Super KEKB Project Status Mika Masuzawa KEK Contents

Super. KEKB Project Status Mika Masuzawa (KEK)

Contents 1. Introduction – – Super. KEKB Luminosity goal What was presented at XI Super. B WS @LNF Dec. 2009 by Ohmi 2. Strategy for nano-beam scheme – – Much smaller y* Larger crossing angle at IP & low emittance Same xy as KEKB Higher beam currents than KEKB 3. What we need – – – Lattice design for the Nano-beam scheme IR design Hardware 4. Summary　(& budget) – – – Where we are The comments from 15 th KEKB review last month Budgets

1. Introduction Super. KEKB Luminosity goal What was presented at XI Super. B WS at LNF Dec. 2009 by Ohmi

Luminosity goal 8 x 1035 cm-2 s-1

We worked hard and hard KEKB exceeded 21/nb/s with crab crossing but the beam-beam parameter is still 0. 09 High current & high beam-beam scheme Slides @XI Super. B General Meeting LNF, December 2009 by K. Ohmi (KEK) Low emmittance “Nano-beam” scheme was announced.

2. Strategy Nano-beam scheme – Much smaller y* – Larger crossing angle at IP & low emittance – Same xy as KEKB – Higher beam currents than KEKB

Nano-beam Scheme • The scheme proposed by P. Raimondi and Super. B Group. • y* as small as possible: 0. 27/0. 41 mm. • Assume beam-beam parameter = 0. 09 which has been already achieved at KEKB. • Change beam energies 3. 5 / 8 -> 4 /7 Ge. V to achieve longer Touschek lifetime and mitigate the effect of intra-beam scattering in LER. H. Koiso KEKB Review Feb. 2010

Three key factors for a factor of ~40 gain Stored current: Beam-beam parameter: 1. 7 / 1. 4 A (e+/ e- KEKB) 0. 09 (KEKB) 3. 6 / 2. 6 A (Super. KEKB) 0. 09 (Super. KEKB) Lorentz factor Classical elec. radius Beam size ratio Geometrical correction factors due to crossing angle and hour-glass effect 1(xy) x 20(1/ y*) x 2(I) = 40 Vertical β at the IP: 0. 21 × 1035 cm-2 s-1 (KEKB) 6. 5/5. 9 mm (KEKB) 8× 1035 cm-2 s-1 (Super. KEKB) 0. 27/0. 41 mm (Super. KEKB)

Colliding bunches e- 2. 6 A Nano-Beam Super. KEKB e+ 3. 6 A New Superconducting / permanent final focusing quads near the IP Replace long dipoles with shorter ones (HER). Add / modify rf systems for higher currents. Redesign the HER arcs to reduce the emittance. Low emittance gun Low emittance electrons to inject Ti. N coated beam pipe with antechambers Low emittance positrons to inject New positron target / capture section ~40 times gain in luminosity

Super. KEKB Parameters as of Feb. 15, 2010 KEKB Design KEKB Achieved : with crab Super. KEKB Energy (Ge. V) (LER/HER) 3. 5/8. 0 4. 0/7. 0 Crossing angle (mrad) 22 0 (crab) 83 βy* (mm) 10/10 5. 9/5. 9 0. 27/0. 41 εx (nm) 18/18 18/24 3. 2/2. 4 σy(μm) 1. 9 0. 94 0. 059 ξy 0. 052 0. 129/0. 090 0. 09/0. 09 σz (mm) 4 ~6 6/5 Ibeam (A) 2. 6/1. 1 1. 64/1. 19 3. 6/2. 62 Number of bunches 5000 1584 2503 1 2. 11 80 Luminosity (1034 cm-2 s-1) Parameters presented at KEKB MAC Review Feb. 15 -17, 2010

3. What we need • Lattice design for the Nano-Beam Scheme • IR design • Hardware

Lattice design for the Nano-Neam Scheme • Low βy* • IR optics design, Local Chromaticity Corrector (LCC) • Low emittance • HER - Increase number of arc cells • LER - Longer bending magnets & change the wiggler layout • Wide dynamic aperture IR optics design QC 1, 2 magnets closer to IP Separated final quadrupole magnets Beam energy was changed due to short Touschek lifetime for LER: 3. 5 to 4. 0 Ge. V, HER: 8. 0 to 7. 0 Ge. V Design target (Touschek) lifetime is > 600 sec (min. 400 sec)

Lattice design for the Nano-Neam Scheme A. Morita KEKB Review Feb. 2010

A. Morita KEKB Review Feb. 2010

Super. KEKB arc section Low emittance • HER - Increase number of arc cells • LER - Longer bending magnets & change the wiggler layout LER Longer dipole HER Cells change in HER Grey: Super. KEKB Black : present KEKB

