The Twelfth KEKB Accelerator Review Committee Report

Introduction
The Twelfth KEKB Accelerator Review Committee meeting was held on March 19-21, 2007.
Heino Henke and Shin-ichi Kurokawa were unable to attend this meeting. Appendix A shows
the present membership of the Committee.
The Twelfth Committee meeting followed the usual format of oral presentations by the KEKB
staff members and discussion by the Committee members. The Agenda for the meeting isshown in Appendix B. The first day started with KEKB performance and, in particular, theprogress on commissioning the crab cavities. The Upgrade Studies were then presented andcontinued on the second day. The Committee was again impressed by the high standard of
the talks, both the technical content and the presentations themselves. The recommendationsof the Committee were presented to the KEKB staff members before the close of the meeting.
The Committee wrote a draft report during the meeting that was then improved and finalizedby e-mail among the Committee members.
Contents
Executive Summary
A. Foreword
B. Summary
C. Recommendations
Findings and Recommendations
1) Overview
2) Beam Commissioning before Crab Cavity
3) Belle Status4) BPM Displacement Monitor
5) Crab Cavity Overview
6) RF Design of Crab Cavity
7) Cryogenics, etc.
8) Horizontal Tests for Crab Cavities
9) Installation of Crab Cavity10) Commissioning of Crab RF System
11) Beam Commissioning with Crab Cavity
12) Beam-Beam Effect with Crab Cavity13) Observation of Crab Crossing with Streak Camera
14) Recent Upgrade Studies of Vacuum Components
15) Secondary Electron Yield
16) Electron Cloud Measurement and Vacuum Chamber Design17) Development of Pulsed Quadrupoles18) QCS for SuperKEKB19) Crab Waist Optics
20) Lattice Design for Super B
21) Beam-Beam Effects in Super B
Page 1 of 2422) Fuji Test Beam Line23) First application of a tungsten single-crystal positron source at the KEKB injector
linac24) Injector Upgrade25) Control Room with beam

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Executive SummaryA) Foreword
KEKB continued to make excellent progress since the last Committee meeting. The peakluminosity has increased to a new world record of 1.71 x 1034 cm-2s-1, 71% above the design
luminosity of 1034 cm-2s-1 (at this time last year it was 1.627 x 1034 cm-2s-1 and the year before
it was 1.52 x 1034 cm-2s-1). The Committee congratulates the entire KEKB project staff on thisnew record. However, it is clear that the luminosity is almost saturated and it will need a new
initiative like the crab cavities to make a significant improvement over the present record.
The BELLE detector has accumulated 710 fb-1, another world record (563 fb-1 at the last
meeting) and has published, or submitted for publication, a total of 206 papers in refereed
journals (163 at the last meeting).
The meeting was devoted to the present status of KEKB, the accelerator physics limitations to
the luminosity and, in particular, progress with the crab cavity – a world first! There werealso many talks on the R&D for upgrading KEKB to a luminosity of 6-8 x 1035 cm-2s-1.
Unfortunately, there was still no news on the plans for the SuperKEKB project as the proposal
for SuperKEKB has not been actively pursued by KEK. This is because the laboratory iscommitted to completing J-PARC as soon as possible, and this takes most of the (reduced)
budget. The Committee continues to endorse the proposal for SuperKEKB, particularly inlight of the number of High Energy Facilities that are planned to close in the next two to three
years (HERA, PEP-II, and Tevatron). The Committee hopes that funding will become
available for upgrade KEKB, as this would keep KEK at the forefront of High Energy Physics
research for the next two decades.
The KEKB machine group has done an enormous amount of excellent work, and is to becongratulated on the impressive results that have been achieved.
B) Summary
KEKB continued to make excellent progress over the last year, with new luminosity records:
highest peak luminosity: 1.712 x 1034 cm-2s-1, highest daily integrated luminosity: 1.232 fb-1,
highest seven-day integrated luminosity: 7.81 fb-1, and highest 30-day luminosity: 30.21 fb-1.
The luminosity increased slowly until December, but as predicted, no large improvements
were seen, despite testing many different ideas. The crab cavities were installed during a
shutdown in January and commissioning was continuing at the time of the Review. The
implementation of crab cavities is a world first and is an indication of the capabilities of the
KEK staff.
The Belle detector has now accumulated 710 fb-1, of which 147 fb-1 were obtained since thelast Review. The “Oide scenario” made several years ago was that 750 fb-1 would beaccumulated by this time – a very accurate forecast. The agreement would have been evenbetter, but the budget forced a reduction in operations from 274 days in FY05 to 227 days in
FY06 (a ~20% reduction). The crab cavities should increase the luminosity accumulation rate
when they are fully commissioned, and if everything proceeds according to plan, the time lostto commissioning should made up by the time of the next Committee meeting. KEKB still
appears to be on track to accumulate 1 ab-1 by summer 2008.
Most of the running this year has been at the Upsilon 4S state, but the accelerator was tuned to
the Upsilon 5S state for a successful three-week run. This is an exciting new Physics
opportunity for BELLE.

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The Belle detector is generally working well but has been upgrading the data acquisition
system to reduce the deadtime. Backgrounds are low, and losses during beam injection aresmall. Continuous injection has been acceptable to the detector but has necessitatedsuppressing 3.5 ms of data taking during each injection cycle. Overall, the Belle collaboration
is extremely pleased with the quality and quantity of the beam being provided by theaccelerator.
C) Recommendations
Last year, the Committee made many recommendations, and the KEKB staff hasaddressed all of them. Some of these related to the priorities of the program and arereiterated below, together with recommendations for continuing the work that has
already been started.
1. While the Committee believes that the crab cavity program will be successful, it requests
that the KEK management create a road map for KEKB operations under two different
scenarios:a. The crab cavity is successful and KEKB operations continue at ~400 fb-1 per year.
b. If after considerable effort, the crab cavity is unsuccessful, KEKB operations
continue at ~200 fb-1 per year.
It would also be extremely helpful for planning and optimizing operations if the KEK
management could provide an indication of the kind of information that would influence a
decision on SuperKEKB
2. The Committee endorses the studies to design a major luminosity upgrade (SuperKEKB)
aimed at a luminosity of 8 x 1035 cm-2s-1 and recommends that they be continued.
3. The Committee strongly endorses the plan to continue preparations for simultaneous
injection in all four rings.
4. The Committee recommends continuing the studies of a movable mask which is‘electrically invisible’ (rod with ceramic support) and has a much lower loss factor. A
significant amount of R&D remains to demonstrate a reliable, operational movable maskwith a reduced loss factor.
5. The Committee feels that HOMs is one of the limiting factors in increasing the current.
Detailed studies of the vacuum components including proper damping and component
cooling should be continued. Continued follow-up of the failures of the standard vacuum
components should be made to establish critical operating parameters, and to put limits on
them.
The Committee has made new recommendations throughout the different sections below.
Highlights of these recommendations are summarized here.
6. The Committee recommends extended alternating high and low beam current studies toimprove the chances of success with crab cavities and to make sure there is sufficientbeam study time to obtain satisfactory results and complete understanding. BELLE could
take data during the high current running.
7. The Committee recommends that KEK participate in the multi-laboratory studies of aSuper-B Factory based on extremely low emittances and long bunches colliding at a large
angle with a “crab waist.”

