# **Fermilab Accelerator Advisory Committee**

# **Report of the Meeting of February 4-6 2002**

**Committee:** V. Balakin BINP, J.P. Delahaye CERN, N. Holtkamp ORNL,
J.P. Koutchouk CERN, Joseph Rogers Cornell, Thomas Roser BNL, Lucio
Rossi CERN, Ronald Ruth SLAC, Ferdinand Willeke DESY, Jonathan Wurtele
LBL

**Apologies**: T. Shintake KEK

**Observer:** P. Debenham DOE

## Introductory Remark

The Committee enjoyed the interesting and well-prepared meeting with
excellent presentations and open discussions during the plenary and
breakout sessions. We would like to thank the Fermilab staff for good
co-operation.

**[General Comments]{.underline}**

Since the last AAC meeting, tremendous progress has been made with the
TEVATRON. The peak Luminosity has surpassed the Run I luminosity. The
integrated luminosity per week delivered to each of the experiments
amounts to a respectable 4-6 pb^-1^. The usable antiproton production
has been improved by implementing the dual lattice in the accumulator
ring and by the upgrade of the cooling system. The recycler-ring has
developed beyond the experimental stage. Although, a lot of improvement
still remains to be achieved, there are now concrete plans to integrate
the recycler-ring in the antiproton production chain.

The committee congratulates the laboratory on this good progress. It is
aware, that this is the result of hard work and dedicated commitment of
the entire staff. The committee is pleased to see that the focusing of
the whole laboratory on the TEVATRON turns out to be fruitful. The
committee would like to encourage the laboratory to pursue this course.

**[Response to the Charge]{.underline}**

***Assessment of potential impediments to achievement of the luminosity
goals established for FY2003, namely a peak luminosity by the end of
September 2003 of 5-81031 cm-2sec-1 in the Tevatron, and an integrated
luminosity of 220-320 pb^-1^.***

The luminosity goals for the operation in fiscal year 2003 (FY03) ask
for an increase of the present peak value of L = 3.7 x 10^31^
cm^-2^sec^-1^ by a factor of 1.6. The integrated luminosity of ∫Ldt =
320pb^-1^ can be reached if the present weekly luminosity production
rate can be increased by a factor of 1.5.

In order to achieve these goals, a continuous effort will be necessary
to keep the accelerator complex going with high efficiency. This is not
an easy task, even without any improvements. The committee is
particularly concerned about the situation with spares for critical
accelerator components. At present, downtimes of up to 3 month or even
more may become necessary in case of a fatal failure of one of the
critical components. The committee considers this a high-risk situation,
which threatens to jeopardize the luminosity program on the short and
long term run.

The increase in luminosity is based on a moderate increase of the
antiproton production rate and of the proton intensity per bunch. The
improvements to achieve this and which should allow to surpass the base
line goal of an integrated luminosity of ∫Ldt = 250 pb^-1^ in FY03 have
already been implemented in the shutdown in January. The major
improvement was to remove an aperture limitation by a no longer needed
septum magnet. This will allow for an increase in the beam separation in
the TEVATRON. As a consequence more intense proton bunches in the
TEVATRON will be possible without impact on the lifetime of antiprotons.

Further improvements such as improvement of the debuncher longitudinal
cooling system are well underway.

The committee is confident that these improvements will become effective
very soon. The committee does not see a specific major obstacle, which
would prevent achieving the FY03 performance goals. However the progress
of improvement of slowed down by missing and inappropriate diagnostics.

***Evaluation of the overall strategic approach to achieving the peak
luminosity goal of 81031 cm-2sec-1 in the Tevatron by the end of
September 2003.***

A very detailed and prioritized plan for progress with the TEVATRON
luminosity has been presented to the committee. The committee
acknowledges that the elements in this plan are related in a complex and
complicated way.

At this point the committee has the impression that the priorities on
the various improvement projects are set from the viewpoint of each
accelerator.

In order to assure optimum planning, the committee encourages the beams
division to continuously develop this plan. It encourages to carefully
integrating the plan across the complex to identify true bottlenecks.

