The Ninth KEKB Accelerator Review Committee Report
Introduction
The Ninth KEKB Accelerator Review Committee meeting was held on February 16-18, 2004.
The Committee welcomed one new member: Oswald Gröbner from CERN, one of theworld’s experts on accelerator vacuum systems. Two other members have been appointed
and will attend the meeting next year: Trevor Linnecar from CERN and Heino Henke from
Berlin University, both experts on accelerator RF systems. Appendix A shows the present
membership of the Committee.
The ninth 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. As usual, the Committee was impressed by the high standard of thetalks, both the technical content and the presentations themselves. The recommendations of
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
1) Forward2) Summary3) Comments
Findings and Recommendations
1) KEKB status2) Experience on High Current
3) Physics of BELLE, today and tomorrow4) Upgrade plan overview
5) Beam-beam interaction
6) Crab cavities: Status & Plan
7) Crab cavities: Cryostat R&D
8) Crab cavities: Nb-Cu coaxial coupler R&D
9) Crab crossing optics
10) Crab cavities for high currents
11) RF system upgrade
12) ARES upgrade
13) SCC upgrade
14) Klystrons
15) Vacuum system upgrade16) IR upgrade overview
17) Superconducting magnets
18) Special magnets
Page 1 of 2219) Optics upgrade
20) Beam Instabilities
21) Beam diagnostics system upgrade22) Installation
23) Linac upgrade: overview
24) Linac upgrade: C-band linac progress - RF source25) Linac upgrade: C-band linac progress - accelerator section
26) Linac upgrade: beam instrumentation
27) Design of damping ring28) Beam lifetimeA) Executive Summary
1) Foreword
KEKB has made excellent progress in the year since the last Committee meeting. The peakluminosity has increased to a new world record of 11.6 x 1033 cm-2s-1 (at this time last year it
was 8.26 x 1033 cm-2s-1, the year before 6.65 x 1033 cm-2 s-1). KEKB exceeded the design
luminosity of 1034 cm-2 s-1 on May 9, 2003. The Committee congratulates the entire KEKB
project staff on achieving this major milestone. Continuous injection has been in regular
operation since January 2004, and has helped to increase the daily integrated luminosity byalmost a factor of two since last year. The BELLE detector has accumulated 197.5 fb-1,
another world record (107.4 fb-1 last year and 56 fb-1 the year before) and has published a totalof 83 papers in refereed journals (55 last year). In the two-day meeting, only a few of thetalks dealt with present status of KEKB, while the remainder covered the plans for upgrading
KEKB to a luminosity of 1035 – 1036 cm-2 s-1. The KEKB machine group had done anenormous amount of excellent work, and is to be congratulated on the impressive results thathave been achieved.
2) Summary
KEKB has made spectacular progress over the last year, breaking all of the worldwide
luminosity records: highest peak luminosity: 11.6 x 1033 cm-2s-1, highest daily integrated
luminosity: 819 pb-1, highest weekly integrated luminosity: 4.745 fb-1, and highest 30-day
luminosity: 17.24 fb-1. The machine is running exceptionally well (the daily record was
exceeded during the meeting) and it is expected that the luminosity will continue to slowly
increase during the year. However, no large factors of improvement seem likely until the crab
cavities can be installed. The KEKB team has made many hardware and tuning
improvements in order to reach this performance and they are to be congratulated on the
excellent results.
The BELLE detector has now accumulated 197.5 fb-1, and of these 90 fb-1 were obtained thisyear. The BELLE detector is working extremely well and has had no major difficulties.
Backgrounds are low, and losses during beam injection are small. Continuous injection has
been acceptable to the detector but has necessitated suppressing 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 the accelerator.

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3) Comments
The Committee has made recommendations throughout the different sections below.
Highlights of these recommendations are summarized here for convenience.
1. The Committee believes that improving the luminosity of KEKB is the highest priority,and experimental and theoretical studies to improve luminosity should be given
precedence.
2. The Committee strongly endorses the proposal to construct, test, and install a crab
cavity in one ring with the highest priority, and recommends that a second cavity beinstalled in the other ring as soon as possible. In the meantime, detailed theoreticalstudies of the beam dynamics of the ring with a single crab cavity should continue.
3. Recognizing the criticality of the prediction of a high beam-beam parameter, theCommittee strongly recommends an even more in-depth examination of thesesimulations. This is an exciting possibility, which has large potential for improving
the luminosity of KEKB and also SuperKEKB.
4. The Committee would like to encourage studies leading to increased luminosity in the
short term; e.g. electron cloud clearing in the quadrupoles, study of 3.5 bunch spacing,
fast ion instabilities, reducing beta*, working point, shortening the abort gap, etc.
5. The Committee recommends that BELLE implement an azimuthally localized vetosimilar to that of BaBar to avoid the 3% loss in luminosity caused by the detector
trigger veto during injection.
6. The Committee endorses the direction of the present studies to design a major
luminosity upgrade (SuperKEKB) aimed at a luminosity of 1035 – 1036 cm-2 s-1 andrecommends that they be continued.
7. The Committee would like to see an integrated schedule for SuperKEKB, consistent
with the external constraints, that can be used as the basis for defining the internal
priorities for research and development, and can help focus detailed budget andscheduling work.
8. The Committee recommends carrying out a detailed evaluation of all of the effects thatwould impact the choice of which beam goes in which ring.
9. The Committee recommends installing one or more test chambers in the ring to study
the effect of clearing electrodes, coatings, etc.
10. The Committee recommends that design studies of the ultimate damping rates of thetransverse damping systems be continued in view of the importance of the fast ion
instability.
11. The Committee recommends continued participation in the collaboration with SLAC
to develop a new digital signal processing system for the multi-bunch feedback systemand endorses the proposal to initiate a new collaboration with SLAC, BNL and otherlaboratories on electron cloud instabilities.

