Date: August 1, 1998
Creator: Trbojevic, D.; Courant, E.; Peggs, S. & Hahn, A.
Partner: UNT Libraries Government Documents Department

RHIC injection kicker impedance

Description: The longitudinal impedance of the RHIC injection kicker is measured using the wire method up to a frequency of 3 GHz. The mismatch between the 50 ohm cable and the wire and pipe system is calibrated using the TRL calibration algorithm. Various methods of reducing the impedance, such as coated ceramic pipe and copper strips are investigated.
Date: May 1, 1995
Creator: Mane, V.; Peggs, S.; Trbojevic, D. & Zhang, W.
Partner: UNT Libraries Government Documents Department

A lattice for the 50 GeV muon collider ring

Description: A recent progress report on the lattice design of the 50-50 GeV muon collider is presented. The ring circumference needs to be as small as possible due to the short lifetime of the 50 GeV muons. The background at the detector is affected by the continuous decay of muons into electrons which requires a dipole between the high focusing quadrupoles and the detector. To obtain a luminosity on the order of 1{times}10{sup 33} cm{sup {minus}2} s{sup {minus}1} it is required to have beam intensities on the order of 1{times}10{sup 12} particles per bunch. The rms momentum spread of the beam is equal to 0.12% and the beta functions at the interaction point are equal to 4 cm. The maxima of the betatron functions at these quadrupoles are 1,300 m, resulting in large chromaticities which must be corrected by local chromatic correction. Pairs of horizontal and vertical chromatic sextupoles are located at locations where the corresponding betatron functions are 100 m and the values of the horizontal dispersion functions are 3 and 2 m, respectively. They are carefully placed so that most of their nonlinear effects are canceled. The dynamic aperture is larger than 7 times the mean size of the beam for the momentum offsets larger than {minus}6 and +10 sigmas.
Date: August 1, 1998
Creator: Trbojevic, D.; Ng, K.Y. & Weishi, W.
Partner: UNT Libraries Government Documents Department

RHIC sextant test: Accelerator systems and performance

Description: One sextant of the RHIC Collider was commissioned in early 1997 with beam. We describe here the performance of the accelerator systems, instrumentation subsystems and application software. We also describe a ramping test without beam that took place after the commissioning with beam. Finally, we analyze the implications of accelerator systems performance and their impact on the planning for RHIC installation and commissioning.
Date: August 1, 1997
Creator: Pilat, F.; Trbojevic, D. & Ahrens, L.
Partner: UNT Libraries Government Documents Department

The Lattice for the 50-50 GeV Muon Collider

Description: The lattice design of the 50-50 Gev muon collider is presented. Due to the short lifetime of the 50 GeV muons, the ring needs to be as small as possible. The 4 cm low betas in both planes lead to high betatron functions at the focusing quadrupoles and hence large chromaticities, which must be corrected locally. In order to maintain a low rf voltage of around 10 MV, the momentum-compaction factor must be kept to less than 10{sup -2} , and therefore the flexible momentum-compaction modules are used in the arcs. The dynamical aperture is larger than 6 to 7 rms beam size for {+-}5 rms momentum offset. Comments are given and modifications are suggested.
Date: February 1, 1998
Creator: Ng, K.-Y., Trbojevic, D.
Partner: UNT Libraries Government Documents Department

Results from betatron phase measurements in RHIC during the sextant test

Description: The Sextant Test of the Relativistic Heavy Ion Collider (RHIC) was an important step towards its completion. One sixth of the two RHIC accelerators was fully commissioned. gold ion beam was injected and transported through one sextant of one of the two rings. The betatron phase advance per cell was measured by recording differences in the horizontal and vertical positions of the beam at the end of the sextant due to a sequence of correction dipole kicks along the beam line. Measurement results show excellent agreement with predicted values, confirming that production measurements of the integral functions of the quadrupoles were very accurate, and that the polarity of all elements (correction dipoles, quadrupoles, dipoles etc.) was correct.
Date: August 1, 1998
Creator: Trbojevic, D.; Connolly, R. & Fischer, W.
Partner: UNT Libraries Government Documents Department

The effect and correction of coupling generated by the RHIC triplet quadrupoles

Description: This study explores the possibility of operating the nominal RHIC coupling correction system in local decoupling mode, where a subset of skew quadrupoles are independently set by minimizing the coupling as locally measured by beam position monitors. The goal is to establish a correction procedure for the skew quadrupole errors in the interaction region triplets that does not rely on a priori knowledge of the individual errors. After a description of the present coupling correction scheme envisioned for RHIC, the basics of the local decoupling method will be briefly recalled in the context of its implementation in the TEAPOT simulation code as well as operationally. The method is then applied to the RHIC lattice: a series of simple tests establish that single triplet skew quadrupole errors can be corrected by local decoupling. More realistic correction schemes are then studied in order to correct distributed sources of skew quadrupole errors: the machine can be decoupled either by pure local decoupling or by a combination of global (minimum tune separation) and local decoupling. The different correction schemes are successively validated and evaluated by standard RHIC simulation runs with the complete set of errors and corrections. The different solutions and results are finally discussed together with their implications for the hardware.
Date: May 1, 1995
Creator: Pilat, F.; Peggs, S.; Tepikian, S.; Trbojevic, D. & Wei, J.
Partner: UNT Libraries Government Documents Department

