Report from the
5 Meeting of the Accelerator Technical Advisory
Committee for the Japan Proton Accelerator ResearchComplex (J-PARC)
th

February 23-25, 2006
JAEA
Tokai, Japan

Table of Contents
Page No.

Introduction, Summary, and Major Recommendations.............................................1
Linac.........................................................................................................................10
3 GeV Rapid Cycling Synchrotron ..........................................................................1250 GeV Main Ring Synchrotron ..............................................................................15
RCS & MR RF systems ...........................................................................................18
Controls and Global Systems...................................................................................21
Commissioning and Accelerator Physics ................................................................24

Appendix: Review Agenda

INTRODUCTION, SUMMARY, AND MAJOR RECOMMENDATIONSThe Accelerator Technical Advisory Committee (ATAC) for the J-PARC Project held its fifth
meeting over the period February 23-25, 2006 at the JAEA site in Tokai, Japan. The committee
heard presentations from project staff on the 23rd and 24th, held several closed sessions to discuss
reactions and opinions, and presented a verbal report to project management on the 25th. In
addition the committee was given a comprehensive tour of the project on the 24th. The meeting
agenda is attached in the Appendix.
Committee members in attendance at this meeting included: R. Garoby/CERN, D. Gurd/ORNL, I.
Gardner/RAL (deputy chair), S. Holmes/Fermilab (chair), A. Noda/Kyoto, T. Roser/BNL, L.
Young/LANL (retired), and J. Wei/BNL.
Y. Cho/ANL and I. Hoffman/GSI were unable to attend.
The ATAC wishes to express its appreciation to JAEA and KEK management and support staff
for their hospitality during this meeting.
Excellent progress is evident on a wide range of fronts over the last year. The committee offers
its congratulations to the entire J-PARC team! The committee heard excellent presentations
covering all aspects of the project. These presentations were very responsive torecommendations from the March 2005 meeting.
The J-PARC project is now well advanced both in terms of civil construction and accelerator
component fabrication. Installation is underway and planning for commissioning is welladvanced relative to a year ago. Nonetheless there are several areas of concern that thecommittee feels will require particular attention to bring the project to successful completion:•

Performance of rf accelerating cavities for the RCS and 50 GeV MR•

RCS and Main Ring performance with the 181 MeV linac•

The budget and schedule to completion•

Installation and commissioning planning, including the transition to operations

These will all be discussed in this report. In particular we have devoted a single chapter to theissues related to the rf accelerating cavities in acknowledgement of their critical role in the
successful completion of the J-PARC project.
Summary and Major Recommendations
Linac
Excellent progress is evident on all fronts. The linac enclosure and service buildings arecomplete and installation is underway, aimed at a December 2006 start for beam commissioning.
The decision has been made to utilize a non-cesiated tungsten filament ion source for initial
operations. All DTL tanks are complete and installed. SDTL tanks are complete and are in the
final phase of high power testing/installation. The long range plan remains to upgrade the linac-1-

energy to 400 MeV based on the addition of an annular coupled structure (ACS) linac following
completion of Phase 1. Prototyping is now underway. The committee applauds the start ofpreparations; however, funding for the upgrade remains unsecured.
•

The ion source lifetime remains a concern. The expected 800+ hour lifetime is based on
extrapolation and not on performance of a functioning source in the proposed
configuration. The performance characteristics and lifetime of the source need to be
confirmed before the start of linac commissioning.
Recommendation: Efforts should be pursued with the goal of a full demonstrationof the ion source Phase 1 design specification by the start of linac beamcommissioning.

•

Resources required to meet the installation and commissioning schedule appear marginal.
Forty-three people are currently assigned full time in the linac group. It is estimated thatan additional six are required to support critical items within the commissioning plan.
Recommendation: Augment the staff of the Linac Group as necessary to support
commissioning goals.

•

The committee concurs with prior years’ assessments that the linac is likely to achieve
design performance goals at 181 MeV operations. However, performance of the RCS andMR will suffer from the lowered linac energy.
Recommendation: We continue to urge the identification of funding forrestoration of the linac energy to 400 MeV as a high priority item.

RCS (Other than accelerating cavities)
Good progress has been achieved on many fronts over the last year. Component procurements
for the RCS are well advanced, with the exception of the accelerating cavities, and the initiationof installation in the RCS enclosure is imminent (March 2006). Delays have been induced in theschedule relative to last year due to funding shortfalls and difficulties in the accelerating cavity
development program. The longer range plan is now to initiate hardware commissioning in April
2007 (9 month delay relative to a year ago) and beam commissioning in September 2007 (4month delayed). Extensive measurements of magnets have been undertaken and results are being
incorporated into a more comprehensive simulations program as recommended in last years
report. Vacuum chambers are also progressing satisfactorily. In response to prior year
recommendations a design has been developed for momentum collimation in the L3BT line.
Many constraints exist due to the location of magnets in the line being fixed at this point in time,
but the design is still able to achieve a momentum acceptance of ±0.5%.
•

The committee notes that more realistic simulation of the injection process has led to theconclusion that the circulating beam remains on the foil approximately three times as-2-

long as previously estimated. The lifetime of standard carbon stripping foil remains a
concern to the committee. The test proposed last year at KEK has not yet beenaccomplished. The plan is to do the test soon, following the shutdown of the KEK PS in
March.
Recommendation: Test new foils with H- beam as soon as possible and compare
the stripping foil tests with the lifetime tests performed at BNL with H- beam.
•Single particle tracking simulations are more comprehensive than a year ago, including
the integration of measured magnetic field errors, longitudinal painting and tracking up
the ramp, and transverse painting with space charge. The simulations show significant(7%) beam loss for operations at 0.6 MW and 181 MeV injection. However they are still
not comprehensive and could be improved in their treatment of the following:– Magnetic field interferences– Leakage fields from septum magents– Power supply tracking– BPM resolution
Recommendation: Continue to improve the integrated tracking simulation to
include all relevant effects.

•

The committee remains concerned about the operational margin designed into thecollimation system. Total design load on collimators is 4 kW (at 1 MW operation ). The
collimator design has been modified to provide enhanced cooling via cooling fins andforced air flow. As a result the collimators are now considered capable of 0.7 kW(horizontal, per jaw) and 0.4 kW (vertical, per jaw). However, no operational scenario
has yet been developed to assure that no collimator operates above its specification. The
committee suggests being more conservative on the design specifications.
Recommendation: Design the RCS collimator system with sufficient margin tocope with realistic operations scenarios.

