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Alignment and stability of future machines

Description: Leading accelerator laboratories mount serious efforts in alignment and vibration studies concerning stability of future accelerator facilities such as photon and meson factories, future linear colliders (LCs), and hadron supercolliders (HCs). Some 200 publications covered the topic since late 80s, following pioneering works of G.E. Fischer. Four International workshops on accelerator alignment were held since 1989 at SLAC, DESY, CERN and KEK. The SSCL hosted the workshop on vibration control and dynamic alignment (1992). This article briefly covers some present achievements and issues in the field. We discuss major effects and tolerances for the future accelerators, results of measurements up-to-date, correction techniques and make some conclusions.
Date: June 1, 1996
Creator: Shiltsev, V.D.
Partner: UNT Libraries Government Documents Department

Alignment of the Fermilab D0 Detector

Description: The Fermilab D0 detector was used for the discovery of the top quark during Run I in 1996. It is currently being upgraded to exploit the physics potential to be presented by the Main Injector and the Tevatron Collider during Run II in the Fall of 2000. Some of the essential elements of this upgrade is the upgrade of the Solenoid Magnet, the Central Fiber Tracker, the Preshower Detectors, the Calorimeter System, and the Muon System. This paper discusses the survey and alignment of the these detectors with emphasis on the Muon detector system. The alignment accuracy is specified as better than 0.5mm. A combination of the Laser Tracker, BETS, and V-STARS systems are used for the survey.
Date: July 20, 2001
Creator: Oshinowo, Babatunde O'Sheg
Partner: UNT Libraries Government Documents Department

All hadronic B decay trigger with the CDF silicon vertex tracker

Description: Silicon Vertex tracks are of fundamental importance for reconstructing B meson decays at a hadron collider. The upgraded CDF detector will deploy an online Silicon Vertex Tracker in the level 2 trigger. We have studied how this new device exploits the Tevatron large B meson production to select hadronic B decays fundamental for measuring CP violation and B{sub s} mixing.
Date: October 19, 1999
Creator: Donati, Simone
Partner: UNT Libraries Government Documents Department

Analysis and measurements of Eddy current effects of a beam tube in a pulsed magnet

Description: The power supply design of the {gamma}{sub f} - jump system in FNAL Main Injector uses a resonant circuit. A critical design parameter is the ac losses of the beam tube in a pulsed quadrupole. This paper gives an analysis to this problem. An equivalent circuit model based on the impedance measurement was established. The measured and calculated losses are in agreement. Another effect of the eddy current is the distortion of the magnetic field inside the beam tube. A Morgan coil was used for field measurements up to 10 KHz. These results are presented in this paper.
Date: May 1, 1997
Creator: Fang, S.
Partner: UNT Libraries Government Documents Department

Analysis of Lifetime Data for the Linac 201 MHz Power Amplifiers

Description: This document analyzes data on the lifetime of the 201-MHz triode power amplifier (PA) vacuum tube, model number 7835, used in the low-energy half of the Linac. We observe that a 7835 power amplifier vacuum tube has historically provided about one and one-third years service in the Linac. The lifetime of recently re-manufactured tubes is somewhat less, but it is not clear if this is because the manufacturer is ''loosing their touch,'' or because tubes cannot be effectively rebuilt after a certain number of times. Taking into account the expected tube lifetimes, the statistical fluctuations on this number, and the amount of time it takes for the manufacturer to make good tubes, we require about 14 tubes either operating, ready as good spares or being manufactured, in order to have sufficient spares to run the Linac. As a hedge against supplier drop out, we need to increase our inventory of good spare tubes by about three tubes per year for the next few years.
Date: July 9, 2002
Creator: Webber, Elliot McCrory and Robert C.
Partner: UNT Libraries Government Documents Department

1-GeV Linac Upgrade Study at Fermilab

Description: A linac injector for a new proton source complex at Fermilab is assumed to have a kinetic energy of 1 GeV. This linac would be sized to accelerate 100 mA of H{sup -} beam in a 200 microsecond pulse at a 15 Hz repetition rate. This would be adequate to produce {approximately}10{sup 14} protons per pulse allowing for future improvements of the new proton source complex. An alternate proposal is to add 600 MeV of side coupled cavity linac at 805 MHz to the existing 400 MeV Linac. This addition may either be in a new location or use the present Booster tunnel. A discussion of these possibilities will be given.
Date: September 1998
Creator: Popovic, M.; Moretti, A.; Noble, R. & Schmidt, C. W.
Partner: UNT Libraries Government Documents Department