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8. The Committee recommends that the KEK management provide the necessary support tocreate the Fuji test beam line facility.

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B) Findings and Recommendations
1) Overview
KEKB has performed well last year; the record peak luminosity of 1.781 x 1024 is extremely
impressive. As expected, the luminosity is about saturated and there is unlikely to be muchincrease in luminosity without a major change in configuration. The many years ofinvestment in the crab cavities has finally paid off, and two cavities were completed, tested,
installed, and successfully commissioned during a long shutdown in January and February.
Beam commissioning with crab cavities is going well but several mysteries still present themselves.
The importance of this new capability cannot be underestimated. The idea is now 23 years
old, and the conceptual design for the actual cavities is 15 years old. However, no otherlaboratory has been able to carry out the necessary development, and results from KEK areeagerly awaited. Given the short amount of commissioning time, the results are extremely
encouraging with a 15% increase in specific luminosity having already been demonstrated.
The plan to continue commissioning for 2-3 weeks of low current studies then 1 month ofhigh current crab cavity study may be too restrictive. A more productive approach would be
to alternate 2 week of low current operation and 2 weeks of high current operation until all
avenues have been studied. For example, there may be high current effects which need sometime to fix and then try again.
The many R&D activities aimed at upgrades and future accelerators are very important andhave produced significant new capabilities (e.g. in-situ SEY measurements) and component
improvements. The design of SuperKEKB is progressing well with exciting IR concepts
under investigation. We suggest continuing to improve the design in the context of theemerging global Super B-Factory collaboration until the laboratory is able to commit to a
specific course of action.
2) Beam Commissioning before Crab Cavity
KEKB is a mature machine with an outstanding record of advances that have made it theundisputed highest luminosity collider world wide, as well as exceeding its own design goals
by over 70%. This is a remarkable achievement that has the highest respect andcommendation of this Committee.
It is not at all surprising that the luminosity is beginning to approach an asymptotic level.
This was foreseen, and plans to add crab compensation to the beams crossing angle to enablea large factor improvement in luminosity were made long ago. Still, measurable
improvements in performance have been made in several areas since the last meeting of thisCommittee. Better understanding of optics and improvements in operating point were factors,
as well as improved hardware reliability.
In the past year peak luminosity has increased from 16.27 to 17.12 x 1033-cm-2-sec-1 andintegrated luminosity per day from 1.18 to 1.23 fb-1. Constraints on operating time reduced
the number of HEP days from 274 to 227. Nevertheless, the total integrated luminosity hasreached 710.3 fb-1. During operations, frequent topping up has kept the luminosity duty factor
close to 1. Beam aborts continue to be reduced, and the reliability of hardware components
has improved during this year.
The decrease in number of operating days in 2006 is distressing, as is the outlook for 2007
due to budget constraints. In spite of this constraint, the KEKB staff has delivered an
impressive integrated luminosity.
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Several changes in optics and tuning techniques were explored. A slight lowering of HER
tunes and the introduction of sextupole tuning as part of coupling reduction have improved
the luminosity by a few percent. The sextupole effect is not understood, though orbit control
may be a factor (as presented by Fukuma). Discovery of a skew quadrupole power supply in
the LER that took on unpredictable (minimum) values has improved luminosity recovery timeafter accelerator maintenance periods.
However, it was found that lowering the LER horizontal emittance from 18 to 10nm did not
produce the expected performance benefit due to coherent beam-beam effects which limited
the bunch current. Increase the strength of 1452 electron cloud suppression solenoids did not
produce observable benefits, and a trial with smaller β*X in both rings resulted in short beam
lifetimes in the limited tuning time available.
The process of improving performance of such complex systems must involve some trial-anderror. We applaud the continuing initiatives of the KEKB accelerator staff to find
improvements in machine operating parameters.
A significant investment in hardware reliability was made with the installation of supports toprevent flexing of vacuum bellows and their sliding RF fingers caused by temperature cycles
during beam current changes. The measured motion was reduced by a factor 2-2.5 in 80
bellows. However, since the supports have not completely prevented failures, further
improvements are being explored.
The Committee recognizes the talented and dedicated work to improve KEKB operations.
The present focus is correctly on successful implementation of crab compensation of thecrossing angle. In addition we encourage continued work to improve reliability and tolerance
to high currents at short bunch lengths.
Recommendations:
1) Continue the study of the role of sextupole strengths in tuning coupling and luminosity.
2) Continue parameters exploration to search for luminosity gains, big or small. Do not be
discouraged that many changes may turn out to be unproductive.
3) Continue the emphasis on improving reliability through reduction of beam aborts, recovery
time, and hardware failures.
3) Belle Status
With KEKB consistently providing high luminosities, Belle has been collecting data at a highrate, accumulating a total of 710/fb at the time of this meeting. An Ypsilon (5S) run was also
carried out at a reduced beam intensity. During FY2006, thirty-two papers describing physics
results at Belle were published.
Belle reduced its unscheduled downtime significantly since 2005. In 2006 hardware problems
in Belle kept the machine off less than 1% of the year compared to over 7% the previous year.
While the present DAQ system is adequate even for the impressive luminosity delivered by
KEKB, the higher luminosity possible with the crab compensation would result in excessive
dead time. Therefore a new "Copper" DAQ with a pipelined architecture has been
designed. The Belle team is presently upgrading to this system that, when completed, is
expected to shorten the dead time per event by a factor of 10 from 30 microseconds to 3
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microseconds, assuring efficient data acquisition for foreseeable upgrades to KEKB
luminosity.
One of the most significant recent results from Belle has been the detection (with 3 sigma
resolution) of D0-D0bar mixing by measuring the lifetime differences between the various
decay modes of D0. In addition, Belle data confirmed the B-Bbar entanglement and thus
established quantum mechanics in the 10 GeV energy regime. A third significant
accomplishment to search for dark matter candidate showed a negative result with a newupper bound of dark matter production at 1 GeV level.
Belle accumulated 275 million B-Bbars up to 2005, 535 million B-Bbars up to 2006, and isaiming for 1 billion B-Bbars soon. With the expectation that the luminosity might be doubled
with a successful operation of the crab cavities, the Belle-KEKB team has adopted a strategy
to allow sufficient operation and machine study time for commissioning the crab cavities. The
Committee endorses this strategy, and wishes to re-emphasize the fact that the crab cavity is apioneering R&D project. Sufficient study time should be provided to reach its maximum
benefits. This is the case even with a reduced KEKB budget in the present fiscal year.
4) BPM Displacement Monitor
Although the BPMs in KEKB rings are fixed to quadrupoles, the thermal stress from beam
heating causes motion of the BPM relative to the magnets, and particularly, the sextupoles.
KEK staff has developed, carefully characterized, and are implementing capacitive gap
detectors to monitor changes in relative position between the sextupoles and the BPMs so that
offsets can be applied to correct the beam position measurements.
Data show that moderately fast horizontal movements of the BPMs relative to nearby
sextupoles of up to 0.9 mm take place during beam aborts, and somewhat smaller motions
occur during machine startup periods. The vertical movements are an order of magnitude
smaller. Simulation and measurements correlating changes in betatron tune with this motion
confirm the link to beam properties.
Other data show that there is motion of the BPM relative to the quadrupole of roughly 2/3 thisamount. We observe that, while there is a direct (and rather robust) mechanical connection of
the BPM to the quadrupole, the structure appears insufficient to compete with the thermal
stress produced on the chamber.
A simple and precise capacitive gap detector with a resolution of 0.2 µm and a range of 0.5 –2.5 mm has been developed at KEK. The reproducibility of the sensor is about 1 µm and thecontribution from the non-corrected non-linearity is +/- 2 µm over the measurement range.
Currently the biggest source of error is the thermal movement of the fixing arm which is 20µm/10 deg. (horizontal) and 5 µm/10 deg. (vertical) which, with a tunnel temperature stabilityof about 1 degree correspond to errors of 2 µm in the horizontal and 0.5 µm in the verticaldirections. If necessary, these errors could be reduced by designing fixing arms with better
thermal properties, a solution proposed by the KEKB staff.
The plan to measure the BPM positions relative to the sextupoles and correct the BPM offset
accordingly should provide the means to compensate for the errors described above.
Since the gap detectors will be essential elements in maintaining accurate orbits, the reliabilityof their operation is quite important. Algorithms to detect malfunctioning gap detectors will
be necessary.
Comments:
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1) The plan presented is a good approach to mitigate the effects of beam duct motion
2) The algorithm to correct the BPM data based on the capacitive gap detector readouts must
be robust; bad data from the gap detectors must be identified and appropriate compensation
made.
5) Crab Cavity Overview
The main attraction for the Twelfth KEKB Accelerator Review was the completion, testingand initial operation of the two crab cavities, one placed in each ring. The Committee is very
gratified to see this development, which has been the subject of recommendations for several
years. Before proceeding to more detailed observations and discussions, the Committee
would like to note the tremendous amount of creative engineering and effort that has gone
into the successful implementation of these systems. Even in the very earliest days of theiroperation, the cavities have demonstrated some of the potential for increasing luminosity thatwas the reason for their construction. The KEK machine group has our very high regard forthis tremendous effort.
After some initial difficulties in assembly, tooling improvements enabled a smooth assemblyof both cavities. Initial testing at the D10 Test Stand began with a very careful cooldown,
motivated by a desire to avoid generating vacuum leaks through thermal stresses
accompanying a too-rapid cooldown. This approach was completely successful and no leaks
were created.
Some performance issues first appeared in the horizontal test. (That such issues should arisein the first operation of a new and innovative cavity design is not surprising. It is somewhat
surprising that the cavities work as well as they do!) In particular, problems of range,
linearity and backlash were first observed with the HER cavity tuner. In this cavity, the tuner