•

The extraction kicker appears to the committee as a potentially important component of
the impedance budget. The committee heard a presentation on the measured impedanceof the device but the measurement did not appear to include the PFN and cabling(transverse).
Recommendation: Complete the transverse impedance measurement of the RCS
kicker that includes the powering cables and pulse forming network.

•

Currently assigned resources appear marginal for meeting the schedule. Fifty people areassigned, of which 33 are permanent. The shortfall for meeting project goals is estimate
to be 10 persons.
Recommendation: Augment the staffing needs of the RCS Group as necessary tosupport commissioning goals.
-3-•The committee concurs with prior years’ assessments relative to RCS performance: 0.33
MW beam power represents a lower limit on what will be achieved with the RCS in
Phase 1; 0.4-0.6 MW with 181 MeV injection into the RCS is plausible, but requires
more developed simulations and a better understanding of losses to provide confidence.
This assessment assumes success in overcoming issues in the rf system as described
below. Recovery of 1 MW performance will require restoration of the linac energy to 400
MeV.

MR (Other than Accelerating Cavities)
Good progress has been made on many fronts. Dipole, quadrupole, and sextupole fabrication arecomplete and installation into the MR enclosure is underway. The schedule shows the start ofbeam commissioning in May 2008 (6 month delayed relative to a year ago). Delays are due tofunding shortfalls and difficulties in the accelerating cavity development program.
The committee received very comprehensive and responsive presentations on the installation
schedule, the strategy for dealing with activated components, single pulse accidents, and theelectron cloud instability. In addition an integrated plan was presented for commissioning andtransition to operations as requested.
•

The plan for initial operations remains to utilize the h=9 rf system in the MR. This will
limit performance to roughly 0.45 MW based on the 181 MeV linac. This approach isbased on the expectation that the 400 MeV linac upgrade will occur within the first few
years after Phase 1 completion. While the h=18 plan has not been further developed in
the last year, several alternative options have been identified.
Recommendation: Continue work to identify alternative routes to 0.75 MW, andthen develop an implementation plan as a fallback in case the 400 MeV linac
upgrade is delayed.

•

A self-consistent model of electron cloud effects has been developed and indicates thatstability is not an issue in the MR.
Recommendation: Continue to mitigate sources of electrons at the source to theextent practical. Look for other implications of electrons beyond beam instability.

•

A model of single pulse accidents based on simplified and conservative assumptions
indicates a potential problem in the MR.
Recommendation: Develop a more realistic model and evaluate plausible fault
conditions, and corrective actions if indicated.

-4-

•

Potential performance issues (mechanical stability and risetime) have been identified withseveral pulsed devices associated with beam transfers into the MR. These need to beresolved as soon as possible.
Recommendation: Resolve issues with the pulsed devices as soon as possible.

•

Currently assigned resources appear adequate for meeting the schedule. Sixty two people
are now assigned full time and the inflow from KEK has started. The issue of staff forlonger term operational support, estimated at 44, is now under discussion with KEK and
JAEA.

•

The committee concurs with last year’s assessment relative to MR performance with h=9
and 181 MeV linac: 0.45 MW is the likely performance level in this mode. This
assessment assumes success in the RF development program. Recovery of the 0.75MW
performance goal will require restoration of the linac energy to 400 MeV (preferred) or
implementation of alternative harmonic number operations in the MR or RCS.

RF Cavities for the RCS and MR
Difficulties have been encountered in the fabrication of accelerating cavities for the RCS and
MR. The current design is based on a “cut” core which raises the Q of the cavity to tailor the
bandwidth to high intensity operational requirements. A grind stone cutting method has beendeveloped over the last year which replaces the previous water jet method that produced
unacceptable results. A number of cut cores have failed under high power testing in both the
RCS and MR cavities. Failures have developed rather quickly—all in time periods under 200
hours. Uncut cores have also been tested and seem to be much more robust. The current theory isthat acid, that is used for etching to remove short circuits between Finemet layers after cutting, isbeing trapped by the water sealant inside the cores and subsequently does damage when exposed
to high power.
The current delay in the development program is endangering the installation and commissioning
schedule of both the RCS and MR. The strategy proposed by the project team is to assemble one
RCS accelerating cavity with cut cores fabricated under a modified fabrication process in April.
The cavity will then be tested in May, and if it performs satisfactorily procurement of the balanceof cores for the remaining nine cavities will commence. If the testing is unsatisfactory the RCS
cavities will be produced entirely with uncut cores for the initial RCS operation. The current
assessment of project staff is that uncut cores will support roughly 100 kW of beam power in the
RCS. While the committee believes such an implementation will limit RCS intensity we do nothave sufficient information to make a quantitative assessment.
The ATAC views on this issue are as follows:• The committee is deeply concerned about the status of the RCS and MR RF systems.
There is no convincing demonstration that cavities with an acceptable life-time can bebuilt, no operational parameters for reliable, long lived cavities have been established andtime is now very short if program milestones are to be met. Only one off-line test stand-5-

exists for both RCS and MR and it is not yet equipped with the low level RF electronics
to allow correct amplitude and frequency control.
•

If issues are not resolved correctly performance of these systems could severelycompromise the J-PARC project.

•

We believe that MA-based cavities remain a valid and promising technology for J-PARC.
Similar cavities have been run for extended periods at the KEK PS booster synchrotron,
where uncut cores with force air cooling produce 14 kV/m with 40 kW/m input power.
Systems have also been operated, although at much lower power and/or gap voltages, at
COSY, HIMAC, CERN, BNL, and FNAL.

•

Meeting the installation and commissioning milestones, even at reduced initial power, iscritical for the J-PARC Project.

•

The ATAC believes the proposed strategy for resolving this problem is unrealistic. It
assumes that the underlying problem is understood and will be solved on the first pass. It
also assumes that one month testing of a single cavity will be sufficient to establish
confidence in the long term performance of complete systems. We do not believe eitherof these assumptions is justified. It is the view of the committee that developing a robust
solution will require an extended effort beyond the three months allocated in the current
schedule.
Recommendation: The committee recommends a two component, parallel
approach:
1. Establish a short term solution that will support installation andcommissioning goals for the RCS and MR. We suggest an initial installation
based on uncut cores in the RCS and an immediate evaluation of the need forcut cores in the MR at reduced beam intensities. The staff should establish
immediately the safe operating power/voltage for such cavities, via an
extended testing (>1000 hours) program, and implement on a scheduleconsistent with the current installation schedule.
2. In parallel pursue a comprehensive development program that aims to
support the 1 MW RCS and 0.75 MW MR performance goals. This program
could extend over a year or two without impacting the long term J-PARC
goals. Given that the MR production schedule is delayed by 10 months
relative to the RCS we suggest that it would make sense to develop the MR
cavities first.
The development program should be focused both on identifying theunderlying problem and solving via revised fabrication techniques, and on
examining alternative design approaches for both the cavities and/or the
RCS itself. Among the alternatives that might be considered are:
– Increase the number of cavities in the RCS and MR.
–

Oil cool uncoated cores instead of water cooling coated cores.