Super. KEKB IR Left LER HER Low βy* , smal beam size • IR optics design Local chromaticity corrector in both LER & HER Grey: Super. KEKB Black : present KEKB

Super. KEKB IR Right HER Low βy* , smal beam size • IR optics design Local chromaticity corrector in both LER & HER Grey: Super. KEKB Black : present KEKB

Super. KEKB wiggler section Low emittance • HER - Increase number of arc cells • LER - Longer bending magnets & change the wiggler layout

3. What we need • Lattice design for the nano-beam scheme • IR design • Hardware

IR design QC 1 magnets closer to IP Superconducting & permanent magnets 83 mrad Full crossing Boundary between accelerator & detector is same as at present M. Tawada KEKB Review Feb. 2010

IR design Superconducting magnets • Leakage fields of SC magnets canceled by correction windings on the other beam pipe • Warm bore Permanent magnets (pros) • Cryostats can be made small • Assembly of vacuum chamber can be simple • Vacuum pump can be located near IP Permanent magnets (cons) R&D work Temperature dependence Tunability (an additional magnet is needed when changing the energy) M. Tawada KEKB Review Feb. 2010

Belle rotation Pros. No conclusion – We don’t need to rotate HER orbit – Extra space for PXD/SVD cables and tubes will be available – EM force will be reduced if the radius of anti-solenoid would be smaller Cons. – Expensive (3 oku yen for belle rotation) – Need to modify the concrete bases and shields – Belle people worry about the damaging Cs. I calorimeter yet M. Tawada KEKB Review Feb. 2010

3. What we need • Lattice design for the Nano-Beam Scheme • IR design • Hardware

Injectors & Damping ring • The injected beam should have very low emittance because of poor dynamic aperture of the main rings. • We have decided to construct a damping ring for the LER and a low emittance RF-gun for the HER.

(1)Damping Ring for LER Injection M. Kikuchi KEKB Review Feb. 2010 Lattice Design almost completed. (2)Low emittance RF gun for HER S. Ohsawa, T. Sugimura KEKB Review Feb. 2010

Vacuum Straight duct Bellows chamber BPM RF-shield (gate valve) Y. Suetsugu Feed through for NEG Gate valve Basic R&D on components has almost finished. Optimization of design should be required considering the cost. Aluminum beam ducts can be used for LER.

Vacuum: Electron cloud suppression Beam ducts with ante-chambers – Low beam impedance • Pump ports and SR masks locate in an antechamber. – Fit to the existing (reused) magnets. Material – LER: Aluminum alloy is now available. – LER wiggler sections: Copper is required. – HER: Copper is required. Pump (NEG) is installed into one of the ante-chamber (inside of the ring) – Distributed pump system for effective pumping. S ~ 80 l/s/m. – Inserted from end flanges. NEG strip Y. Suetsugu KEKB Review Feb. 2010

Vacuum: Electron cloud suppression Clearing electrode has been said to be very effective to reduce EC in magnetic field. – Impedance and heating of electrode have been serious problems for intense e+ beam. ⇒Very thin electrode structure was developed. – 0. 2 mm Al 2 O 3 and 0. 1 mm tungsten (W) electrode formed by a thermal spray method. 1 k. V is OK. – Good heat transfer and low beam impedance – Flat connection between feed-through and electrode An insertion for test with a thin electrode 400 mm x 40 mm Tungsten (t 0. 1) Connection to feed through To feed-through Al 2 O 3 (t 0. 2) Feed-through Stainless steel Y. Suetsugu, H. Fukuma, M. Pivi and L. Wang, NIM-PR-A, 598 (2008) 372 Y. Suetsugu KEKB Review Feb. 2010

Vacuum: Electron cloud suppression Grooved surfaces: geometrically reduce SEY. – The properties were studied in a wiggler magnet using the same experimental setup to that of the clearing electrode. – B = 0. 78 T (Roundness) Rt B Parameters of grooves – Material: Cu, Al-alloy, SS – : 20~30 , Rt: 0. 1~0. 2 mm d – d: 2. 5~5 mm by L. Wang et al. (Depth) For countermeasures against electron cloud in a dipole field, clearing electrodes and grooved surface are found to be very effective. Groove 7 R 4 Y. Suetsugu, H. Fukuma, M. Pivi and L. Wang, Monitor NIM-PR-A, 604 (2009) 449 Y. Suetsugu KEKB Review Feb. 2010

RF system Higher-Order Mode dampers 2 ARES cavties/klystron to 1/klystron for more power Low total RF voltage is obtained while each cavity is operated at a high voltage.

