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The ionization beam profile monitor system for the Main Injector ring is under construction at Fermilab. The beam profile detector unit is installed inside the main magnet gap. The magnet has a novel configuration previously used for this type of application in the Main Injector. However, this magnet is far more compact with a higher quality field. Most flux from the main gap returns symmetrically along the beam pipe through two side gaps. It provides nearly full compensation to yield integrated magnetic field close to zero, and helps eliminate distortions of the circulating proton beam. The permanent magnet poles are assembled from SmCo5 bricks (0.5''×1''×2''), which have good thermal stability and reasonable cost. Further integrated field reduction is obtained by the use of a ferromagnetic plate that shunts the main gap. The plate position and flux shunting are adjusted in conjunction with magnetic measurements. Three permanent magnets were successfully fabricated and measured. Results of the magnet design, 3-D FEA analysis, and magnetic measurements by the rotational coil and the 3-D Hall probe will be presented.

A Superconducting transmission line magnet test system for the stage 1 accelerator of a staged VLHC proton-proton collider has been built and operated at Fermilab. The 1.5 m long, twin-aperture, combined function dipole magnet of 2 Tesla field is excited by a single turn 100 kA transmission line superconductor. The 100 kA dc current is generated using dc-dc switching converters powered by a bulk 240 kW supply. A pair of horizontally placed conventional leads facilitates transfer of this current to the magnet transmission line superconductor operating at liquid helium temperature. Fabrication of magnet components and magnet assembly work are described. The magnet test system and its operation are presented, and the performance is summarized

The proposed Next Linear Collider (NLC) will require over 1400 adjustable quadrupoles between the main linacs' accelerator structures. These 12.7 mm bore quadrupoles will have a range of integrated strength from 0.6 to 132 Tesla, with a maximum gradient of 135 Tesla per meter, an adjustment range of +0 -20% and effective lengths from 324 mm to 972 mm. The magnetic center must remain stable to within I micrometer during the 20% adjustment. In an effort to reduce estimated costs and increase reliability, several designs using hybrid permanent magnets have been developed. All magnets have iron poles and use either Samarium Cobalt or Neodymium Iron to provide the magnetic fields. Two prototypes use rotating rods containing permanent magnetic material to vary the gradient. Gradient changes of 20% and center shifts of less than 20 microns have been measured. These data are compared to an equivalent electromagnet prototype.

The magnets of the circular accelerators that comprise the Fermilab complex have contributed to, responded to, and solved a string of accelerator physics issues. Most importantly, the magnets are supposed to generate high quality magnetic fields needed for stable long-term dynamics of the particles circulating in the rings. The quality of the transverse magnetic field B is given by the multipole coefficients in the expansion: $$ {B}_x+i\cdot {B}_y={B}_0{\displaystyle \sum_{n=0}\left({b}_n+i{a}_n\right){\left[\frac{x+ iy}{R_0}\right]}^n}, $$ (3.1) where R 0 is the reference radius (1 in. in the Fermilab accelerators), the pole number is 2(n + 1) and b n (a n ) are the normal (skew) multipole coefficients, and b 0 is unity. For example, the multipoles allowed by dipole symmetry, b 2, b 4, b 6, … are designed to be small and would be 0 for a pure cos θ coil winding. The precise coil placement, and hence good magnetic field uniformity at the relative level of the multipole coefficients of few 10−4, had the biggest effect on the accelerator performance.

A superconducting transmission line magnet test facility was built and commissioned at Fermilab. The test facility is capable of generating a 100 kA current in a 17-meter length short-circuited superconducting loop, as well as driving 15 m long test magnets. The current is excited by a room temperature primary winding and iron yoke operated as a current transformer. This approach avoids the expense and difficulty of 100 kA current leads, and allows the facility to be Dewar-based. The loop has a replaceable superconductor section 4 m long for testing various types of VLHC transmission line cables. The system design, 3D magnetic field analysis, magnetic force distribution and test results are discussed.