Antiproton acceleration in the Fermilab Main Injector using 2.5 MHz (H=28) and 53 MHz (H=588) rf systems

Description: During the Run II era at Fermilab, the Recycler stores antiprotons at 8 GeV and the Main Injector accelerates the antiprotons and the protons from 8 GeV to 150 GeV for Tevatron injection. The Recycler injects antiprotons to the Main Injector in 2.5 MHz rf buckets. This report presents an acceleration scheme for the antiprotons that involves a slow ramp with initial 2.5 MHz acceleration and subsequent fast acceleration with 53 MHz rf system. Beam acceleration and rf manipulation with space charge and beam loading effects are simulated using the longitudinal simulation code ESME. Simulation suggests that one can expect about 15% emittance growth for the entire acceleration cycle with beam loading compensations. Preliminary experimental results with proton beam will also be presented.
Date: June 10, 2003
Creator: al., Vincent Wu et
Partner: UNT Libraries Government Documents Department

2.5 MHz feedforward beam loading compensation in the Fermilab Main Injector

Description: There are five 2.5 MHz ferrite cavities (h = 28) in the Main Injector with an R/Q of 500 that are presently used for coalescing for the Tevatron. For use with the Fermilab Recycler, feedforward (FF) beam loading compensation (BLC) is required on these cavities because they will be required to operate at a net of 2 kV. Under current Recycler beam conditions, the beam-induced voltage is of this order. Recently a system using a digital bucket delay module operating at 53 MHz (h = 588) was used to produce a one-turn-delay feedforward signal. This signal was then combined with the low level RF signal to the 2.5 MHz cavities to cancel the beam induced voltage. During current operation they have shown consistently to operate with over a 20 dB reduction in beam loading.
Date: May 19, 2003
Creator: Dey, Joseph E.; Kourbanis, Ioanis & Steimel, James
Partner: UNT Libraries Government Documents Department

2 MW upgrade of the Fermilab Main Injector

Description: In January 2002, the Fermilab Director initiated a design study for a high average power, modest energy proton facility. An intensity upgrade to Fermilab's 120-GeV Main Injector (MI) represents an attractive concept for such a facility, which would leverage existing beam lines and experimental areas and would greatly enhance physics opportunities at Fermilab and in the U.S. With a Proton Driver replacing the present Booster, the beam intensity of the MI is expected to be increased by a factor of five. Accompanied by a shorter cycle, the beam power would reach 2 MW. This would make the MI a more powerful machine than the SNS or the J-PARC. Moreover, the high beam energy (120 GeV) and tunable energy range (8-120 GeV) would make it a unique high power proton facility. The upgrade study has been completed and published. This paper gives a summary report.
Date: June 4, 2003
Creator: Chou, Weiren
Partner: UNT Libraries Government Documents Department

2 {times} 2 TeV {mu}{sup +}{mu}{sup {minus}} collider: Lattice and accelerator-detector interface study

Description: The design for a high-luminosity {mu}{sup +}{mu}{sup {minus}} superconducting storage ring is presented based on first-pass calculations. Special attention is paid to two Iowa interaction regions (IR) whose optics are literally interlaced with the collider detectors. Various sources of backgrounds in IR are explored via realistic Monte Carlo simulations. An improved design of the collider lattice in the neighborhood of the interaction points (EP) is determined by the need to reduce significantly background levels in the detectors.
Date: May 1, 1995
Creator: Gelfand, N.M. & Mokhov, N.V.
Partner: UNT Libraries Government Documents Department

