Report from the
6th Meeting of the Accelerator Technical Advisory
Committee for the Japan Proton Accelerator ResearchComplex (J-PARC)

March 1-3, 2007
JAEA
Tokai, Japan

Table of Contents
Introduction, Summary, and Major Recommendations.............................................1
Linac.........................................................................................................................10
3 GeV Rapid Cycling Synchrotron ..........................................................................13
50 GeV Main Ring Synchrotron ..............................................................................16
RCS & MR RF Systems .........................................................................................18
Controls and Global Systems...................................................................................22
Commissioning and Accelerator Physics ................................................................24
Appendix I: Meeting Agenda

INTRODUCTION, SUMMARY, AND MAJOR RECOMMENDATIONSThe Accelerator Technical Advisory Committee (ATAC) for the J-PARC Project held its sixth
meeting over the period March 1-3, 2007 at the JAEA site in Tokai, Japan. The committee heard
presentations from project staff on March 1-2, held several closed sessions to discuss reactions
and opinions, and presented a verbal report to project management on March 3. In addition thecommittee was given a comprehensive tour of the J-PARC facility. 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 committee heard excellent presentations covering all aspects of the project. The committee
appreciates that these presentations were generally responsive to recommendations from the
February 2006 meeting. Significant progress has been made over the last year on all fronts
highlighted by the achievement of full energy beam commissioning of the linac and thedevelopment of a viable strategy for overcoming the problems in the RCS and 50 GeV Main
Ring rf systems as described in last year’s report. The committee offers congratulations on theseachievements to the entire J-PARC team !
The J-PARC project is now nearing completion both in terms of civil construction andaccelerator component fabrication. Installation is complete and beam commissioning isunderway in the linac. RCS beam commissioning is scheduled to start in September of this yearwith Main Ring beam commissioning following in May 2008. This schedule is unchanged froma year ago—an excellent achievement—and will lead to a startup of accelerator operations in
support of the research program in the 3rd quarter of JFY2008. Commissioning plans for the RCS
and MR are also more developed and detailed than a year ago. Nonetheless there are several
areas of concern that the committee feels will require particular attention to bring the project tosuccessful completion:•

Main Ring performance•

RCS performance with the 181 MeV linac•

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

Planning for the transition to operations

These items are discussed in this report. Because of their importance to the successful
completion of the J-PARC Project, and the difficulties being experienced a year ago, we havedevoted a single chapter to issues related to the rf accelerating cavities.
Finally, the ATAC wishes to express its appreciation to JAEA and KEK management andsupport staff for their hospitality during this meeting.

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Summary and Major Recommendations
Linac
Excellent progress has been made since last year’s meeting. Linac installation is now complete
and beam was accelerated to 181 MeV in January, 2007. The committee congratulates the Linac
team on the achievement of this important milestone, ahead of the schedule presented a year ago.
The long range plan remains to upgrade the linac energy to 400 MeV based on the addition of anannular coupled structure (ACS) linac following completion of Phase I. A prototype of the ACS
buncher has been fabricated and tested and preparations are aimed at constructing, installing, andcommissioning the ACS linac over the period JFY08-11. The committee applauds the start ofpreparations; however funding for the upgrade remains unsecured.
Comments and Recommendations•

The ion source remains a concern. The development of a non-cesiated tungsten filamentsource has had difficulty meeting the 33 mA current specification. In response a LaB6
filament is now under development. This filament provides the required current at a 150µsec pulse length, but is unstable at the required 600 µsec pulse length. A stabilization
system has been proposed and testing will start in roughly a week.
Recommendation: The ion source requires continuing management attention. If the
LaB6 source does not meet performance specifications in the next month or two,
consider alternative designs for the operation phase.

•

The committee was not presented with a comparison between achieved (to date) beam
parameters, commissioning goals, and operations goals. See recommendation underCommissioning and Initial Operations.

•

Residual activation levels in the vicinity of the debuncher have been measured at 88µSv/hour. This translates into a fairly significant level when extrapolated to full power (afew mSv/hour).

•

Many of the beam diagnostic devices have been exercised, but are not yet in a state tosupport full characterization of the linac beam as will be required to support RCS beamcommissioning starting in September. (For example BLMs, intensity monitors, andemittance diagnostics).
Recommendation: Diagnostics need to be providing reliable information by thetime of RCS commissioning.

•

The closed loop control on the rf system is still a ways from being complete and working
effectively. The feedback response looks to the committee to be slower than it should be.
In addition the feedforward systems still need to be implemented.

•

The committee remains concerned about noise from the pre-chopper. Since this device
has not yet been powered there is no further information relative to last year. We suggest
continued attention to this item.

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•

The prototype ACS buncher module exhibits a shunt impedance that looks low to thecommittee. We suggest that the result be confirmed.

•

The spares situation in the linac was highlighted as a concern by the linac team. However,a complete risk analysis, which would include expected failure rates and performance
impacts of failures, was not available to the committee. See recommendation underCommissioning and Initial Operations planning.

•

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 for restorationof the linac energy to 400 MeV as a high priority item.

RCS (Other than accelerating cavities)
Excellent progress has been achieved on many fronts over the last year including very significant
progress on the rf structures problem. Installation is well advanced and hardware commissioning
has begun. These activities are heading towards a September 2007 start of beam commissioning,
consistent with the schedule established a year ago. While there is little float associated with thismilestone, the committee regards the September beam commissioning goal as achievable.
Accelerator modeling has incorporated several improvements suggested by the committee a year
ago. The modeling demonstrates, and the committee continues to believe, that the full potentialof the RCS will not be realized until the injection energy is raised to 400 MeV.

Comments and Recommendations•

A problem with loosening of bolts holding quadrupole magnets together has been
identified. The problem was observed during tests of magnets with the design excitation
fields and appears to be due to the torquing procedures. The problem appears to thecommittee to be understood and should not pose a threat to performance provided that it
receives continuous attention in the future.

•

The RCS commissioning plan presented to the committee looked very good. However,
we are concerned that the plan does not extend beyond the start of MR commissioning (atwhich point the RCS is operating at 10 kW).
Recommendation: Extend the RCS commissioning plan to cover the MRcommissioning period and the first several years of operation (see more generalrecommendation under the heading Commissioning and Initial Operations
Planning).

•

The problem of field flatness in the extraction kicker has been solved by offsetting (intime) kicker modules to provide cancellation of non-uniformities. The price is a longer
risetime that does not quite meet the specification. While nominally acceptable the timing
is now tight and leaves little flexibility.