The committee hopes that in this way the resources can be assigned even
more optimally in the case of conflicts or shortfalls of single steps in
the improvement program given shortage of resources.

***Evaluation of the key underlying accelerator physics issues and the
adequacy of the FY2003 plan in addressing these issues.***

The committee believes that the major accelerator physics issues within
the accelerator complex have been identified and investigated in a very
professional way. In general, the planned improvements address these
issues adequately.

The committee would like to see however an even stronger focus on the
issues pertaining to the TEVATRON. The fraction of produced antiprotons,
which are used in collisions, is only about 16%, which leaves quite some
room for improvement.

In order to increase the focus on this fundamental issue, the committee
proposes that the laboratory develop a figure of merit which reflects
this efficiency and which allows to monitor the progress in making
better use of the antiprotons.

***Suggestions for overcoming any identified impediments to FY2003
goals.***

While the committee believes that the goals of the FY03 running can be
achieved and that there are no major impediments, it would like
nevertheless to offer a number of comments about actions to be taken to
assure steady progress.

The committee is aware that progress is the result of a delicate balance
between steady and continuous running and dedicated studies. In the
spirit of the balance, the committee proposes to consider to develop, to
test and to apply improved measurement tools for the verification of the
beam optics. Plans should be made for adequate realignment of the
TEVATRON. It is believed that beam based alignment techniques could be
of significant help. Measurement of the optical mismatch at injection is
considered a promising means for improving performance. The compensation
of the coupling between horizontal and vertical betatron oscillations in
the TEVATRON during acceleration should be given high priority because
it is expected to be the key to a number of performance improvements
which should lead to higher intensities in collisions. Considering the
long operation period, which lays ahead of the TEVATRON, it appears to
be beneficial to realign the accelerator rather sooner if the team can
convince itself that this would improve the high luminosity operation.
An important example of inadequate diagnostics is also the unreliable
emittance measurement in the TEVATRON and in the Main Injector. As
mentioned in previous reports, a well functioning beam position
measurement in every accelerator constitutes the basic beam diagnostics
and is absolutely mandatory for making further progress. These issues
should be resolved on a short time scale.

***Is the strategic approach to increasing luminosity into the range
2-41032cm-2sec-1 sound?***

The committee endorses the merge of Run II a and II b into a continuous
run with staged upgrades aiming at an integrated luminosity of 3
fb^-1^/year or 15 fb^-1^ before 2010 when the LHC is expected to be
fully operational.

The committee endorses the effort to organize the Run II upgrade and
improvement program as a project with clear assignment of
responsibilities including task forces on key issues aiming at a plan
based on WBS and a resource loaded schedule. This is expected to be
helpful in meeting the tight schedule set by the DOE to present the RUN
II plans and the corresponding in June 2003.

The committee welcomes the critical examination of the components of the
previous Run II plans such as recycling and 132ns bunch distance.

As far as planning is concerned, the same comment as for the FY03
planning apply. The committee would like to see prioritizing based on
integrated planning across the complex. Conflicts or unforeseen
technical problems and shortage of resources will be unavoidable in this
ambitious program. The committee expects that unavoidable re-direction
and re-optimization of the assignment of resources would profit from
integrated planning.

A possible element of integrated planning could be to designate an
instrumentation coordinator and a beam study coordinator since both
instrumentation and beam studies are very critical in terms of available
resources.

The integration of electron cooling in the recycler ring is a key item
in reaching the luminosity goal. It will require substantial resources,
which is not reflected in the plan as presented.

***What are the primary accelerator physics and technology risks
associated with this strategy? Can the level of risk be translated into
a luminosity performance uncertainty?***

The TEVATRON performance, with injection, acceleration, helical
separation, parasitic beam- beam interaction issues and increased
intensities, is difficult to extrapolate from present operational
parameters. The uncertainty for high TEVATRON performance should be
reduced by extensive simulations. However, it is also clear, that even
by making intensive use of state of the art tools, there will be a risk
that maximum performance parameters can not be reached simultaneously.
The highest risk which the committee identifies is the possibility that
in the TEVATRON is falling short of the anticipated performance.

