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Characteristics of recently developed F4-Nb3Al strand with low Cu ratio are described. The overall Jc of the Nb3Al strand could be easily increased by decreasing of the Cu ratio. Although the quench of a pulse-like voltage generation is usually observed in superconducting unstable conductor, the F4 strand with a low Cu ratio of 0.61 exhibited an ordinary critical transition of gradual voltage generation. The F4 strand does not have magnetic instabilities at 4.2 K because of the tantalum interfilament matrix. The overall Jc of the F4 strand achieved was 80-85% of the RRP strand. In the large mechanical stress above 100 MPa, the overall Jc of the F4 strand might be comparable to that of high Jc RRP-Nb3Sn strands. The Rutherford cable with a high packing factor of 86.5% has been fabricated using F4 strands. The small racetrack magnet, SR07, was also fabricated by a 14 m F4 cable. The quench current, Iq of SR07 were obtained 22.4 kA at 4.5 K and 25.2 kA at 2.2 K. The tantalum matrix Nb3Al strands are promising for the application of super-cooled high-field magnets as well as 4.2 K operation magnets. [ABSTRACT FROM AUTHOR]

One of the possible practical applications of the Nb3Sn accelerator magnets is the LHC luminosity upgrade that involves replacing the present NbTi focusing quadrupoles in two high-luminosity interaction regions (IR). The IR magnets are exposed to strong radiation from the interaction point that requires a detailed investigation of the magnet operating margins under the expected radiation-induced heat depositions. This paper presents the results of simulation and measurement of quench limits and temperature margins for a Nb3Sn model magnet using a special midplane strip heater. [ABSTRACT FROM AUTHOR]

The U.S. LHC Accelerator Research Program (LARP) has started the fabrication of 3.7-m long Nb3 Sn quadrupole models. The Long Quadrupoles (LQ) are "Proof-ofPrinciple" magnets which are to demonstrate that Nb3 Sn technology is mature for use in high energy particle accelerators. Their design is based on the LARP Technological Quadrupole (TQ) models, developed at FNAL and LBNL, which have design gradients higher than 200 T/m and an aperture of 90 mm. The plans for the LQ R&D and a design update are presented and discussed in this paper. The challenges of fabricating long accelerator-quality Nb3 Sn coils are presented together with the solutions adopted for the LQ coils (based on the TQ experience). During the fabrication and inspection of practice coils some problems were found and corrected. The fabrication at BNL and FNAL of the set of coils for the first Long Quadrupole is in progress. [ABSTRACT FROM AUTHOR]

In support of the development of a large-aperture Nb3Sn superconducting quadrupole for the Large Hadron Collider (LHC) luminosity upgrade, several two-layer technological quadrupole models of TQC series with 90 mm aperture and collar-based mechanical structure have been developed at Fermilab in collaboration with LBNL. This paper summarizes the results of fabrication and test of TQC02a, the second TQC model based on RRP Nb3Sn strand, and TQC02b, built with both MJR and RRP strand. The test results presented include magnet strain and quench performance during training, as well as quench studies of current ramp rate and temperature dependence from 1.9 K to 4.5 K. [ABSTRACT FROM AUTHOR]

Amongst the magnet development program of a large-aperture Nb3 Sn superconducting quadrupole for the Large Hadron Collider luminosity upgrade, six quadrupole magnets were built and tested using a shell based key and bladder technology (TQS). The 1 m long 90 mm aperture magnets are part of the US LHC Accelerator Research Program (LARP) aimed at demonstrating Nb3 Sn technology by the year 2009, of a 3.6 m long magnet capable of achieving 200 T/m. In support of the LARP program the TQS magnets were tested at three different laboratories, LBNL, FNAL and CERN and while at CERN a technology-transfer and a four days magnet disassembly and reassembly were included. This paper summarizes the fabrication, assembly, cool-down and test results of the six magnets and compares measurements with design expectations. [ABSTRACT FROM AUTHOR]

Fermilab has finished the first phase of Nb3 Sn technology scale up by testing 2-m and 4-m long shell-type dipole coils in a `magnetic mirror' configuration. The 2-m long coil, made of Powder-in-Tube (PIT) Nb3 Sn strand, reached its short sample limit at a field level of 10 T. The 4-m long coil, made of advanced Nb3 Sn strand based on the Restack Rod Process (RRP) of 108/127 design, has been recently fabricated and tested. Coil test results at 4.5 K and 2.2 K are reported and discussed. [ABSTRACT FROM AUTHOR]

