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Automatic steering corrections to minimize injection oscillations in the Fermilab Antiproton Source rings

Description: Missteering of particle beam at injection into a circular accelerator produces coherent betatron oscillations. The beam position monitor system in the Antiproton Source at Fermilab can measure the beam position on each turn around the ring during these oscillations. From the amplitude and phase of the oscillations, corrections to the beamline steering are calculated to remove the oscillations. The analysis includes the case where the horizontal and vertical tunes are quite strongly coupled. This technique has proved to be valuable both in operation of the Fermilab Collider and as an analytical tool. 4 refs., 2 figs.
Date: March 1, 1989
Creator: Harding, D.J. & Riddiford, A.W.
Partner: UNT Libraries Government Documents Department

Coil Creep and Skew-Quadrupole Field Components in the Tevatron

Description: During the start-up of Run II of the Tevatron Collider program, several issues surfaced which were not present, or not seen as detrimental, during Run I. These included the repeated deterioration of the closed orbit requiring orbit smoothing every two weeks or so, the inability to correct the closed orbit to desired positions due to various correctors running at maximum limits, regions of systematically strong vertical dipole corrections, and the identification of very strong coupling between the two transverse degrees-of-freedom. It became apparent that many of the problems being experienced operationally were connected to a deterioration of the main dipole magnet alignment, and remedial actions were undertaken. However, the alignment alone was not enough to explain the corrector strengths required to handle transverse coupling. With one exception, strong coupling had generally not been an issue in the Tevatron during Run I. Based on experience with the Main Ring, the Tevatron was designed with a very strong skew quadrupole circuit to compensate any quadrupole alignment and skew quadrupole field errors that might present themselves. The circuit was composed of 48 correctors placed evenly throughout the arcs, 8 per sector, evenly placed in every other cell. Other smaller circuits were installed but not initially needed or commissioned. These smaller circuits were composed of individual skew quadrupole correctors on either side of the long straight sections. These circuits were tuned by first bringing the horizontal and vertical tunes near each other. The skew quadrupoles were then adjusted to minimize tune split, usually to less than 0.003. Initially, the main skew quad circuit (designated T:SQ) could accomplish this global decoupling with only 4% of its possible current, and the smaller circuits were not required at all. The start-up of Run Ib was complicated by what was later discovered to be a rolled triplet quadrupole ...
Date: July 11, 2011
Creator: Annala, G.; Harding, D.J.; Syphers, M.J. & /Fermilab
Partner: UNT Libraries Government Documents Department

Magnetic field strength and shape measurements of the Fermilab main injector quadrupoles

Description: All of the new quadrupoles for the Fermilab Main Injector ring have been built and measured. The magnets are 2.95 m and 2.54 m in length with a 41.7 mm bore. In operation, the magnets run from 1.61 T/m at 8. 9 GeV/c to 15.7 T/m at 120 GeV/c and 19.6 T/m at 150 GeV/c. These points correspond to injection, Main Injector fixed target physics and antiproton production, and extraction for transfer to the Tevatron. Good field uniformity is required to ensure a stable beam over the whole acceleration cycle. A significant octupole is included to assist in resonant extraction. The performance of these quadrupoles, in both integrated strength and field uniformity, is presented. All magnets produced meet the accelerator requirements.
Date: May 1, 1997
Creator: Harding, D.J.; Brown, B.C. & DiMarco, H.H.
Partner: UNT Libraries Government Documents Department

Field shape measurements of prototype Main Injector dipole endpacks

Description: Measurements of the transverse dependence of the flux on the symmetry plane were obtained on a series of endpacks mounted on a Main Injector prototype dipole. From these flux measurements, we determined the endfield shape, expressed in terms of normal harmonics, up to 14-pole. We describe the measurement and analysis procedure, and present the results for all endpacks that were tested. The final endpack (number 10) has a sextupole, normalized to the body, of +0.167 [plus minus] .072 units, and the relative field shape deviates by [lt] 1.2 units relative to the on-axis field strength over the range [vert bar]x[vert bar] [lt] 2.0[double prime]. These measurements indicate that Endpack 10 meets the requirements for the Main Injector dipole.
Date: January 6, 1993
Creator: Glass, H.D.; Brown, B.C. & Harding, D.J.
Partner: UNT Libraries Government Documents Department