The electron cooling in the recycler ring is a challenging and
pioneering project. The project has several elements that have never
been tested before. The success of this project has naturally a high
risk factor. Although this project over the last two committee meetings
has been presented as critical to achieve the luminosity goals, the
allocating of resources and the overall priority does not seem to align
with this statement. We recommend to either develop an operations plan
without electron cooling or to make sure that the necessary resources
are assigned as soon as possible

The upgrade of the antiproton production and cooling systems appear to
be very ambitious. The plan is based on many single steps which all need
to be successful to achieve the final goal.

A failure of any of these projects would affect the achievable
luminosity by a considerable factor. It would be quite difficult to
compensate the corresponding shortfall by improvements in other areas.

***Do opportunities exist for mitigation of these risks through
alternative approaches?***

The committee encourages the Run II project team to consider an even
more drastic modification of the bunch train configuration with respect
to original Run II planning.

More frequent transfers to the recycler ring might help to mitigate
problems in the debuncher-accumulator cooling systems. The possible
difficulties seem to be purely operational. The committee did not see
evidence that this is not possible.

The committee however does not see an alternative to making the electron
cooling work in the recycler ring

***Are operational scenarios developed that appropriately account for
the simultaneous needs of fixed target operations***

The proton source appears to be heavily committed. The plans associated
with maintaining and improving performance appear not to be adequate to
support all programs. Planning for addressing the radiation load has
started and a viable solution seems possible. The management of the
laboratory is encouraged to develop an operations plan that is
consistent with the maximum number of protons that can be achieved after
implementing the upgrades. Main users like Mini-BooNe and NuMi need to
understand the capability of the complex as soon as possible.

The Committee feels that more emphasis should be placed on avoiding
losses via improvements in the transition crossing, the alternative
injection scheme, and the compensation of nonlinear resonances.

## Detailed Comments on the Proton Source: Linac-Booster-Main Injector

### *General Assessment*

The Run II intensity requirements for FY 03 and beyond for the proton
source have been achieved by the linac and the booster synchrotron
systems. Almost sufficient intensity to support the FY03 goal and beyond
has been achieved in the Main Injector as well, but emittance growth has
been observed. This needs to be resolved to make sure that the required
emittance can be provided at the desired intensity. Overall the
technical upgrade programs that were proposed in this area are very
sound and have been thoroughly thought out. Reasonable extrapolations
from present achievements are made and the committee feels comfortable
that the goals can be met. The linac operations runs smoothly and no
major concerns or difficulties were reported. Concerns related to spare
components management were raised. This is related to a more general
issue having to do with the guidance that only spare parts potentially
leading to more than 3 month downtime should be stocked. The three-month
limit seems not to be sufficient, in the long run, to support the
machine availability that was quoted as necessary to achieve run II
goals. Spare part management will be a long-term issue since the run has
been extended to at least 2010.

In spite of all the good work, the committee notes, as the lab
management is aware, that even if all the upgrade programs are
implemented and are 100% successful, there will not be enough protons
available to support all the programs at the same time at their design
level. Therefore we encourage the laboratory to develop a plan
consistent with the foreseen operational level and present this back to
the ACC at the next meeting.

### *The linac and the booster*

The linac and the booster operate very well and currently almost meet
Run II operational requirements. The main demand for additional proton
flux from this part of the complex arises from additional users, namely
MiniBoone, NuMI and the Neutron irradiation facility. Upgrades have been
proposed based on the need to supply these users. The committee heard
concepts to increase the intensity in the booster from 4x10^12^ to
5x10^12^. At present, one can clearly observe that at this intensity
beam losses increase beyond the tolerable threshold of 1 W/m, which
would prevent hands-on-maintenance. Radiation levels in specific areas
are already significant. Increasing the intensity to 5x10^12^ results in
an almost exponential rise in losses. A concept to install a collimation
scheme in combination with increasing the apertures in several areas was
presented; the committee supports this upgrade and considers it very
viable. A larger flux increase stems from the increase in repetition
rate from typically 1 Hz today to 7.5 Hz maximum in the future. Hardware
upgrades and changes to support this operation are under way. The
committee supports efforts to reduce the losses rather than live with
them. The committee applauds the addition of new manpower to the linac
and booster team.