difficulties were removed by replacement of the main copper bellows with a thinner and more
flexible stainless steel bellows. The completed cavity more than met the gradient and Q0
requirements. Quality RF contacts are essential to the performance of the cavity, andimproved RF contact springs were installed when the bellows were replaced. After the repair,the HER cavity tuning and field phase stability were excellent.
Assembly of the LER cavity was briefly delayed by field-emission limited performance of thecavity. This problem was quickly and effectively dealt with by reprocessing the cavity, after
which its performance in vertical test was even better than that of the HER cavity. However,horizontal tests of the LER cavity revealed significant problems with the range and linearityof the cavity tuning system, and significantly higher tuning loads. Reinforcement of theexternal mechanical structure and attempts to reduce friction have so far not been effective in
improving its performance. The next step is to reinforce the support bolts, which will be doneat the next appropriate maintenance down. The alignment of the tuner components should
also be checked as misalignment could cause the observed symptoms.
A second issue, probably connected to the tuning problems with the LER cavity, is a
substantially larger (~x4) spread of tuning phase errors. Neither of these problems has limited
operation of the LER cavity. The desired resonant frequency can be achieved, and since thedriving klystron has sufficient capacity, the low-level RF feedback system is able to maintainfield amplitude and phase within acceptable bounds.
Most recently, the LER cavity has suffered a reduction in the maximum field it can sustain
with an acceptable level of trips. This behavior is similar to that observed in horizontal testsof the HER cavity, where it was corrected by warming the cavity to 80 K and pumping away
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an accumulation of hydrogen and carbon monoxide. A similar outgassing process is planned
for the LER cavity during the next suitable maintenance down.
The crab cavities are presently capable of supporting the crab luminosity optics development
program. The Committee believes that this development should continue, but can foreseecertain cavity failure modes that would justify removal of the cavity or cavities for repair andmodification:
1. Tuner failure that would make it impossible to tune the cavities to the operating
frequency,
2. An increase in the magnitude of the tuner phase fluctuations to the point where the RF
system is no longer capable of maintaining field amplitude and phase within
acceptable bounds,
3. Further reduction of the achievable LER kick voltage to the point where the cavity canno longer support the optics development program, coupled with a failure of theoutgassing cycle to recover cavity performance, or
4. Catastrophic deterioration of the beamline vacuum.
Unless one of these major failures occurs, the crab cavities can continue to support the beamcommissioning activities and the subsequent Physics program.
6) RF Design of Crab Cavity
Considerable efforts have been made on the tricky subject of damping both higher order andlower order modes in the crab cavity, while leaving the main deflecting mode untouched. The
result has been a complex, elegant solution which provides sufficient impedance reduction at
normal operating beam currents with the existing transverse damping system. If however thisdamping system performs less well than anticipated and cannot guarantee the stability ofmodes with growth times longer than 1 ms, then the impedance of the horizontally polarizedTE-λ/4 mode, the most dangerous mode, may limit the beam current.
To prepare for this eventuality a proposal to increase the damping by rotating the slot coupler
at the end of the coaxial line has been suggested. Measurements have shown that a rotation of60°, while splitting the mode into two, nonetheless provides a solution for damping thesemodes while leaving the other modes relatively unaffected. A model cavity has been made,simulations have been performed, and both have been compared with the HER cavity results.
Despite these positive results, there is still some discrepancy between the measured andsimulated Q values. The Committee encourages the team to try and understand thesedifferences, especially those between the HER and the model (these values straddle thesimulation values). The power flow along the line and the power densities at different points
seem to be under control, so if the impedance discrepancies can be sorted out this seems to bea good and simple solution to improving the impedance reduction.
7) Cryogenics, etc
The crab cavity cryostat is complex and well-engineered and -instrumented. It performed
well in cryogenic operation of the crab cavities, so much so that, in the excitement of firstcavity and beam measurements, its excellent performance went largely unremarked.
Static heat leak measurements were carried out. Within experimental error, the two cavities
were nearly the same, indicating reasonable control of the assembly process. Heat leaks forPage 10 of 24both cavities were roughly a factor of two higher than the predicted value, but thisdiscrepancy is almost routine for first articles of any cryostat design, and expected for adesign of this complexity.
Measurements of the installed cavity Q0 as a function of accelerating gradient replicated theresults of isolated cavity tests, although with larger error bars resulting from the mismatch at
the fundamental power coupler in a non-beam-loaded test. This is an additional testament tocareful cavity handling and assembly.
All cryogenic controls and instrumentation worked as designed during horizontal testing andoperation in the machine.
8) Horizontal Tests for Crab Cavities
A complete pre-commissioning of both the LER and HER cavities was undertaken in thehorizontal test stand prior to installation in the machine tunnel. The global result was very
good: both cavities achieved the expected deflecting voltage. However various differences
between the cavities became evident during these measurements.
The major issue found was a problem with non-smooth movement of the HER tuning
mechanism and an inability to tune the cavity to the correct frequency. These were solved bya new less rigid thin-wall stainless steel bellows to allow more tuning stroke and an improved
sliding base mechanism.
Coupler conditioning at room temperature proceeded normally for both cavities.
Anomalous behavior of the LER cavity was seen during cool-down. The pressure apparently
remained at 10-5 Pa until around 40 K when it dropped abruptly to a few 10-7 Pa. The
explanation might be carbon monoxide freezing at low temperatures, or perhaps a problem
with the instrumentation. It is interesting that more or less the same behavior was found laterin the ring.
When cold, the LER cavity showed better RF voltage conditioning performance than the HER.
The HER had to be warmed to 80 K, resulting in the outgassing of substantial quantities ofhydrogen and carbon monoxide, and then cooled again, before 1.8 MV could be reached. In
the LER 1.9 MV was achieved with no problem. Later, in the ring, the LER cavity
performance degraded and it is hoped that warming the cavity to 80 K will have the same
impact as was seen in the HER during horizontal tests. This should be tested at the earliest
convenient time.
The last major difference between the two cavities was the behavior of the tuner and RF noise.
The residual phase noise on the RF when the tuner loop was closed is much higher in the LER
than the HER cavity. This was again found in the ring during beam operation but the RF
feedback system reduced the effect as seen by the beam and it could be controlled. The effectis probably related to an apparent “sticking” or “backlash’ in the tuner mechanism, seen as ahysteresis curve in other measurements of frequency versus tuner position. This in itself canprovide “noise” but more likely creates regions where the tuner loop is inactive and does notcompensate for externally induced vibrations or electronic noise. It is important to study thismatter and understand it, firstly by ensuring that the electronic systems are working correctly
and secondly, when possible, by opening the cryostat and examining the tuner mechanism.
9) Installation of the Crab Cavity
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After the horizontal measurements of the LER and HER crab cavities, these cavities weresuccessfully and safely installed in the D11 and D10 tunnel sections, respectively. The
installation was really not easy due to the very heavy weight of the cavity, the narrow passage
and the limited access. The installation was done by using a carrier for the LER cavity and atirroller for the HER cavity. Six support legs are used for HER cavity, four for weight support
and two to ensure flatness. Finally these two cavities were well aligned to a reference line
defined by the quadrupole magnets.
10) Commissioning of Crab RF System
This has been a most successful RF system commissioning and we would like to congratulate
the entire RF team for getting this complex SCRF deflecting cavity, its RF power system andthe associated beam-control electronics to work so well in such a short time. The result of all
this hard work is an excellent crab RF system providing a deflecting voltage for each beam
sufficient to create the desired crabbed bunches. The amount of measurement data andanalysis carried out in the short time that beam has been available is also very impressive.
Now that the cavities are installed in the machine and interacting with the beam, it is normalthat different problems should arise, but in fact there have been few problems so far.
The issues can be summarized as a fairly large horizontal offset, 4 mm for the HER and 2 mm
for the LER, backlash phenomena in the tuning system of the LER cavity which leads to aphase jitter on the RF, various gas outbursts and the necessity to choose bunch patterns to
avoid beam induced voltage on the accelerating mode. The cavity electrical centre offset canbe compensated by a suitable orbit bump to reduce the klystron power to a minimum but thereason for the offset between the electrical and physical centers should be found. As far as
the beam is concerned, the LER cavity phase jitter is compensated by the RF feedback and istherefore under control. However it does put an increased load on the klystron and with thedifferent transient operating conditions may also be a cause of some vacuum outbursts fromthe coupler or the cavity. It is clearly necessary in the medium term to find the cause of thisjitter and correct it. The vacuum outbursts can also be due to a gradual cleaning of the cavity
surfaces. It is worrying that the LER performance seems to be degrading, but the suggestion
has been made this may be recovered by heating the cavity to 80 K as was done with the HER
cavity. This should be checked as soon as the beam tests have been completed. It is also clear
from the trips that the LER is less reliable – this may be related to the tuner problem. On otherfronts, such as the HOM power, everything seems very satisfactory.
It will surely be a challenge to maintain reliable Crab cavity operation as the total beam
current is raised when increasing the number of bunches and going to the maximum bunch
intensity. The Committee is confident that the RF cavity team will continue to be successful
and surmount new issues as they arise.
11) Beam Commissioning with Crab Cavity
Beam commissioning with crab cavities is going well in KEKB and the Committee strongly
supports these tests. This commissioning with crab cavities is very important not only for
KEKB to ultimately produce more luminosity but also for the field of accelerator physics ingeneral. These tests will help show whether the consequences of the beam-beam interaction
resulting from crossing angle collisions can be corrected with crabbed or tilted bunches,
generated in the KEKB case by transverse RF voltages.