The Fermilab Recycler Ring, part of the Main Injector upgrade, is an 8 GeV storage ring consisting of 362 gradient magnets, 109 quadrupoles, 8 mirror magnets, and 5 Lambertsons. The field is driven by strontium ferrite permanent magnets and shaped by precision pole pieces. Temperature dependence of the ferrite is compensated by the use of Ni (30%) Fe (70%) alloy operating near its Curie point. Temperature stability is held to within 0.004%/spl deg/C rms. over the operating range of 25 to 35 C. Tighter stability requirements (0.001%/spl deg/C) for the high beta quadrupoles are met by active thermal control using heating blankets. Longitudinal uniformity is obtained by distribution of the compensator and ferrite throughout the magnet. Field strength in the magnets are adjusted to be within 0.05% of the design field. The higher harmonics contribute less than 0.01% of the primary field measured at a radius of 25.4 mm. For the gradient magnets custom end shims are made to adjust the harmonics; the field is adjusted by adding or subtracting ferrite. The loss of magnetization is logarithmic in time with a /spl Delta/(M/sub 2//M/sub 1/)=9.0/spl times/10/sup -4/ *log (t/sub 2//t/sub 1/), corresponding to a 0.35% loss of field over the expected operating life of 20 years.

A search for charm hadron decays into two muons plus one or more hadrons has been carried out using a hybrid emulsion spectrometer. This technique is sensitive to modes with missing neutrals, e.g. π0μ+μ− and ϱ±μ+μ−, as well as to constrained modes having visible invariant masses equal to those of charm states. No evidence for any such decays has been found, which allows upper limits at the 90% confidence level as low as 1.8 × 10−4 to be placed on the branching fractions for charm-changing neutral-current and lepton-number violating decay modes.

The relative branching fraction RK = Γ(D0 → K−μ+v)/Γ(D0 → μ−X) has been measured by Fermilab experiment E653, using D0 mesons produced by 600 GeV π−. The semimuonic decay sample of 232 events was identified by the decay chain D ∗+ → D 0 π + , D 0 → μ + h − X , where h is a hadron. The Kμv component was extracted from the joint distribution of these events in the D0 decay variables Mmin and pTh. We find RK = 0.472 ± 0.051 (stat) ± 0.040 (sys), and use a world average of the D0 → Klv branching fraction to obtain the D0 inclusive semimuonic branching fraction B(D0 → μ+X) = (7.67 ± 1.13)%.

A new method, called graphic scanning, was developed by the Nagoya University Group for emulsion analysis in a hybrid experiment. This method enhances both speed and reliability of emulsion analysis. Details of the application of this technique to the analysis of Fermilab experiment E653 are described.

We report the first observation of the Cabibo disfavored semileptonic decay mode D+ → ρ(770)0 μ+v and measure its decay rate relative to the Cabibbo favored mode D + → K ∗ (892) 0 μ + v to be Λ(D + → ρ(770) 0 μ + v Λ(D + → K ∗ (892) 0 μ + v) = 0.044 0.031 −0.025 ( stat. ) ± 0.014 ( syst. ) . The results are compared to theoretical predictions and to previous experimental upper limits.

A search for charm production in the coherent diffractive dissociation reaction pSi→XSi was carried out for the modes D0→K−π+, D0→K−π+π+π−, and D+→K−π+π+. No charm signals were observed, and the 90% confidence level upper limit for coherent charm pair production was determined to be 26 μb per silicon nucleus. The results are interpreted as an upper limit of 0.2% on the amount of intrinsic charm in the proton.

Upper limits at the 90% confidence level are presented for four- and five-prong semimuonic decays of charm mesons. From a study of four-prong vertices we find B ( D 0 → K − π + π − μ + ν )/ B ( D 0 → K − μ + ν ) B (D 0 → ( K ∗ (892)π) − μ + ν)/B(D 0 → K − μ + ν) . The five-prong vertices yield the result B ( D S + → η ′ μ + ν ) / B ( D S + → φμ + ν )