-6-

–
•

Consider ferrite loaded cavities.

Time is unlikely to permit two off-line test stands in the short term but there should be
one for the RCS and one for the MR for the long term development. Two cavities foreach system should be obtained to allow testing on one while modifications are installedin the other.
Recommendation: Construct an additional rf test stand, including full capability
for driving cavities with the operational voltage and frequency programs, that canbe dedicated to ongoing test and development.

•

If problems persist, they will have to be recognized quickly and alternative solutions
developed.
Recommendation: Conduct a review to assess progress on the rf systems, utilizing
internationally recognized experts in rf technology, prior to the initiation of
fabrication of cut cores. Participation of a few ATAC members in such a review
would ensure continuity of the ATAC understanding of the rf issues into thespring 2007 meeting.

•

Implementing such an approach will require augmenting existing resources.
Recommendation: Additional experienced people should be made available toassist in solving this problem.

Controls and Global Systems• The controls group needs the participation of the accelerator physics groups indefining/creating these applications programs that will be used during the commissioning
effort.
Recommendation: Based upon the commissioning plan presented, specify thehigh-level physics applications needed to carry out this plan and begin
development of these applications as soon as possible.
•

The Personal Protection System (PPS) is being implemented using what is now aconventional redundant PLC-based technology. During periods of overlapping
installation and commissioning, it is likely that temporary configurations of the PPS,
possibly including temporary walls and/or gates, will be required. Each of these
configurations will have to undergo a time-consuming certification, and thesecertifications demand that certain equipment be operational. (You need to be able to turnon what the PPS will turn off.) It is important that these activities and constraints beanticipated and included in the overall project schedule.
Recommendation: Review the project schedule to assure that adequate time isincluded for certification of the PPS in possibly required temporaryconfigurations.

-7-

•

The committee heard a presentation on the strategy for dealing with electromagnetic
compatibility (EMC) issues. The action plan appears reasonable and should be pursued.

Installation, Commissioning, and Operations Plan
The ATAC found that planning for installation, commissioning, and the initial operations phaseis advanced relative to a year ago. A first pass at the evolution of beam power in both the RCS
and MR during the initial operational period has been developed. We regard the present level ofplanning as a reasonable start. However, we suggest that the next steps include; integration ofplans across machine boundaries, identification of resource requirements, and identification of
applications program needs during the commissioning period. The ATAC believes that this task
can only be accomplished by establishing a single commissioning team, lead by a full time
dedicated leader with the responsibility and authority for commissioning the accelerator complex.
Recommendation: Establish a commissioning team to coordinate planning andexecution of commissioning activities across the entire complex.
Recommendation: The long-term commissioning plan should be discussed withand published to the user community as soon as possible in order to manage
expectations realistically. The published plan should include estimates ofanticipated reliabilities and the time allocation between users and accelerator
physics.
Management Issues
The overall accelerator construction and commissioning schedule has slipped by roughly 6months in the last year. This is due primarily to the JFY2005 funding shortfall, but technicalissues are also contributing. It is clear there is little-to-no margin on completing Phase 1 in
JFY2007. The current management strategy is to hold the JFY2007 completion date for Phase 1
and JFY2008 completion of the neutrino beamline. The priority is placed on the second of thesedates.
The operating budget for the J-PARC facility has now been estimated at 190 OkuYen/year andthis number has been confirmed by an independent review. The 400 MeV linac upgrade is notincluded in this number, and funding is now being pursued in parallel with operations funding.
•

The J-PARC staffing level, and in some instances financial resources also, appears
marginal for meeting project goals across all machines. The symptoms are that technicaldevelopment is occurring at the last moment in several systems (rf, pulsed devices, andcollimators) and at the same time installation and preparation for commissioning is
occupying a greater share of peoples time. The level of activity is expected to increase as
installation is completed and beam commissioning is initiated shortly. The committee
believes the project requires additional people with experience in installation,commissioning, and operations assigned during the upcoming year. The assessment
received from the machine group leaders totals roughly 20 people. Migration of KEK
staff out of the PS program, along with some reassignment of staff from KEK-B, hasstarted. This is a welcomed sign and needs to continue.

-8-

Recommendation: Do everything possible, including increasing staff support, tohold the schedule, but don’t assume undue risk in the process•

The committee reiterates that the full potential of the J-PARC complex cannot be realizedwith a linac energy of 181 MeV. Our assessment is that the RCS and MR will be limited
in power to roughly 0.4 MW in this configuration. We believe that restoration of theoriginally specified 400 MeV should be pursued with a high priority.
Recommendation: Funding for the 400 MeV upgrade should be pursued with highpriority.