Magnet and power supplies • Main dipole magnets need to be replaced for both HER and LER rings. – LER dipoles become longer (Leff 0. 89 m ⇒ 3. 99 m) : 104 needed – HER dipoles become shorter (Leff 5. 91 m ⇒ 3. 8 m) : 144 needed • 112 wiggler magnets with shorter pole length (half pole)& 56 single pole wiggler needed. • More dipole, quadrupole and sextupole magnets are needed in HER since number of cells increased (~30 % more magnets). ⇒Magnet & power supply design & production & field measurements (from 500 to 1000 magnets need to be measured) • Most of the magnets will be relocated to new positions. ⇒Realignment is necessary. Review committee Report The tightest part of the schedule is the removal and reinstallation of the tunnel components including the magnets, supports, and vacuum beam ducts. The planning for the schedule for these activities should be taken to the next level of sophistication to resolve potential conflicts with resources. Interferences with other laboratory resource needs should be determined and taken into account.

Magnet removal Magnet lifted up Photos are from the KEKB construction days, shown reversely. Magnet on the air pallet Move it up to 1 st floor of the access shaft by crane (one by one) to a storage area (where? ) Magnet taken away from the beam line to an access shaft. (There are 4 access shafts in the tunnel)

Arc section Removing the old (orange) base plates, repairing the floor , surveying, marking the new beam line & installation of the new base plates.

Summary Where we are

40 • Summary Nano-Beam Design: – Lattice: solutions exist, preserving the present tunnel. Optimization of dynamic aperture is ongoing. – IR: large crossing angle, independent quadrupoles for both beams. – Electron cloud mitigation has been studied at KEKB. – RF system will be added and modified to store beam currents twice those of present KEKB. – Design of e+ damping ring has been done. – Low-emittance electron gun will be installed in linac. • Construction Schedule: – Target schedule: Super. KEKB commissioning starts at the beginning of JFY 2014. H. Koiso KEKB Review Feb. 2010

Summary Some from the Review Committee (Feb. 15~17, 2010) Reports

More work needed in: *Further optimization of chromaticity correction, optimization of the local chromatic sections, and ways to control chromatic coupling effects. *Tolerances on field errors and alignments particular to the small x-y coupling. *IR optics (small beta*, large beta_max, correction scheme, solenoid orientation angle, tapered solenoids). IR design in still in flux. Crab waist implementation (although not necessarily on day 1; the option must be kept in lattice design). *Momentum aperture (optimize for Touschek lifetime). *Dynamic aperture (required for injection). *Energy variation (how do solenoids and permanent magnets vary when beam energy is varied? ). *Polarized beams? (Make sure this is NOT needed. Otherwise, this will drive the design in a strong way, so it has to be determined early – cannot retrofit. )

Review Committee Reports The overall R&D and construction schedules for Super. KEKB were shown, and the details discussed. The plan is for a 3. 5 year construction time starting mid-year in JFY 2010. The overall schedule looks well thought out and complete. It appears to have a good chance of being able to be carried out if the funding is provided as proposed. There is some uncertainty, however, because the funding profile for each year is not really known. KEK management should ensure that the resources needed for the Nano-Beam studies are made available (staffing, computing). The most important issue is the established shortfall in staff during the construction period (~30 people) and in the operating era. In this context, the Committee recommends exploring collaborations with universities, industry and other laboratories world-wide.

Budgets

Budget allocated so far • • – Besides the annual operation budget, new budget has been allocated: FY 2009 Supplementary Budget of 25. 5 Oku-Yen (1 Oku-Yen = ~1. 1 M$) was allocated to KEKB for development of low-emittance beam device. – This budget is being used for fabricating a part of ante-chambers for the LER wiggler section, reinforcement of RF system, and R&D for key components such as IR magnets, positron source, etc. FY 2010 a budget of 5. 83 Oku-Yen was allocated for KEKB reinforcement. This single year budget is the first year of three-year plan for the of 25 Oku-Yen. Damping Ring construction in total – An announce was made abroad by the DG of KEK as "The Japanese Government has announced KEK's budget for JFY 2010, in which preliminary approval was given to the KEKB upgrade program, and a budget was allocated to partially start construction. This does not yet constitute full approval of the overall project, but can be interpreted as a provisional decision by the Government in these difficult times of drastic change in the Japanese Government. " K. Akai KEKB Review Feb. 2010