A study of betatron and momentum collimators in RHIC

Description: Two separate accelerator rings in the Relativistic Heavy Ion Collider (RHIC) will provide collisions between equal and unequal heavy ion species up to the gold ions, including the two polarized proton beams. There are six interaction points with two regions with {beta}* = 1--2 m occupied by the large detectors PHENIX and STAR. The transverse and longitudinal emittances of the gold ions 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 where the betatron functions have large values to allow efficient removal of particles with large betatron amplitudes. In this report the authors 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. Additional studies of the detector background due to beam halo and other details about the collimation in RHIC are reported elsewhere, while more information about the momentum collimation was previously reported in Momentum Collimation at Q9 by S. Peggs and G.F. Dell.
Date: December 1, 1997
Creator: Trbojevic, D.; Stevens, A.J. & Harrison, M.
Partner: UNT Libraries Government Documents Department

Is the momentum space optimally used with the FODO lattices?

Description: The available momentum space of a FODO lattice is determined by the maximum value of the dispersion function ({delta}x = D{sub x} {partial_derivative}p/p). In a regular FODO lattice the dispersion function oscillates between its maximum and minimum values, which are always positive. The maximum value of the dispersion function in a FODO cell of a fixed length depends on the cell phase difference. An example of a new lattice, in which the dispersion function is lowered to half its value in the same FODO cell, is presented. ne available momentum space in the new lattice is raised to twice that in the FODO lattice by allowing the dispersion function to oscillate between the same positive and negative values. The maxima of the dispersion function in the new lattice have half the value of those within the regular 900 cells.
Date: July 1, 1993
Creator: Trbojevic, D.; Ng, K.Y. & Lee, S.Y.
Partner: UNT Libraries Government Documents Department

Alignment and survey of the elements in RHIC

Description: The Relativistic Heavy Ion Collider (RHIC) consists of two rings with cryogenic magnets at a 4.5K operating temperature. Control of positions of the dipole and quadrupole cold masses (iron laminations) and the beam position monitors (BPM`s) during production and installation is presented. The roll of the dipoles is controlled by a combination of rotating coil measurements with the surveying measurements. The center of the quadrupole magnetic field is obtained by direct measurement of the field shape within a colloidal cell placed inside the quadrupoles. Special attention is given to the triplet quadrupole alignment and determination of the field center position.
Date: May 1, 1995
Creator: Trbojevic, D.; Cameron, P. & Ganetis, G.L.
Partner: UNT Libraries Government Documents Department


Description: A non-scaling FFAG lattice design to accelerate electrons from 3.2 to 10 GeV is described. This is one of possible solutions for the future electron-ion collider (eRHIC) at Relativistic Heavy Ion Collier (RHIC) at Brookhaven National Laboratory (BNL). The e-RHIC proposal requires acceleration of the low emittance electrons up to energy of 10 GeV. To reduce a high cost of the full energy super-conducting linear accelerator an alternative approach with the FFAG is considered. The report describes the 1277 meters circumference non-scaling FFAG ring. The Courant-Snyder functions, orbit offsets, momentum compaction, and path length dependences on momentum during acceleration are presented.
Date: July 5, 2004
Partner: UNT Libraries Government Documents Department

A design of a quasi-isochronous storage ring

Description: Isochronous electron storage rings may offer advantages for future high luminosity meson factories. A Quasi-isochronous lattice based on the design principle of flexible {gamma}{tau} lattice is studied. The emittance and chromatic properties of such a lattice are studied. Applications of this design techniques for electron storage rings will be discussed.
Date: July 1, 1993
Creator: Lee, S. Y.; Ng, K. Y. & Trbojevic, D.
Partner: UNT Libraries Government Documents Department

An improved imaginary transition. gamma. sub t lattice for the Main Injector

Description: An improved imaginary-{gamma}{sub t} lattice for the 150 GeV Fermilab Main Injector is presented. It has the properties of small dispersion function, good tunability, small tune dependences on momentum with the presence of chromaticity sextupoles, and a large dynamical aperture. In addition, many of the quadrupoles can be recycled from the present Main Ring.
Date: August 1, 1992
Creator: Ng, K. Y. & Trbojevic, D.
Partner: UNT Libraries Government Documents Department