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B) Findings and Recommendations
1) KEKB status
KEKB has progressed very well over the past year and more than reached its goals. The
luminosity has reached 11.6 x 1033 cm-2 s-1, a new world’s record that exceeds the design
value. The accelerator continues to set integrated luminosity records, for example, 819 /pb per
day and 17.24 /fb in 30 days. The total integrated luminosity over the life of KEKB hasreached 197.5 /fb.
On the technical front, injection of both beams while the detector is taking data was
successfully achieved early last month. This continuous injection mode greatly increases theaverage luminosity. Also, the horizontal tune of the Low Energy Ring (LER) was recently
moved closer to the half integer tune (0.505) which, with the use of IP tuning knobs, gives
higher luminosity. Feedback on the bunch tunes has also greatly stabilized colliding beam
operation.
KEKB now operates with about 1,200 bunches but with beam currents near the design values.
This high bunch charge is well tolerated by the beam-beam interaction and, as a result, gives
more luminosity. The design number of bunch (5,000) would allow for more current andluminosity in the future. However, the number of bunches is presently limited in the LER by
the Electron Cloud Instability (ECI). The KEKB staff is looking at measures to increase thecurrent and specific luminosity.
The high bunch currents and short bunch lengths have stressed several vacuum chambers withhigh temperatures and forces. Several vacuum leaks have occurred, and these chambers havebeen replaced and upgraded. The committee suggests continued vigilance watching for the“next” chamber to have problems.
The number of beam aborts has averaged about four per day in each ring since May 2002.
Since continuous injection has been implemented, the beam aborts have had a noticeable
impact on the average luminosity (~5%). The causes have been carefully documented andassigned to different categories. It would be interesting to study these beam aborts in moredetail to try and eliminate them. This would be good for the present KEKB and, more
importantly, provide useful information for SuperKEKB.
2) Experience on High Current
The committee was very pleased to learn that beam currents of 1.5 A and 1.1 A have beenreached, record currents for a superconducting cavity system. The machine is operated with
1284 bunches which implies much higher bunch currents than the design value, because theelectron cloud instability is the limiting effect for increased luminosity. A large HOM power
is deposited in vacuum system components as a consequence of the high bunch currents.
Major problems that were encountered during the last year were excessive heating of thebellows near movable masks, heating of NEG elements, and increased outgassing of a getter
cartridge in a pumping port. In several cases the excessive heating or arcing resulted in
vacuum leaks that had to be repaired. To avoid such problems in the future, the cooling
capacity of the critical elements has been increased. On one occasion, thermal deformation ofa vacuum chamber provoked displacement of a magnet resulting in a loss of luminosity. It
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would be desirable to monitor closely the temperature of all critical components in order toavoid vacuum incidents and to anticipate problems,
Following the opening of the vacuum system during a shutdown, a series of sudden beamlosses has been observed in the electron ring, which was attributed to dust particles.
Fortunately, these incidents have the tendency to disappear after a relatively short period of
operation. The Committee recommends monitoring such events as they represent a nonnegligible loss of the integrated luminosity.
Following the successful implementation of continuous injection into KEKB, the beams canbe maintained at a stable currents throughout the run and this has considerably improved thethermal conditions of the vacuum system, thus reducing movement of vacuum components
and undesirable thermal cycles.
The electron cloud situation has improved considerably since the addition of solenoids
wherever the beam pipe is accessible. The Committee recommends continued exploration ofthis approach, and to add solenoids to any remaining field free space. The question of the
optimum field orientation of adjacent solenoids windings has been raised and whether or not
this matters at all. The Committee recommends that this be studied theoretically.
The available data on vacuum scrubbing of the two rings shows a reduction in outgassing by
many orders of magnitude and appear to have reached around a few 10-7 molecules/ photon.
In the HER the clean up appears to be levelling off at a few 10-7 molecules/ photon. The
reason for the saturation in the HER is not entirely understood but a plausible explanation
could be increased thermal outgassing of the vacuum system due to chamber heating. As longas the achieved pressures are sufficiently low, this effect should not limit the operation at
higher current.
3) Physics of BELLE, today and tomorrow
Belle has logged world records in peak luminosity, daily, monthly and totally accumulated
luminosity of 197.5 fb-1, which gives the prospect of collecting 500fb-1 by 2007. What could
be measured with luminosities from 5000 to 50000fb-1 is now being studied. Since the higher
number is somewhat optimistic, it would be wise to avoid raising expectations too high. The
Belle detector has been working very well. There are no major difficulties and thebackgrounds are low. The new silicon vertex chamber has been working well with no reported
problems.
Continuous injection has been implemented and works very well. The detector currently
vetoes 3.5ms after every injection, which amounts to a 3% loss in luminosity. To avoid thisloss, an azimuthally localized veto similar to that of BaBar should be implemented.
Additional loss of luminosity is due to beam aborts. With the top up mode, a beam abort
always happens at maximum current and therefore leads to significant loss in luminosity. A
detailed abort analysis is encouraged, associated with an effort to reduce the number of aborts.
Belle has already been a very productive experiment. Currently 90 publications have been
written. So far, the main mission of Belle was a test of CP-violation in the Standard Model by
the Kobayashi-Maskawa mechanism. All three angles in the unitarity triangle have beenmeasured. Furthermore, several searches for new physics have been published, for example
via penguin diagrams. A new narrow resonance in B decays has been found that does not
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seem to be a charmonium state and more data is needed to understand the associated particle.
Hints at a new CP violating phase in b to s coupling have been found. If this can be confirmedwith more data, luminosity upgrades would lead to a very successful future of the B-factories.
4) Upgrade plan overview
The upgrade plan for SuperKEKB has been summarized in a Letter of Intent to be submitted
to the KEK LCPAC in February 2004. A draft of the LOI was given to this Committee. The
design target for the luminosity of SuperKEKB is 2.5 to 5 x 1035 cm-2 s-1. There is a sounddesign strategy that 1) reuses as much of KEKB as possible, 2) maintains acceptable detector
backgrounds, 3) has a new powerful injector, 4) has a low beta function interaction region
with a crossing angle, and 5) has high beam currents. Many accelerator advances are required
for SuperKEKB to carry out this approach. These include new superconducting magnets in
the interaction region, an upgraded linac to provide high-energy low-emittance positrons forinjection, a flexible arc lattice, an enhanced RF system for high currents, a new high power
vacuum system and improved beam diagnostics.
The Letter of Intent calls for a ten-year construction project starting as early as FY2004 andcontinuing until FY2013. The strategy calls for building most of the components forSuperKEKB in the first few years while continuing to operate the present rings. Then, there
would be a one to two year down to install the components around FY2007. The new
SuperKEKB accelerator would turn on in the fifth year of the proposed plan. Additional
upgraded components would be installed over the following five years during the summer
downs while the accelerator is off.
A large factor in increasing the luminosity comes from an increase in the assumed beam-beaminteraction. Computer simulations have shown a factor of two-to-four increase in the beambeam parameter at high tune shifts due to the use of crab-cavities. These cavities reduce theeffects of the required large crossing angles at the interaction point making them look similar
to head-on-collisions. These simulations use macro-particle tracking codes with transverseand longitudinal motion of the particles. The KEKB staff is aware that the highest values of
the tune-shift are obtained from gaussian model simulations that might not be realistic. The
Committee recommends that additional simulations be continued to make absolutely sure that
this anticipated luminosity gain is realizable and to understand the errors that could reduce
this factor. Possible reductions may come from non-linearities in the arc lattice (e.g.
chromaticity, sextupole errors, etc), longitudinal effects (number of simulation slices), or any
interaction region error (coupling, dispersion, etc).
The upgraded KEKB will have bunch lengths of about 3 mm. The Committee suggests
continued studies of bunch length effects including coherent synchrotron radiation (CSR),
enhanced Higher Order Modes (HOM), and bunch lengthening.
Overall, the plan for SuperKEKB is well thought out and many successful prototype tests
have been completed. The Committee recognized the hard work that has been done for thedesign. The Committee believes that a better definition the possible funding timetable would
help in making decisions on the relative priority of the research and development program.