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Recommendation: Evaluate the relative impact of not meeting the design value for
the RCS extraction kicker risetime, which is 263 ns, and pulse flatness, which is 1%.
•

The committee found the RCS simulations to be much more realistic than a year ago,
now including power supply tracking, BPM resolution, and magnetic interferences.
However, the simulations indicate that the 4 kW loss budget cannot be met with adelivered beam power of 600 kW, based on a 181 MeV injection energy. The simulations
extrapolate satisfactorily to 1 MW of beam power with a 400 MeV injection energy.
Recommendation: Continue to utilize the integrated tracking simulations as an aid
to evaluating the loss budget.

•

The committee believes the collimators still represent a major performance risk. The
collimation design requires that the 4 kW of loss power be distributed over the tencollimator jaws in a manner than none receive more than 400-700 W of load. The
simulation presented to the committee indicated that the individual jaw specification
would be achieved with 20% margin at 0.6 MW of total beam power. The committee
does not regard this margin as adequate.
Recommendation: Prepare an improvement plan for the RCS collimator system toprovide sufficient margin to cope with realistic operations scenarios.

•

In last year’s report we recommended coating the ferrite and aluminum surfaces of theextraction kicker with TiN to suppress secondary electron yield. This recommendation
appears to have been misinterpreted to be aimed at improved vacuum. The
recommendation is repeated here.
Recommendation: Consider coating the Ferrite and aluminum surfaces of theextraction kicker. Coating with TiN was successfully achieved for the SNS project.

•

Tests of the stripping foil with H-, as suggested by the committee last year, have been
initiated. However, the stripping foil still does not show the required lifetime. A new foilmaterial, hybrid boron carbon (HBC), is under development and shows promise for being
more robust than commercially available carbon foils.

•

Several items are on the critical path to the scheduled start of beam commissioning in
September (corrector power supplies, rf stations (10 stations minimum), and septa).
While our judgment is that the schedule is achievable these items represent a schedulerisk and will require continuing attention.

•

The transverse impedance of the extraction kicker has now been measured, as
recommended in last year’s report. The result is higher than anticipated. The level is highenough to provide a potential limitation in beam intensity in the RCS.
Recommendation: Verify the impedance measurement and, if confirmed, prepare
appropriate remedies and a back-up plan.

•

The committee concurs with prior years’ assessments relative to RCS performance: 0.33
MW beam power represents a lower limit on achievable performance in the RCS with a
181 MeV injection energy. 0.4-0.6 MW remains plausible, but will require successful
solutions to the collimator and, possibly, the kicker impedance issues described above.

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Recovery of 1 MW performance will also require restoration of the linac energy to 400
MeV.
•

To summarize: The committee has assessed the most significant impediments to full (1MW) performance in the RCS as follows:– 181 MeV injection energy– Collimation system/loss budget– Potential beam instabilities due to either kicker impedance and/or electron cloud

MR (Other than Accelerating Cavities)
Good progress has been made on many fronts. Dipole, quadrupole, and sextupole installation areroughly 90% complete and very significant progress has been made on the rf structures problem
identified last year. Activities are aimed at a May 2008 start of beam commissioning, consistent
with last year’s schedule. Accelerator modeling has incorporated several improvementssuggested by the committee a year ago. The modeling raises several concerns in our mind as
described below.
Comments and Recommendations•

The single pulse accident, identified in the worst case as an unintended extraction kicker
fire, is now recognized as potentially destructive to the extraction septum. The proposedsolution, a passive mask in front of the current septum, appears to the committee as apotentially viable solution and should be pursued.

•

Serious problems have been identified in the extraction kicker including failure to meetboth risetime and voltage requirements. Potential solutions have been identified but willtake a while to confirm and implement. A strategy has been developed for operations
through the summer of 2010 including: MR operations with 6 bunches, rather than 8, andmodification of the kicker magnet to increase the voltage capability. The committee notesthat this mode of operation implies a 25% reduction in beam power.
Recommendation: Develop and install a kicker meeting the performance
specification as a high priority item.

•

Comprehensive modeling was presented which indicates that the loss budget for the MR(450 W on an individual collimator) cannot be met with a beam power above 150-200
kW. The committee regards this as a serious issue that must be overcome.
Recommendation: Reassess the operating scenario to establish a goal of 450 kW
performance with the 181 MeV linac. Such a reassessment could include increasing
the loss budget at 3 GeV, means for providing longer bunches, and/or possible
reduction in the cycle time.
Recommendation: Depending upon the outcome of the above reassessment,
reexamine the decision to operate the neutrino program at 30 GeV, rather than 40
GeV.

•

The issue with the extraction kicker, plus problems with cracked ceramics in theextraction septum, represent the primary risks to achieving the May 2008 date for start of
MR beam commissioning.
-5-•The transverse impedance measurement described above on the RCS kicker has not been
completed on the MR extraction kicker.
Recommendation: Complete transverse impedance measurements of the MR
kicker including the powering cables and the pulse forming network.

•

The commissioning schedule and initial operations plan shows operations at 100 kW
through 2010. The committee believes this is too modest a goal (especially in 2010).

•

The plan for restoration of full (~750 kW) beam power with the 181 MeV linac is now
based on 8 bunch (h=9) operations in the MR, coupled with h=1 operations of the RCS.
There are sufficient accelerator physics uncertainties associated with such a scenario thatthe committee is unable to comment on viability. Among the issues that need to bestudied are modifications to the RCS rf system, space charge, and beam stability issues in
the MR.

•

The committee concurs with last year’s assessment relative to MR performance with h=9
and 181 MeV linac: 0.45 MW should be achievable in this mode contingent on resolutionof the loss management and kicker issues described above. The committee remains
convinced that the minimal risk path to 750 kW in the MR includes a 400 MeV linac•

To summarize: The committee has assessed the most serious impediments to full (0.75
MW) performance in the MR as follows:– Management of losses in the 3 GeV transfer line and during injection into the MR– 181 MeV linac– Extraction kicker– Possible beam instabilities related to either kicker impedance or electron cloud

RF Cavities for the RCS and MR
Significant effort has been invested in the last year in overcoming the serious difficulties
identified in the accelerating structures for the RCS and MR. Great progress has been made onunderstanding the source of a variety of problems, developing a strategic approach that addresses
short, long term, and, initial operations needs, and engineering innovative solutions. As a result
cavity fabrication and testing is proceeding and four (of the 10 required) rf stations have beentested and are now installed in the RCS.

Comments and Recommendations•

A very significant mobilization of effort was undertaken over the last year to address therf issues. Two new test stands were brought on line, one at KEK and one at JAEA,
supporting extended testing of a wide variety of cavity configurations.

