> **M[ain]{.smallcaps} I[njector]{.smallcaps}**

**19.d. [Background]{.underline}**

The Main Injector was commissioned in FY99. Since the completion of the
project by meeting the seven DOE commissioning milestones, the Main
Injector has been providing beam for the Fermilab High Energy Physics
programs and Antiproton production and Tevatron Run II operations.

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### 19.f. Accomplishments in FY04

Since June 1999, the Main Injector (MI) studies concentrated on
achieving the operational goals of the Main Injector in support of Run
II. The Main Injector has met the beam intensity and quality demands for
Run II. The Main Injector also provided beam for the Recycler
commissioning and studies for the SY120 and NuMI programs.

The Main Injector operated as a high intensity, fast cycling proton
synchrotron for antiproton production. It delivered in excess of 5.5 x
10^12^ protons per batch at 120 GeV with the design ramp rate of 1.46
sec and with better than 95% efficiency to the Antiproton production
target. The small growth in the transverse emittances of the high
intensity proton beam between injection and flattop energies is
acceptable. The significant increase in longitudinal emittance of proton
beam through the acceleration cycle was greatly reduced with the
implementation of the feed-forward beam loading compensation up the ramp
and by the longitudinal bunch-by-bunch dampers. The 95% bunch length at
extraction is now 0.8 nsec.

The Main Injector has also provided coalesced proton and antiproton
beams for Tevatron operation and studies. The Run II goal of 3.5 x
10^11^ protons per bunch has been met. The Run II transverse emittance
goal for both the proton and antiproton beam at 150 GeV has also been
met. The longitudinal bunch-by-bunch damper was introduced in FY04. Its
use has removed the need to increase the longitudinal emittance in the
Booster in order to avoid instabilities in the Main Injector and has led
to a 25% reduction of the longitudinal emittance after coalescing.
Typical 95% longitudinal emittances for seven bunch coalescing of
2.1-2.2 eV-sec have been achieved and are expected to be further reduced
to 2.0 eV-sec or smaller.

Further improvements in beam loading compensation have been implemented
allowing the 53 MHz stations to be turned off during the 2.5 MHz
rotation, thus improving the coalescing efficiency and reducing the
sensitivity on paraphasing. Coalescing efficiencies for both protons and
antiprotons of greater than 90% are routine. An antiproton intensity of
60 x 10^9^ per bunch has been achieved at flattop after coalescing.

Studies directed towards Run II upgrades, in particular coalescing, slip
stacking, 2.5 MHz acceleration, damper commissioning, lattice studies,
Recycler transfer studies and other hardware commissioning were also
significant activities. FY04 saw the first time antiprotons from the
Recycler were transferred to the Main Injector, accelerated to 150 GeV,
coalesced and transferred to the TeV and used to produce luminosity.

Beam studies and component installation for NuMI were a significant
activity. The NuMI extraction Lambertsons were installed and space
cleared for the NuMI kickers. A beam intensity of 3.3 x 10^13^ was
circulated and the effectiveness of the transverse bunch-by-bunch
dampers, critical for high intensities, was verified.

Fast and slow spill beams for SY120 were demonstrated. Beam was
delivered for both M-Test and M-Center experiments and work devoted to
optimizing the spill length and quality.

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### 19.g.1. Accomplishments Expected in FY05

The Main Injector will continue to serve its role as a high intensity,
fast-cycling machine primarily for antiproton production and for
Tevatron injection for each collider store. It is expected that slip
stacking will be operational in early FY05 roughly doubling the stacking
intensity for antiprotons. Starting in FY05 NuMI will become an integral
part of Main Injector operations; NuMI commissioning will be a major
priority.

When the NuMI beam is in operation, the Main Injector will be delivering
2.5 x 10^13^ protons to the NuMI target station every two seconds.
Combined with the antiproton production cycle with slip stacking this
means the Main Injector beam will reach a total intensity of 3.3 x
10^13^ protons each two seconds, roughly six times higher than in FY04.
To minimize losses at extraction, 4" aperture quadrupoles will be
installed to replace the present 3'' quadrupoles in all the Main
Injector extraction regions. These magnets are expected to be ready for
installation during the summer shutdown. The possibility of using a
collimation system in the Main Injector for additional control of the
losses will also be investigated.

2.5 MHz acceleration will be fully developed to allow antiprotons from
the Recycler to be accelerated directly without the need for forming 53
MHz bunches, thus avoiding the emittance growth from coalescing. The
Main Injector BPM upgrade is expected to be implemented thus providing
the ability to determine the position of 2.5 MHz bunches.

The possibility of using slip stacking or a barrier bucket-stacking
scheme in the Main Injector for increasing the beam intensity for NuMI
will be investigated.

Slow spill for SY 120 will continue to be a routine part of Main
Injector operations.

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### 19.g.2. Future Accomplishments Expected in FY06 and Beyond

The operation of the Main Injector is expected to be somewhat stable
towards the end of FY05. The Main Injector is expected to provide beam
for the Run II operation, for NuMI and for SY120.

Studies and R&D will be performed for the Run II operation of the
accelerator complex and some form of multi-batch stacking is expected to
be available in Main Injector for protons for NuMI in addition to the
slip stacking for antiproton production.

Options for increasing the RF power and ramp power will be investigated.
It is planned to have a collimation scheme in place for commissioning.