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Several observations have been obtained with these crab cavity commissioning tests. A newvertical tune shift record in the KEKB HER to 0.078 has been achieved and is a strong
indication that crab cavities do improve the beam-beam interaction. The fractional verticaltunes were moved to higher values from about 0.535 to 0.585 to increase the luminosity
which was also predicted by beam-beam simulations. The horizontal offset of the two beams
at the IP needs to be kept below 40 microns to maintain the luminosity. This level should be
rechecked with additional measurements as a function of horizontal and vertical crossing
angles. The specific luminosity drops slowly with the product of the bunch currents and ishigher with crab cavities than without by about 20% historically but about 50% with theparticular accelerator parameters used in these tests. The lifetime drops sharply at midcurrents and may be related to the vertical tunes shifts, or perhaps horizontal tune shifts,
reaching new levels. This sharp drop should be studied in detail.
There is a question whether transverse wake fields in the crab cavities can cause different
bunches to have different trajectories and thus different luminosities. We recommend thatchecks be made to see if the luminosity is the same for all of the 51 bunches in the train and,
if not, investigate the cause.
It is very important to conclude these beam commissioning tests with a definitive outcome,understanding all the details of the beam-beam interaction with crab crossing. The Committee
is concerned that these tests may end too early. The plan for studies is to have 2 to 3 weeks
more of low current studies and then one month of high current running. There may be abetter strategy where every two weeks low current then high currents studies are alternately
done. This scheme allows some time for the scientists to study the data already taken and forthe high current effects to be discovered and cured by different team members. The beam
experimenters need time to analyze the data, make plans for new proposed experiments, andthen carry out the new experiments. This proposed alternating schedule gives some time torespond or fix accelerator components which cause trouble. Also, high current operation will
include a different cast of personnel to understand the issues. We recommend alternating highand low current operation (beam tests) to improve the chances of success with crab cavities
until a satisfactory result is obtained.
The horizontal beta functions at the IP in both rings are higher now than in the previous beamrunning. They are higher because, given the crab voltages, higher betas are needed to get theproper beam tilt angle at the IP. It would be very insightful in some way to change thehorizontal betas at the IP with a different configuration to see the effect on the limit of
specific luminosity and current limits. One method for this change may be to warm up bothcrab cavities to 80 degrees K, to clean them, and then cool them again. This cycling will
likely increase the achievable peak voltage, as shown for the LER before, allowing thehorizontal betas to be reduced.
The effect of the horizontal dispersion at the IP, on the order of 10 mm, should be checked for
its effect on crab correction. Horizontal dispersion can make the horizontal beam-beam tune
shifts sensitive to the horizontal beta function value.
Why the luminosity scans with voltage are so flat is a very interesting question when the
beam-beam simulations seem to indicate a much sharper curve should be seen.
Many IP variables have been adjusted one at a time to try to improve the luminosity. A few
have succeeded but most have had no effect. It may well be that combinations of variables
may have a better chance for luminosity improvement. One example may be transverse
offsets coupled with re-optimized vertical angles. Another possibility is that the beam at the
IR is rotated around its longitudinal axis and does not collide head-on on the left and right
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edges. The suggestion is to adjust the skew quadrupoles that rotate the beam at the IP alongwith adjustments to the crab angle.
Tests could be performed to study the effect, if any, of crab bunch tilts on the Electron Cloud
Instability around the LER ring. These tilts could affect the instability limits and size blow up
as the electrons collect differently along the length of the bunch. These proposed tests may
answer whether bunch tilts could affect how the electrons are trapped from head to tail in thebunches. Short bunch trains could help answer this question with out the need for high total
current.
Recommendation: Continue to study why the luminosity scans with crab voltage are so flat
since the beam-beam simulations indicate a much sharper curve.
Recommendation: Investigate whether all 51 bunches in the present beam tests have the same
luminosity. If not, what is the cause?
Recommendation: Make a test of the crab crossing with adjusted lattice parameters such thatthe horizontal tune shifts are closer to the old values and not twice as high as in the present
tests.
Recommendation: We recommend alternating high and low beam current studies to improvethe chances of success with crab cavities and make sure there is sufficient beam study time toobtain satisfactory results and complete understanding.
12) Beam-Beam Effect with Crab Cavity
Beam-beam simulation predicted a serious enhancement in the luminosity performance of
KEKB by implementing the crab crossing. This effectively compensates the crossing angle atthe IP, thus switching the collision into a head-on mode. From the beam-beam simulations for
the KEKB working point, the expected gain in the beam-beam parameter (and thereby in theluminosity) is about a factor of two. The experimental studies of the crab crossing so far show
an increase of about 20% in the beam-beam parameter, providing that the geometric gain fromavoiding the collision crossing is already subtracted. Some experimental results give
asymmetric dependencies (e.g. HER beam lifetime vs. the horizontal collision offset) in cases
where symmetry is expected, and this peculiarity has no explanation from the simulation yet.
To understand the discrepancy and continue optimization of the crab collision, it is desirable
to obtain guidelines from more detailed simulations. The simulation results available so far,already show a very steep dependence of the luminosity on scanning one of the important
machine parameters, e.g. the collision offset, or the residual crossing angle(s). A list of
relevant parameters includes: i) residual crabbing angles of the bunches (i.e. the crab cavity
voltages), ii) horizontal and vertical collision offsets, iii) the respective orbit crossing angles
at the IP, iv) a full set of Twiss parameters (including x and y dispersions), and v) the set oftransverse coupling coefficients R1–4, etc.
The critical questions now are: with a multi-parametric scan, can we see a steepest ascent pathto the maximum luminosity in simulations? And what is the best strategy of tuning the beambeam performance with the crab collision?
The strong-strong 3D beam-beam simulation tools available at KEKB provide self-consistent
distributions of colliding bunches, hence the data on the beam size blowup (and corresponding
degradation of the specific luminosity) is readily available. The data on the expected beam
lifetime (both from counting particles lost from the mesh and from far tails of the resulting