Specifically we recommend the following studies that should help to make
decisions on further intensity increases:

-   Studies on the implementation of the ~T~-jump in combination with
    stop-band tuning, 2^nd^ harmonic cavities and the extended list that
    was presented by C. Anckenbrandt. After evaluation, a proposal for
    implementation of the most effective machine improvements should be
    worked out.

-   A study should be undertaken to evaluate the losses between using a
    chopped beam at injection, as compared with the present unchopped
    beam.

-   Lower intensity at higher repetition rate could provide overall
    higher proton flux with less overall losses and should be evaluated
    experimentally.

### *The Main Injector*

For proton acceleration in the main injector, the primary issue that was
identified was the emittance blow up in the longitudinal phase space.
The blow up mechanism was measured very carefully and a mitigation plan
is well underway. Presently the longitudinal emittance is blown up
artificially in the booster before injection into the Main Injector in
order to stabilize the beam. A damping system to suppress the
longitudinal motion is under construction and should be in place by this
summer. The transverse emittance growth is well under control in the
horizontal plane. The measured emittance in the vertical plane is not
trusted because of uncertainty in the diagnostics. We expect that the
uncertainty in the measurement will be resolved soon; a plan for fixing
the emittance growth, if it real, should developed. Other upgrade
programs in diagnostics, e.g. BPMS, IPMs etc are under way but have been
identified as lower priority items. The committee agrees with this
assessment.

### 

Making the beam loading compensation system work is clearly one of the
most obvious achievements with excellent results. Overall implementation
for all power stations is encouraged and should be implemented as soon
as is possible. It is understood that there is still a ways to go
(\~x10) before design intensities are achieved for the slip stacking
operation. Study time will be necessary and priorities should be
assigned to where most of the benefit is expected for P-bar production.

### *Conclusion* 

Overall the proton source and the Main Injector are in a very good
position for the FY03 proposed program and are almost there to support
the RUNII upgrade proposal as presently presented. The team should be
congratulated for their achievements. Overall it would be very helpful
to see enough diagnostics in place that is trusted to measure the
necessary beam parameters (~x~ ,\_~y~, ~long~, current etc) so that the
input and output parameters of each accelerator complex are well defined
and accelerator physics effects can be clearly pinpointed to happen
upstream or downstream of each hand-off point.

**[Antiproton Source and Recycler Ring]{.underline}**

Since the last visit of the AAC there has been tremendous progress.
There has been a momentum shift that can be felt throughout the
presentations. There is also the sense that everyone is contributing not
only towards in getting the complex running but also to plan for Run II
upgrades which will fulfill the goals for the long term.

######### Antiproton Source

Excellent progress has been made on the antiprotons source since the
last meeting of this committee. The core cooling upgrade has been
finished and the shot-lattice has been implemented in the Accumulator to
reduce the emittance blowup caused by intrabeam scattering. Emittance
reduction and a 40% increase of luminosity were achieved due to these
upgrades. The peak stacking rate was increased to 13x10^10^/hr and peak
stack size increased to 225 x 10^10^. The complex is running more
reliably than in Run 1b.

Several cooling improvements remain to be implemented by the end of FY03
to increase the stacking rate to 18 x 10^10^/hr with a small stack. In
particular, the momentum spread in the Debuncher must be reduced to
improve the cycle time. The antiprotons source group has identified the
cause of the large momentum spread in the Debuncher, and has a plan to
address it by reducing the notch filter dispersion in each band. Plans
have been made for several other FY03 upgrades. Overall the last 9
months have seen remarkable progress in this system, and the present
antiprotons source performance is close to the FY03 goals. We expect
that the antiprotons complex can reach those goals.

######## ***Recycler Ring***

The committee was pleased to note the steady progress in commissioning
and improving the Recycler Ring since last May. The primary use of the
Recycler is now envisaged to be electron cooling of antiprotons after
they have been transferred from the Accumulator small stack. Everything
we have seen during this meeting suggests that recycling antiprotons may
not be worth the significant effort it requires.