-9-

LINAC
Progress with the preparation of the linac has been the subject of 4 presentations. The Committee
was very favorably impressed by the care taken by the project staff to address the issues raisedby ATAC in 2005 and to adopt the associated recommendations.
Ion source
After due analysis by the project team, a specific type of source has been selected. Degradation
processes are claimed to be understood. Additional corrective measures are expected to makethis source capable of meeting the required current and life-time (> 500 h) without resorting to
the use of Cesium. This remains however to be demonstrated on a real device. The source itself
was installed at the front end of the Linac in September 2005 and the high voltage power supply
arrived in February 2006.
Pre-chopper and chopper
The pre-chopper and chopper line have been fully assembled and tested with beam. Overall
performance is at the required level. The driver of the pre-chopper as well as the ion source andpre-chopper will all be installed in a shielded enclosure to minimize the electrical disturbance tothe nearby electronics.
RF
All accelerating structures have been delivered to Tokai and 23 of them are installed. Racks arein place in the equipment hall and numerous components of the RF systems are ready (reference
distribution, a number of amplifiers, most of the waveguide networks…). High power RF tests of
klystrons have begun two weeks ago.
The Low Level RF uses a combination of Digital and Analog feedback loops. (The analog
feedback loop is just around the klystron which avoids the problem of integrating incompatible
Analog with Digital feedback systems.) Prototype hardware has been built (cPCI standard) andits performance on a complete RF chain has been shown to precisely match the simulations andcomfortably exceed specifications. In particular, RF tests on the SDTL showed that driving two
SDTL tanks with a single klystron resulted in excellent control of the relative phase of the twotanks. The phase was controlled by moveable tuners in the two tanks. Tuning errors wereautomatically corrected with the LLRF system controlling the moveable tuners. The Vector Sum
control of the amplitude and phase worked very well in this test.
Debunching
A new set-up has been designed for the debunchers, which reduces the total energy range of thelinac beam to 0.27 MeV (Jitter: 0.17 MeV – Spread: 0.1 MeV). No simulation has been shown of
the longitudinal capture process in the RCS with these new parameters.
Energy upgrade to 400 MeV
An ACS prototype is under construction, preparing for a full blown implementation. Delays wereencountered during the construction of the ACS prototype structure (buncher using 5+5 cells anda bridge cavity), partly because of an accident in the factory. It will be tested with high RF power
in a few months.

-10-However, as decided three years ago, the beam energy will be limited to 181 MeV in Phase 1,
and the beam current to 30 mA. The nominal parameters (400 MeV and 50 mA) need
supplementary resources which have not yet been allocated.
Planning
Hardware commissioning will last between April and November 2006. Commissioning withbeam will start in December 2006 – September 2007. Injection into the RCS area begins in
September 2007.
Comments and Recommendations
The impressive progress achieved since last year’s ATAC meeting leaves little to be desired. The
linac is now in an advanced stage of construction. The assembly of the L3BT line is almost
complete. These are all reasons to believe that the foreseen goal to start beam tests in December
2006 will be met. Nevertheless, for the sake of completeness, the following issues still deserve
some attention:•

Ion source: adequate characteristics can theoretically be expected from the device now
installed. However, this remains to be observed on a real device.
Recommendation: Efforts should be pursued with the goal of a full demonstrationof the ion source Phase 1 design specification by the start of linac beamcommissioning.
Recommendation: The shielded enclosure surrounding the ion source and prechopper system should be installed and tested as soon as possible to make sure it
reduces adequately the electrical disturbance to the nearby electronics.

•

The LLRF system appears to be working well. However, the communication between thecPCI host and the server and/or PLC is still under development. In addition, the Server dataacquisition software is under development. This development must be completed for thecommissioning of the linac with beam to commence in December, 2006.

•

Longitudinal capture in the RCS has to be optimized for the new set-up of the debunchers.

•

Electromagnetic compatibility: analysis has started, and a reasonable action plan has beenpresented. In this domain also, success will only come from the continuity of the efforts.

•

Bringing the linac energy to its nominal value of 400 MeV is essential for the JPARC facility
to reach the foreseen beam power both at 3 and 50 GeV. The Committee considers that theplanning presented for this upgrade is realistic. We underline that 4 years are necessary
after the decision is made to reach 400 MeV.

•

The schedule for the ACS buncher has slipped by nearly 1 year since ATAC 2005.
Recommendation: More effort should be placed on development of the ACS
accelerator so that once the decision is made to extend the linac to 400 MeV, thepersonnel responsible for the fabrication of the ACS accelerator will be ready.

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3 GeV RAPID CYCLING SYNCHROTRON
The design parameters for the 3 GeV Rapid Cycling Synchrotron (RCS) consists of a beam
intensity of 8.3×1013 protons per cycle, a repetition rate of 25 Hz and, with an injection energy of
400 MeV, a 1 MW beam power at the 3 GeV extraction energy. The lower injection energy of
181 MeV that is part of the present Phase I construction project reduces the beam power of the
RCS to .33 to .6 MW (2.6-4.8×1013 protons per cycle). At the upper end of this range the beamloss may exceed limits in the RCS and in the transport lines to the neutron spallation target andthe Main Ring.
In many excellent presentations the present status of the RCS was described to the committee.
The civil construction was complete in April 2005. The component construction is proceedingwell and is about 70% complete. Installation is starting now and is expected to be completed by
the end of 2006. After component testing first beam is expected by September 2007. This
constitutes a delay relative to the last year’s schedule of about 4 months mainly due to reduced
budget. Note that findings, comments and recommendations with regard to the RCS rf system areincluded in the separate rf section.

Comments and Recommendations
All dipole and quadrupole magnets for the RCS were measured and the field uniformity is within
the design value of ± 5×10-4. The magnets were measured with a cycle that goes from 181 MeV
to 3 GeV with the design rate of 25 Hz. The measurement of the sextupole and steering magnets
is starting.
•

The excitation functions of the dipole and quadrupole magnet and the tracking
differences with the 25 Hz cycle were measured. Higher harmonic components (50 Hz
and higher) were less than 2%. The data has not yet been used to determine the variationof the lattice functions and parameters throughout the magnet cycle.
Recommendation: Use the measured magnet data to determine the lattice
parameters throughout the magnet cycle and develop remedies if the variations
are outside of acceptable limits.

•

The RCS dipole vacuum vessel with its rf screen and its support looked good. Full power
AC tests on more than one magnet and vacuum vessel should be considered to ensure no
problems arise from vibration. Short circuit failure of two or more RF screen capacitors
should also be checked to ensure the resulting eddy currents cause no problems. It may bebetter to consider ceramic rather than plastic capacitors and to avoid soldering as repair
may have to be carried out when the vacuum vessels are active.
Recommendation: Consider if re-soldering capacitors is possible if the vacuum
vessels are active.

•

Multiple particle tracking calculation with space charge were presented that include themulti-pole components and field and alignment errors of the dipoles and quadrupoles,-12-

longitudinal injection painting and the proper evolution of the bunch shape. For 0.3MW
operation the losses were less than 1%. For the 0.6MW operation the losses were
unacceptably high. These tracking calculations should be extended to include magnetic
field interferences, leakage fields from the septum magnets, and power supply tracking
throughout the whole magnet cycle. Also consider extending the search for good tune
working points to the whole range of vertical and horizontal tunes between 6 and 7.
Recommendation: Continue to improve the integrated tracking simulation to
include all relevant effects.
•

The predicted beam loss levels assumed very good correction of the COD. This relies on
good accuracy of the beam position monitors (<0.5 mm) and very good stability ofseveral magnet power supplies.
Recommendation: Ensure that these accuracies are achievable.