Page 14 of 24

distributions) is less reliable, because of small statistics. The available weak-strong simulation
codes oriented for the lifetime evaluation can be used to provide this information.
The Committee puts an emphasis on the survey of the crab collision parameters by means of
the beam-beam simulations and recommends multi-parametric analysis of the beam-beamsimulation results, aiming to formulate an efficient strategy for experimental optimization of
the crab collision regime.
13) Observation of Crab Crossing with Streak Camera
A streak camera has been installed in the synchrotron radiation monitor hut of each ring topermit direct observation of the crab angle at the location of the synchrotron radiation monitor.
Horizontal and longitudinal beam profiles are measured to check the crabbing angle.
The longitudinal scale (time) is calibrated by Hamamatsu. The horizontal scale is calibratedusing a +/- 2mm parallel bump at the synchrotron radiation monitor locations.
The crab angle has been measured with crab cavity off, and with crab on with normal andopposite phase. The sign of the crab angle has the same sign at the synchrotron radiation
monitor location as at the IP. The correct crab sign has been verified.
The accuracy of the measurement of has been determined to be about 10%.
Measured LER crab angle values at the synchrotron radiation monitor locations are consistent
with expected values, but the HER values are off by a factor of two for yet unknown reasons.
On the other hand, the observed orbit distortions with a 360 degree crab phase scan are inexcellent agreement with crab kick voltage calibration.
Recommendation:
The Committee strongly recommends clarifying and identifying this discrepancy byadditional cross-checks of streak camera calibration and beam optics functions as soon as
possible. If the streak camera crab angle measurements are correct, this could certainly
explain why the relatively narrow peak in luminosity enhancement expected from simulation
for head on collisions has not yet been observed.
14) Recent Upgrade Studies of Vacuum Components
The ongoing work for the upgrade of vacuum components has been presented to theCommittee. The previous design of the beam duct, which was based on a welded structure
made out of pressed half-shells has been improved. The new design consists of a cold-drawn
copper pipe without longitudinal welds. This guarantees tighter mechanical tolerances. The
cross section consists of a circular beam channel with two ante-chambers for synchrotron
radiation and to accommodate NEG strips. The proposal is to install a total of 30 m of thisvacuum chamber in a wiggler section of KEKB during the coming summer. With theproposed symmetric cooling channels the transverse temperature gradient should be strongly
reduced with respect to the old, asymmetric KEKB beam duct. Reduced thermal stress will
ensure that that the straightness of the beam pipe is maintained under the increased
synchrotron radiation load from the wigglers.
The beam pipe design incorporates a new flange design with the matching aperture. New
flanges are of the MO-type (Matsumoto-Ohtsuka). The flange design has been tested toconfirm the required leak tightness. The special feature is that the vacuum gasket is mounted
flush with the inner wall of the beam pipe and this eliminates the longitudinal and transverse
Page 15 of 24