We present a study of the Cabibbo-allowed semimuonic decay modes of the DS+ produced in 600 GeV c π − -emulsion interactions. From a signal of 18.7±4.9−0.7+0.4 events in the DS+ → oμ+υ channel, the product of production cross section and partial width is measured with respect to that for D + → K ∗0 μ + υ to be ( σ(D S + ) σ(D + )) . (Λ(D S + → oμ + ν)Λ(D + → K ∗0 μ + ν)) = 0.56 ± 0.14 ± 0.12. The form factor ratios in the decay, obtained by fitting to the decay angles and q2, are A 2 (0) 1 (0) = 2.1 −0.5 +0.6 ± 0.2 and V (0) A 1 (0) = 2.3 −0.9 +1.1 ± 0.4 , where A1 (0) and A2 (0) are the axial vector form factors and V(0) is the vector form factor, evaluated at q2 = 0. The first observation of DS+ → (ημ+υ + η'μ+υ) is also reported, and Γ (D S + → (ημ + υ + η'μ + υ)) Γ (D S + → oμ + υ) is determined to be 3.9 ± 1.6.

We report on the production characteristics and total cross section for 9 beauty hadron pairs produced by a 600 GeV/ c π − beam, the first such information in this energy region. The events were detected in the hybrid emulsion spectrometer of Fermilab Experiment E653. The measured pair cross section for all χ F , assuming linear A dependence, is 33±11 (stat.)±6(syst.) nb/nucleon. Fits of the inclusive single-hadron production distribution to the forms d σ d χ F ∝ (1−|χ F −χ 0 |) n and d σ d p T 2 ∝ exp (−bp t 2 ) give n=5.0 −2.1−1.7 +2.7+1.7 , χ 0 =0.06 −0.07−0.03 +0.06+0.02 , and b=0.13 −0.04−0.02 +0.05+0.02 ( GeV /c −2 . .The pairs tend to be produced back-to-back.

The branching ratio for the decay mode D + → K ∗0 μ + ν has been measured with two methods. The first uses D0→K−μ+ν for normalization, and yields the result B( D + → K ∗0 μ + ν)=(3.25±0.71±0.75)% . From this method we also obtain the direct measurement Γ( D + → K ∗0 μ + ν)/Γ( D 0 → K − μ + ν)=0.43±0.09±0.09 . The second method uses the mode D+→K−π+π+ for normalization and yields B( D + → K ∗0 μ + ν)=(4.18±0.66±0.96)% . Combining the results of the two methods yields B( D + → K ∗0 μ + ν)=(3.57±0.96)% .

We present total and differential cross sections for charm mesons produced in 600 GeV/c π- emulsion interactions. Fits to d2σ/dxF dpT2∞ (1−|xF|)nexp (-bpT2) for 676 electronically reconstructed D mesons with xF>0 give n=4.25±0.24 (stat.)±0.23 (syst.) and b=0.76±0.03±0.03 (GeV/c)-2. The total inclusive D+ and D0 cross sections are σ(π-N→D±; xF>0) = 8.66±0.46±1.96μb nucleon and σ(π - N→D 0 D 0 ; x F >0)=22.05±1.37±4.82μb nucleonk, where a linear dependence on the mean atomic weight of the target is assumed. These results are compared to next-to-leading order QCD predictions.

A measurement of the form factor ratios in the decay D + → K ∗ (892) 0 μ + ν is obtained by fitting to the decay angles and q2 of 305 events. The results, evaluated at q2 = 0, are A2(0)/A1(0) = 0.82+0.22−0.23 (stat.)±0.11 (sys.) and V(0)/A1(0) = 2.00+0.34−0.32±0.16, where A1 and A2 are the axial vector form factors and V is the vector form factor. The corresponding ratio of the longitudinal to transverse polarization of the K ∗0 is 1.18±0.18±0.08. These results are compared with other experimental results and with theoretical predictions.

It was observed during the early part of Run II that dipole corrector currents in the Tevatron were changing over time. Measurement of the roll for dipoles and quadrupoles confirmed that there was a slow and systematic movement of the magnets from their ideal position. A simple system using a digital protractor and laptop computer was developed to allow roll measurements of all dipoles and quadrupoles. These measurements showed that many magnets in the Tevatron had rolled more than 1 milli-radian. To aid in magnet alignment a new survey network was built in the Tevatron tunnel. This network is based on the use of free centering laser tracker. During the measurement of the network coordinates for all dipole, quadrupole and corrector magnets were obtained. This paper discusses roll measurement techniques and data, the old and new Tevatron alignment network.