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5) Beam-beam interaction
Extensive efforts were invested in the development of a 3-D simulation code for the beambeam interaction. This code has been benchmarked against the present operation of the KEKB.
An effort has also been made to compare it with another code independently developed at
SLAC, which has been benchmarked against PEP-II operation and in general, good agreement
has been obtained between the simulations and the real machines. This simulation code is
now being used to extrapolate to SuperKEKB. It predicts a substantial increase of the beambeam parameter (from the present KEKB level of 0.05 to the predicted level of 0.14) when the
beams collide either head-on, or with crab crossing. The SLAC code also makes the same
prediction. This result offers an exciting path to higher luminosities, and in fact lays thefoundation for a predicted luminosity for SuperKEKB of 2.5 x 1035 cm-2 s-1.
Recognizing the criticality of the prediction of a high beam-beam parameter, the Committee
strongly recommends an even more in-depth examination of these simulations. In particular,
linear and nonlinear optics errors in the ring lattice should be included in the simulations.
Attention should be paid to possibility of beam-beam induced synchro-betatron resonances.
The Committee feels that the criticality of the issue justifies continued scrutiny.
Another intriguing observation made in this study is to suggest that quantum excitation plays
an important role in blowing up the vertical beam size so that the blowup is extremely
sensitive to the crossing angle and the x-y coupling. Since the prediction of the increased
beam-beam parameter is related to this observation, it is suggested that this observation bebenchmarked against other simulation codes and/or other colliders.
It is suggested that emphasis be concentrated on a strong-strong simulation using the PIC
technique. The weak-strong and/or the Gaussian model simulations, which have been carriedalong in the studies, do not reflect the KEKB reality but may be useful in special situations.
6) Crab cavities: Status & Plan
It is a pleasure to see the significant progress made on the crab cavity development, as well asplanning for testing and installation. The crab cavities are the core component of both the
KEKB luminosity upgrade and the future SuperKEKB. The Committee strongly believes thatthe design, construction, and testing of these cavities should be given the highest priority, as
this is one of the few proposals that could lead to a significant enhancement in the KEKB
luminosity in the years before SuperKEKB goes online.
The fast processing of the cavities and the maintenance of a low breakdown rate is very
encouraging. The cryostat design is advancing well and it will be important to maintain thisprogress to meet the scheduled test date in mid-2004. The beam test in 2005 will be amilestone in accelerator physics.
Several areas of the crab cavity system are covered in more detail below.
7) Crab cavities: Cryostat R&D
It is gratifying to see that work has started on the design and construction of the crab cavity
cryostat. Given the importance of this device to future luminosity improvements it is greatly
hoped that resources will be available to aggressively pursue completion and early testing.
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Considerable work has gone into calculating heat leaks, which look reasonable. If possible,
additional heating due to beam-driven trapped modes should be ruled out, since it could leadto the need to modify the design of the helium vessel or cryostat.
The cavity is only supported from the top, raising the possibility of motion during cool down.
If not done already, we suggest a complete analysis of the mechanical aspects during cavity
cool down.
The mechanism proposed for tuning the cavity appears mechanically reasonable, but thedesign details presented do not make it immediately obvious that the necessary degree ofpitch and yaw control can be achieved.
8) Crab cavities: Nb-Cu coaxial coupler R&D
The presentation on the RF design of the input coupler showed that considerable thought hasgone into this effort, with the result that there seem to be several design choices that can bemade to work. One issue that was not addressed in the presentation to the Committee was thethermal design of the outer conductor, which is tied to 4.5K at the beam pipe, 80K somewhere
along its length, and 300K at the cryostat wall. Relative thermal contraction of the inner andouter conductors will modify Qext, making strong reflections, large VSWR and outerconductor heating likely.
Equal care has gone into the RF design of the coaxial coupler where the effects of differential
thermal contraction will be even more significant, since the operation of the coupler depends
on the existence of relatively high-Q resonances. Thermal effects will shift these resonances,
so the effects of cool-down will have to be considered in the engineering design. The coupler
penetrates into the high RF magnetic fields in the center of the cavity, resulting in excitationof substantial eddy currents. Clearly, the surface resistivity will have to be low enough, andthe thermal conductivity back to the helium bath high enough, such that the current-carrying
surfaces remain superconducting. It would be prudent to use bulk niobium for this coupler. It
is not clear that a sufficiently high quality niobium film can be created for this purpose
without significant effort, and that effort might be better applied to solving other problems ofthe cryostat. Analysis of heat transfer in the coupler will determine the allowable losses due
to eddy current heating of the coupler tip.
9) Crab crossing optics
The Committee encouraged expediting the crab-collision test at KEKB in the previous
Review. The economic option is to use one crab cavity per ring, which is also potentially an
important test prior to producing the full set of 2×2 needed for compensated crab kicks in both
LER and HER.
Since the last review, the KEK staff has developed optics schemes that meet the basic
requirements of the single crab cavity installation. The previous HER lattice has been
modified to reduce the cost of ring components, and the LER lattice is a new design.
The proposed changes are generally reasonable and address most of the needs of the crab
cavity compensation. The crab compensation is potentially a major factor in the performanceof KEKB, as well as in future machines. Demonstration of the effectiveness of crab
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compensation will be a major step forward in colliding beam accelerators. The importance of
crab compensation merits a detailed examination of all the potential effects on machine
performance.
The horizontal position of the beam in the crab cavity must be controlled to approximately ±1
mm to avoid loss of control of the crabbing mode field due to beam loading. (The exact limit
is dependent on the choice of the cavity RF coupling coefficient.) In the HER with βX = 200m this corresponds to 0.5 beam sigma. A reliable feedback system will be needed tominimize beam aborts from exceeding this limit.
The single-particle dynamics analysis was performed with the crab-cavity by the 6D linear
optics code used at KEK (SAD). It includes the coupling of x- and z-emittance, beam sizes of
the coupled beam, and excitation of the first-order synchro-betatron resonances. The latter areof importance with regards to the preferred working point between the half integer and the 1st
sideband. The realization of effective compensation of the crossing angle was implicit in thepresentations. However, details, including the 6x6 (or even 4x4) coupled one turn matrix at
the interaction point were not presented. Similarly, it was not clear that the dispersion in the
crab cavities has to be zero. While this may not be a major issue in KEKB, if it is intended touse a single crab cavity in SuperKEKB, zero dispersion would leave no opportunity to control
beam emittance with wigglers since the wigglers in Oho will have to be removed for
installation of the RF cavity.
The dynamic aperture simulation demonstrates acceptable values and is maintained until thelimits of the detuning of the betatron phase advance between the Crab cavity and the IP fromthe lambda/4 condition are approached.
Collective effects, including the static current-dependent head-tail tilt of a bunch as the bunchis crabbing around the ring circumference, should be the subject of further studies. The
Committee recommends simulation of the single-bunch electron-cloud instability withcrabbing bunches.
Finally, we note that the mask phase to the IP for the D09H1~D09H4 mask is changed by 108
degrees. No implications of the change were presented.
10) Crab cavities for high currents
Those considering the problem of a crab cavity for the high currents of SuperKEKB haveproduced an excellent RF design, and have correctly identified the removal of HOM power asa critical concern. They have accordingly proposed the installation of three different types of
HOM couplers: waveguide couplers sited at the points of maximum electric field in the
crabbing mode, coaxial couplers along the line of symmetry between those points, and beam
pipe absorbers.
The designers plan to dissipate the HOM power at 300K, which should be fairly
straightforward for the coaxial coupler and the beam pipe absorbers, but could be difficult forthe crossed waveguides. Consideration of the engineering design should be an early priority.
Although the coaxial coupler will not couple crab mode power out to the load if it isaccurately located along the line of symmetry, it will nonetheless be supporting large crab