•

The utilization of trim quadupoles to provide control of tunes throughout the acceleration
schedule is planned but not formally included in the baseline of the project. The
committee believes that a trim quadrupole system will be necessary to provide optimum
performance of the RCS and should be formally incorporated into the project baseline.

•

Impedance calculations and measurements for the RCS components were presented thatwere generally quite complete and the agreement between measurement and calculations
are good. Transverse and longitudinal impedances were measured for the extraction
kickers. However, the important measurement of the transverse impedance of theextraction kickers that include the powering cables and the pulse forming network has not
yet been done. The result should then be included in the RCS stability analysis.
Recommendation: Complete the transverse impedance measurements of the RCS
kicker that include the powering cables and the pulse forming network.

•

The pulse flatness of the extraction kicker magnets was measured to be 6.4%. To achieve
the design flatness of 1% it was proposed to miss-time the individual modules, which
improves the overall flatness at the expense of the kicker rise time. This is a serious
degradation of the kicker performance. The project should reevaluate the specification for
the kicker flatness and, if less than 9.3% is indeed needed, it should attempt to improve
the presently existing impedance miss-match to achieve the necessary flatness but
preserve the present good kicker rise time.
Recommendation: Reevaluate the RCS extraction kicker flatness requirement andmeet the requirement by improving the impedance matching between power
supply and kicker magnets.

•

All ceramic vacuum chambers are being coated with TiN to reduce the secondary
electron yield. This should suppress the formation of an electron cloud, which otherwise
can lead to beam instability and residual gas pressure rise. There is presently no plan to-13-coat the Ferrite and aluminum surfaces of the extraction kicker but instead outgas thesesurfaces by baking. These surfaces have large SEY coefficients, which can only be
improved by coating them. Such surfaces have been successfully coated at BNL for the
SNS project. This should also be done for the RCS. The TiN coating should also be
extended to the collimator jaws. Coating the collimator jaws is superior to applying asolenoid field to suppress electron multi-pacting.
Recommendation: Consider coating the Ferrite and aluminum surfaces of theextraction kicker and the surfaces of the collimator jaws. Coating with TiN was
successfully achieved for the SNS project.
•

No new studies of the stripping foils were presented. The plan is still to test foil life timewith the 750 keV H minus beam at KEK. These tests should proceed as soon as possible
and results should be compared with to foil lifetime tests performed with H- at BNL.
Recommendation: Test new foils with H- beam as soon as possible and compare
the stripping foil tests with the lifetime tests performed at BNL with H- beam.

•

In the RCS five transverse collimator systems will be installed to capture halo particles.
Each collimator jaw is capable of absorbing 0.4 kW beam power in the vertical plane and0.7 kW in the horizontal plane. The total design beam loss on all collimators is 4 kW. No
operational scenario has been developed to assure that the heat load on an individual
collimator jaw doesn’t exceed its specification. The RCS collimator system should bedesigned much more conservatively since it will be difficult to operate with little or no
margin of beam load on the collimator system.
Recommendation: Design the RCS collimator system with sufficient margin tocope with realistic operations scenarios.

•

A careful and conservative analysis of single pulse failures in the RCS was presented tothe committee. It showed that the RCS can not be damaged by a single beam load. With afast Machine Protection System (MPS) that inhibits further injection after a fault
condition has been detected the RCS can therefore be fully protected from beam induced
damage.

-14-

50 GeV MAIN RING
The installation plan of the magnets is reported, which extends until the early part of 2007 andassumes their precise alignments at the later part of the year. Day-1 beam commissioning isscheduled from May to July and October to November in 2008 sharing the beam with MLF. At
this stage protons with an intensity of 0.8 x 1012 ppp are assumed for acceleration up to 40 GeV
with 1 batch injection (h=9). Beam commissioning of slow extraction and the hadron beam line
is scheduled for December of 2008, while commissioning of 40 GeV fast extraction and theneutrino line is to be done in April 2009. Beam intensity is to be raised up gradually until 2010
utilizing 8 batches injection and finally arrive at 400 kW beam power, which seems reasonable.

Comments and Recommendations•

The allowable injection time from the point of view of beam loss is estimated to be lessthan the design injection time.
Recommendation: Carefully review the injection simulation both for reliability of
the calculation and for the tolerable power level on beam collimators.

•

A scheme to produce the neutrino beam with 30 GeV instead of 40 GeV protons was
discussed as a possible means of increasing the repetition rate and available beam power.
The committee notes that such a scheme could result in somewhat higher beam loss andsuggests integrating study of such losses into any further development of the 30 GeV
concept.

•

Following the tour of the Main Ring it was evident that the water and electricalconnections to the magnets appeared to be made on the inside of the ring where there was
not much room. It may be better if these connections are extended to the outside of thering for easier servicing when the components become active.

•

The commissioning schedule should account for time and manpower needed for studies
involving the tracking between magnets, calibration of beam monitors, and beam loss
survey.

•Assignment within the straight sections for injection and extraction equipment, beam
monitoring, and RF cavities should be carefully studied, using the detailed drawings ofthe equipment including the vacuum vessels, with the goal of eliminating interferences
and possibly creating room for additional rf cavities.

•

Realistic beam loss simulations, including both slow extraction and 30 GeV fast
extraction to the neutrino beamline, and including measured magnetic fields, should be
performed as early as possible.

•

Tracking program between dipole and quadrupole magnets should be analyzed taking
into account the measured characteristics on saturation.

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•

The assumed beam losses based upon the simulation at various stages, the radiation levels
at the boundary of the radiation controlled area and the J-PARC site need to be carefully
investigated in connection with the radiation regulations. Radiation margins to support
the operating program should be understood.

•

Consider the actions necessary to remove a magnet when it has become active. Local
shielding can be very effective in reducing radiation dose and this may be more effective
for personnel working on the outside of the ring.

•

The plan for initial operations remains to utilize the h=9 rf system in the MR. This will
limit performance to roughly 0.45 MW based on the 181 MeV linac. This approach isbased on the expectation that the 400 MeV linac upgrade will occur within the first few
years after Phase 1 completion. While the h=18 plan has not been further developed in
the last year, several alternative options have been identified.
Recommendation: Continue work to identify alternative routes to 0.75 MW, andthen develop an implementation plan as a fallback in case the 400 MeV linac
upgrade is delayed.