•

The initial RCS rf system is being fabricated from uncut cores, augment by parallel
inductors to provide the required cavity Q. Water cooling has been retained. Performanceon the test stand has been good. All stations are subject to 300 hour high power testing
before installation in the RCS.

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•

The initial MR rf system is being fabricated from cut cores, with the gap subject todiamond polishing. This process eliminates the acid etch that was deemed the primarysource of the problems. Because the polished surface does not allow for utilization of asealant, deoxygenated water is used as the coolant. Two such accelerating cavities havebeen successfully subjected to more than 1000 hours of high power testing. Only fivecavities are planned to be available for commissioning. Adequate resources remain to beallocated for modifying an existing prototype which would provide a sixth system.
Recommendation: Provide adequate resource for the sixth rf system to be installedin the MR.

•

In acknowledgement that problems could occur over the long term an R&D team has
been assembled and is investigating the possibility of developing a cavity based on
utilization of oil (paraffin) as the cooling medium.
Recommendation: Studies of alternative cooling schemes should be actively
pursued.

•The committee believes the strategy being pursued is technically sound and is likely tosupport the needs of the J-PARC complex throughout commissioning and the first year or
two of operations. However, long term performance remains a risk.
Recommendation: Continue to follow the new strategy for the RCS and MR rf
systems, including the development of longer term solutions. One additional systemof each type should be built to allow this effort to be pursued and to serve as
potential spares in case of a major failure.

•

The committee is concerned that the capability for high power testing of complete
accelerating cavities at JAEA will disappear shortly as the test stand is relocated into the
RCS as part of the RCS rf system. It is the opinion of the committee that this capability
must be retained to support the long term goals of the J-PARC complex.
Recommendation: Retain a high power test stand on the JAEA site.

Controls and Global Systems
The controls system has successfully supported the commissioning of the linac. This significant
achievement demonstrates the basic viability of the system. The committee offers ourcongratulations to the controls group.
Comments and Recommendations•

The committee is concerned about the development of high level applications programs
to support the commissioning and operations of all machines. The development andimplementation of HLAs requires close coordination between the controls group and thecommissioning teams. Although there are regularly meetings between these two teams, it
did not appear to the committee that a master list of required applications, accompanied
by detailed specifications, manpower estimates, and assignment of responsibilities, had
yet been developed.

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Recommendation: Based upon the commissioning plan presented, specify the highlevel physics applications needed to carry out this plan and begin development ofthese applications as soon as possible.
•

The staffing level of the controls group appears marginal to the committee. However, we
do not have sufficient information to assess the overall need. We suggest thatmanagement review the staffing level of the group.
Recommendation: Management should review the staffing level of the controls
group in parallel with the identification of needs implied by the above
recommendations.

Commissioning and Initial Operations Planning
The ATAC found fairly detailed plans covering the period of final installation andcommissioning of the RCS and MR.
Comments and Recommendations•

The committee did not see the level of integration across machine boundaries, theidentification of required resources, and specification of required HLAs that we would
have expected. The committee believes that successful integration of this activity and thetransition to operations can only be accomplished under the direction of a full time
dedicated leader with the responsibility and authority for commissioning the accelerator
complex.
Recommendation: Identify a commissioning team leader with responsibility andauthority for coordinating the commissioning of the entire J-PARC complex,
including the transition to operations. An integrated commissioning plan should be
developed containing the roadmap towards Phase I design goals and defining
technical, schedule, cost, and personnel requirements.

•

While the RCS and MR commissioning plans were well thought out and sufficiently
detailed, the RCS plan did not extend beyond the start of MR beam commissioning, andthe MR plan extended through first year of operations.
Recommendation: The integrated commissioning plan should include the transition
to operations and should be discussed with, and made available to, the user
community. The published plan should include estimates of performance,
anticipated reliabilities, and the time allocation between users and accelerator
physics.

•

The committee feels establishment of a downtime log, and an equipment tracking log, isan important component of optimizing efficiency of operations within the complex. Sucha log should be established immediately.

•

The committee found it difficult to assess progress against commissioning goals because
no document exists in which operational and commissioning performance goals are
succinctly described and compared with current achievements.

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Recommendation: Establish and maintain tables of major beam parameters
containing Phase 1 design goals, commissioning goals, and currently achieved
performance for each element of the accelerator complex.
•

The committee is concerned about the availability of spare parts and components ascommissioning and subsequent operations are initiated. For example, the number of spare
klystrons currently available is based on an expected (but unconfirmed) lifetime (30,000
hours) and the leadtime for procuring a klystron (1 year).
Recommendation: Establish a spares strategy based on a risk analysis
incorporating mean time between failure (MTBF), performance impacts of failures,
fabrication/procurement lead times, costs, etc. Such a strategy should be used as abasis for establishing the spares component of the operations budget.

-9-LINAC
Three presentations were given on the progress and commission of the linac. The Committee wasimpressed with the great progress on the Linac commissioning: achievement of a 5 mA, 50 µs,
2.5 Hz, 181 MeV beam after a very short time and on schedule. Further progress included single
shot operation and beam to the 0˚ and 30˚ beam dumps.
The ease with which the beam set up was achieved owed much to the accurate alignment of thelinac components and to the foundations which showed good stability following the initial
settlement of a few mms.
Linac operation, at the current intensity, is now licensed following a satisfactory government
inspection.
Ion Source
A new ion source has been selected since ATAC in 2006 using a LaB6 filament to increase thesource life time and increase the ion current. This source can operate at the beam current andduty factor required for the J-PARC #1 stage. The problem with this source is the unstable
operation at high duty factor at 30 mA of H current. The plans are to install a new hybrid arc
power supply to stabilize the arc current. The hope is that this power supply will solve thestability problem and the pulse current sag of about 10% for the 600 µs beam pulse.
Pre-chopper and chopper
The pre-chopper and ion source have been installed in a shielded enclosure but the the prechopper has not been used for first four linac commissioning runs. The plan is to only use thechopper for the 5 mA beam current and short pulse lengths needed for the preliminarycommissioning of the RCS. The chopper will be able to chop the beam and the chopper slits will
tolerate this low beam current. Preliminary test indicate a Graphite target may withstand full
beam of 30 mA, 25Hz and 500 µsec with chopping ratio of 50%. These tests were only for one
hour so the life time of the chopping target at this high current has not been proven to be
sufficient. Chopping the beam is required for injection of the beam into the RCS. It is importantto test the pre-chopper as soon as possible to test the effectiveness of the shielded enclosure. In
addition, making the pre-chopper and chopper work together to minimize the beam striking the
chopper target is difficult. The committee remains concerned about noise from the pre-chopper
and we suggest continued attention to this item.
RFThe 20 Klystron rf systems are now operating well with closed loop control over the field
amplitude and phase. This includes many systems with one klystron feeding two SDTL cavities
and control is via the summed vector cavity fields of the two cavities, leading to a good reductionin the number of klystrons. The trip rate on the Klystrons may be a little high for full operation
but it is assessed that this is due to noise in the crowbar trigger circuits which is being worked on.