mode eddy currents, with the possibility of significant heating due to its exposure to the RF
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magnetic field. The thermal design of this coupler should therefore be a priority activity,
particularly for the normal conducting version of the crab cavity.
For SuperKEKB the crossing angle is increased from 22mrad to 30mrad. The required
strength of the crab cavities is not increased however since an appropriate increase of the beta
function at the crab cavities is planned. While this measure reduces the required kick strength,
it limits the tolerable transverse impedances to smaller values. Furthermore, larger beta
functions reduce the tolerable closed orbit amplitudes and an orbit feedback becomes
necessary.
The high current crab cavity design presented is rather new and no construction plans havebeen developed, yet. Since the SuperKEKB luminosity prediction relies on the success of the
crab cavity concept, the Committee recommends early planning for the production of highcurrent crab cavities.
The abort gaps cause a shift of the synchronous RF phase that increases with the distance
between the bunch and the abort gap. This leads to different closed orbits for different
bunches in both rings. While the shifts in the two rings lead to displacements at the IP that arein the same direction, their amplitude is not the same and a beam offset of ±14 micron in thehorizontal plane has been computed. Considering the sensitivity to transverse displacements
at the IP that has been observed at PEP-II, we recommend fighting this effect by controlling
the RF phase shift with a feed forward system.
11) RF system upgrade
The existing ARES and SCC RF systems are presently operating with remarkable reliability
and appear to be very well engineered for the present currents. For the planned SuperKEKB
upgrade a current increase to 9.1 A in the LER and 4.1 A in the HER is required. An upgrade
plan was presented that re-uses as much as possible of the present RF hardware. This creates
several major challenges in the ARES and SCC RF system:a) Fast growth of the ARES fundamental RF driven longitudinal -1 mode, τ = 0.3 msb) Longitudinal coupled bunch instability driven by the RF cavity HOMs which exceeds
the radiation damping: τ = 5 ms in LERc) Fast longitudinal coupled bunch instabilities driven by unbalance of the ARES cavity
impedance of 0 and π modes: τ = 3 – 4 msd) Much larger HOM power per cavity for both ARES and SCC cavities: factors of 3 to 7
times higher.
e) Required beam power increased by about a factor 4: 18.4 MW (LER) and 16.0 MW(HER).
f) Increased beam gap transients due to the increased currents.
The proposed plan and R&D programs underway to address these issues look healthy and arelikely to succeed. The very short growth time due to the ARES fundamental mode isincreased to a more reasonable 1.6 ms by increasing the stored energy in the ARES cavities(R/Q decreased from 15 to 9 ohms), which reduces reactive beam loading detuning from 65 to
45 kHz in LER. This requires modifications to the coupling between the ARES cavities. The
coupled-bunch modes will be damped by a bunch-by-bunch longitudinal damper using aDaphne type kicker with a damping time of about 1 ms; adequate for b) and c), but marginal
for a).
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The existing mode -1 damper using the RF system will be upgraded to a much faster damping
rate. A detailed plan on how to achieve this was not presented. It is suspected that the groupdelay of the present narrow band signal processing of the mode -1 damper does not permit afast enough damping rate to damp the τ = 1.6 ms with an adequate safety margin (say 3 to 4).
Another worry is how the transfer function of the heavily loaded cavity changes with highbeam loading. Under heavy beam loading, the geometry of the klystron and beam RF vectors
is such that an amplitude modulation of the klystron is required to achieve a phase modulationof the cavity voltage.
The Committee recommends that these issues be studied in more detail to demonstrate fast
damping rates of the -1 mode in the LER at high current. Operating the cavity at a lower
voltage than nominal can simulate the modifications of the klystron and cavity transfer
functions due to heavy beam loading.
To provide the required increase in beam power, the existing ARES RF system will be
modified such than one klystron only supplies one cavity instead of two, as only a modest
increase in total voltage is called for. Later, additional ARES and SCC cavities will be
installed, more than doubling the total number of klystrons: 28 klystrons per ring. The SCC
cavities will be modified for increased beam power per cavity. The loss factor will be
reduced from 2.46 to 1.69 pC/cavity by increasing the beam pipe diameter (150 to 220 mm).
The HOM power handling capability will need to be increased to 57 kW per cavity. These
modifications allow for the increased beam power, while maintaining an acceptable increase
in total HOM power and beam gap transients.
To reduce the beam gap transients at the higher currents, the ion clearing and abort gap will
be reduced from 5% (0.5 µs) to 2% (0.2 µs). The implications of the reduced abort gap were
not presented at this meeting.
12) ARES upgrade
The ARES upgrade and R&D plans that were presented look solid and well justified. The
coupling between the Accelerating cavity and the Coupling cavity needs to be increased toincrease the stored energy. R&D is in progress to modify the waveguide HOM dampers tocope with 80 kW of HOM power per cavity and to test the bullets with a higher power L-band
klystron. Also the ‘Grooved Beam Pipe’ HOM loads need to be tested to 20 kW per cavity.
They may possibly evolve into the “Winged Chamber” HOM loads already used for the
movable mask HOM loads. These need to be tested for power levels up to 5 kW per absorber(bullet). The input coupler will need to be upgraded and tested up to 1 MW, and a test stand toprovide this power is being set up. There is a problem with single surface multipacting thatwill be addressed by a TiN coating of the outer conductor of the coaxial line of the input
coupler.
13) SCC upgrade
The two key issues for the superconducting cavities will be the increase in HOM power thatneeds to be dissipated in the ferrite loads, and the need for a 220 mm gate valve occasioned by
the increase in the size of the beam tube. The existing design of the ferrite-loaded damper isthought to be limited to below 60 kW by the need to keep the ferrite temperature below its
Curie point at 280°C. Although this problem is real, a test stand has been set up to obtain
more information to guide redesign, and an effective solution is likely.
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Higher Order Mode power heating of the new gate valve is also a real issue that would benefit
from application of additional engineering resources.
14) Klystrons
There are 26 klystrons currently in use at KEKB. The klystron lifetimes have been good, withtube lifetimes of order of about 18 thousand hours for the Philips tubes and about 47,000
hours for the Toshiba tubes. One Toshiba tube is still working after 73,000 hours.
A recent Toshiba klystron has reached 1.3 MW output power in a bench test, a world record.
The window of that klystron operated well at 1.3 MW, and has a special design and coolingmechanism.
There has been much work to increase the power capability of the output windows. Using atest area, the klystron group has successfully developed a coating procedure for the TiNxOy
layer that provides for the best surface structure and high resistivity. This anti-multipacting
coating is optimized at about 100 angstroms.
The number of RF stations will increase with SuperKEKB up to 58, 32 more stations than are
now present. With this large number of tubes and with the additional tubes needed to replace
failed klystrons over the upcoming years at the existing KEKB, there is some concern that the
klystron production rate in industry may not keep up with demand. Careful production
planning will be needed.
15) Vacuum system upgrade
The beam parameters for the HER and LER vacuum system upgrade are 4.1 A and 9.4 A
respectively with a total of 5,018 bunches. The key issues to be addressed are the intense
synchrotron radiation, the high bunch currents and the very large total stored current. With thebunch length of 3 mm, impedance considerations and HOM power losses dictate the design ofthe vacuum system.
With the large number of bunches, the current per bunch is less than at present and is notexpected to pose problems. Nevertheless, in order to add some safety, it is recommended thatthe vacuum system design should be more conservative and should be based on a larger bunch
current, which needs to be defined.
The vacuum upgrade assumes that the present limitations by the electron cloud instability has
been overcome and that this effect no longer limits the minimum bunch spacing. It will beessential to start an intensive research program to meet this challenging goal with the aim of
exploring a variety of possibilities.
The main hardware of the upgraded vacuum system for both rings is a completely redesigned
copper vacuum chamber with an antechamber. The choice of the antechamber concept offers
the possibility to absorb the intense synchrotron radiation distributed along the cooled face ofthe chamber and thus far removed from the beam. It has been shown that photoelectrons
produced in the antechamber no longer reach the beam with the addition of a solenoid fieldaround the beam pipe, and their contribution to the electron cloud will be suppressed by morethan two orders of magnitude (a factor of 300 has been deduced from the measurements).
Page 12 of 22