Effective length measurements of prototype Main Injector Dipole endpacks

Description: An endpack design has been developed for the Fermilab Main Injector Dipole. A major part of the design process was the testing of a series of prototype removable endpacks. The magnetic parameters that were tested included the effective length and the field shape variation. This report presents a description of the measurement techniques and the results for the effective length. The final endpack has an effective length at 1500 A (0.29T) of 2.6 [plus minus] 0.3 mm greater than the steel length, and the change in effective length from 1500 A to maximum current of 9500 A (1.74T) is [minus]1.88 [plus minus] 0.05 mm.
Date: March 3, 1993
Creator: Glass, H.D.; Brown, B.C. & Harding, D.J.
Partner: UNT Libraries Government Documents Department

Magnet reliability in the Fermilab Main Injector and implications for the ILC

Description: The International Linear Collider reference design requires over 13000 magnets, of approximately 135 styles, which must operate with very high reliability. The Fermilab Main Injector represents a modern machine with many conventional magnet styles, each of significant quantity, that has now accumulated many hundreds of magnet-years of operation. We review here the performance of the magnets built for this machine, assess their reliability and categorize the failure modes, and discuss implications for reliability of similar magnet styles expected to be used at the ILC.
Date: August 1, 2007
Creator: Tartaglia, M.A.; Blowers, J.; Capista, D.; Harding, D.J.; Kiemschies, O.; Rahimzadeh-Kalaleh, S. et al.
Partner: UNT Libraries Government Documents Department

New corrector system for the Fermilab booster

Description: We present an ambitious ongoing project to build and install a new corrector system in the Fermilab 8 GeV Booster. The system consists of 48 corrector packages, each containing horizontal and vertical dipoles, normal and skew quadrupoles, and normal and skew sextupoles. Space limitations in the machine have motivated a unique design, which utilizes custom wound coils around a 12 pole laminated core. Each of the 288 discrete multipole elements in the system will have a dedicated power supply, the output current of which is controlled by an individual programmable ramp. This paper describes the physics considerations which drove the design, as well as issues in the control of the system.
Date: June 1, 2007
Creator: Prebys, E.J.; Drennan, C.C.; Harding, D.J.; Kashikhin, V.; Lackey, J.R.; Makarov, A. et al.
Partner: UNT Libraries Government Documents Department

Hybrid permanent quadrupoles for the 8 GeV transfer line at Fermilab

Description: Hybrid Permanent Magnet Quadrupoles for specialized portions of the 8 GeV transfer line from the Fermilab Booster to the new Main Injector have been built, tested and installed. These magnets use a 0.635 m long iron shell and provide an integrated gradient of 1.48 T-m/m with an iron pole tip radius of 0.0416 m. and pole length of 0.508 m. Bricks of 0.0254 m thick strontium ferrite supply the flux to the back of the pole to produce the desired 2.91 T/m gradient. For temperature compensation, Ni-Fe alloy strips are interspersed between ferrite bricks to subtract flux in a temperature dependent fashion. Adjustments of the permeance of each pole using iron from between the pole and the flux return shell permits the matching of pole potentials. Magnetic potentials of the poles are measured with a Rogowski coil and adjusted to the desired value to achieve the prescribed strength and field uniformity. After these adjustments, the magnets are measured using a rotating coil to determine the integral gradient and the harmonics. These measurements are used to calibrate the production Rogowski coil measurements. Similar quadrupoles are included in the design of the Fermilab Recycler.
Date: June 1, 1997
Creator: Pruss, S. M.; Foster, G. W.; Glass, H. D.; Harding, D. J.; Jackson, G. P.; May, M. P. et al.
Partner: UNT Libraries Government Documents Department

Design for Fermilab main injector magnet ramps which account for hysteresis

Description: Although the dominant fields in accelerator electromagnets are proportional to the excitation current, precise control of accelerator parameters requires a detailed understanding of the fields in Main Injector magnets including contribution from eddy currents, magnet saturation, and hysteresis. Operation for decelerating beam makes such considerations particularly significant. Analysis of magnet measurements and design of control system software is presented. Field saturation and its effects on low field hysteresis are accounted for in specifying the field ramps for dipole, quadrupole and sextupole magnets. Some simplifying assumptions are made which are accepted as limitations on the required ramp sequences. Specifications are provided for relating desired field ramps to required current ramps for the momentum, tune, and chromaticity control.
Date: May 1, 1997
Creator: Brown, B.C.; Bhat, C.M.; Harding, D.J.; Martin, P.S. & Wu, G.
Partner: UNT Libraries Government Documents Department