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The 12 MHz optical reference has been replaced with a 312 MHz reference to remove a sourceof phase error. The 312 MHz reference is used directly as the local reference frequency
eliminating most sources of phase error. The 312 MHz optical reference line has proven to bevery stable.
The performance of the feed back system could be improved. There appears to be about a 6%
over shoot when filling the cavities. The beam loading from a 5 mA 20 µs pulse caused theamplitude in the cavity to drop by about 2%. The response time of the feedback appears to beabout 20 µs so the feedback system will not be able reduce this transient and when the beam
current is increase to 30 mA the drop in the cavity field will increase proportionally. Feedforward will be required to reduce the drop in the cavity fields when the beam is turned on. The
plans are to implement feed forward.
MEBT, DTL, and SDTL tuning.
The bunchers in the MEBT were commissioned with the aid of fast current transformers (FCT).
The FCT’s were used to measure the time of flight of the beam to measure the energy. Byscanning the phase of the bunchers and measuring the beam energy the phase and amplitude of
the bunchers could be measured. This technique showed the bunchers could be adjusted to within
5% and 5 deg. of the required accuracy.
The DTL’s were also adjusted with the aid of the FCT’s. The amplitude and phase of the SDTL
tanks were scanned and a particular signature of the variation of the beam energy exiting the
DTL versus phase and amplitude was used to set the phase and amplitude of each of the 3 DTL
tanks in turn.
The SDTL’s are too short to look for a particular signature to adjust the amplitude and phase. So
the phase of the SDTL’s were scanned over a much larger phase range to measure the fullchange in energy the SDTL could apply to the beam. The amplitude and phase were then set
from this information. For the initial tuning of the SDTL only the 2 FCTs that were placed
between pairs of SDTL tanks were used so that the measurement could proceed quickly. The
entire SDTL was commissioned in only one day with this quick procedure. The commissioningof the SDTL was accomplished by adjusting the amplitude and phase from the local control
panels at each klystron, not from the control room. A more accurate procedure is planned withmore widely spaced FCT’s, but this more accurate procedure requires the SDTL tanks between
the FCT’s be detuned.
Beam Diagnostics.
Use of the beam diagnostics for intensity, beam position and beam loss monitoring allowed
testing of all these devices and provided a useful start to beam parameter measurements. Someelectronic noise problems were detected.
The beam loss monitor (BLM) near the debuncher 2 entrance showed some signal of beam loss
and a steering magnet was adjusted to minimize this signal. The residual radiation level after run
3 was 88 µSv/h at the entrance of the second debuncher. This is a fairly high radiation level after
a short run with low beam current. The beam loss monitor signal was small so it may not besensitive enough to minimize the beam loss.
Debuncher tuning.

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FCT’s and time-of-flight measurements of centroid beam energy will be used to tune the phaseand amplitude of the debunchers. This may be sufficient to set the phase and amplitude to thetheoretical values that give the minimum energy, but without some means to measure the energy
spread of the beam there is no guarantee the debunchers will be set correctly.
ACS accelerator.
Conventional Annular Coupled Structures (ACS) with two coupling slots between theaccelerating cells and coupling cells are subject to problems from higher order modes in theannular coupling cavity. The J-PARC ACS structure has been designed with four coupling slots
so the quadrupole mode in the coupling cavity is not coupled to the accelerating cavity. This
completely eliminates problems with higher order modes in the coupling cavity. The first higher
order mode in the coupling cavity that could couple to the accelerating mode would be an
Octupole mode. The Octupole mode will be much higher in frequency and can safely be ignored.
Good progress has been made with the ACS cavities. The manufacturing technique has been
established with the component machining and brazing being carried out in industry. The method
for obtaining the correct frequency of the bridge couple cavities is well established. However,with only one company involved it is estimated to take three years to manufacture a full set ofcavities for the 400 MeV upgrade. The prototype ACS buncher module exhibits a shunt
impedance that looks low to the committee. We suggest that the result be confirmed.

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3 GeV RAPID CYCLING SYNCHROTRONThe 3 GeV Rapid Cycling Synchrotron(RCS) is located in a 348 m long tunnel and will provide
proton beam to a high power neutron spallation target as well as to the 50 GeV Main Ring (MR).
With a beam intensity of 8.3×1013 protons per cycle, a repetition rate of 25 Hz and an injectionenergy of 400 MeV, the RCS can deliver 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 endof this range the beam loss is likely to exceed beam loss limits in the RCS and in the transportlines to the neutron spallation target and the Main Ring.
In many excellent presentations the impressive progress in the component construction andequipment installation in the RCS tunnel was described to the committee. Although thecompletion of the hardware construction has slipped significantly compared to last year’sschedule 90% of the subsystems are complete. Four out of the ten rf accelerating systems are
installed and the remainder will be installed from April along with 54 calibrated beam position
monitors. The project is still planning to start beam commissioning in the RCS by September
2007 and a detailed commissioning plan has been prepared.
Note that findings, comments and recommendations with regard to the RCS rf system areincluded in the separate rf section.

Comments and Recommendations•

The new Hybrid-Boron Carbon (HBC) foils, developed by the project team, have beentested both with low energy Ne beam that simulates the foil heating of the full intensity
H- beam as well as with 750 keV H- beam. The performance was compared with theperformance of diamond foils that are used by SNS and Carbon foils used at LANL. The
HBC foils have a very long lifetime exceeding the performance of the diamond foils byan order of magnitude. The only concern is the existence of a number of pinholes in fresh
HBC foils that increases with irradiation. This may be overcome with better
manufacturing or use of multiple thinner foils. The project has also increased the power
capacity of the beam dump for the unstripped H- to 4 kW.
Recommendation: None•

In the RCS five transverse collimator systems are being 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. The
RCS collimator system should be designed much more conservatively since it will bedifficult to operate with little or no margin of beam load on the collimator system. The
project’s simulations show a 20% margin for each jaw and it has decided to test thecurrent system during commissioning and upgrade or replace it later if needed. The
committee still thinks that it is likely that under operational conditions, with up to 36 kW
of beam power from the 181 MeV linac, the heat load on an individual collimator jaw-13-will exceed the specification. The design of a new collimation system for the RSC withimproved cooling and shielding should start as soon as possible.
Recommendation: Prepare an improvement plan for the RCS collimator system toprovide sufficient margin to cope with realistic operations scenarios. Ensureradioactive handling equipment, such as container flasks, is available forexchanging the collimators.
•