Unfortunately, direct measurements in the LER have shown that the number of secondary
electrons originating in the beam duct proper will still be sufficient to trigger multipacting. It
will be essential to address this problem of secondary electrons.
Beam induced outgassing imposes a very effective pumping system with the very large fluxof synchrotron radiation photons. A combination of ion pumps and NEG pumps has been
proposed in the present design, with the NEG ribbons positioned above and below theantechamber. The total pumping speed has been estimated to be sufficient to achieve therequired pressure of 5 10-7 Pa. However, the pumping capacity is small because of the limited
quantity of getter material, and hence the interval between the reconditioning of the getter
appears impractically short. It will be important to improve this situation by either increasing
the getter capacity or by adding more pumps to the system. This is an entirely new regime ofbeam currents and may also need a new concept for the vacuum pumps.
The proposed design of an electron beam welded copper chamber is technically very
challenging, since it has to meet very tight mechanical tolerances in addition to the ultra-highvacuum requirements. A prototype chamber has been tested and installed in the ring. The
wall thickness of approximately 6 mm raises some concern, since it reduces the height of theantechamber.
Since the chambers have to be mounted in the magnet gap mechanical tolerances are very
tight, and the Committee is concerned about the very limited space for the NEG ribbons.
Low HOM losses and small impedance represent very stringent requirements for the design
since any section change must be kept very small. All components like flanges, bellows andvacuum valves are critical items because of the very large beam currents. The antechamber
requires tapered end sections for impedance reasons. It is necessary to define a maximum
step size for the design of the vacuum hardware and to specify an acceptable angle for tapered
cross section changes.
The LER bending magnets produced a synchrotron radiation fan that could hit thedownstream bellows and the quadrupole chambers. The layout should ensure that this is not
the case and, if necessary, a shift of the bending magnets towards the upstream quadrupole
could improve the situation.
A novel design of a comb RF-bridge for the bellows was presented. The design looks very
promising and should guarantee a smooth cross section of the beam aperture. The Committee
agrees that the proposed design should be adapted to different cross sections, and it would bedesirable to obtain a larger stroke and more flexibility. In-situ testing of this new RF-bridge
design for the expansion bellows has been very satisfactory.
Movable masks and HOM dampers require new solutions since the estimated power values
are prohibitively large. The proposed design with a ceramic rod support must guarantee thatelectric charge-up of the device is prevented
Some further optimization of pumping slots is recommended in view of the 3 mm bunch
length. The actual design appears to have rather large slots and may not avoid the problem of
RF fields penetrating into the pump duct and heating up the structure.