•

A model of single pulse accidents based on simplified and conservative assumptions
indicates a potential problem in the MR.
Recommendation: Develop a more realistic model and evaluate plausible fault
conditions, and corrective actions if indicated.

•

Potential performance issues (mechanical stability and risetime) have been identified withseveral pulsed devices associated with beam transfers into the MR. These need to beresolved as soon as possible.
Recommendation: Resolve issues with the pulsed devices as soon as possible.

•

Currently assigned resources appear adequate for meeting the schedule. Sixty two people
are now assigned full time and the inflow from KEK has started. The issue of staff forlonger term operational support, estimated at 44, is now under discussion with KEK and
JAEA.

•

The committee concurs with last year’s assessment relative to MR performance with h=9
and 181 MeV linac: 0.45 MW is the likely performance level in this mode. This
assessment assumes success in the RF development program. Recovery of the 0.75MW
performance goal will require restoration of the linac energy to 400 MeV (preferred) or
implementation of alternative harmonic number operations in the MR or RCS.

-16-RCS & MR RF SYSTEMSThe RCS RF system needs to produce up to 450 kV, h=2 accelerating voltage at 0.9 – 1.7 MHz.
The use of 181 MeV compared with 400 MeV injection energy has increased both the frequency
range and the required accelerating voltage. The increased acceleration voltage is offset, to someextent, by the reduced beam power for Phase 1. Magnetic Alloy (MA) disk loaded cavities with
Q=2 are proposed to achieve this in a minimum of straight section space, achieving a factor of
two improvement in voltage gradient compared with ferrite loaded cavities. The low Q removes
the need for a tuning loop and allows an h=4 component to be fed through the same RF chain
providing a larger stable phase area and thus a more intense beam. Ten three gap cavities areproposed, a reduction of one from last year, giving a maximum gap voltage of 15 kV. HighPower Drives (HPDs) with two push-pull tetrodes in each provide up to 600 kW of drive foreach cavity and its beam power. It is estimated that the accelerating voltage will vary over therange 60 – 450 kV during the acceleration cycle. The maximum voltage will occur at 1.6 MHz.
The MR RF system needs to produce up to 280 kV, h=9 at 1.67-1.72 MHz. Six RF systems
similar to the RCS are proposed. However, unlike the RCS the frequency is almost constant andthe accelerating voltage also remains constant inferring a gap voltage of 16 kV during theacceleration period of about 1.5 s. Some consideration is also being given to operation with h=18
as an alternative means to recovering the full specified beam power prior to upgrade of the linac
injector to 400 MeV.

RF amplifiers
All high power amplifiers have been built (10 for the RCS, 6 for the MR) and the power supplies
will be delivered by March 2006. RCS cavities will be installed in January-February 2007, andMR cavities in October – November 2007. The first drive amplifier (CERN-designed 8kW) built
by Japanese industry was delivered and successfully tested in 2005. The 10 units necessary for
the RCS will be built in 2006 and the rest will be ordered during FY2006.
Low Level RF
The design of the VME-based Low Level RF started in 2004 and testing is progressing
satisfactorily. All RF signal generator and frequency pattern cards are planned to be built in 2006.
The other cards for feedback and feed-forward will be ordered during FY2006. Beamsynchronization between RCS and MR has been studied and a procedure for the generation of
the reference signal to be used by the RCS beam control has been worked out.
Cavities
Based on their outstanding capability to attain large accelerating gradient, at low frequency,
FineMet-based cavities were selected early in the JPARC project for the RCS and MR
synchrotron. This technology has been demonstrated at other locations using lower peak gradientand mean power dissipation. However, the JPARC project will be their first, full scale
operational application in high current / high power particle accelerators.

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The high gradient requirement means high power dissipation in the MA cores. During thedevelopment phase, this lead to the decision to directly immerse the cores in the cooling water,
the consequence being that an adequate coating has to be applied to avoid corrosion.
To minimize potential well distortion from the high beam current it is estimated that a Q of 2 isneeded to limit the bandwidth of the cavity. The MA cores are therefore cut by grind stone toprovide a small gap between the two halves. Control of the gap size enables control of the cavity
Q. A technique has been developed to cut the cores without creating short-circuits between
successive turns of the FineMet strip. The cut surface must be very smooth to prevent
overheating from the RF power.
The development of the coating and cutting techniques has been actively pursued by the RF teamfor many years. Good progress was achieved up to 2005 although a final solution had not beenfound. Solutions were expected prior to construction starting this year. However, althoughprogress has been made, the cores are still damaged after a few hundred hours of high power
tests. First signs of degradation are color changes, followed by dark/burned spots and sometimes
peeling of the coating material. A very thorough investigation has been conducted and identified
four possible causes of damage to the cores, namely; chemical (oxidation at the contact of water,acid etching…), average power levels, peak power levels and forces from the mechanicalsupports.
The proposed future work program will test the next batch of cut cores which have beenprocessed differently to remove any contamination and with different core supports. If the cavity
operates with no apparent damage then it will be subjected to longer term testing. If the cavity
shows damage then the production cavities will be completed with uncut, coated cores. This will
result in operation with lower Q, reduced gap voltage and reduced beam power. The estimatedbeam power that these cavities could produce is ~100 kW but this figure was not substantiated.
Mixed cut and uncut cores have also been considered.

Comments
The ATAC committee is deeply concerned about the status of the synchrotron RF systems. Thereis no convincing demonstration that cavities with an acceptable life-time can be built. No
operational parameters for reliable, long lived cavities have been established and time is now
very short if program milestones are to be met. Only one off-line test stand exists for both RCS
and MR and it is not yet equipped with the low level RF electronics to allow correct amplitudeand frequency control.
However, MA-based cavities remain a valid and promising technology for the JPARC
synchrotrons. Moreover, the impact of a delay in the installation of the RF cavities would behighly detrimental to the whole JPARC project. Therefore, a 2-prong approach is recommended
to develop RF systems that work for phase 1 and at the same time develop RF systems that workfor full beam power.
Recommendations

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•

RCS cavities should be equipped with uncut cores. The resulting limitations inaccelerator performance should be detailed during the next ATAC meeting.

•Operational parameters for reliable, long lived cavities using uncut cores should beestablished.

•

When the next tests are completed on the cut-cores at the end of March 2006, theATAC committee would like to receive a summary of the test results.

•

Realistic tests are necessary. The correct voltage and frequency program should be
used for the RCS and MR cavities. A cavity design must correctly survive a test run
exceeding 1000 hours before it can be considered as viable.

