• D. J. Harding, C. L. Bartelson, B. C. Brown, J. A. Carson, W. Chou, J. DiMarco, H. D. Glass, D. E. Johnson, V. S. Kashikhin, I. Kourbanis, W. F. Robotham, M. Tartaglia
  Fermilab, Batavia, Illinois

During the design of the Fermilab Main Injector synchrotron it was recognized that the aperture was limited at the beam transfer and extraction points by the combination of the Lambertson magnets and the reused Main Ring quadrupoles located between the Lambertsons. Increased intensity demands on the Main Injector from antiproton production for the collider program, slow spill to the meson fixed target program, and high intensity beam to the high energy neutrino program have led us to replace the aperture-limiting quadrupoles with newly built magnets that have the same physical length but a larger aperture. The magnets run on the main quadrupole bus, and must therefore have the same excitation profile as the magnets they replaced. We present here the design of the magnets, their magnetic performance, and the accelerator performance.

• W. Chou, J. R. Lackey, Z. Tang
  Fermilab, Batavia, Illinois
• M. A. Kostin
  NSCL, East Lansing, Michigan
• R. J. Macek
  LANL, Los Alamos, New Mexico
• P. S. Yoon
  Rochester University, Rochester, New York

Carbon foils are widely used in charge-exchange injection in high intensity hadron accelerators. There are a variety of physics issues associated with the use of carbon foils, including stripping efficiency, energy deposition, foil lifetime (temperature rise, mechanical stress and buckling), multiple Coulomb scattering, large angle single Coulomb scattering, energy straggling and radiation activation. This paper will give a brief discussion of these issues based on the study of the Proton Driver and experience of the Fermilab Booster. Details can be found in Ref*.

* W. Chou et al., "Transport and Injection of 8 GeV H^- Ions," Fermilab-TM-2285 (2007).

• W. Chou, D. Capista, E. Griffin, K. Y. Ng, D. Wildman
  Fermilab, Batavia, Illinois

Two barrier rf systems were fabricated, tested and installed in the Fermilab Main Injector.* Each can provide 8-10 kV rectangular pulses (the rf barriers) at 90 kHz. When a stationary barrier is combined with a moving barrier, injected beams from the Booster can be continuously deflected, folded and stacked in the Main Injector (MI), which leads to doubling of the beam intensity. This paper gives a report on the beam experiment using this novel technology.

* W. Chou, D. Wildman and A. Takagi, "Induction Barrier RF and Applications in Main Injector," Fermilab-Conf-06-227 (2006).

• W. Chou, C. L. Bartelson, B. C. Brown, D. Capista, J. L. Crisp, J. DiMarco, J. Fitzgerald, H. D. Glass, D. J. Harding, B. Hendricks, D. E. Johnson, V. S. Kashikhin, I. Kourbanis, W. F. Robotham, T. Sager, M. Tartaglia, L. Valerio, R. C. Webber, M. Wendt, D. Wolff, M.-J. Yang
  Fermilab, Batavia, Illinois

A two-year Large Aperture Quadrupole (WQB) Project was completed in the summer of 2006 at Fermilab.* Nine WQBs were designed, fabricated and bench-tested by the Technical Division. Seven of them were installed in the Main Injector and the other two for spares. They perform well. The aperture increase meets the design goal and the perturbation to the lattice is minimal. The machine acceptance in the injection and extraction regions is increased from 40π to 60π mm-mrad. This paper gives a brief report of the operation and performance of these magnets. Details can be found in Ref**.

* D. Harding et al, "A Wide Aperture Quadrupole for the Fermilab Main Injector," this conference.
** W. Chou, Fermilab Beams-doc-#2479, http://beamdocs.fnal.gov/AD-public/DocDB/DocumentDatabase

• X. Zhang, A. Z. Chen, W. Chou, B. M. Hanna, K. Y. Ng, J.-F. Ostiguy, L. Valerio, R. M. Zwaska
  Fermilab, Batavia, Illinois

Estimates indicate that the electron cloud effect could be a limiting factor for Main Injector intensity upgrades, with or without a the presence of a new 8 GeV superconducting 8GeV Linac injector. The effect may turn out to be an issue of operational relevance for other parts of the Fermilab accelerator complex as well. To improve our understanding of the situation, two sections of specially made vacuum test pipe outfitted for electron cloud detection with ANL provided Retarding Field Analyzers (RFAs), were installed in the Tevatron and the Main Injector. In this report we present some measurements, compare them with simulations and discuss future plans for studies.