Over the last two years corrections have been made for the skew quadrupole moment in 530 of the 774 installed dipoles in the Tevatron. This process of modifying the magnets in situ has inherent risk of degrading the performance of the superconducting accelerator. In order to manage the risk, as well as to ensure the corrections were done consistently, formal quality tools were used to plan and verify the work. The quality tools used to define the process and for quality control are discussed, along with highlights of lessons learned.

In early 2003 it was realized that mechanical changes in the Tevatron dipoles had led to a deterioration of the magnetic field quality that was hindering operation of the accelerator. After extensive study, a remediation program was started in late 2003 that will continue through 2005. The mechanical and magnetic effects are discussed. The readjustment process and experience are reported, along with other observations on aging magnets.

Beam loss and emittance dilution during ramping from injection to collision energy is observed in the Tevatron, now in its collider run-II stage. Imperfect control of the machine chromaticity during the injection porch and the ensuing ramp to collision could contribute to the beam loss. Dipole magnets are the main source of chromaticity in the Tevatron. Sextupole correctors are distributed around the ring to compensate for the sextupole from the dipole magnets. Furthermore, the sextupole component in the superconducting Tevatron dipole magnets decays during the injection plateau and snaps back to the value before the start of the decay at the start of the ramp. The chromaticity correctors also correct for this so-called dynamic sextupole behavior. To determine if the sextupole compensation is working successfully in the Tevatron a thorough investigation of the sextupole (b2) in Tevatron dipole magnets was recently conducted. This included an extensive series of off-line magnetic measurements on several Tevatron dipole magnets from the spare pool. Traditionally one differentiates between three different b2 components, geometric, hysteretic and dynamic. This note discusses the results of these measurements. The experiments were also complemented with magnetic field calculations and analysis of data from the Tevatron magnetic measurement archive. On the basis of this document it is hoped that the chromaticity correction scheme in the Tevatron can be improved. Such improvements, however, are discussed in a separate note on the Tevatron chromaticity compensation (TD-03-008 - Revision I). This work is essentially a continuation of a similar study conducted in 1996 (1), on the basis of which the chromaticity correction scheme for the Tevatron run II was devised.

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, a database-driven design was chosen for control of the measurement system. A relational database will be used to describe the measurement subjects and equipment. A logbook system defined in the database will provide for prescription of measurements to be carried out, and a comment database for less-structured information. The operator interface will be built on X-windows.<>

The Table of Tables' application system captures in a set of SYBASE tables the basic design specification for a database schema. Specification of tables, columns (including the related defaults and rules for the stored values) and keys is provided. The feature which makes this application specifically useful for SYBASE is the ability to automatically generate SYBASE triggers. A description field is provided for each database object. Based on the data stored, SQL scripts for creating complete schema including the tables, their defaults and rules, their indexes, and their SYBASE triggers, are written by TOT. Insert, update and delete triggers are generated from TOT to guarantee integrity of data relations when tables are connected by single column foreign keys. The application is written in SYBASE's APT-SQL and includes a forms based data entry system. Using the features of TOT we can create a complete database schema for which the data integrity specified by our design is guaranteed by the SYBASE triggers generated by TOT. 3 refs.

The time behavior of the sextupole component of the Tevatron superconducting dipoles under ramping conditions was studied. Large time-dependent sextupole corrections are necessary to maintain constant chromaticities in the Tevatron. The authors discuss the implementation and results of these corrections in terms of emittance growth and intensity loss during the Tevatron ramp

The time variation in the magnetic field of a model Tevatron dipole magnet at constant excitation current has been studied. Variations in symmetry allowed harmonic components over long time ranges show a log t behavior indicative of `flux creep'. Both short-time-range and long-time-range behavior depend on the excitation history. Similar effects are seen in the remnant fields present in full-scale Tevatron dipoles following current ramping. Both magnitudes and time dependences are observed to depend on details such as ramp rate, flattop duration, and number of ramps. In a few magnets, variations are also seen in symmetry-disallowed harmonics

The time dependence of magnetic fields in the superconducting magnets of the Fermilab Tevatron is discussed. A field variation of order 1 G at the aperture radius is observed. Studies on both full-sized Tevatron dipoles and prototype magnets have been used to elucidate these effects. Explanations based on eddy currents in the coil matrix or on flux creep in the superconducting filaments are explored with these tests. Measurement results and techniques for controlling the effect based on novel laboratory tests and the latest accelerator operation are presented. It is shown that small but important changes in the fields occur with (ln t) time dependencies. For accelerator operation, in both laboratory and accelerator measurements, some events which might be associated with nonsmooth behavior (sudden changes on the relevant time scale) and with deviations at long times from observed (ln t ) behavior have been seen