Air-cooled trim dipoles for the Fermilab Main Injector

Description: New horizontal and vertical trim dipoles have been designed for the Fermilab Main Injector (FMI) and are being assembled in the Fermilab Technical Division. Magnets are 42.6 cm in length (30.5 cm steel length) and have similar cross-section dimensions. The horizontal (vertical) magnet gap is 50.8 mm (127 mm) and the target integrated strength is 0.072 T*m (0.029 T*m). The major design effort lay in making air cooling possible for these magnets. This report presents the magnets` thermal and magnetic properties and discusses the limitation on excitation current.
Date: May 1, 1997
Creator: Harding, D. J.; Chester, N. S.; Garvey, J. D.; Krafczyk, G. E.; Makarov, A. I. & Terechkine, I.
Partner: UNT Libraries Government Documents Department

The main injector chromaticity correction sextupole magnets: Measurements and operating schemes

Description: The Fermilab Main Injector (FMI) is a high intensity proton synchrotron which will be used to accelerate protons and antiprotons from 8.9 GeV/c to 150 GeV/c. The natural chromaticities of the machine for the horizontal and the vertical Planes are {minus}33.6 and {minus}33.9 respectively. The {Delta}p/p of the beam at injection is about 0.002. The chromaticity requirements of the FMI, are primarily decided by the {Delta}p/p = 0.002 of the beam at injection. This limits the final chromaticity of the FMI to be {plus_minus}5 units. To correct the chromaticity in the FMI two families of sextupole magnets will be installed in the lattice, one for each plane. A sextupole magnet suitable for the FMI needs has been designed and a number of them are being built. New chromaticity compensation schemes have been worked out in the light of recently proposed faster acceleration ramps. On an R/D sextupole magnet the low current measurements have been carried out to determine the electrical properties. Also, using a Morgan coil, measurements have been performed to determine the higher ordered multipole components up to 18-poles. An overview of these result are presented here.
Date: May 1, 1995
Creator: Bhat, C.M.; Bogacz, A.; Brown, B.C.; Harding, D.J.; Fang, S.J.; Martin, P.S. et al.
Partner: UNT Libraries Government Documents Department

Experience with the Source Evaluation Board method of procuring technical components for the Fermilab Main Injector

Description: Fermilab has adopted the Source Evaluation Board (SEB) method for procuring certain major technical components of the Fermilab Main Injector. The SEB procedure is designed to ensure the efficient and effective expenditure of Government funds at the same time that it optimizes the opportunity for attainment of project objectives. A qualitative trade-off is allowed between price and technical factors. The process involves a large amount of work and is only justified for a very limited number of procurements. Fermilab has gained experience with the SEB process in awarding subcontracts for major subassemblies of the Fermilab Main Injector dipoles.
Date: May 1, 1993
Creator: Harding, D.J.; Collins, J.P.; Kobliska, G.R.; Chester, N.S.; Pewitt, E.G. & Fowler, W.B.
Partner: UNT Libraries Government Documents Department

Measurements of beam pipe eddy current effects in Main Injector dipole magnets

Description: The dipole magnets for the proposed Main Injector project at Fermilab are designed to ramp to maximum field (1.7 T) at rates over 2.5 T/s. These ramp rates will produce eddy current effects which degrade overall field quality. A harmonics probe was constructed for the purpose of measuring eddy current field components during the ramp cycle. Three separate ramp rates were employed ranging from 1.3 T/s to 2.7 T/s. Tests were performed using beam pipes with two different resistivities. The dominant multipole contribution resulting from eddy current effects in each beam pipe was sextupole. The sextupole component closely matched the calculated prediction.
Date: August 1, 1992
Creator: Walbridge, D. G. C.; Bleadon, M. E.; Brown, B. C.; Glass, H. D.; Harding, D. J.; Mazur, P. O. et al.
Partner: UNT Libraries Government Documents Department