2 x 2 TeV mu(superscript +) mu (superscript) collider

Description: The scenarios for high-luminosity 2 x 2 TeV and 250 x 250 GeV {mu}{sup +}{mu}{sup -} colliders are presented. Having a high physics potential, such a machine has specific physics and technical advantages and disadvantages when compared with an e{sup +}e{sup -} collider. Parameters for the candidate designs and the basic components - proton source, pion production and decay channel, cooling, acceleration and collider storage ring - are considered. Attention is paid to the areas mostly affecting the collider performance: targetry, energy spread, superconducting magnet survival, detector backgrounds, polarization, environmental issues. 13 refs., 9 figs., 4 tabs.
Date: October 1, 1996
Creator: Mokhov, N.V. & Noble, R.J.
Partner: UNT Libraries Government Documents Department

An 8-GeV Synchrotron-Based Proton Driver

Description: In January 2002, the Fermilab Director initiated a design study for a high average power, modest energy proton facility. Such a facility is a possible candidate for a construction project in the U.S. starting in the middle of this decade. The key technical element is a new machine, dubbed the ''Proton Driver,'' as a replacement of the present Booster. The study of an 8-GeV synchrotron-based proton driver has been completed and published. This paper will give a summary report, including machine layout and performance, optics, beam dynamics issues, technical systems design, civil construction, cost estimate and schedule.
Date: June 4, 2003
Creator: Chou, Weiren
Partner: UNT Libraries Government Documents Department

The 8-GeV transfer line injection into main ring

Description: Included in this report are a brief review of the design lattice of the 8-GeV beam transfer line and the Main Ring, the recent measurements on the 8-GeV line lattice function as well as that of the Main Ring at 8-GeV. The injection matching is a very important part of the MR operation. Mismatches such as energy, timing, or position are easily corrected because they cause oscillations which are visible on the Turn-By-Turn (TBT) TV monitor display. Mis-matches due to beta and dispersion functions are detected only by using the Flying Wire or by doing measurements during beam study. A new method which makes use of the available data from TBT hardware was used to obtain the beam phase space ellipse. Data taken from Main Ring at injection gives the beta function needed for transfer matching from 8-GeV line. The result of this measurement is also presented here.
Date: June 1, 1995
Creator: Yang, M.J.
Partner: UNT Libraries Government Documents Department

30 years of high-intensity negative ion sources for accelerators

Description: Thirty years ago, July 1, 1971, significant enhancement of negative ion emission from a gas discharge following an admixture of cesium was observed for the first time. This observation became the basis for the development of Surface Plasma Sources (SPS) for efficient production of negative ions from the interaction of plasma particles with electrodes on which adsorbed cesium reduced the surface work-function. The emission current density of negative ions increased rapidly from j {approximately} 10 mA/cm{sup 2} to 3.7 A/cm{sup 2} with a flat cathode and up to 8 A/cm{sup 2} with an optimized geometrical focusing in the long pulse SPS, and to 0.3 A/cm{sup 2} for DC SPS, recently increased up to 0.7 A/cm{sup 2}. Discovery of charge-exchange cooling helped decrease the negative ion temperature T below 1 eV, and increase brightness by many orders to a level compatible with the best proton sources, B = j/T> 1 A/cm{sup 2} eV. The combination of the SPS with charge-exchange injection improved large accelerators operation and has permitted beam accumulation up to space-charge limit and overcome this limit several times. The early SPS for accelerators have been in operation without modification for {approximately} 25 years. Advanced version of the SPS for accelerators is described. Features of negative ion beam formation, transportation, space-charge neutralization-overneutralization, and instability damping is considered. Practical aspects of SPS operation and high brightness beam production is discussed.
Date: July 25, 2001
Creator: Dudnikov, Vadim
Partner: UNT Libraries Government Documents Department

53 MHZ Feedforward beam loading compensation in the Fermilab main injector

Description: 53 MHz feedforward beam loading compensation is crucial to all operations of the Main Injector. Recently a system using a fundamental frequency down converter mixer, a digital bucket delay module and a fundamental frequency up converter mixer were used to produce a one-turn-delay feedforward signal. This signal was then combined with the low level RF signal to the cavities to cancel the transient beam induced voltage. During operation they have shown consistently over 20 dB reduction in side-band voltage around the fundamental frequency during Proton coalescing and over 14 dB in multi-batch antiproton coalescing.
Date: May 19, 2003
Creator: al., Joseph E Dey et
Partner: UNT Libraries Government Documents Department