Page 13 of 22

The Committee strongly supports the study of possible means of coating against multipacting,e.g. a getter film like that which has been adopted for the room temperature long straightsections in the LHC. This may imply baking to activate the getter coating. A method, which
has been tested in the laboratory at CERN, has been to produce carbon films using glow
discharge with a suitable gas (Freon).
Both measurements and simulations of the electron cloud have shown that it forms vertical
stripes in the dipoles. A possible means to reduce the intensity of the electron cloud could be
to introduce slots through which electrons can escape and reach a clearing electrode that isshielded from the beam.
The Committee notes that the proposed design pressure of 5x10-7 Pa may not be sufficient toallow control of fast ion instabilities in SuperKEKB.
16) Interaction Region upgrade overview
The luminosity upgrade of SuperKEKB is based on three principles: more current, crab
crossing, and lower beta functions in the interaction region. It is proposed to reduce thevertical beta function from 10 mm to 3 mm in both rings, which requires a reduction of thebunch lengths from 5 mm to 3 mm. The proposed horizontal emittances of 24 nm and thehorizontal beta functions of 20 cm have been optimized using strong-strong beam-beamsimulations. The crossing angle has to be increased from 22 mrad to 30 mrad in order toseparate the beams sufficiently before the first aperture.
No simulations of parasitic collisions were presented, and these should be computed for thefull number of bunches.
The physical aperture of the ring becomes too small to accept the current positron emittanceof the linac so that a damping ring for positrons becomes necessary. This leads to positron
emittances in the linac that are half the electron emittances. It is planned to implement the
new IR design several years before the lepton species are exchanged in the LER and HER.
Therefore the new IR is specified to accept the larger electron emittance in the LER as well as
in the HER. It is recommended to study whether the IR design could be improved if it only
had to accommodate the final choice of lepton species. Furthermore, it is recommended to
study how the IR could be improved if the electron beam would also be damped in thedamping ring. The required injection and extraction systems for the reverse direction of theelectrons in the damping ring could be worth the investment.
Heating of IR components due to HOMs will become more pronounced with shorter bunches
and needs to be studied. Studies of heating due to synchrotron radiation hitting IR
components has started, but needs to be performed in much more detail including CSR andscattering of radiation. Studies of detector backgrounds also need to be added, including
electron loss, secondary electrons, and possibly Compton scattered radiation.
In the current IR upgrade plans, the boundary between the beam line magnets and Belle is notchanged, making major changes in Belle unnecessary. Nevertheless it is recommended toproceed with Belle upgrade plans simultaneously with KEKB upgrade plans so that the timing
can be synchronized.

Page 14 of 22

17) Superconducting magnets
The SuperKEKB design team has made excellent progress in designing new magnets for theInteraction Region, including a novel 6-layer design for QCS. This design has favorable
effects on the operating margin of the refrigerator and ideally produces a quadrupole fieldwith low harmonic components. The newest design better balances the offsets of themagnetic center between QSCR and QSCL magnets. A 2-section anti-solenoid has been
designed to reduce the longitudinal forces to acceptable values. The influence on the field in
the BELLE tracking volume is similar to the present IR magnets. This design has thepotential to offer challenges in construction and operation and the Committee recommends
early prototyping of the magnet.
The upgrade of the IR design also calls for a reduction on the distance from the IP to the final
focusing quadrupoles. To achieve this, the team has had to come up with a design thatembeds the quadrupole inside the compensation solenoid. The present solution is designed tobe compact and to have minimum electromagnetic forces by using an innovative split
solenoid. At this time, the design has all been done using 2-D simulations. The Committee
recommends that it be checked with 3-D codes as soon as possible, followed by prototypingof the compensation solenoids so that they can be assembled with the QCS to confirm bothmagnetic and mechanical designs.
Based on the design of the magnet and experience with the present superconducting
quadrupoles in the KEKB IR, the field harmonics are likely to be acceptable. The field
quality is critical with the large (300-400 m) vertical beta in these quadrupoles and the effectsof conductor placement errors should be evaluated.
The Committee also recommends that the design team estimate the magnitude of the flux ofhigh-energy Compton-scattered synchrotron radiation photons contributing to heating of the
IR region superconducting magnets.
18) Special magnets
A preliminary design of the special magnets for the SuperKEKB IR was presented in thismeeting. There are 4 special magnets for HER and 2 for LER. The design parameters of these
normal conducting magnets are closely related to the crossing angle, and the beam aperture,
acceptance and aperture for synchrotron radiation look reasonable. Due to the larger crossing
angle of 30 mrad, the space between QC1 and detector is very tight, since the QCS heliumtransfer line, support table, vacuum chamber, etc. must also be installed in this space. Hencethe Committee recommends that further design efforts on QC1 and QC2 should be made,including the leakage field effect on QC1 magnets, and the interference with the vacuum
chambers, Belle detector, and the support system.
19) Optics upgrade
The KEKB lattice design is sufficiently flexible that the arc lattice does not require significant
modifications for SuperKEKB, so essentially all the modifications occur in the IR. The
present optimization suggests that the beta x* should be reduced from the present 30 cm to 20
cm, and the crossing angle should be increased from 22 mrad to 30 mrad. The Committee ispleased to see these study efforts, and suggests that it be continued as it expects that thedesign will continue to evolve.
Page 15 of 22

One issue of particular concern is the optics requirement to provide a short 3-mm bunch
length. The present approach is to provide the short bunches by using a small momentum
compaction lattice. However, this would only work if (a) the microwave instability is wellunder control, (b) the reduced synchrotron tune does not make synchro-betatron resonances
worse and (c) the dynamic aperture has been fully evaluated. These questions will require
more studies to settle. The Committee suggests that some experiments be performed to
explore the feasibility of short bunches with a small momentum compaction lattice.
Locations exist for the possible installation of crab cavities in the IR. The betatron phaseadvances are slightly off, and the beta function is too small. More work is needed to makesure this option is optimized in the lattice design.
The design as presented provides adequate, but tight, dynamic aperture for both rings. Morework is needed to increase the dynamic aperture, particularly since the dynamic aperture is
expected to deteriorate when various error sources are included. If necessary, sextupole
movers may be considered.
It is not clear whether the optics must satisfy the condition that dispersion must vanish at the
crab cavity. The Committee suggests reviewing the beam dynamics of this issue. In the same
review, the strength of synchro-betatron coupling due to crab cavity should be included.
The RF transient in the bunch spacing due to beam loading will cause a bunch-to-bunch
separation of ±14 microns. The effect of this separation on beam-beam interaction should bestudied, perhaps by simulation.
20) Beam Instabilities
The Electron Cloud Instability (ECI) has been the major problem in LER during thecommissioning period. To achieve the SuperKEKB parameters, the beam pipe will be
seriously modified to suppress the electron cloud. The recent results of simplified simulationsof the electron cloud predict stability of the design bunch. However, a realistic simulationaccounting for the antechamber shape (and the solenoid field imposed) is highly advisable asa next step.
A preliminary estimation of the resistive wall effect has been carried out, even before theimpedance budget becomes available, including all the new components to be designed. The
Closed-Orbit Instability threshold estimation is optimistic, however the safety margin of its
threshold is surprisingly small for the design beam intensity of 6×1014! Detailed studies ofthis effect should be pursued.
On the other hand, the growth rate of the Coupled-Bunch Instability due to resistive wall isfound to lie well within the damping capability of the bunch-by bunch feedback system. In
view of the important limitation caused by this fast growing instability, ways to increase theuseful gain limit of the transverse bunch-by-bunch feedback systems should be investigated.
Having four systems with feedback delays of a quarter of a turn instead of the present one turnsystem (or effectively 1.5 turns with 2 equal taps) could potentially result in four times fasterdamping rate, but straight signal paths cutting across the arcs must be provided to match thebeam flight time. This also assumes that no power limit will limit the gain. To confirm theexpected gains, experiments should be carried out to compare the measured maximum
Page 16 of 22