First measurements of the longitudinal and transverse impedance of the RCS extraction
kicker system that included the powering cable and the pulse forming network were
presented. The measurements agree reasonably well with calculations. Due to reflectionsin the cable the transverse impedance reached values of up to 105 Ohms/m. This issignificantly above the calculated instability threshold. Possible schemes to suppress thereflections with diodes were discussed. Alternatively the kicker impedance could bematched to the cable impedance at a significant loss of kicker strength. It is difficult toaccurately predict whether this impedance will actually lead to instabilities in the RCS.
However, contingency plans for this possibility should be developed as soon as possible,
which could include the construction of a transverse damper and/or a redesign of the RCS
extraction kicker.
Recommendation: Verify the impedance measurement and, if confirmed, prepare
appropriate remedies and a back-up plan.

•

The pulse flatness of the extraction kicker magnets was improved to ± 2.7% by better
impedance matching and by compensation from the induced flux from the opposite ctype core. The design flatness of 1% was then achieved by miss-timing individual
modules at the expense of increasing the kicker rise time from about 250 ns to about 360
ns. This rise time is now slightly bigger than the bunch gap of 350 ns. The project should
continue with its program to improve the RCS extraction kicker rise time and pulse
flatness and also evaluate the relative beam loss associated with not meeting the design
value for rise time (263 ns) and pulse flatness (1%).
Recommendation: Evaluate the relative impact of not meeting the design value for
the RCS extraction kicker rise-time, which is 263 ns, and pulse flatness, which is1%.

•

The full hardware commissioning of the resonant power supplies powering the sevenquadrupole circuits in the RCS ring has mainly been completed and the commissioning of
the main dipole power supply will start in April. Tracking errors were reduced to lessthan 1.5% by adjusting amplitude and phase of the power supplies. The resulting
expected tune swing is less than 0.02. Further reduction to the design value of 0.01 will
require additional higher harmonic drive of the power supplies. Detailed measurements ofthe effect of close placement of one magnet to another showed that few problems existed
and that any that did could be corrected by small changes in the correcting magnet
currents.
After powering the quadrupole magnets a problem with loosening of bolts holding-14-

quadrupole magnets together has been identified. The problem appears to be due to thetorquing procedures. The problem appears to the committee to be understood and should
not pose a threat to performance provided that it receives continuous attention in the
future.
Recommendation: None.
•

An improved multiple particle tracking calculation with space charge was presented that
includes the multi-pole components and field and alignment errors of the dipoles,
quadrupoles, and sextupoles, and the measured power supply tracking errors. These
calculations include longitudinal injection painting and the proper evolution of the RFbunch shape throughout the acceleration cycle. For 0.3MW operation the losses were lessthan 1 kW. For the 0.6MW operation the losses exceeded the collimator limit of 4 kW.
Recommendation: Continue to utilize the integrated tracking simulations as an aid
to evaluating the loss budget.

•

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 tocoat 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.
Recommendation: Consider coating the Ferrite and aluminum surfaces of theextraction kicker. Coating with TiN was successfully achieved for the SNS project.

•

The RCS commissioning plan includes storage ring operation of the synchrotron at the
injection energy. Use will be made of the extraction kickers to extract the beam byindependently triggering two halves of the kicker to deal with the lower rf at injection.
An alternative method to consider would be use of the steering magnets to dump thebeam on the collimators. This would also allow the safe dumping of an unbunched beam
or a beam that is debunching due to its inherent momentum spread when no rf is on. The
debunching time provides a good measure of the linac momentum spread after passing
through the injection foil.

-15-

50 GeV MAIN RING
Installation of magnets, vacuum vessels, and other equipment is underway almost on schedule
for the end of Nov. 2007. All components except for injection and extraction septa (to beinstalled in Feb. 2008 tentatively) will be installed and machine commissioning will be started
from Dec. 2007 without beam. The first stage of beam commissioning including beam injection,
COD correction, RF capture will be performed in May and June, 2008. The second stage ofbeam commissioning, which is assumed to take place tentatively from Dec. 2008 to Feb. 2009
includes beam acceleration to 30 GeV and slow extraction. The third stage including fast
extraction to the neutrino facility is tentatively assumed to be performed from Apr. 2009. Everystage is expected to attain at least the 20% power level of commissioning goal in order to beapproved from the point of view of radiation safety. Although the attainable beam power for day
1 operation of 0.1MW will match the user’s minimum requirement for T2K collaboration (askingfor 0.1MW beam delivery up to 2010 summer shutdown), the strategy to realize a final goal ofbeam power of 0.75MW with 50 GeV has not been clearly demonstrated.
The beam loss during the injection/extraction process of MR has been investigated. Matching
between the beam emittance and hardware aperture is investigated in connection with beamcollimation and emittance growth taking the loss budget into account. The beam loss during theinjection process of four butches (8 bunches) is investigated including space charge effects bysimulation and this beam loss seems to be in the acceptable range of beam collimator of MR only
up to beam powers in the range 150-200 kW. Additionally, a protection device like a “dummy
septum” might be needed to protect the extraction septum from single shot beam loss damage inthe case of fire failure of the extraction kicker. The rise time of the extraction kicker is found to
be too long at 1.6 µsec. If its modification is confined in the range of technically reliable one,then 6 (rather than 8) bunch operation with harmonic number 9 is proposed at the first stage inorder to cope with this situation. As for the intensity upgrade plan to 0.6 MW, the harmonic 1
operation of RCS is mentioned, which, however, seems to require careful numerical studies
concerning the space charge effects due to higher beam line density.
The magnets of the MR are evaluated in detail by field measurement with AC excitation
including the effect of eddy current in the vacuum duct and they seem to be well in the tolerance
for real usage, although evaluation of the AC characteristics at the beginning of ramping isfurther required for dipole and quadrupole and sextupole magnets.
Many technical problems related to the injection and extraction equipments are presented
together with the possible improvement scheme. It is required to list the attainable beam
parameters at each stage of beam commissioning with use of the presently available equipment
in connection with the strategy to reach to the final design goal of the project with reference tothe required additional resources.
RF status is discussed in the RCS and MR RF section of this report.
Comments and Recommendations•

The commissioning strategy for the MR, including the interdependencies with the otheraccelerators, is not yet totally well developed. See our recommendation underCommissioning and Initial Operations Planning.