The Committee heard about significant progress in bringing the Recycler
to the state of a fully commissioned machine. The Recycler program is
now supported with routine antiprotons transfers of leftovers after
Tevatron loading as well as dedicated stacks and transfers. The
stochastic cooling system has been shown to work. A very large number of
Recycler hardware, beam dynamics, and operational problems have been
aggressively attacked. Much remains to be done, and this well-planned
program continues. The Recycler Ring is well on its way to being
integrated into operations. The committee notes the good cooperation
between groups in the effort to integrate the Recycler into the
accelerator complex.

## *Antiproton source and Recycler long range planning and performance*

Planning for the long-range goals for Run II is moving forward quickly.
These place special emphasis on the antiprotons complex. These are
addressed by using electron cooling in the Recycler to achieve a large
stack and by increasing the antiprotons production rate to about
40e10/hr. It appears that the recycling process will not produce a
significant performance enhancement and perhaps should be abandoned even
for the stretch goals. This would allow the team to focus on other
critical upgrades.

The plan presented to this committee for upgrading the antiproton source
appears to be realistic and well developed, but the ultimate goals are
challenging. The plan includes a number of ambitious improvements,
including slip-stacking in the main injector to double the proton
intensity on target, a new higher-gradient lithium lens design, a large
increase of the AP2 beamline and Debuncher physical aperture, and
substantial upgrades to the stochastic cooling systems. It appears that
the Debuncher acceptance may be the most difficult bottleneck to
achieving the desired stacking rate. An antiprotons production rate of
40 x 10^10^/hr is critical to meeting the ultimate Run II goals. The
plans for the antiprotons system appear to be pushing several systems to
their limits. We urge the team to try to find margin wherever possible
to gain some flexibility in the final operational configuration. To
handle the 40 x 10^10^/hr rates from the Accumulator, it will be
necessary to get early experience with rapid, automated transfers to the
Recycler.

As pointed out by the speakers in this meeting, success of electron
cooling in the Recycler is crucial to meeting the long-term Run II
goals. The electron cooling system will operate in a new regime (high
gamma, angular-momentum-dominated transport, and weak solenoids) and has
very demanding specifications. The electron-cooling project needs to
have the engineering and technical resources appropriate to its
importance in meeting long-range goals. It is especially important to
get an early understanding of the system in order to address potential
problems.

The committee would have liked to get a better inside why the present
systems do not provide an antiproton flux of 30 x 10^10^h^-1^. The
committee considers it more than desirable the shortcomings are
understood, before a new design is implemented.

**[TEVATRON]{.underline}**

The Tevatron performance has made great strides since the last meeting.
A peak luminosity of 3.7 x 10^31^ cm^-2^sec^-1^ has been achieved. The
progress is mainly due to a dramatic increase of the anti-proton
intensity at low-beta but also due to a substantially better
understanding of the Tevatron.

The table below shows the dramatic progress achieved so far exceeding
the Run1b performance by about a factor of two:

![](media/image1.wmf)

As can be seen the total number of anti-protons at store increased
three-fold. Also listed is the antiprotons "burn" efficiency, which is
defined as the ratio of the rate with which antiprotons are used in
collisions ("burn rate") and the antiprotons production rate. It shows
that the increase in anti-proton intensity was achieved without loss of
"burn" efficiency. The normalized "burn rate", which is the "burn rate"
divided by the total number of antiprotons, however, decreased as
compared to Run1b. This indicates that antiprotons at store are
presently used less efficiently than during Run1b (26% compared to 39%
during a typical 22-hour store).

The last two columns show the goals for FY2003 and Run II. Note that
reaching the FY2003 goal depends on successfully doubling the normalized
burn rate. This requires an increase in proton bunch intensity and/or
reduction of the beam emittances.

The luminosity improvements in the Tevatron have leveled out for the
last few months. This is partly due to the fact that further increases
in anti-proton intensity are limited by the strong long-range beam-beam
effect from the proton beam at the Tevatron injection energy. Further
improvements require that several issues be systematically addressed.

Orbit coupling in the Tevatron is quite large and might affect injection
matching, instability damping and tune control during ramping. Coupling
should be measured systematically at injection and on the ramp and
corrected if possible locally otherwise globally. Effective operation
and instability control would also benefit from online chromaticity
measurements at injection and on the ramp. 