•

Every effort should be made to arrive at a conclusive demonstration for cut-cores
prepared with the latest technique within 10 months (before the end of 2006), so that
the MR cavities could still benefit from cut-cores.

•

If no convincing result is obtained before the end of 2006, it is likely that the only
possible solution to start the MR on time will be to equip the cavities with uncut
cores. The resulting limitations in accelerator performance should be detailed
during the next ATAC meeting.

•Time is unlikely to permit two off-line test stands in the short term but there should
be one for the RCS and one for the MR for the long term development. Two cavities
for each system should be obtained to allow testing on one while modifications are
installed in the other.

•

If problems persist, alternative solutions should be pursued and presented in detailat the next ATAC meeting. The following could be considered:
1. Increase the number of cavities in the RCS and MR. ATAC04 RCS drawing
shows 12 cavities with room in the extraction straight for 6 more. (An increase
from 10 to 14 would half the power dissipation in the cavities and reduce the gap
voltage to 10kV).
2. Oil cool uncoated cores instead of water cooling coated cores.
3. Ferrite loaded cavities.

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CONTROL AND GLOBAL SYSTEMSGeneral: The controls team is now assembled at the J-PARC site and has made considerable
progress during the past year. Network equipment for the central control room has been installed
and tested. Controls equipment for the Linac, L3BT and RCS has also been installed and iscurrently under test. Basic application programs for the Linac have been developed andsuccessfully tested. Equipment for the Linac Machine and Personnel Protection Systems has
been installed in the klystron gallery and in the control room and are also currently under test.

Schedule and staffing: Staff currently numbers 16.5 FTEs, including staff members andcontractors from both KEK and JAEA. The staffing plan calls for this number to increase to 19(increase of 2.5 FTEs) effective April 1. It is important that this increase take place as and whenplanned, because software development appears to have fallen behind by 2-3 months andwithout the planned new staff members is at risk of falling even farther behind. Because higherlevel beam commissioning applications are necessarily done last, it is these that would becompromised in the event of a schedule slip.
Recommendation: Assure that the increase in software manpower in the current
staffing plan is carried out as soon as possible.

Commissioning Plan and High-Level Applications: In response to a specific recommendation
made at last year’s A-TAC meeting, the committee was pleased to hear preliminary details of acommissioning plan for the entire accelerator chain. It is essential that this plan be “fleshed out”
in more detail, with specifics as to the measurements to be made, with what instruments, as afunction of what machine parameters and finally what calculations and/or actions are to be donewith the results. These details are required at least six months before commissioning is scheduled
to begin for any machine, so that high-level applications can be developed and tested well inadvance. This is particularly urgent for the Linac, the commissioning of which is scheduled forlater this year. If possible, it is preferable that these applications be written by the Accelerator
Physics staff as they will be the primary “customers.”
Recommendation: Based upon the commissioning plan presented, specify thehigh-level physics applications needed to carry out this plan and begin
development of these applications as soon as possible.
Recommendation: The long-term commissioning plan should be discussed withand published to the user community as soon as possible in order to manage
expectations realistically. The published plan should include estimates ofanticipated reliabilities and the time allocation between users and accelerator
physics.

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Personal Protection System: The Personal Protection System (PPS) is being implemented
using what is now a conventional redundant PLC-based technology. Two independently
developed ladder-logic programs are used. Certification of the first part of this system is plannedfor March. During periods of overlapping installation and commissioning, it is likely that
temporary configurations of the PPS, possibly including temporary walls and/or gates, will be
required. Each of these configurations will have to undergo a time-consuming certification, andthese certifications demand that certain equipment be operational. (You need to be able to turnon what the PPS will turn off.) It is important that these activities and constraints be anticipatedand included in the overall project schedule.
Recommendation: Review the project schedule to assure that adequate time isincluded for certification of the PPS in possibly required temporaryconfigurations.

Machine Protection System (MPS): The MPS design and installation (in the Linac) is welladvanced, and it appears that the system will meet the timing requirements imposed by theworst-case accident scenario outlined to the committee. The system will have of order 1000
inputs all of which are potential sources of annoying “false positives.” All of these inputs can beeasily bypassed in software and the temptation to bypass will be great during commissioning,both because of equipment failure and because of the need for unusual and possibly
unanticipated operating modes.
Recommendation: To avoid compromising machine protection duringcommissioning, a philosophy and protocol for controlling and monitoring MPS
bypasses should be developed and implemented before commissioning begins.

Security Plan: In response to a recommendation last year that a computer security plan be
developed, the committee was shown an architecture that protects the accelerator network
making use of firewalls and protected access policies. Perhaps the most difficult issue in amodern distributed system such as J-Parc’s is preventing infected or malicious computers fromconnecting directly to the network by simply plugging in to an available port. There are many
good reasons to facilitate the connection of a standard PC laptop to the accelerator network –programming a PLC is only one – so a protocol needs to be established and then enforced toprevent access by unauthorized or unscreened (for viruses) computers. A policy requiring any
computer plugged into the network to have been scanned in advance may be appropriate.

Configuration Management: In response to a recommendation made last year the committee
learned that a uniform Application Development Environment (ADE) using the Concurrent
Version System (CVS) is being developed. At the same time, a mechanism for producing EPICS
database and graphical user interface files directly from a relational database has beensuccessfully deployed. This approach has many advantages; however it could provide a-21-mechanism for bypassing the CVS control mechanisms. Procedures should therefore be
developed and enforced to assure reliable configuration management of all control system EPICS(and other) files.

LLRF Controls: The committee heard an excellent report on impressive progress andperformance with the LLRF systems. These systems communicate with the EPICS layer by aroundabout path through a PLC to the PCI interface. EPICS has access only to those data which
are explicitly transmitted to the PLC. In the spirit of the excellent design principal of “No
Hidden Data,” it would be wise to make a practice of sending all LLRF data, including tuning
parameters, to (and from) the PLC which is used to communicate with EPICS, rather than adding
one parameter at a time when it is found to be required.

Equipment Testing: Most equipment testing (non-beam testing) appears to be done using the
EPICS software. It is important to follow this approach wherever possible because any testingthat is done stand-alone will have to be repeated later in end-to-end tests, adding unnecessaryschedule delays. Testing this way puts pressure on the controls team to be ready (not a badthing); but encourages early reliance (and hopefully confidence) in the control system.