gap of conventional CF-flanges. The Committee agrees that this will be a very important next
step to validate both the proposed beam duct design and the manufacturing method.
The Committee was updated on the recent progress made with the comb-type RF-bridges,
which will be fitted into the vacuum bellows and gate valves. Machine tests have beenencouraging and have shown a much reduced temperature rise. Nevertheless the concern
persists that arcing between adjacent fingers could occur when the RF-bridges are not
perfectly aligned.
Given the reported failure rate of the standard RF-bridges in KEKB during last year’s andthis year’s meetings, the Committee recommends that the development of the new design
should receive the necessary support so that components will be available as a replacement.
To reduce the secondary electron coefficient of the surface the new beam duct will be sputter
coated with a thin layer of TiN. The effectiveness of this type of surface coating has been
demonstrated by the extensive work of S. Kato. A dedicated facility is being set-up to coat up
to 7 m long vacuum chambers in vertical position. The Committee recommends that thisfacility be used to coat existing standard vacuum chambers for KEKB to validate the longterm behavior of the TiN layer under real machine conditions.
First results from a beam test of a prototype vertical movable mask for LER have beenpresented to the Committee. The aim of these tests has been to validate the HOM power
estimates and to measure the resulting temperature rise of the absorber. Since the head canlose its power only by radiation, the estimated temperature becomes very high. On the
prototype, the temperature could be measured through a window with a pyrometer. By thismethod, temperatures approaching, or even exceeding 600 C could be measured. After thetests, the metal coatings of Cu and/or Ti appeared to have evaporated.
The Committee is aware of the difficulty to find a good solution for the very demanding mask
design and strongly encourages the continuation of this work.
15) Secondary Electron Yield
An impressive set of experimental results obtained with a dedicated system for in-situ
measurements of the secondary electron yield (SEMS) has been reported by S. Kato. Thissystem is specially dedicated to the surface measurements under uhv conditions and fitted in astraight section (Fuji) of the LER e+ ring. The merit of this experimental program is a directcomparison of earlier laboratory results (10. KEKB Mac) with in-situ measurements underreal beam conditions and exposed to e-cloud. The system comprises a primary electron beamwith a scanning capability, a monitor for the electron activity, a sample loading system and asolenoid magnetic field. The secondary electron yield and the surface characteristics of asample can be measured before and after beam exposure. A dose of 1020 e-/cm2 can beaccumulated within 2 weeks. With this dose, S. Kato finds a very significant reduction of theinitial secondary emission yield (SEY) from about 1.8 to 1.1 and even less. In situ surface
analysis after exposure reveals predominantly graphitic carbon on the surface, which agrees
well with his earlier laboratory measurements. Graphite is known to have a low SEY. In termsof SEY, TiNx gives better results than copper and NEG samples.
The set of data include measurements of the angular dependence of the SEY, particularly at
grazing incidence, as well as dependence on the primary energy; this data will be very
valuable as input for electron cloud simulations.
In view of the very low SEY of graphite, S. Kato suggests that this material could even be
used for vacuum chambers.
Page 16 of 24

The Committee acknowledges the large effort which went into this work and hopes that morevaluable results will be forthcoming.
16) Electron Cloud Measurement and Vacuum Chamber Design
Electron monitors, have been developed and installed in the pumping ports of many different
vacuum chamber configurations in the LER. These monitors estimate the electron density
near the beam by measuring the fast electron current above a predetermined energy threshold.
The electron current monitors are equipped with grids which act as a retarding field analyzer
such that only electrons above a predetermined energy threshold, typically 1 keV, aremeasured.
The relation between electron cloud density near the beam axis and the measured anodecurrent can be determined from the electron monitor geometry.
These electron cloud monitors permit in situ measurement of electron cloud densities withdifferent chamber geometries, different levels of synchrotron radiation, different surface
coatings, different bunch patterns and changes in secondary electron yield (SEY) as a functionof in situ electron dose.
It has been quantitatively confirmed that-

The electron current is strongly correlated with the intensity of synchrotron radiation-

The antechamber design drastically reduces the electron cloud density-

The removal of photoelectrons in the antechamber geometry is not complete comparedwith locations where the synchrotron radiation is negligible-

Under synchrotron radiation, the effect of TiN coating alone is not as effective as theantechamber structure-

In areas with low synchrotron radiation intensity, the effectiveness of NEG and TiNcoating has been measured-

Some inconsistency between the in situ SEY measurements and the electron cloudmeasurements has been revealed and need further study including simulation-

Under various bunch patterns, the average electron cloud density versus beam current
is similar for different bunch patterns if the electron cloud density is plotted against
linear density of stored current.

-

If direct synchrotron radiation intensity is negligible, the density of electron cloud in a
TiN coated chamber is lower than the critical density for the single bunch head tailinstability

These measurements are extremely valuable for verification of electron cloud simulations andvalidation of the proposed measures to reduce electron cloud problems in future machines likeSuper-KEKB and ILC damping rings. The results are complementary to the laboratory studies
of SEY and the in situ measurements of SEY of various materials and surface coatings.
Further refinement and continuation of these studies can certainly be recommended.
It would be very interesting to obtain in situ measurements of electron cloud density at thebeam axis for chambers with C-magnets mounted on the antechamber or for chambers withsolenoid fields. However, the current design of electron cloud monitors is probably not well
suited for this purpose, and some bright new ideas may be required.
Page 17 of 24