The coupling originates from significant rolls of the main dipoles and
quadrupoles. These beam element misalignments should be carefully
measured using both conventional and beam-based methods and the elements
should then be realigned as soon as possible.

There is concern that some basic information on the Tevatron is still
not complete. The effort in understanding effective rolls and
displacements of the magnets and their influence must be continued with
a vigorous plan. This may led to a decision to review the alignment of
the whole Tevatron or of some sectors. Plans to accommodate this action
which may be a necessary and rewarding \"investment\" for a solid base
of 6-7 year long operation, should be implemented at short term.

It is suspected that the injection mismatch into the Tevatron causes
about 40% emittance growth of the anti-proton beam. Either
non-destructive or destructive turn-by-turn profile monitors should be
installed to diagnose optical matching at injection.

Reviewing the magnetic property of the main magnets led to a correction
of the persistent current re-induction phenomenon. This analysis should
be pursued by carrying out more measurements on the spare magnets in
order to obtain more reliable data and better understanding of
persistent current effects at injection and during acceleration. However
it is difficult to determine if there is a spare magnet which would
represent the ring magnets as a reference. Therefore, this analysis on
the spare magnets should be combined with careful studies of the effects
on the beam (i.e. the integrated effect of the whole ring). This is
expected to be sufficient to solve the uncertainties related to
persistent current and superconducting cable effects. 

It is not clear if there is a serious danger that with increased proton
intensity, the risk of quenching the magnet \"too easily\" (at 980 TeV)
will become a limitation to the integrated luminosity.

**[Comments on the Run II TEVATRON Upgrade Project]{.underline}**

######### General Assessment

The committee appreciates that, following the recommendations made at
the last AAC meeting and by the DOE review end of 2002, a timely review
was made of the goals and plans of the Tevatron run II. The committee
endorses the merge of Run II*a* and *b* into a continuous run with
staged upgrades aiming at an integrated luminosity of 3 fb^-1^/year or
15 fb^-1^ before 2010 when the LHC is expected to be fully operational.
The goal is ambitious, without contingency in performance, but
consistent with the accumulated expertise and experience of the
TEVATRON.

######### Project Organization

The Run II Upgrade project appears well structured, well integrated in
the laboratory organization, with clear assignment of responsibilities.
The committee is pleased to acknowledge this organizational progress.
The plan based on WBS and Resource loaded schedule should help meeting
the tight DOE schedule for presenting the project and the corresponding
required resources in June 2003.

In view of the Run II*a* experience, the increased complexity to be
expected from ambitious performance and a tight schedule, we recommend
identifying two supplementary topics as components of the project:

-   Beam diagnostics, with the aims of *a)* specifying the
    instrumentation requirements starting from beam dynamics, using the
    now large Run II*a* experience *b)* managing the priorities for
    upgrades or design/implementation of new instruments across the
    complex.

-   Machine studies, with the aims of evaluating and managing the study
    time dedicated to the Upgrade Project and the priorities of the
    study topics.

***Strategy***

The committee especially appreciates the search for the best trade-off
between performance and risks, namely

-   First it is discussed to retain the present Run II*a* bunch number
    and pattern for the Upgrade. This would avoid the need of a crossing
    angle at the IP's and a further increase of the already notorious
    long-range beam-beam interactions. The limitation on the number of
    interactions per bunch, which can be accepted by the detector
    appears to be mitigated by luminosity leveling with the present
    number of bunches and a corresponding reduction of luminosity of
    only about 12%.

-   Second, it is considered to abandon the recycling of antiprotons
    after realizing that the corresponding reduction of luminosity could
    be limited to 10% by compensating with longer stores.

The preference given to a simpler and less critical operation is
expected to pay off in integrated luminosity. The committee supports
these two positions defined by the project leader to start the study. It
is pleased to see that the final set of parameters will be defined in a
bottom-up approach by the task forces and working groups.

The committee encourages investigating whether some increase beyond 36
bunches is acceptable as far as the long-range beam-beam effect is
concerned and whether some small variations of the bunch number can
reduce the spread of the parameters of the leading, nominal and trailing
bunches.

