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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

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

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

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

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

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

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

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: June 26, 1998
Creator: TRBOJEVIC, D.
Partner: UNT Libraries Government Documents Department

A LATTICE FOR THE 50 GEV MUON COLLIDER RING.

Description: A resent 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 x 10{sup 33} cm{sup {minus}2} S{sup {minus}1} it is required to have beam intensities on the order of 1 x 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 1300 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: June 28, 1998
Creator: TRBOJEVIC,D.
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 77K 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: June 26, 1998
Creator: TRBOJEVIC, D.
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: June 26, 1998
Creator: TRBOJEVIC, D.
Partner: UNT Libraries Government Documents Department

A STUDY OF RHIC CRYSTAL COLLIMATION.

Description: The Relativistic Heavy Ion Collider (RHIC) will experience increasing longitudinal and transverse heavy ion emittances, mostly due to intra-beam scattering (IBS). The experiments in RHIC are expected to not only have reduced luminosities due to IBS but also background caused by beam halo. Primary betatron collimators will be used to remove the large amplitude particles. The efficiency of the primary collimator in RHIC strongly depends on the alignment of the jaws which needs to be within about ten micro-radians for the optimum conditions. As proposed by V. Biryukov [1] bent crystals could be used to improve the efficiency of an existing collimation system by installing them upstream of the collimator jaws. Bent crystals have been successfully used in SPS, Protvino and Fermilab for extraction of the beam particles channeled through them. This study examines possible improvements of the primary collimator system for heavy ions at RHIC by use of bent crystals. Bent crystals will reduce the collimator jaws alignment requirement and will increase collimator efficiency thereby reducing detector background.
Date: June 26, 1998
Creator: TRBOJEVIC,D.
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

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

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

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

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

A first order matched transition jump at RHIC

Description: RHIC, the Relativistic Heavy Ion Collider at Brookhaven National Laboratory, will be the first superconducting accelerator to cross transition, when ramping begins in 1998. All ion species except for protons will cross transition. Simulations show gold ion losses of 70%, and longitudinal emittance growth of 60%, if nothing is done to ameliorate the crossing. RHIC will also be the first accelerator to use a matched first order transition jump to modify {gamma}T for a short time, by pulsing a set of quadrupoles, so as to cross transition rapidly, with little beam disturbance. ``First order`` means that the change in {gamma}T is proportional to the pulse current. ``Matched`` means that the quadrupole arrangement minimizes optical distortions. Crucially, the maximum dispersion is only 2.30 meters, compared to the unperturbed value, of 1.84 meters. This paper describes the transition jump design, and reports on its performance in the lattice RHIC92.3.
Date: June 1, 1993
Creator: Peggs, S.; Tepikian, S. & 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

Low emittance lattices for electron storage rings revisited

Description: Conditions for the lowest possible emittance of the lattice for electron storage rings are obtained by a simplified analytical approach. Examples of electron storage lattices with minimum emittances are presented. A simple graphical presentation in the normalized dispersion space (Floquet`s transformation) is used to illustrate the conditions and results.
Date: August 1, 1994
Creator: Trbojevic, D. & Courant, E.
Partner: UNT Libraries Government Documents Department