Selection Tests of MnZn and NiZn Ferrites for Mu2e 300 kHz and 5.1 MHz AC Dipoles

Description: Mu2e, a charged lepton flavor violation (CLFV) experiment is planned to start at Fermilab late in this decade. The proposed experiment will search for neutrinoless muon to electron conversions with unprecedented sensitivity, better than 6 x 10{sup -17 }at 90% CL. To achieve this sensitivity the incoming proton beam must be highly suppressed during the window for detecting the muon decays. The current proposal for beam extinction is based on a collimator design with two dipoles running at {approx}300 kHz and 5.1 MHz and synchronized to the proton bunch spacing. The appropriate choice of ferrite material for the magnet yoke is a critical step in the overall design of the dipoles and their reliable operation at such high frequencies over the life of the experiment. This choice, based on a series of the thermal and magnetic measurements of the ferrite samples, is discussed in the paper. Additionally, the first results from the testing at 300 kHz of a prototype AC dipole are presented.
Date: September 9, 2011
Creator: Bourkland, K.; Elementi, L.; Feher, S.; Harding, D.J.; Kashikhin, V.S.; Makarov, A. et al.
Partner: UNT Libraries Government Documents Department

AC field measurements of Fermilab Booster correctors using a rotating coil system

Description: The first prototype of a new corrector package for the Fermilab Booster Synchrotron is presently in production. This water-cooled package includes normal and skew dipole, quadrupole and sextupole elements to control orbit, tune and chromaticity of the beam over the full range of Booster energies (0.4-8 GeV). These correctors operate at the 15 Hz excitation cycle of the main synchrotron magnets, but must also make more rapid excursions, in some cases even switching polarity in approximately 1 ms at transition crossing. To measure the dynamic field changes during operation, a new method based on a relatively slow rotating coil system is proposed. The method pieces together the measured voltages from successive current cycles to reconstruct the field harmonics. This paper describes the method and presents initial field quality measurements from a Tevatron corrector.
Date: July 1, 2006
Creator: Velev, G.V.; DiMarco, J.; Harding, D.J.; Kashikhin, V.; Lamm, M.; Makulski, A. et al.
Partner: UNT Libraries Government Documents Department

Design and fabrication of a multi-element corrector magnet for the Fermilab Booster synchrotron

Description: To better control the beam position, tune, and chromaticity in the Fermilab Booster synchrotron, a new package of six corrector elements has been designed, incorporating both normal and skew orientations of dipole, quadrupole, and sextupole magnets. The devices are under construction and installation at 48 locations is planned. The density of elements and the rapid slew rate have posed special challenges. The magnet construction is presented along with DC measurements of the magnetic field.
Date: June 1, 2007
Creator: Harding, D.J.; DiMarco, J.; Drennan, C.C.; Kashikhin, V.S.; Kotelnikov, S.; Lackey, J.R. et al.
Partner: UNT Libraries Government Documents Department

Test Results of the AC Field Measurements of Fermilab Booster Corrector Magnets

Description: Multi-element corrector magnets are being produced at Fermilab that enable correction of orbits and tunes through the entire cycle of the Booster, not just at injection. The corrector package includes six different corrector elements--normal and skew orientations of dipole, quadrupole, and sextupole--each independently powered. The magnets have been tested during typical AC ramping cycles at 15Hz using a fixed coil system to measure the dynamic field strength and field quality. The fixed coil is comprised of an array of inductive pick-up coils around the perimeter of a cylinder which are sampled simultaneously at 100 kHz with 24-bit ADC's. The performance of the measurement system and a summary of the field results are presented and discussed.
Date: June 25, 2008
Creator: DiMarco, E.Joseph; Harding, D.J.; Kashikhin, V.S.; Kotelnikov, S.K.; Lamm, M.J.; Makulski, A. et al.
Partner: UNT Libraries Government Documents Department

System overview for the multi-element corrector magnets and controls for the Fermilab Booster