***Collision***

With the increase of the proton beam current, the head-on beam-beam
effect will increase and reach the highest values anticipated for proton
colliders. It is therefore essential to reduce or compensate the
long-range beam-beam effect to prevent enhancement of the overall effect
far beyond the regime already explored. The committee is confident that
the beam-beam effect could be made acceptable during collisions at high
energy if the helix can be substantially increased, as proposed. The
committee recommends carefully assessing possible side effects. The
alternative is the active long-range beam-beam compensation.

***Injection and Ramp***

An efficient injection is likely to be the critical path for the Upgrade
in the TEVATRON ring. The committee is concerned that the difficulties
already observed at the present performance level, attributed largely to
the long-range beam-beam effects, are not specifically addressed in the
upgrade program. It recommends studying an active correction with a high
priority. Depending on the number of correctors required, the
implementation could rely on the Electron Lens or on Wire Correctors or
a combination of both.

The comments on emittance preservation, optics controls and associated
instrumentation upgrade made in the TEVATRON section apply as well and
even more for the Upgrade Project.

The investment in preserving the beam quality at injection can only be
effective if it is maintained during the ramp by properly controlling
tunes, chromaticity and coupling.

***Collective Effects***

The increase beam current is not considered critical. The committee
notes that the intensity issue is investigated and addressed with
actions already carried out, such as the removal of the Lambertson
septum, which reduces the overall impedance, the use of dampers and
octupole fields for more Landau damping. The committee feels confident
that instabilities can be kept under control.

######### Assessment of Risk

The committee welcomes the development of a parametric model simulating
the luminosity behavior in the TEVATRON. It appears to reproduce
accurately the present peak performance and shows that, at collision
energy; the luminosity lifetime with the present parameters is dominated
by Intra-Beam Scattering. This gives confidence that the same
phenomenology should be observed after the Upgrade provided the
long-range beam-beam effect is minimized by a significant increase of
the helix separation. The committee encourages a further development of
the model to include the beam-beam effect, tune modulation...with a
systematic comparison with the present observed performance.

The extreme sensitivity of beam stability to betatron tunes may cause a
number of quenches by particle losses. The committee recommends
investigating the medium--strong beam-beam effects when the antiproton
bunch population will approach half of the proton one.

As already mentioned, the committee is concerned that the issue of the
enhanced beam-beam effect at 150 GeV leaves an uncertainty. It is
presently about a factor of 2 in performance for Run II*a* and is likely
to increase significantly for the Upgrade. The committee reiterates its
recommendation to consider active long-range beam-beam compensation with
sufficient priority.

The planned antiproton emittance reduction and helix optimization should
probably be kept as contingencies to minimize the risk associated with
this new approach.

**[Reliability Issues]{.underline}**

The amount of luminosity, which is lost by failure or limited
availability of components, is considerable. Vice versa, there is a
considerable improvement in performance to gain by increasing the over
all reliability of the complex.

The effort to assess reliability in a global way across the entire
accelerator complex is welcomed and endorsed by the committee.

A vulnerability report, which was produced in 2002, has been made
available to the committee. The committee considers this report as an
important step forward in avoiding significant problems in the future. A
large number of components have been identified that in case of failure
would interrupt operations for a time span as long as 3 months. This
appears to be quite frightening. The cost to provide spares and quick
replacements for the critical components is large. However, this cost
must be compared to the waste of resources during a long down time,
which would be caused by the failure of a single critical component.

The committee recommends that the most urgent items of this list should
be identified and addressed as soon as possible. It suggests furthermore
that this list be updated and developed. The progress of reducing
vulnerability should be reviewed regularly.

The Committee is disturbed by the relatively large number of
beam-induced quenches and the sensitivity of the superconducting magnet
system to beam manipulations. Stores ended by quenches are the most
prominent item on the list of unintentionally ended stores. In view of
the large recovery time from a high energy quench and the corresponding
large downtime, the committee encourages to consider implementing beam
loss monitor system to help prevent beam induced quenches.

Reviewing the presented information, the committee would like to mention
that a certain lack of basic maintenance of equipment such as magnet
stands and cabling in the TEVATRON appears to be a concern.