62-TeV center of mass hadron collider with capability for super bunch beams

Description: A 60 TeV center of mass hadron collider is proposed, which has capability of using Superbunch beam. With Superbunch beam, the luminosity is expected to be increased by a factor of 20, compared with conventional acceleration using RF cavities. This hadron collider will be built in two stages with a low field magnet ring first and a high field magnet ring later in the same tunnel. The low field magnet rig will be built with Pipetron scheme, with 7 TeV and 7 TeV proton beams, making a 14 TeV center of mass energy high luminosity collider, using Superbunch beams. In the second stage 10 Tesla high field magnets with twin beams, will be installed. It also utilizes Superbunch beams, realizing high luminosity collider. To accelerate Superbunch beams, the barrier bucket and acceleration induction cells will be used, which are made of induction cells, utilizing FINEMET material. The core loss of the FINEMET is estimated for the whole collider is estimated. The synchrotron radiation of the collider is also estimated. Merits of Superbunch beams over RF bunched beams for the high energy experiments is described.
Date: August 22, 2001
Creator: Takayama, Ryuji Yamada and Ken
Partner: UNT Libraries Government Documents Department

62-TeV center of mass hadron collider with superbunch beams

Description: The scheme of a 62-TeV center of mass p-p collider with superbunch beams at Fermilab is proposed as a practical and realistically achievable future project. It will be built in two stages, using the same tunnel, first with a 2 Tesla low field magnet collider ring and later with a 10 Tesla high field magnet collider ring. Both low and high field magnets have twin bore aperture and will be installed in the tunnel with the circumference of 87.25 km. In each bore a proton beam is accelerated, using induction cavities to increase luminosity. In the first stage they install a 7 TeV accelerator ring with operating field of 2 Tesla, based on the superferric transmission-line design. This ring will be operated at a 14-TeV center of mass collider. This will have the same energy as the LHC, but it will have 15 times higher luminosity, namely 1.5 x 10{sup 35}/cm{sup 2}/sec. The estimated synchrotron radiation is negligible with this machine. The existing Fermilab accelerator system, including the 150 GeV main injector, will be used as the injector system. Its rough cost estimation and schedule for this first stage are presented. In the second stage proton beams are accelerated, also using induction cavities up to 31 TeV with the 10 Tesla dipole magnets. The counter circulating beams will collide with the 62-TeV center of mass energy. With the superbunch beams they can expect the luminosity can be increased about 15 times more than the conventional method with RF cavities. It will be 10{sup 35}/cm{sup 2}/sec. In the second stage, the synchrotron radiation power will be about 12 W/m, and they need an elaborated beam screen.
Date: November 5, 2001
Creator: al., Ryuji Yamada et
Partner: UNT Libraries Government Documents Department

205 kA pulse power supply for neutrino focusing horns

Description: A new underground beamline is being constructed at Fermilab to generate and focus a beam of neutrinos on a detector 450 miles away in Soudan, Minnesota. A compact modulator utilizing capacitive energy storage and SCRs as the switching element has been built and tested at Fermilab. The 0.9 F capacitor bank operates at less than 1 kV. It delivers its output of up to 240 kA directly to the two series connected focusing horns via a multi-layer radiation hard stripline [1]. Dual pulse width capability allows for ready selection of 5.2 ms, for slow beam spills, or 2.6 ms operation for reduced thermal stresses on the focusing horns during fast spill. Intended for installation in an underground equipment room, the design incorporates several novel features to facilitate transport, installation, and maintenance. Various designs were examined to arrive at the most economical approach for providing the high pulse currents to the horns located in the very high radiation field, up to 3 x 10{sup 7} kRads/yr absorbed dose of the beamline. These included charge recovery and electronic polarity reversal systems. The direct coupling approach was selected for its overall economy and compactness. The system has been operational for several months and results of those tests will be discussed. Controls and safety issues will also be discussed.
Date: June 21, 2002
Creator: Kenneth R. Bourkland, Kevin Roon and David Tinsley
Partner: UNT Libraries Government Documents Department