Description: To better control the beam position, tune, and chromaticity in the Fermilab Booster synchrotron, a new package of six corrector elements has been designed, incorporating both normal and skew orientations of dipole, quadrupole, and sextupole magnets. The devices are under construction and will be installed in 48 locations in the Booster accelerator. Each of these 288 corrector magnets will be individually powered. Each of the magnets will be individually controlled using operator programmed current ramps designed specifically for each type of Booster acceleration cycle. This paper provides an overview of the corrector magnet installation in the accelerator enclosure, power and sensor interconnections, specifications for the switch-mode power supplies, rack and equipment layouts, controls and interlock electronics, and the features of the operator interface for programming the current ramps and adjusting the timing of the system triggers.
Date: June 1, 2007
Creator: Drennan, C.; Ball, M.; Franck, A. R.; Harding, D. J.; Kasley, P. A.; Krafczyk, G. E. et al.
Partner: UNT Libraries Government Documents Department

Results on Fermilab main injector dipole measurements

Description: Measurements of the Productions run of Fermilab Main Injector Dipole magnets is underway. Redundant strength measurements provide a set of data which one can fit to mechanical and magnetic properties of the assembly. Plots of the field contribution from the steel supplement the usual plots of transfer function (B/I) vs. I in providing insight into the measured results.
Date: June 1, 1995
Creator: Brown, B.C.; Baiod, R.; DiMarco, J.; Glass, H.D.; Harding, D.J.; Martin, P.S. et al.
Partner: UNT Libraries Government Documents Department

Hybrid permanent magnet quadrupoles for the Recycler Ring at Fermilab

Description: Hybrid Permanent Magnet Quadrupoles are used in several applications for the Fermilab Recycler Ring and associated beam transfer lines. Most of these magnets use a 0.6096 m long iron shell and provide integrated gradients up to 1.4 T-m/m with an iron pole tip radius of 41.6 mm. A 58.4 mm pole radius design is also required. Bricks of 25. 4 mm thick strontium ferrite supply the flux to the back of the pole to produce the desired gradients (0.6 to 2.75 T/m). For temperature compensation, Ni-Fe alloy strips are interspersed between ferrite bricks to subtract flux in a temperature dependent fashion. Adjustments of the permeance of each pole using iron between the pole and the flux return shell permits the matching of pole potentials. Magnetic potentials of the poles are adjusted to the desired value to achieve the prescribed strength and field uniformity based on rotating coil harmonic measurements. Procurement, fabrication, pole potential adjustment, and measured fields will be reported.
Date: October 1, 1997
Creator: Brown, B.C.; Pruss, S.M.; Foster, G.W.; Glass, H.D.; Harding, D.J.; Jackson, G.R. et al.
Partner: UNT Libraries Government Documents Department

Software design for a database driven system for accelerator magnet measurements

Description: Measurements of more than 1000 new magnets are needed for the Main Injector Project at Fermilab. In order to achieve efficiency and accuracy in measurements, we chose a database driven design for control of the measurement system. We will use a relational database to describe the measurement subjects and equipment. A logbook system defined in the database will provide for prescription of measurements to be carried out, description of measurements as they are carried out, and a comment database for less structured information. The operator interface will be built on X-windows. This paper will describe our system design. 2 refs.
Date: May 1, 1991
Creator: Brown, B.C.; Bleadon, M.E.; Glass, H.D.; Glosson, R.; Hanft, R.W.; Harding, D.J. et al.
Partner: UNT Libraries Government Documents Department

Hybrid permanent magnet gradient dipoles for the recycler ring at Fermilab

Description: Hybrid permanent magnets provide the magnetic fields for an anti- proton storage ring which is under construction at Fermilab. Using a combined function lattice, gradient magnets provide the bending, focusing and sextupole correction for the regular cells. Shorter magnets without sextupole are used in dispersion suppressor cells. These magnets use a 4.7 m ( 3 m) long iron shell for flux return, bricks of 25.4 mm thick strontium ferrite supply the flux and transversely tapered iron poles separated by aluminum spacers set the shape of the magnetic field. Central fields of 0.14 T with gradients of {approx}6%/inch ({approx}13%/inch) are required. Field errors are expected to be less than 10{sup -4} of the bend field over an aperture of {+-}40 mm (horizontal) {times} {+-}20 mm (vertical). Design, procurement, fabrication, pole potential adjustment, field shape trimming and measured fields will be reported.
Date: November 1, 1997
Creator: Brown, B.C.; Dimarco, J.; Foster, G.W.; Glass, H.D.; Haggard, J.E.; Harding, D.J. et al.
Partner: UNT Libraries Government Documents Department