damping rates of a one-turn delay system with the optimum gain that can be expected fromtheory.
The ion instability for electrons in the LER (rather than in the present HER) is shown to be
detrimental to the vertical emittance in spite of the fact that beam loss is likely to be prevented
by the feedback at its gain limit. These results put a question mark on the polarity switch
proposal. The Committee recommends clarifying the pros and cons of the polarity switch assoon as possible. It is suggested that a controlled vacuum leak experiment be designed andperformed. Results can then be extrapolated to provide more guidance for the SuperKEKB
charge switch scenario. Beam shaking can be considered in this exercise.
The detailed short-bunch feasibility study has high priority to justify the upgrade plans. The
Committee recommends putting the emphasis on obtaining a detailed impedance budget. The
impact of the Coherent Synchrotron Radiation (CSR) on the short bunch stability should also
be studied, with a complete account of the transient CSR shielding effects, using the CSR
shielding code now available at KEK.
21) Beam diagnostics system upgrade
The present KEKB has a complete variety of beam diagnostic techniques, and they performed
successfully during the commissioning period. Special mention is due to the gatedmeasurements of the bunch parameters (size, tune) as a function of its position in the bunchtrain. These measurements were very efficient for understanding the electron-cloud effects.
The high-current operation of the SuperKEKB presents a challenge to existing diagnostic
techniques, both RF and synchrotron radiation based. The serious R&D program presented to
the Committee is aimed at improvement of diagnostics and making it compatible with thedesign parameters of SuperKEKB. The Committee concurs with the diagnostics R&D
program and recommends speeding up the development and testing of the prototype
diagnostic units at the existing KEKB rings.
The Committee puts the emphasis on continuing machine studies on bunch lengthening(streak-camera, other techniques), and improving the bunch-length measurement accuracy, inview of the short bunch lengths needed for the SuperKEKB.
22) Installation
A preliminary time schedule was presented in this meeting for the design, construction andinstallation of vacuum system, magnet system, RF system, BPM system, IR vacuum and IR
magnets and utilities for SuperKEKB. Most components of these systems were listed in theschedule. The Committee recommends that the schedule for the damping ring and linac
upgrade be integrated into the schedule, and the operating schedule and beam performance
profile should also be included to have a clear and complete time schedule for the whole
SuperKEKB plan.
The schedule showed that the major production period would be two years after the start ofthe project, with installation a year later. The most critical issue in the installation may be thereplacement of all vacuum chambers in 14 months. However, by the estimation of time taken
to remove the upper halves of about 1250 magnets, to replace about 2000 beam pipes withnew ones, and to re-install the upper halves of these magnets, it seems to be possible to finish
Page 17 of 22

this job within this tight time schedule. However, the additional installation time requiredwith the new bellows and RF shields should be further investigated. A more detailed andcomplete time schedule is foreseen in the near future.
23) Linac upgrade: overview
The injection system will also be upgraded to provide the very high beam currents in the tworings; in particular, both rings will be injected with 2-bucket beams. A flux concentrator will
be installed on the positron target. For charge switching, the positron beam will be sent to adamping ring at 1 GeV, and the following linac will be C-band with 42 MV/m acceleration
gradient, twice that of the S-band linac. New modulators of a much more compact design areneeded because the number of klystrons is to be doubled from 24 to 48, while the klystronhousing is limited in space. A waveguide resonant ring was built to test the window
breakdowns. These R&D studies have been continuing well and the Committee finds themsatisfactory.
A C-band accelerator module has been high power tested and was found to be mostly
satisfactory. The only problem concerned the input coupler that breaks down near the peak
power. A more rounded coupler design should solve this problem, and will be incorporated in
the second C-band prototype. The Committee looks forward to the resolution of this problem.
24) Linac upgrade: C-band linac progress - RF source
Two C-band RF assemblies have been designed, constructed and tested, and one of them has
been successfully used in the high power test and beam test for the first prototype of the Cband accelerating structure.
A lot of present S-band components of the RF assembly, such as many parts of low levelsystem, pulse transformer, PFN, thyratrons, etc., are reused in the C-band RF assembly for thecost reduction.
The C-band modulator is well designed to be compact, using an inverter power supply insteadof the original large charging system. Hence the total 48 C-band RF units can be installed in
the same space of existing 24 S-band RF units. The measured pulse stability has reached its
design value of ±0.15%, but the flatness from pulse to pulse of 1.3% (peak-to-peak) is larger,
caused by an unstable thyratron. After changing the thyratron, the stability was drastically
improved.
A new type of C-band RF window has been developed. Unlike the pillbox type window, it
uses a mixture of two modes (TE11 and TM11) to generate a traveling wave in the ceramic of
the window to lower the electric field strength at the edge of the window and reduces theelectron emission to help avoid breakdown in the window. This window has been successfully
tested using the newly constructed C-band high power resonator ring.
The Committee congratulates the KEKB Linac RF group for the good progress in the C-band
RF system development, and recommends the further studies of improving its stabilities andreliability.