1400 Liter 1.8K Test Facility

Description: A double bath superfluid helium dewar has been constructed and operated at Fermilab`s Magnet Test Facility. The 1.8 K portion of the dewar is sized to contain a superconducting magnet up to 0.5 meters in diameter and 4 meters long in a vertical orientation in 0.12 MPa pressurized superfluid. The dewar can also provide a subcooled Helium I environment for tests; the entire temperature range from 4.4 K to 1. 8 K at 0.12 MPa is available. This paper describes the system design, lambda plate, heat exchanger, and performance.
Date: August 1, 1997
Creator: Peterson, T.J.; Rabehl, R.J. & Sylvester, C.D.
Partner: UNT Libraries Government Documents Department

2D/3D quench simulation using ANSYS for epoxy impregnated Nb3Sn high field magnets

Description: A quench program using ANSYS is developed for the high field collider magnet for three-dimensional analysis. Its computational procedure is explained. The quench program is applied to a one meter Nb{sub 3}Sn high field model magnet, which is epoxy impregnated. The quench simulation program is used to estimate the temperature and mechanical stress inside the coil as well as over the whole magnet. It is concluded that for the one meter magnet with the presented cross section and configuration, the thermal effects due to the quench is tolerable. But we need much more quench study and improvements in the design for longer magnets.
Date: September 19, 2002
Creator: al., Ryuji Yamada et
Partner: UNT Libraries Government Documents Department

Aspects of operation of the Fermilab Booster RF System at very high intensity

Description: The purpose of this note is to examine the likelihood and problems associated with operation of the Fermilab Booster rf systems as it presently exists, or with only minor modifications, at beam intensity approaching 5x10{sup 13} protons per pulse. Beam loading of the rf system at such an intensity will be one order of magnitude larger than at the present operation level. It is assumed that the injection energy will be raised to 1 GeV with no major increase in the injected energy spread (longitudinal emittance). The beam will be bunched by adiabatic capture as is presently done although it may be necessary to remove one or two bunches prior to acceleration to allow clean extraction at 8 GeV. At very high intensity the charge in each bunch will interact with the vacuum chamber impedance (and with itself) in such a way as to reduce in some cases the bucket area generated by the rf voltage. Because this decrement must be made up by changes in the rf ring voltage if the required bucket area is to be maintained, these effects must be taken into consideration in any analysis of the capability of the rf system to accelerate very large intensity.
Date: April 1, 1996
Creator: Griffin, J.E.
Partner: UNT Libraries Government Documents Department

An asymmetric {mu} - p collider as a quark structure microscope: Luminosity consideration

Description: An asymmetric muon-proton collider is proposed as an instrument for possible quark structure search. Energy of proton beam is supposed to be some 5-6 times of muon energy. Estimated luminosity of the collider with two rings-the Tevatron accelerator and {mu}-ring-is found to be of the order of 10{sup 33} s{sup {minus}1} cm{sup {minus}2}.
Date: April 23, 1996
Creator: Shiltsev, V.D.
Partner: UNT Libraries Government Documents Department

An asymmetric muon-proton Collider: Luminosity Consideration

Description: An asymmetric muon-proton collider is proposed as an instrument for possible quark structure search. Energy of proton beam is supposed to be some 5-6 times of muon energy. Estimated luminosity of the collider with two rings--the Tevatron accelerator and {mu}-ring--is found to be of the order of 10{sup 33} s{sup -1} cm{sup -2}.
Date: April 1, 1997
Creator: Shiltsev, V. D.
Partner: UNT Libraries Government Documents Department

The azimuthal decorrelation of jets widely separated in rapidity

Description: We study the azimuthal decorrelation between jets with pseudorapidity separation up to six units. The data were accumulated using the D0 detector during the 1994-1995 collider run of the Fermilab Tevatron at {radical}s = 1.8 TeV. The data are compared to two parton shower Monte Carlos (HERWIG and PYTHIA) and an analytical prediction using the leading logarithmic BFKL resummation. The final state jets as predicted by the parton showering Monte Carlos describe the data over the entire pseudorapidity range studied. The prediction based on the leading logarithmic BFKL resummation shows more decorrelation than the data as the rapidity interval increases.
Date: November 1, 1997
Creator: Abbott, B. & Collaboration, D0
Partner: UNT Libraries Government Documents Department