-16-

•

Simulation of slow beam extraction including the space charge effect is still to be
performed.
Recommendation: Slow beam extraction is also required to be simulated including
space charge effect.

•

It is pointed out that no storage space to keep activated equipments to cool down isprepared for MR.

•

For the purpose of reducing the human exposure to radiation, a linear motion guide rail
will be provided in order to expedite the servicing of highly activated components. Sucha driving and positioning mechanism is found to be tolerable up to 10 MGy irradiation.
Recommendation: Storage space of radioactive materials should be prepared
before the first beam commissioning also for MR in order to restrict the human
exposure to the radiation at the minimum possible level.

•

Beam simulation including space charge effects and beam losses has been performed,
demonstrating allowable beam losses during the injection process for the beam powerfrom RCS up to 200 kW. Because some modification of injection equipment is expected,
it is not clear if the simulation is performed assuming the real magnetic field errors.
Recommendation: Re-assess the operating scenario to establish a goal of 450 kW
performance with the 181 MeV linac. Such a reassessment could include increasing
the loss budget at 3 GeV, means for providing longer bunches, and/or possible
reduction in the cycle time.
Recommendation: Establish the equipment list (especially for equipment such as
kickers and septa to be modified or replaced) to be utilized for day 1 operation, andincorporate their field characteristics and dynamic performance into thesimulation as soon as possible. Careful review of the reliability of the calculationand the tolerable power level on beam collimators is inevitable.
Recommendation: Complete transverse impedance measurements of the MR
kicker including the powering cables and pulse forming network.

•

It is pointed out that the floor level is still varying. As almost all large facilities havebeen already constructed the floor level variation will become smaller.
Recommendation: Carefully monitor floor variations and modify magnet
alignments as necessary.

•

The committee remains convinced that the minimal risk path to 750 kW in the MR
includes a 400 MeV linac.

-17-

RCS & MR RF SYSTEMS
Magnetic Alloy (MA) disk-loaded cavities are planned for the RCS and MR synchrotrons of the
J-PARC facility. This new type of cavity can provide a larger accelerating gradient thanconventional ferrite-loaded devices, without needing any tuning system. It introduces however
technological difficulties due to the nature of the magnetic alloy material and to the large heatdissipation which requires a very efficient cooling scheme, presently based on immersion of thecores in a flow of cooling water. The reports made during the ATAC meeting in 2006 showedthat these issues were not yet satisfactorily resolved, the cores degrading fast in typical operating
conditions for the RCS and MR. The ATAC report therefore recommended a vigorous set ofactions to demonstrate as soon as possible the benefits of the planned improvements during test
runs exceeding 1000 hours and to start investigating alternative possibilities.
Each cavity requires an amplifier capable to deliver 600 kW of RF power. A number of thesedevices had already been built and operated since a few years, and series construction wasplanned during the year 2006.
A sophisticated low level RF system is necessary in both synchrotrons to provide the traditional
phase and radial loops, to allow for synchronization between the accelerators at beam transfer
and to compensate beam loading in the cavities. The fundamental design principles werereported in 2006, and construction of most of the electronics was foreseen during the following
months.
Findings
Cavities technology
The “natural” Q with uncut MA cores is lower than 1. To minimize potential well distortion fromthe high beam current, a slightly reduced cavity bandwidth and hence a slightly higher Q arenecessary. This can be obtained by cutting the MA cores and providing a small gap between thetwo halves. Control of the gap size enables control of the cavity Q.
Because of the need of immersion in cooling water, water-tight coating is needed.
Although the development of the coating and cutting techniques have been refined for many
years by the RF team, many processes combine to degrade the cores after testing during a few
hundred hours at high beam power. Efforts have been considerably increased during the lasttwelve months to address these problems, and two additional RF test stations have been set-up,
one at J-PARC and one at KEK. As a result, significant progress has been made in theunderstanding and cure of these phenomena.
For the uncut cores, the following sources of troubles are now diagnosed:-

anomalous reduced resistance between layers,-

scratches on the core surface.

Their treatment involves numerous changes in the production process, like the silica coating, thewinding of the cores which has to be horizontal with dual ribbons and with a rather weak tension,
epoxy immersion, etc. Moreover, a very careful handling during manufacture and a detailed
quality control procedure based on visual checks and electrical measurements are now-18-systematically applied. In total, some 150 cores have been characterized during 2800 hours ofhigh power tests.
The situation seems now reasonably mastered, uncut cores fabricated with that last procedure
having successfully passed the 1000 hours high power test in an RCS cavity.
For the cut cores, many problems have been understood as related to short-circuits between
layers of the FineMet winding and chemical activity of the remaining acid used in some cases to“clean” the cut pieces. Many different cutting and cleaning techniques have been tried.
Good results have finally been obtained combining water-jet cutting with diamond polishing of
the cut part. Because of the very smooth surface after diamond polishing (“mirror-like”), epoxy
coating does not hold and therefore cannot be applied. Therefore very low oxygen-content watermust be used as the cooling fluid. Two 1000 hours high power tests have validated this solution
and series production of cut-cores for the MR has now started.
For the RCS, the initial plan was to use cut cores also. However, since a Q of ~2 is needed(instead of ~10 for the MR), the gap between the half cores has to be smaller than 1 mm (insteadof ~10 mm for the MR). This is uncomfortably small in terms of machining precision and forcooling reasons. Therefore the proposal has been made to connect an external inductor in parallelwith the cavity using uncut cores, to reduce the overall inductance and increase the quality factorof the resonator.
After testing, this new technique has been properly demonstrated and will be systematicallyapplied in the RCS.
A longer term work program has been launched in parallel to investigate the possibility to avoid
using water as the cooling fluid. Normal paraffin has been selected as the most promisingmaterial, because of its characteristics and because of the existing experience in KamLAND and
KEK-B. Preliminary investigations have shown that similar cooling performance to water can inprinciple be obtained (although at higher flow), and that radiation should not noticeably alter thecharacteristics.
A mock-up test for the oil flow is in preparation and a full design of a cavity will be ready for thesummer 2007. The construction of a prototype system will then be considered, but no time scale
has been given.
Cavities fabrication
For the RCS, 10 cavities will be available in time for commissioning (4 are already installed).
For safety, they will not operate beyond 85% of the nominal accelerating field. No spare isincluded. The RF team asks for 2 more systems, to bring the total number to the initially foreseenamount of 12.
For the MR, six cavities are foreseen. Five are being prepared for installation according to the
MR planning. The 6th one being a prototype, it will take more work and resources for-19-