17) Development of Pulsed Quadrupoles
Due to the photo-electron cloud effect in the LER, the vertical betatron tune is lower for thehead of the bunch train than the rest of the bunch train and it causes some beam loss in theleading bunches. A fast pulsed quadrupole magnet with a ferrite core and a water-cooled
ceramic chamber will be installed this year to enhance the LER luminosity by stabilizing thefront part of the bunch train. The pulsed power supply needs a high repetition rate of 100 kHz
with 100 A in a half sine waveform. It is a challenging task to realize the power supply. On theother hand, the non-collision pilot bunch in the HER is often lost at a lower horizontal betatrontune. The same kind of quadrupole magnet is planned to keep this bunch with a higher currentof 175 A. The Committee endorses this experiment of stabilizing the bunch trains, but would
like to se simulations of the effect to help guide the beam commissioning program.
18) QCS for SuperKEKB
The QCS-R for the super-KEKB was successfully tested at 4.2K. It met the current
requirement of 1,187 A, and the quench location was identified at the 2nd quadrant coils due tofabrication errors. The field measurements including high-harmonic components will be
conducted this year. The corrector and the compensation solenoids are under fabrication, andthey will be tested this year. The Committee is convinced that the magnet R&D program isprogress smoothly as planned.
19) Crab Waist Optics
A novel mode of operation for high performance factories, referred to as crab waist, has beenstudied for Super-B. (Similar idea could conceivably be applied to Super-KEKB and even to a
KEKB upgrade). In this mode of operation, the traditional head-on collision with hourglass
effect is replaced by collision with a large crossing angle whose waist position is made tocorrelate with the horizontal position of collision. This crabbed waist is provided optically by
two sets of sextupoles around the interaction point with proper betatron phases. A gain of
luminosity then results, first from the small beam sizes and then from the crabbed waist,
without a corresponding increase of beam intensity.
A significant effort has been invested at KEKB in search of an optimized lattice design
including a crabbed waist. The crabbed waist has been satisfactorily produced. In addition to a
crabbed waist, it has become necessary to take account of other associated nonlinear effects of
the optics design. In particular, sextupole scheme optimizations, together in some cases withadditional octupoles, have been tested. However, it was found that the introduction of the crab
waist sextupoles significantly reduced the dynamic aperture of both the HER and particularly
the LER. This lack of dynamic aperture not only cut into the beam lifetime, but also prevented
smooth operation of beam injection. In the pursuit of the source of the loss of dynamic
aperture, it was found that in some cases the fringe fields and the kinematic nonlinearities ofthe magnets between the sextupoles make significant contributions. The Committee feels thissomewhat surprising result requires more scrutiny. Because of the lack of dynamic aperture,crab waist optics does not have an acceptable solution at the present time. This is known to
the KEKB team, and more studies are planned. The Committee endorses the multi-parametricstudy suggested by the KEKB team. The Committee further emphasizes that this work could
benefit greatly from collaboration with other labs.

Page 18 of 2420) Lattice Design for Super B
A comparison of the dynamic aperture in SuperKEKB and the Super-B accelerator designs
has been made by the KEKB staff. This comparison includes the sextupoles for the crab waist
beam-beam correction. Overall, SuperKEKB has more conservative lattice parameters withhigher emittances and larger IP beta functions but, conversely, has higher beam currents andlarger AC power. The Super-B collider concept has smaller emittances and IP betas, thus
being less conservative, but conversely has correspondingly significantly smaller beam
currents and AC power, but also potentially higher luminosity.
Many topics have been included in the simulations of the dynamic aperture. The effect of the
sextupoles that provide the crab waist correction on the dynamic aperture has been studied.
The crab waist sextupoles produce a non-linearity which can affect the dynamics aperture of
the rings. These calculations show a sharp reduction in the dynamic aperture in the
SuperKEKB ring geometry. The dynamic aperture gets smaller with increased crab sextupole
but is acceptable without crab waist sextupoles. The non-linear effects of chromaticity havealso been studied. Higher multipoles, in the form of octupoles, have been shown to degrade
the dynamic aperture in the present configuration with the crab waist sextupoles.
Recommendation: The crab waist scheme for a Super-B Factory is a new idea that can saveconsiderable construction costs as well as potentially producing higher peak luminosity. The
Committee recommends a continued search for a magnetic lattice configuration with good
dynamic aperture with the crab waist sextupoles turned on.
21) Beam-Beam Effects in Super B
The SuperB design approach pursued by Frascati-SLAC-KEK collaboration and based oncollisions with a large Piwinski angle opens up the way to using a very low beta-y at the IP(~0.1 mm) without strong limitations on the colliding bunches’ lengths (6 mm). A reasonably
small horizontal size of the colliding bunches’ overlap area can be reached due to the arclattice providing a small horizontal emittance (< 1 nm). For a high luminosity (~1036cm-2s-1),
an extremely small x-y coupling is needed to obtain the tiny vertical spot size at the collision
point (~15 nm!). As a result, the horizontal beam-beam parameter is small, and the verticalone is raised to an achievable limit. The collision becomes effectively one-dimensional. The
betatron coupling resonances are suppressed by using the crabbed-waist collision optics.
This low-emittance approach has a major advantage of employing moderate currents incolliding beams, at the expense of complications both in the arc and IR optics. However, thechallenging set of the optics parameters has much in common with the task for the ILC
Damping Rings, synergistic efforts should help to find solutions to critical problems in bothprojects (dynamic aperture limitation, complicated injection scheme, electron cloud instability
and other collective effects).
A comparison of the high-current (SuperKEKB) and low-emittance (SuperB) approaches has
been done, with new emphasis on the latter. Both envisage the crossing collision, so term-byterm analysis of the nonlinear (4th order) perturbations coming from the beam-beam kick withthe crossing angle has been performed in order to reveal the most important terms. Special
attention was paid to the effect from the crabbed waist sextupoles. They are shown to cancel
some of the perturbation terms responsible for the nonlinear x-y coupling, but they tend toenhance the synchrobetatron terms. From the tune scan, the parameter range was found thatthe crab waist is efficient: mostly only for small synchrotron tunes.
Page 19 of 24