The first model of a superconducting quadrupole for use in a Linear Accelerator was designed, built and tested at Fermilab. The quadrupole has a 78 mm aperture, and a cold mass length of 680 mm. A superferric magnet configuration with iron poles and four racetrack coils was chosen based on magnet performance, cost, and reliability considerations. Each coil is wound using enamel insulated, 0.5 mm diameter, NbTi superconductor. The quadrupole package also includes racetrack type dipole steering coils. The results of the quadrupole design, manufacturing and test, are presented. Specific issues related to the quadrupole magnetic center stability, superconductor magnetization and mechanical stability are discussed. The magnet quench performance and results of magnetic measurements will also be briefly discussed. [ABSTRACT FROM AUTHOR]

In collaboration between NIMS and Fermilab, we have made copper stabilized Nb3Al Rutherford cables, using Nb-matrixed and Ta-matrixed strands. First these cables were investigated at high current in low self field using a flux pump. Using these Rutherford cables, we built and tested small racetrack magnets. The magnet made with the Nb-matrixed strand showed the flux jump instability in low field. The small racetrack magnet wound with the Ta-matrixed Nb3Al Rutherford cable was very stable at 4.5 K operation without any instability, as well as at 2.2 K operation. With the successful operation of the small racetrack magnet up to its short sample data, the feasibility of the Nb3Al strand and its Rutherford cable for their application to high field magnets is established. The characteristics of Nb3Al Rutherford cable is compared with that of the Nb3Sn Rutherford cable and the advantages of Nb3Al Rutherford cable are discussed. [ABSTRACT FROM AUTHOR]

Novel configurations of superconducting magnets for helical muon beam cooling channels and demonstration experiments are being designed at Fermilab. The magnet system for helical cooling channels has to generate longitudinal solenoidal and transverse helical dipole and helical quadrupole fields. It was found that this complicated field configuration can be made by a helical solenoid, which is a set of circular coils shifted in transverse directions in such a way that their centers lay on the center of the helical beam orbit. This paper discusses the possibility of combining two such channels in one mechanical structure to allow beams of positive and negative muons to be cooled at the same time. The status of a short model helical solenoid prototype to study its magnetic and mechanical properties is also described. [ABSTRACT FROM AUTHOR]

Streptococcus pneumoniae (the pneumococcus) is a major cause of bacterial pneumonia, middle ear infection (otitis media), sepsis, and meningitis. Our previous study demonstrated that the choline-binding protein A (CbpA) of S. pneumoniae binds to the human polymeric immunoglobulin receptor (pIgR) and enhances pneumococcal adhesion to and invasion of cultured epithelial cells. In this study, we sought to determine the CbpA-binding motif on pIgR by deletional analysis. The extracellular portion of pIgR consists of five Ig-like domains (D1-D5), each of which contains 104-114 amino acids and two disulfide bonds. Deletional analysis of human pIgR revealed that the lack of either D3 or D4 resulted in the loss of CbpA binding, whereas complete deletions of domains D1, D2, and D5 had undetectable impacts. Subsequent analysis showed that domains D3 and D4 together were necessary and sufficient for the ligand-binding activity. Furthermore, CbpA binding of pIgR did not appear to require Ca[sup 2+] or Mg[sup 2+]. Finally, treating pIgR with a reducing agent abolished CbpA binding, suggesting that disulfide bonding is required for the formation of CbpA-binding motif(s). These results strongly suggest a conformational CbpA-binding motif(s) in the D3/D4 region of human pIgR, which is functionally separated from the IgA-binding site(s). [ABSTRACT FROM AUTHOR]

During the past 30 years superconducting magnet systems have enabled accelerators to achieve energies and luminosities that would have been impractical if not impossible with resistive magnets. By far, NbTi has been the preferred conductor for this application because of its ductility and insensitivity of Jc to mechanical strain. This is despite the fact that Nb[sub 3]Sn has a more favorable Jc vs. B dependence and can operate at much higher temperatures. Unfortunately, NbTi conductor is reaching the limit of it usefulness for high field applications. Despite incremental increases in Jc and operation at superfluid temperatures, magnets are limited to approximately a 10 T field. Improvements in conductor performance combined with future requirements for accelerator magnets to have bore fields greater than 10 T or operate in areas of large beam-induced heat loads now make Nb[sub 3]Sn look attractive. Thus, laboratories in several countries are actively engaged in programs to develop Nb[sub 3]Sn accelerator magnets for future accelerator applications. A summary of this important research activity is presented along with a brief history of Nb[sub 3]Sn accelerator magnet development and a discussion of requirements for future accelerator magnets. [ABSTRACT FROM AUTHOR]