Early in Run2, there was an effort to compare the different emittance measurements in the Tevatron (flying wires and synchtotron light) and understand the origin of the observed differences. To measure the beta function at a few key locations near the instruments, air-core quadrupoles were installed. By modulating the gradient of these magnets and measuring the effect on the tune, the lattice parameters can be extracted. Initially, the results seem to disagree with with other methods. At the time, the lattice was strongly coupled due to a skew component in the main dipoles, caused by sagging of the cryostat. After a large fraction of the superconducting magnets were shimmed to remove a strong skew quadrupole component, the results now agree with the theoretical values to within 20%.

An adjustable strength permanent magnet quadrupole suitable for use in Next Linear Collider has been built and tested. The pole length is 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient length (GL) is 68.7 Tesla. This paper describes measurements of strength, magnetic CL and field quality made using an air bearing rotating coil system. The magnetic CL stability during -20% strength adjustment proposed for beam based alignment was < 0.2 microns. Strength hysteresis was negligible. Thermal expansion of quadrupole and measurement parts caused a repeatable and easily compensated change in the vertical magnetic CL. Calibration procedures as well as CL measurements made over a wider tuning range of 100% to 20% in strength useful for a wide range of applications will be described. The impact of eddy currents in the steel poles on the magnetic field during strength adjustments will be reported.

In the commissioning of the Fermilab Recycler ring the need for higher order corrector magnets in the regions near beam transfer lines was discovered. Three types of permanent magnet skew quadrupoles, and two types of permanent magnet sextupoles were designed and built. This paper describes the need for these magnets, the design, assembly, and magnetic measurements.

The procedure for automatically producing customized end shims for the Recycler Antiproton Storage Ring gradient magnets is described. Magnets were first measured with a harmonics probe. The observed field defects were then fed into a computer program (initially a spreadsheet) which generated the toolpath code for a numerically controlled milling machine which produced individually customized end shims that eliminated the measured defect. Field defects through decapoles were corrected to an accuracy (limited by the reproducibility of the measurement apparatus) to a few /spl times/10/sup -5/.

Permanent magnets built using strontium ferrite bricks have been tested for stability against demagnetization. Ten test dipoles were built to monitor ferrite behavior under a variety of stressing conditions, including irradiation, mechanical shock, extreme thermal excursions, and long term magnetization stability. The test magnets were geometrically similar to, but much shorter than, the magnets built for the 8 GeV transfer line at FNAL. No loss of magnetization was observed for bricks exposed to a proton beam, and a magnet exposed to several Gigarads of Co/sup 60/ gamma radiation suffered no measurable demagnetization. The magnet strength was observed to decrease logarithmically with time, consistent with the expected effect of thermal fluctuations. Irreversible demagnetization of /spl sim/0.1% was seen in cooling magnets to 0/spl deg/C, and the loss was /spl sim/0.2% for magnets cooled to /spl sim/20/spl deg/C. No additional demagnetization was seen on subsequent cycling to 0/spl deg/C. Finally, one of the long dipoles built for the 8 GeV line was periodically tested over the course of 3 months, and showed no measurable demagnetization.

The transfer line that will serve to transport 8 GeV protons from the Booster to the new Fermilab Main Injector has been built using permanent magnets. A total of 46 horizontal bend dipoles and 5 vertical bend dipoles were built for this beamline; 67 gradient magnets were also built. The magnets were built using magnetized strontium ferrite bricks. Thermal compensation of these bricks was effected by use of a nickel-iron alloy. The dipole magnets were built with a mean integrated strength of 0.56954 T-m, and an rms spread of 0.06%. The magnets were thermally cycled from 20/spl deg/C to 0/spl deg/C to condition the ferrite against irreversible thermal losses, and the compensation was measured with a flipcoil. The magnet strength was adjusted by varying the number of bricks installed at the magnet ends. Details of the assembly process and a summary of magnetic measurements are presented here.