We have experimentally simulated the wedge regions of the winding of the Superconducting Super Collider dipole and studied the propagation of quenches in them. This study is relevant for proper selection and design of the quench protection scheme. The windings of these 16.6 m long dipoles incorporate copper wedges in order to achieve the required magnetic field uniformity, and the delay that they impose on the transverse spreading of normal zones is one of the needed data that we present here. Quenches under constant currents were triggered with spot heaters, and their development recorded from voltage taps strategically located. Currents as high as 6 kA were used. Under zero magnetic field conditions the delays are too long for self-protecting schemes.

of the magnets. A means is needed to accurately determine the ac electrical characteristics of the superconducting magnets. The ac characteristics of magnets will be used to predict the ripple distribution of the long string of superconducting magnets. Magnet ac characteristics can also provide necessary information for the regulation loop design. This paper presents a method for measuring the ac characteristics of superconducting magnets. Two collider dipole magnets, one superconducting and one at room temperature, were tested at Brookhaven National Lab.

The Fermilab design of a 5 T, 5 cm aperture superconducting dipole is described, that attempts to integrate essential cryogenic details with a low cold mass, low heat leak magnet containing a coil surrounded by aluminum collars. Operating characteristics of coils made with aluminum collars are presented along with harmonic data obtained from 1 meter long 5 cm aperture collared coils. A summary of results obtained from cold tests of a 7.6 cm aperture, 6 m long aluminum collared coil in an iron vacuum vessel cryostat are reviewed. Results from the measurement of heat leak to 4.5K, 10K, and 80K are discussed for a 12 m prototype cryostat. Calculations are summarized for passively correcting the persistent current sextupole fields.

Proposed colliding beam particle accelerators for high energy physics research will employ superconducting accelerator rings. The rings' superconducting magnet systems must provide the required magnetic function, have low refrigeration load, operate with very high reliability and be manufacturable at a low cost. The cryogenic aspects of a conceptual design for a 5T field, 5cm aperture, 12m long superconducting dipole magnet suitable for a 20 TeV proton-proton collider are presented.

The quench and field properties of Energy Saver dipole and quadrupole magnets are measured at the Fermilab Magnet Test Facility shortly after the magnets have been produced. It is important that magnet properties remain unchanged with time. This question has been investigated by remeasuring magnets at a later time and comparing the two sets of measurements. Three sets of unbiased data are available: 1) Fifteen dipole magnets were remeasured after they were removed from the "B12" cryoloop test location. At B12, they were subjected to repeated thermal cycles, quenches at high current, steady state operation at high current, and ramping to high current with an accelerator type ramp cycle. The average time between the original measurement and the remeasurement was 22 months. 2) Five standard length (66 inch) quadrupole magnets were remeasured after an elapsed time averaging 5 months. These magnets were in storage during the period between the two sets of measurements. 3) Six long (99 inch) quadrupole magnets were remeasured after an average time of 12 days. These were also in storage. The remeasurements agree well with the original measurements. The measurement techniques and magnet properties obtained from the full magnet samples are described elsewhere.

Emmitance blow-up and beam loss are among the main limitations to ultimate luminosity in the Tevatron, currently in its run-II stage. It is well known that tunes and chromaticities are changing as the magnetic multipoles of the superconducting magnets decay during injection and snap-back during the ensuing start of the ramp. Fast changing tunes and chromaticities could contribute to the luminosity limitations. In the context of a renewed effort to improve the quantitative understanding of the decay and snapback characteristics of the superconducting magnets in the Tevatron, a series of magnetic measurements on spare Tevatron dipoles was started in the fall of 2002. In order to support the magnetic measurements, magnetic field models of the Tevatron dipole magnets were generated. The models were calibrated on the archival magnetic measurement data of all Tevatron dipoles built as well as on recent magnetic measurements. The magnetic model of the Tevatron dipole magnet presented here is therefore believed to be representative of the "average" Tevatron dipole magnet. This note was updated in November 2003 to include the results of z-scan measurements in a Tevatron dipole using a short rotating coil probe. These measurements were used to fine- tune the end-field model. The improved end-field model is presented. The second revision in April 2004 includes new calculations of the multipole hysteresis due to the superconductor magnetization.