preparation. For safety, these cavities will be limited to 90 % of the nominal accelerating field.
The RF team asks for the construction of an additional system as a spare.
For the needs of installation in the RCS and MR, the existing test stands will be dismantled, sothat no more high power tests will be possible outside the rings.
RF amplifiers
All high power amplifiers have been built (10 for the RCS, 6 for the MR), as well as the DC
power supplies. The 10 drive amplifier units (CERN-designed 8kW) for the RCS are available.
Three units for the MR will be delivered in March 2007; the remaining three will be ordered in
April for delivery in August 2007. Four parasitic resonances have been found in the high power
amplifier and cavity combination. The frequencies range from just over 1MHz to 20 MHz. The
causes and damping mechanisms are being considered.
Low Level RF
The LLRF for the RCS and MR includes all the necessary loops to stabilize the beam, to control
the field in the cavities even in the presence of heavy beam loading and to synchronize RFs forbeam transfer. The design and construction of the VME-based electronics is well advanced(almost fully ready for the RCS – in construction for the MR) and most functionalities havealready been tested. A procedure for adjusting the beam loading compensation has been
elaborated. The principles for the generation of the beam-related timing and for thesynchronization between successive accelerators have been well thought-out.

Comments & recommendations•

The ATAC acknowledges the large efforts made in the study of the MA-loaded cavities
and of the FineMet cores. We note that last year’s recommendations have been seriously
taken into consideration.

•

Remarkable progress has been obtained, to the point where cavities can be confidently
prepared and installed in the RCS and MR, with the perspective of at least a few years ofoperation without trouble. The solution selected for the RCS is original and allows forusing uncut cores while providing adequate RF performance for full beam power for the
RCS. The solution adopted for the MR is also satisfying, but will require a carefully
controlled water cooling circuit with minimum oxygen content.

•

In all cases, experience is lacking on the long term evolution in operational conditions
and high RF power. Therefore the committee is satisfied that the study of oil-cooling has
been launched as a potential alternative solution in the long term.
Recommendation: Actively pursue the study of the solutions that will be
implemented in both rings and the possibility to improve them, as well as thedevelopment of alternative cooling schemes. Consider the safety requirements
associated with the use of paraffin.

-20-

•

The foreseen dismantling of the existing high power test places will not allow for thesemandatory developments to continue.
Recommendation: Preserve at least one high power RF test stand. Use the test
facility to find solutions for damping the parasitic resonances in the cavity
amplifier combination that may be excited by the intense beam current.

•

Moreover, the planned number of RF systems to be installed in both rings will be
marginal, especially considering the need to operate them 10 to 15% below their nominal
gradient, no spares are included, and no system will be left available outside of the rings.
Recommendation: Provide adequate resource for a sixth RF system to be installedin the MR and for building one additional system of each type to allow thedevelopment effort to be pursued and to serve as potential spares in case of a major
failure.

-21-

CONTROLS AND GLOBAL SYSTEMSThe committee notes the important contributions made by the controls team to the successful andtimely commissioning of the linac. All critical systems – including the PPS, MPS, timing andnetwork infrastructure – were available when needed and performed well. The control room wasequipped to support initial operations and some high-level applications were available to support
the physics program. Equipment installation for the RCS is keeping pace. Together, this is anotable achievement for so small a group.

Comments and Recommendations•

The committee is concerned about the development of high level application programs(HLAs) to support the commissioning and operation of all machines. The development
and implementation of HLAs requires close coordination between the controls group andthe commissioning team. Although there are regular meetings between these two teams,
and a detailed commissioning plan was presented for both the RCS and the MR, it did notappear to the committee that a master list of required applications, accompanied bydetailed specifications, required dates, manpower estimates and responsibility
assignments, had yet been developed. In addition to preparing for RCS and main ringcommissioning, improvements are required to existing applications, including automationof phase scanning support for the linac and improvements to orbit correction programs.
Recommendation: Based upon the commissioning plan presented, specify the highlevel physics applications needed to carry out this plan and begin development ofthese applications as soon as possible.

•

Some existing applications, in particular those relating to the setting of or the collection,
analysis and distribution of waveforms, do not yet operate at the necessary 25Hz rate.
Some redesign of drivers or even of interface hardware may be required to meet thisrequirement. It is important to be realistic with the requirements specification here – not
all waveforms may need to be collected at the full repetition rate.

•

The proposed use of virtual servers to help address some of the configuration
management concerns related to large numbers of servers is applauded. Care must be
taken in the configuration of such a set-up, however, and precautions taken against single
points-of-failure.

•

There is no consistent tool in use for alarm handling. This is not a satisfactory situationfor operations, where a consistent view and response is required.
Recommendation: Identify one tool for alarm handling in the control room, andapply it uniformly to all parts of the accelerator complex. Any one tool will do –more than one will not.

•The staffing level of the controls group appears marginal to the committee. We do nothave sufficient information to assess the overall need; however the controls group leader
acknowledged difficulty himself in assessing availability of resources, and concern about-22-

achieving “full device control” in time for RCS commissioning. Device control is below
the level of the HLAs, and a necessary prerequisite.
Recommendation: Management should review the staffing level of the controls
group in parallel with the identification of needs implied by the above
recommendations.

-23-

COMMISSIONING, INITIAL OPERATIONS, AND ACCELERATOR PHYSICS
Beginning in November 20, 2006, 9 linac beam commissioning runs are planned each lasting for
12 days. During each run, beam is on 12 hours a day. At the time of this A-TAC review, 4 suchruns have been concluded. At run-1, the H- beam energy reached 3 MeV with a pulse width of
50 us and a peak current of 30 mA at a repetition rate of 5 Hz. At run-3, the H- beam energy
reached 181 MeV with a pulse width of 50 us and a peak current of 5 mA at a repetition rate of
2.5 Hz. At run-4, the beam was chopped at 50% duty within the macro-pulses.
Beam commissioning of the RCS is scheduled to start in September 2007. Beam commissioningof the MR is scheduled to start in May 2008. Experiments are scheduled to start sometime inJapanese Fiscal Year 2008.
Comments and recommendations•

As the project approaches the final period of construction, budget, schedule, andpersonnel needs are increasingly demanding. It is necessary to clearly define the project
goals of phase I and the commissioning goals in comparison with the achieved status interms of major machine and beam parameters including energy, intensity, repetition rate,emittances and momentum deviation, and beam loss/activation through all major sectionsof the accelerator complex. It is also necessary to develop a clear roadmap towards thephase I goals so that budget, schedule, and personnel needs can be planned.
Recommendation: Establish and maintain tables of major beam parameters
containing phase I design goal, commissioning goal, and currently achieved
performance on each section of the accelerator complex. Develop a roadmap
towards the phase I design goals defining technical, schedule, cost, and personnel
requirements.