Page 18 of 2225) Linac upgrade: C-band linac progress - accelerator section
A C-band accelerating structure has been developed in order to double the accelerating
gradient for the increase of the positron energy from 3.5 GeV to 8.0 GeV. The first proto-typeof 1-meter C-band structure is designed as a scale-down of the present S-band 2-m structure,and has been constructed, high power tested and successfully beam acceleration tested withthe acceleration gradient of 42 MV/m. The Committee congratulates the KEKB Linac Groupfor this impressive progress since last review meeting. The remaining problem with thisstructure is RF breakdown around the input coupler, which will be improved in the 2nd
prototype structure.
The Committee encourages further work to develop a 2-meter C-band structure, which will
provide a complete test of the proposal for the future positron energy upgrade.
26) Linac upgrade: beam instrumentation
Beam energy and position feedback are presently used successfully in the linac. Energy
spread can be measured with a fluorescent screen monitor at a location with dispersion, but
the measurement is destructive. Feedback to stabilize beam energy spread is highly desirable.
An eight electrode strip line monitor with associated acquisition and signal processing has
been developed which allows measurement of the quadrupole moment with respect to thebeam centre <x2> - <y2> and eliminates the contribution from position errors <x>2 - <y>2
present in the quadrupole moment with respect to the pick-up centre. If dispersion is
sufficiently large, the energy spread will make a dominant contribution to the quadrupole
moment measured thus allowing a non-destructive monitoring of the energy spread.
Feedback to correct this is planned, but the details of how to use this signal to correct thecauses of momentum spread was not presented. Usually the momentum spread is minimized
by maintaining the bunch on the RF crest. It may be difficult, but not impossible, to use theenergy spread signal from the quadrupole monitor to correct the phase of acceleration.
As an alternative feedback scheme to minimise the energy spread, the modulation scheme
implemented at Jefferson Laboratory could be considered. The accelerating phase is given atiny modulation with a low frequency signal and the resulting energy modulation is measured
at a dispersive location by synchronous detection of the position modulation. The off-crest
phase (with sign) is proportional to the first harmonic of the position modulation, so it can beused to correct the phase in the right direction. (See Tiefenback, Lebedev, and Musson, PAC
1999).
In any case the non-destructive monitoring of the momentum spread by the quadrupole
moment is extremely useful as it permits the measurement of differences between the twobunches. At Jefferson Lab thin foils and OTR are used for non-destructive monitoring,
however these techniques do not give information on the time structure and cannot separate
the two bunches.
27) Design of damping ring
A Damping Ring (DR) is proposed for use with the injector of SuperKEKB to reduce theemittance of the positron beam before it is subsequently accelerated in the linac and injected
Page 19 of 22

into the SuperKEKB positron ring. The reduced emittance will allow for cleaner injection,and thus an enhanced filling time and lower detector backgrounds. The damping ring will belocated midway along the linac and have an energy of about 1 GeV.
The positron beam from the upstream linac that enters the DR will have a large energy spread(about ±4%) that needs to be accepted by the DR. The acceptance will be greatly improved by
the addition of the proposed Energy Compression System ESC to reduce the energy spread to±1.5 % that can be safely accepted by the DR. Similarly, a bunch lengthening system on the
beam line after extraction from the ring but before the linac is used to match the bunch lengthwith the C-band linac. The DR magnetic lattice design is a new design and is very reasonable.
This design gives a factor of 100 reduction in beam emittance. Four bunches will be stored ata time and two bunches will be produced at a rate of 50 Hz.
The Committee supports the planned mode of operation where the linac and DR can be
operated in pulse mode where either beam can be injected continuously into the SuperKEKB.
A damping ring for the electrons would also allow for an improved rapid injection of theelectrons into the high-energy ring and lower backgrounds but is not planned at this time. The
Committee suggests considering the use of the same damping ring for both electrons andpositrons while alternating the injected beams on successive pulses.
28) Beam Lifetime at SuperKEKB
The various contributions to the beam lifetime at SuperKEKB were presented, including theeffects of quantum fluctuations, Touschek, beam-beam, luminosity, and vacuum. The
combined overall lifetimes are about 20 and 50 minutes with and without the beam-beameffect, respectively, for both beams. These values require that the beams be continuously
injected to maintain luminosity. The Committee recommends that the required injection rate(including all of the efficiencies) be checked against the planned production rate of particles
from the upgraded linac and damping ring complex. Furthermore, the Committee suggeststhat the required vacuum pressure level needed in each ring be carefully specified so that thevacuum designers can adequately plan.

Page 20 of 22

Appendix A
KEKB Accelerator Review Members
Andrew Hutton

JLabChairmanAlexander Chao

SLAC

Warren FunkJLabOswald Gröbner

CERN (retired)Georg Hoffstaetter

Cornell

Won Namkung

Postech (Unable to attend)

Fleming Pederson

CERN

Eugene A. Perevedentsev

BINP

David Rice

CornellJohn Seeman

SLAC

Wang Shuhong

IHEP

Katsunobu OideKEK Secretary, Accelerator

Masanori Yamauchi

KEK Secretary, BELLE

Page 21 of 22

Appendix B
Agenda of the Eighth KEKB Accelerator Review Committee
Feb. 16 (Mon.)
8:30- 9:00
9:00- 9:15
9:15- 9:30
9:30-10:10
10:10-10:30
10:30-11:00
11:00-11:30
11:30-12:00

Executive session
WelcomeOverview of KEKB project
KEKB status
Break
Experience on High Current
Physics of BELLE, today and tomorrow
Upgrade plan overview

12:00-13:00
13:00-13:30
13:30-13:50
13:50-14:10
14:10-14:30
14:30-14:50
14:50-15:10
15:10-15:30
15:30-15:50
15:50-16:15
16:15-16:40
16:40-17:00
17:00-17:30

Lunch
Beam-beam interaction
Crab cavities: Status & Plan
Crab cavities: Cryostat R&D
Crab cavities: Nb-Cu coaxial coupler R&D
Crab crossing optics
Crab cavities for high currents
Break
RF system upgrade
ARES upgrade
SCC upgrade
Klystrons
Vacuum system upgrade

17:30-18:30
18:30-20:00

Executive session
Reception

Feb. 17 (Tue.)
8:30- 9:00
9:00- 9:20
9:20- 9:40
9:40-10:00
10:00-10:20
10:20-10:40
10:40-11:05
11:05-11:30
11:30-11:50
11:50-13:00
13:00-13:20
13:20-13:40
13:40-14:00
14:00-14:20
14:20-14:50
14:50-15:10

Executive session
IR upgrade overview
Superconducting magnets
Special magnets
Optics upgrade
BreakBeam Instabilities
Beam diagnostics system upgrade
Installation
Lunch
Linac upgrade: overview
Linac upgrade: C-band linac progress - RF source
Linac upgrade: C-band linac progress - accelerator section
Linac upgrade: beam instrumentation
Design of damping ring
Beam lifetime

15:00-18:00
18:00-20:00

Executive session
Working dinnerFeb. 18 (Wed.)
8:30-10:30
10:30-11:00
11:00-11:30

Executive session
Interaction with KEKB staff members
Closing

Page 22 of 22

Y. Totsuka
K. OideH. KoisoY. Suetsugu
M. Hazumi
Y. Ohnishi
K. OhmiK. Hosoyama
H. NakaiK. Nakanishi
A. Morita
K. Akai
K. AkaiT. Kageyama
S. Mitsunobu
S. Isagawa
Y. Suetsugu

Y. Funakoshi
N. Ohuchi
M. Tawada
H. Koiso
H. Fukuma
J. Flanagan
R. Sugahara
T. Kamitani
S. Michizono
T. Kamitani
M. Satoh
M. Kikuchi
Y. Ohnishi