**Appendix**

**[Charge (Rev. 23-Dec-02)]{.underline}**

The February 2003 meeting of the Fermilab Accelerator Advisory Committee
(AAC) will focus on the status of Tevatron Collider Run II operations
and development of plans for maximizing output of the Tevatron Collider
in the pre-LHC era. Reference materials for the review will include the
plan for FY2003 developed during the fall of 2002 and material
supplementary to the Plan for Run IIB released in December 2001.

The committee is asked to review and comment on the recent operational
experience and short term plans for Run II with particular emphasis on
the following points:

-   Assessment of potential impediments to achievement of the luminosity
    goals established for FY2003, namely a peak luminosity by the end of
    September 2003 of 5-81031 cm-2sec-1 in the Tevatron, and an
    integrated luminosity of 220-320 pb^-1^.

-   Evaluation of the overall strategic approach to achieving the goal
    of 81031 cm-2sec-1 in the Tevatron by the end of September 2003.

-   Evaluation of the key underlying accelerator physics issues and the
    adequacy of the FY2003 plan in addressing these issues.

-   Suggestions for overcoming any identified impediments to FY2003
    goals.

The committee is further asked to review and comment on the elements of
a longer-term plan for maximizing performance of the Tevatron over the
period beyond FY2003 and through the initiation of LHC physics. In
particular we would appreciate the committee's view on the following:

-   Is the strategic approach to increasing luminosity into the range
    2-41032 cm-2sec-1 sound?

-   What are the primary accelerator physics and technology risks
    associated with this strategy? Can the level of risk be translated
    into a luminosity performance uncertainty?

-   Do opportunities exist for mitigation of these risks through
    alternative approaches?

-   Are operational scenarios developed that appropriately account for
    the simultaneous needs of fixed target operations?

Any further comments or suggestions the committee would like to make
are, as always, welcomed and appreciated. It s requested that a concise
report responsive to this charge be forwarded to the Fermilab Director
by March 7, 2003.

Agenda

##### Tuesday, February 4

8:30 Executive Session -- Willeke (20 minutes)

8:50 Welcome and Presentation of Charge -- Holmes (10 minutes)

#### Collider Run II in FY2003 (Organized by Mike Church)

9:00-9:25 Overview of Current Performance and Plan for 2003 (Church)

9:25-9:50 Proton Source Operations in Support of Collider Operations
(McCrory)

9:50-10:20Antiproton Source Operations Status (Harms)

10:20-10:45 Break

10:45-11:15 Main Injector Operations Status (Johnson)

11:15-12:15 Tevatron Operations Status (Martens)

12:15-12:30 Discussion

12:30-1:30 Lunch

1:30-2:15 Recycler Status and Integration Plan (Mishra)

2:15-2:45 Proton Source Requirements in the Run II Era (Prebys)

2:45-3:15 Reliability and Maintenance Requirements (Czarapata)

Discussion

3:30-3:50 Break

###### Collider Run II Beyond FY2003/Upgrades (Organized by Jeff Spalding)

3:50-4:15 Overview of Run II Strategy Beyond FY2003 (Spalding)

4:15-5:00 Discussion

5:00-6:30 Committee Executive Session

***[Wednesday, February 5]{.underline}***

###### Collider Run II Beyond FY2003/Upgrades (continued)

8:00-8:40 Tevatron Task Force (Lebedev)

8:40-9:20 Stacking and Cooling Task Force (McGinnis)

9:20-9:40 Summary of Parameters and Issues (TBA)

9:40-10:00 Discussion

10:00-10:15 Break

10:15-10:45 Protons on Target (Kourbanis)

10:45-11:15 Antiproton Acceptance (Werkema)

11:15-11:45 Stacking and Cooling (McGinnis)

11:45-12:15 Tevatron and Beam-beam (Shiltsev)

12:15-12:30 Discussion

12:30-1:30 Lunch

1:30-7:00 Supplementary presentations and/or breakout discussions as
requested by the committee. Committee Executive Session

####### Thursday, February 6

8:30-10:30 Committee Executive Session

10:30-12:00 Closeout (60 minutes)