•

As the committee has observed and recommended in previous years, J-PARC is acomplex facility consisting of linac, RCS, MR, transfer lines connecting various
accelerators, transfer lines to various experimental stations, and beam dumps. It isessential to identify a leader on accelerator physics coordinating the overall physics
design, interfacing, and design and construction “quality assurance”. This leader should
coordinate the overall commissioning and plan the path beyond.

•

Presently, the committee did not see the level of integration across machine boundaries,
the identification of required resources, and specification of required HLAs that wewould have expected. The committee believes that successful integration of this activity
and the transition to operations can only be accomplished under the direction of a fulltime dedicated leader with the responsibility and authority for commissioning theaccelerator complex.

-24-

Recommendation: Identify a commissioning team leader with responsibility andauthority for coordinating the commissioning of the entire J-PARC complex,
including the transition to operations. An integrated commissioning plan should be
developed containing the roadmap towards Phase I design goals and defining
technical, schedule, cost, and personnel requirements.
•

For SNS, effects of beam coupling impedance from extraction kickers and their power
supply PFN have been of major concern. Many years of efforts were made including
terminating the PFN to a resistor, optimizing the inner dimension of the kickers, andselecting the permeability of the ferrite, resulting in orders-of-magnitude reduction ofimpedances comparing with non-optimized designs. Another SNS concern was on bareferrite surfaces without TiN coating, since the electron secondary emission yield can beexceedingly high resulting in excessive electron-cloud formation causing performancedegradations. ISIS experience indicated that programming of the transverse tunes withtrim quadrupoles was essential in avoiding resistive wall instabilities after injection
painting. Such experiences should be carefully studied and compared.
Recommendation: Perform beam collective-effect analysis assessing the impact of
extraction kicker coupling impedance and realistic electron secondary-emission
yield from uncoated surfaces of the beam chamber including the extraction kickers
in both RCS and MR. Develop remedies and back-up plans. Optimize back-up
designs under the guidance of impedance measurement and analysis.

•

As the project team realized, spares is an important issue affecting commissioning
progress and project cost. Two classes of spares can be defined: construction spares andoperational spares, and non-constructional funds may be sought after to cover part of theneeded spares. A formal document containing performance risks, mean-time-betweenfailure, procurement lead time, and cost of all major components can be important both in
the planning and in convincing the management agencies.
Recommendation: Prepare a document on construction and operational sparescontaining mean-time-between-failure, performance impact of failures,procurement/fabrication lead time, and cost of major components.

•

Areas of bottlenecks will exist limiting the intensity/power performance and upgrade of
the facility. Activation level will be high in such “hot spots”. For example, a possible spotis the collimation region of the transfer line between RCS and MR when the acceptance
reduces from more than 320 pi mm mr to 53 pi mm mr at the collimators. Special
attention is needed in assuring machine performance, maintenance, and future upgrades.
Recommendation: Continue to identify potential “hot spots” and intensity/power
bottlenecks across the whole accelerator complex. Develop back-up plans on theoperation and maintenance of such areas, for example the collimation region of the
RCS-to-MR transport line.

•

As shown in SNS ring construction and commissioning experience, injection region
demands special attention due to technical challenges of the pulsed systems, complexityof the devices, space limitation between the components, and maintenance demands.
Recommendation: Perform beam-dynamics simulations of both the circulating
beam and the beam to the injection dump of the RCS incorporating measured-25-

magnetic fields, magnet interferences, magnet and stripping foil placement, andchamber aperture of the entire injection region.
•

According to the experience at ISIS and BNL AGS/Booster, transverse tune control withtrim quadrupole and resonance correction with multipole correctors are essential in beamloss reduction and high intensity operations. Presently, trim quadrupoles are not in the
project baseline for RCS, and implementation may require significant modification of theinstalled components.
Recommendation: Develop designs and implementation plans of trim quadrupoles
for tune programming in the RCS and resonance corrections in both RCS and MR.

-26-

Appendix: Meeting Agenda
ATAC2007 Agenda
March 1, Thursday
periodCategory(min)
15 Accelerator Overview
20 Executive session
15 Linac
40
20
20
20
20
70
30 RCS
20
20
20
20
20
20 Project status
40 Ring RF
15
30 Control
60 Executive session

time

Title

910
925
925
945
in camera
945
1000
Status of Linac
1000
1040
Beam Commissioning Results for the Linac<< coffee break >>
1100
1120
Ion Source Issues
1120
1140
Conditioning and Tuning of the RF system & Cavities
1140
1200
R &D Status of the ACS for the Linac Energy Recovery<< lunch >>
1310
1340
Status of RCS
1340
1400
Beam Commissioning Strategy
1400
1420
Beam Simulations in the RCS
1420
1440
Field Measurements and Power Supply Commissioning
1440
1500
Charge Exchange Stripping Foil<< coffee break >>
1520
1540
Status of Ring RF
1540
1620
1620
1635
RF Cavity with Oil Cooling MA Cores
1635
1705
Status of Control System
1705
1805
in camera
RECEPTION
1845 ~ 2045 (Bus starts at 18:25 from the meeting place to the restaurant)
March 2, Friday
830
900
930

900
930
950

30 Executive session
30 MR
20

950

1010

20

1010
1025
<< coffee break >>
1045
1100
1100
1115
1115
1155
1155
1215
<< lunch >>

15
20
15
15
40
20 Impedance and instability
60

1315

1630

195 Tour J-PARC

1630

1800

90 Executive session

March 3, Saturday
900
1100
1100
1200
<< lunch >>adjourn

120 Executive session
60 Report to project team75

Speaker
Y Yamazaki
K Hasegawa
M Ikegami
H Oguri
T Kobayashi
H Ao
H Suzuki
H Hotchi
P SahaN Tani
I Sugai
S Nagamiya
M Yoshii
J Kameda
N Yamamotoin camera
MR overview
Beam Loss Estimate of MR Injection/Extraction
Space Charge Simulation and Beam Losses of MR
with Realistic Conditions
Maintenance Scenario for Radioactive Component

M Yoshioka

Commissioning and Initial Operation Plan
Magnet Tracking
Pulse Device Issues
Impedance and Instability of RCS/MR

T Koseki
K Niki
H Matsumoto
T Toyama

H Kobayashi
M Tomizawa
A Molodozhentev

N Ouchi (Linac) /M Kinsho (RCS/HENDEL) /M Yoshioka (MR)in camera
S Holmes-27-