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 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.

This paper will show and discuss the simple design of a permanent magnet Lambertson used to extract and inject the 8 GeV beam from the Fermilab Main Injector Ring to the Recycler Ring, and from the Recycler Ring to the Main Injector. Pictures will show how four different magnets used to form the injection and extraction double dog legs are made from one universal design. Detailed assembly drawings will illustrate the construction techniques using solid pieces of steel instead of laminations. The field strength in both the bending region and the field free region will be discussed along with temperature compensation of the strontium ferrite magnetic bricks.

The use of permanent magnets for transporting the 8 GeV proton beam from the Fermilab Booster to the new Fermilab Main Injector accelerator has been implemented and the magnets for a new 8 GeV ring to be installed in the Main Injector tunnel for increasing the luminosity of pbar/p collisions in the Tevatron are about to start being produced. Strontium oxide ferrite was selected for the magnets due to it's low cost and satisfactory magnetic properties for the 1.5 kilogauss fields required in the 2-inch gap magnets. Fermilab has received 96,000 pounds of ferrite and by working with the Vendor (HITACHI, Edmore, MI) improved uniformity of Residual Induction (Br) has reached 3905 gauss /spl plusmn/0.65%. Further details are given in the paper. Overcoming the magnetic field variation when the temperature of the magnets changes is accomplished by incorporation of approximately 30% nickel steel alloy. The ferrite changes approximately-0.2% per degree C, which is compensated for by the 13% by volume of compensator alloy incorporated in the magnet. Fourteen thousand (14,000) pounds of this material has been received and in order to obtain sufficient uniformity we mixed equal amounts from each batch into each magnet. Results of this process are given in the paper.

The 8 GeV transfer line feeding protons into the new Fermilab Main Injector has been built using strontium ferrite permanent magnets. This article addresses the design and manufacture of the 67 combined function magnets; permanent horizontal and vertical bend dipoles and quadrupoles were also built. The combined function magnets were built with a mean integrated strength at midaperture of 0.56953 T-m (central field nominally 0.15 T), and a gradient of 3.23% per cm relative to the dipole strength (nominal gradient=0.48 T/m). Thermal compensation of these bricks was effected by use of a nickel-iron alloy. The magnets were thermally cycled from 20/spl deg/C to 0/spl deg/C to condition the ferrite against irreversible thermal losses; the compensation was measured with a flipcoil and verified with a rotating harmonics coil. We present details of the magnet assembly process and also summarize the magnetic measurements.

Field strengths for strontium ferrite permanent magnets built for the Fermilab Recycler and the 8 GeV transfer line have been measured for the past 4 years. The ferrite magnetization exhibits a time dependence parameterized by M1/M/sub 2/ = -9 /spl times/ 10/sup -4/ /spl times/ log (t/sub 1//t/sub 2/) as determined from measurements of a gradient magnet. This parameterization has been checked against several other styles of permanent dipoles, and quadrupole magnets with good agreement.

The Recycler Ring Gradient Magnets were designed with end shims which correct the field shape (harmonic components up to 10-pole). A standard correction was employed at one end to correct the average properties. A variable correction was used at the other end to correct individual magnet variations during the fabrication process. An initial Recycler operation revealed that the quadrupole fields did not produce the desired tune. In part, this was due to the sextupole of the end-shim interacting with the curved orbit through the straight magnet. The standard end-shim was replaced on all regular cell gradient magnets. Details of these end corrections and the resulting successful modification of the lattice are described.

An ionization profile monitor can collect either ions or electrons produced from residual gas ionization. A magnetic field can be used to confine the drift path of the electrons, reducing distortion introduced into the clearing electric field by the beam space charge. We have designed, built, measured, and installed in the Fermilab Main Injector a permanent magnet for this purpose. We discuss the requirements for such a magnet, especially the effect of magnetic strength and imperfections on the measured electron profiles, and the performance of the magnet as built.