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COMMISSIONING AND ACCELERATOR PHYSICS
Due to adjusted funding profiles, the projected commissioning dates were adjusted. The newly
projected beam commissioning is from December 2006 to October 2007 for the linac, from
October 2007 to April 2008 for the RCS, from May to June 2008 for the MR slow
extraction/hadron program, and from October to November 2008 for the MR fast
extraction/neutrino program.
Projected beam power ramp-up profiles were shown for both RCS and MR with and without theenergy upgrade. Significant progresses have been made to address important accelerator physics
issues associated with the physical design and technical engineering, and to respond to concerns
raised in the previous review.
During the 2005 ATAC review, there were seven recommendations raised in the area ofaccelerator physics. They were:
1. Evaluate the optics design of the linac and the mechanisms of beam quality deterioration
along the linac using measurements performed in the linac commissioning.
2. Optimize the L3BT optics within the present hardware constraints to facilitate momentum
diagnostics and momentum collimation.
3. Optimize the layout and design of the collimation systems based on a comprehensive
evaluation of beam loss distribution in the collimator region under both normal and fault
conditions, emphasizing engineering robustness, operational reliability, and maintainability.
4. Perform comprehensive impedance and instability analysis of the extraction kicker
assembly including the kicker modules, the pulse-forming network, and the cabling as a
guide in optimizing the engineering design.
5. Implement an integrated tracking simulation including alignment errors, real fields
including both systematic and random, space charge, injection chicane, and magnet
interferences. Evaluate correction strategy in the presence of such complications.
6. Evaluate electron cloud formation using actual beam and vacuum surface parameters (e.g.
coating pattern and measured SEY) and optimize mitigation scenarios in both RCS and MR
7. Benchmark electron-proton instability calculation with observed thresholds in machines
like PSR, and improve the model if necessary.
Several talks were presented during this review addressing these topics.

During the commissioning on September 2004, H- beam of up to 30mA peak current and 250 µs
pulse length were accelerated at 25 Hz to the end of the DTL tank-1 with energy of 19.7 MV.

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The transmission efficiency was near100%. The set point accuracy of 1 degree and 1% wasachieved. After further analysis during the last year, the measured rms emittances were
determined to be 0.28 (H) and 0.26 (V) mm mr. In comparison, the design goal for the phase I of
181 MeV linac operation is 30 mA, 500 us, 25 Hz. The design goal for 400 MeV linac operations
is 50 mA, 500 us, 25 Hz. The design transverse emittance is 0.25 mm mr.
A momentum collimation design was presented for the L3BT capable of cleaning the beam at±0.5% momentum deviation. The budget needed to implement the design is not yet available.
For the RCS collimators, the heat capability is 700 (x2) W on horizontal jaws, and 400 (x2) W
on vertical jaws. The expected beam loss is 1.2 kW. For the 3 GeV beam transport collimator,
the capability is 450 W, while the expected beam loss at 0.6 MW (181 MeV) operational
scenario is 1.2 kW.
Measurements were performed on the longitudinal beam coupling impedance of the RCS
extraction kicker together with the PFN and cables, and on the transverse impedance of theextraction module alone.
High electron-cloud concentration is identified for the RCS collimation and extraction areas in
the absence of mitigation. The electron neutralization is near 100% at the extraction area due tothe high secondary emission yield of the ferrite surfaces. The chance of electron-proton
instability is predicted to be small due to available Landau damping of the beam.

Comments and Recommendations
Commissioning of the J-PARC accelerator complex, first on major engineering systems and thenwith the beam, is a challenging task demanding a dedicated team experienced with accelerator
commissioning and technology. We encourage the project to organize and strengthen a central
accelerator physics/commissioning team with experienced physicists and engineers from KEK
and other institutes, and to extensively collaborate with high intensity accelerator teams in theworld to benefit from the expertise of the community.
Recommendation: Establish a commissioning team to coordinate planning andexecution of commissioning activities across the entire complex.
Several key J-PARC systems are at the engineering frontier of accelerator technology: the RCS
and MR RF system, the injection, extraction, and switching magnets and power supplies, thelarge-size braided-coil magnets and their power supplies with tight tracking and field
specifications, the ceramic vacuum chamber with external RF shielding, etc.
Recommendation: Perform full duty factor tests as early as possible on all majorstate of the art systems and components in order to identify possible engineering
problems that can either delay the commissioning or compromise future
operations.

We commend the practice of developing back-up scenarios for challenging engineering systems
like the ring RF and MR septum magnet.
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Recommendation: To ensure high reliability of the project, back-up scenarios
should be developed on items including the above-mentioned challenging
engineering systems and beam scraping/collimation system.
We reiterate our comments at the last review that the present collimation philosophy needs to be
critically reviewed for a robust performance not only under normal operations but also under offnormal and fault conditions, with increased complexity of mitigating electron cloud in the region.
In comparison, we note that the ISIS collimator can take beam loss of their entire linac beam
power at about 15 kW; the SNS collimators can each take beam power from 2 to 10 kW.
The momentum collimation scheme developed at L3BT is encouraging. We feel that collimation
at ±0.5% can effectively protect the system and enhance the performance. Further analysis canbe made on optimizing its performance along with the selected locations of the debunchers.
Studies are also encouraged on developing beam scraping at low energy, possibly at the locationof the MEBT bending dipole.
The present study of machine protection from one-shot accident needs to be expanded to analysisof plausible fault conditions, especially in the MR.
Recommendation: Develop a more realistic model and evaluate plausible fault
conditions, and corrective actions if indicated.
Measurement of the transverse beam coupling impedance of the extraction kicker needs to be
expanded to include the pulse-forming network and cabling. Theoretical results should be closely
communicated to the engineering team to optimize the design.
The study on electron cloud should include not only electron-proton instability but also othereffects including vacuum pressure rise and system interferences. Present studies identified theextraction and collimation areas where electron cloud concentration is significant. Mitigation
scenarios should be developed possibly including patterned coating of the extraction module,
coating of all interior surfaces of the collimation area, and implementation of solenoids andclearing electrodes.
Recommendation: Continue to mitigate sources of electrons at the source to theextent practical. Look for other implications of electrons beyond beam instability.
Computer simulation is a powerful tool to enhance our understanding of complex mechanisms.
On the other hand, the simulation results should be carefully validated with physicalunderstanding and detailed benchmarking with experimental observations and with othersimulation codes.
Applications software needs to be planned and developed for the commissioning of the machines.
A database should be developed and filled with design parameters and engineering data.

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APPENDIX: A-TAC Meeting Agenda-26-