For the low-beta and low-emittance option, the existing strong-strong simulation tool comesto the limit of available computer power because too many longitudinal slices are needed tomodel the bunch whose length is much longer than the vertical beam size at the IP. Only
weak-strong simulation results are presently available for these studies.
The Committee supports the efforts for understanding which is the most efficient way to thesuper-high luminosity in SuperB projects, and formulating a coherent machine parameter list.
The Committee reminds that the beam-beam simulation findings be confirmed bydemonstration of a wide, realistic tolerance range in the appropriate multi-parametric space.
The Committee strongly recommends to continue and reinforce the existing collaboration on
SuperB projects between LNF-INFN, SLAC, KEK and other laboratories.
22) Fuji Test Beam LineThe Fuji test beam line is a new test beam facility at KEK, which is planned to deliver a beam
to the test station starting in September 2007. It uses the 100 m-long straight section of the
HER ring in the Fuji interaction region. The “Turtle” simulation of the Bremsstrahlung
photons from the beam due to residual-gas scattering shows predicts a flux of about 1.6×105
photons/second. Based on the Geant4 simulation these photons will be converted to anelectron or positron beam using a tungsten converter of 3mm thickness. This gives a rate ofabout 200 Hz (continuous beam) and with an energy spread of 0.4%, at any energy between
0.5 GeV and 3.4 GeV. These is very good performance for the test beam. The converted
particles will be extracted outside of the KEKB tunnel by additional magnets. This beam line
can be operated about 240 days per year (KEKB operation time) without any performancedegradation for the KEKB beam. It is really a very good idea to establish this new beam lineby sharing with KEKB straight section. The Committee recommends that the KEK
management provide the necessary support to create this beam line facility.
23) First application of a tungsten single-crystal positron source at the KEKB injectorlinac
A single crystal tungsten target has been installed in the KEKB injector linac which hassignificantly improved the positron yield. The use of orientated crystals in positron sources ismotivated by the enhanced gamma radiation along the crystallographic axes or planes and thecorresponding enhancement in pair production.
While the idea has been presented many years ago, and several successful experiments havebeen performed at different laboratories, this is the first time an operational positron
production facility has been equipped with a single crystal tungsten target.
The optimum target thickness for a single crystal tungsten target with its <111> crystal axis
aligned with the beam direction, has been experimentally determined at the KEKB injector
linac. The optimum thickness for maximum yield has been found to be about 10 mmcompared with 14 mm for a conventional amorphous tungsten target.
The target axis is not moveable, but the target assembly has been precisely aligned andmachined to insure its crystal axis is parallel to the beam axis.
The improvement in positron yield is remarkable:-

a 25% improvement in positron yield has been obtained-

a 20% reduction of energy deposited in the target has also been achieved
Page 20 of 24

The target has so far been in operation for two months, and based on radiation damage studies
done at SLC at SLAC, it is expected that the target will last at least a year with no degradationin performance.
This relatively simple and very effective improvement of positron yields works so well that it
is surprising that it has not been done sooner.
24) Injector Upgrade
Phase 1 of the Injector Upgrade was completed last year with a new bypass transport line to
the Photon Factory, reducing the beam switching time by one half. In order to serve four
different machines continuously, the injector requires a common transport lattice and manyother features, such as a positron target with an electron-bypass hole, pulsed switchingmagnets, and fast control of the klystron phases. In Phase 2, a fast beam-mode switch isplanned for the KEKB electron ring and the Photon Factory, while Phase 3 includes the
KEKB positron ring. With test runs this year, the injector group plans to establish routine
operations, providing beams to all four rings simultaneously. The Committee is quite
convinced that the Injector Group will accomplish all the planned schemes as scheduled. On
the other hand, the top-up mode operation for the Photon Factory Accumulation Ring would
be very difficult without an extensive budget.
25) Control Room with beam
The Committee was taken to visit the KEKB Control Room. It was clear that the number ofcomputer screens had doubled since our last visit, and the screens were larger and displaying
more information. The Control Room is extremely functional and at least twenty people wereactively involved in the crab cavity commissioning. The control system provided automatedparameter scans, a vital tool when searching for an optimum working point with at least
twenty different parameters to vary.
It was clear that there was a very cooperative attitude between the physicists and engineers of
KEK and the operators from Mitsubishi and this will be important as routine operations areturned back over to the operators.
The Committee was extremely impressed with the organization of the commissioning effort,
which gives confidence that the commissioning will lead to successful routine operation withthe crab cavities.

Page 21 of 24

Appendix A
KEKB Accelerator Review Members
Andrew Hutton

JLab (Chairman)

Alexander Chao

SLAC

Warren FunkJLabOswald Gröbner

CERN (retired)

Heino Henke

Technical University, Berlin – unable to attend

Trevor Linnecar

CERN

Won Namkung

POSTECH

Fleming Pedersen

CERN

Eugene A. Perevedentsev

BINP, Novosibirsk

David Rice

CornellJohn Seeman

SLAC

Wang Shuhong

IHEP, Beijing

Katsunobu OideKEK Secretary, Accelerator

Shin-ichi Kurokawa

KEK Secretary, Accelerator – unable to attend

Page 22 of 24

Appendix B

Agenda of the twelfth KEKB Accelerator Review Committee
March 19-21, 2007 in the Meeting room on the first floor of Building No.3, KEK
8:30- 9:00

Executive Session

9:00- 9:10

WelcomeF. Takasaki

9:10- 9:25

Overview

K. Oide9:25- 9:55

Beam Commissioning before Crab Cavity

Y. Funakoshi

9:55-10:15

Belle Status

Y. Ushiroda

10:15-10:35

Coffee10:15-10:35

BPM Displacement Monitor

H. Fukuma================ Crab Cavity ================
10:55-11:30

Crab Cavity Overview

K. Hosoyama

11:30-12:00

RF Design of Crab Cavity

Y. Morita

12:00-13:00

Lunch

13:00-13:20

Cryogenics, etc.

K. Nakai

13:20-13:45

Horizontal Tests for Crab Cavities

Y. Yamamoto

13:45-14:05

Installation of Crab Cavity

M. Ono

14:05-14:35

Commissioning of Crab RF System

K. Akai

14:35-15:10

Beam Commissioning with Crab Cavity

H. Koiso15:10-15:30

Coffee15:30-15:50

Beam-Beam Effect with Crab Cavity

K. Ohmi

15:50-16:10

Observation of Crab Crossing with Streak Camera

H. Ikeda============== Upgrade Studies ==============
16:10-16:35

Recent Upgrade Studies of Vacuum Components

Y. Suetsugu

16:35-16:50

Secondary Electron Yield

S. Kato16:50-17:05

Electron Cloud Measurement and Vacuum Chamber Design

K. Kanazawa

17:05-17:20

Development of Pulsed Quadrupoles

T. Mimashi

17:30-

Reception

8:30- 9:00

Executive Session

Page 23 of 24

9:00- 9:20

QCS for SuperKEKB

N. Ohuchi

9:20- 9:40

Crab Waist Optics

A. Morita

9:40-10:00

Lattice Design for Super B

Y. Ohnishi

10:00-10:20

Beam-Beam Effects in Super B

K. Ohmi10:20-10:40

Coffee10:40-11:10

Fuji Test Beam LineJ. Haba

11:10-11:30

First application of a tungsten single-crystal positron source at
the KEKB injector linac

T. Suwada

11:30-12:00

Injector Upgrade

M. Satoh

12:00-13:00

Lunch

13:00-14:00

Executive Session

14:00-15:00

Seminar: Design of Super B (3G Seminar Hall)

P. Raimondi================ Crab Tour ================
15:00-15:30

Control Room with beam

H. Koiso15:30-16:30

Nikko Tunnel without beam

K. Hosoyama

16:30-

Executive Session

8:30- 11:00

Executive Session

11:00- 12:00

Close-out with KEKB Staffs

12:00

Adjourn

Page 24 of 24