Committee for large-scale projects • A committee that discusses large-scale academic projects was established last year under Science and Technology, Academic Council in MEXT. – The committee discusses ways to promote large-scale academic projects in Japan. – Roadmap in each research field is being discussed in the Science Council of Japan, which will be submitted to the committee. The committee will discuss and settle on the roadmap. The committee is to decide which projects to be pushed forward in coming years. – The decision will be made by this summer, hopefully. K. Akai KEKB Review Feb. 2010

Presuppositions • We present fastest possible schedule with following presuppositions: – Not a small part of budget allocated to KEK in JFY 2010 be assigned to KEKB upgrade by the KEK Executive Board. – Positive decision be made by the committee for large-scale projects in “MEXT “ (Ministry of Education, Culture, Sports, Science and Technology, ) by this summer. – Budget for the Damping Ring tunnel and buildings be allocated in JFY 2011 by the Japanese Government. – Full approval of the overall project, Super. KEKB, be made in JFY 2011 by the Japanese Government. K. Akai KEKB Review Feb. 2010

Super. KEKB Main Ring schedule FY 2009 FY 2010 FY 2011 FY 2012 FY 2013 FY 2014 MR commissioning Beam operation Tunnel clear Remove magnets and beam pipes Base plates Beam pipes (LER_wiggler) Fabrication Ti. N coating Beam pipes (LER_arc) Design Install Fabrication Ti. N coating Beam pipes (HER_arc) Design Fabrication Install Magnets & Power supplies Design / Fabrication Field measurement Install Cabling / Check Alignment Beam monitors and Control R&D / Fabrication Test RF reinforcement Layout change / Add stations / Cavity improvements IR hardware QCS R&D QCS fabrication 2 nd? Condit ioning Install & test K. Akai KEKB Review Feb. 2010

49 Cost estimation 1 (Oku-Yen) = 1. 1 M USD = 0. 8 M EUR (as of 12 Feb, 2010) Components Linac upgrade and Damping Ring Cost (Oku-Yen) 31 Remarks e+ matching and L-band acc. , RF-gun and laser system, Damping Ring components Vacuum System 135 Magnet System 93 magnets, power supplies, cables IR upgrade 20 QCS and other hardware RF System 25 add 9 RF stations, improve cavities (coupler, HOM damper) Beam monitor and control 32 BPM, SRM, feedback, control system, etc. Belle upgrade Total beam pipes (ante-chambers, electrodes, etc), pumps and other vacuum components for 3 km x 2 rings 14. 7 350. 7 l Cost for DR tunnel construction is not included in the list. Also cost for buildings and facilities for Linac, DR and MR is not included. These costs are about 30 Oku-Yen in total. l This list is what went to MEXT last year. According to recent estimation, cost for some components increases, but some others decrease. K. Akai KEKB Review Feb. 2010

J. Flanagan 50 /ab 1. 2 /ab/month (8 x 1035 /cm^2/s) Physics Program Evaluation 0. 9 /ab/month (6 x 1035 /cm^2/s) 0. 6 /ab/month (4 x 1035 /cm^2/s) Shutdown for Upgrade Learning Curve Shifted by 0. 5 year Target schedule: Super. KEKB commissioning starts at the beginning of JFY 2014.

Facilities • • Storage and staging areas needed for magnet and vacuum components. Need increased cooling water for klystrons and magnets: – – • 24 klystrons for ARES cavities, 8 klystrons for SCC Magnet cooling water needs double (4 plants -> 8) Electricity: Electricity Consumption: June-09 KEKB/KEK total (Design option) KEKB: MW ΔMW Present(Average) 45 KEK: MW ΔMW 64 Nano Beam: June-09 70. 7 24. 3 96 32 Upgrade: Feb. -09 94. 8 49. 8 120 56 Super: ‘ 07 -July 102. 6 57. 6 128 64 Recent Design(Feb. -10): Add 2 ARES units--> +(3~4)MW M. Ono KEKB Review Feb. 2010

Beam Instrumentation: BPMs H. Fukuma LER chamber Design strategy a) Development of a new button electrode for higher currents Button with small (6 mm) diameter, pin type inner conductor b) Development of a new narrow-band detection module for 509 MHz detection for precise measurements. Lower detection frequency to get below cut-off frequency due to antechambers (900 -990 MHz) c) Development of a medium-band detection module for orbit stabilizing feedback and gated turn by turn orbit measurement for optics measurement. d) Development of a special detection module for collision feedback. ◊Feedback needs to have a gain in the region < 100 Hz. Required rep. rate of the measurement of ~ several k. Hz (e. g. 5 k. Hz). e) Use of displacement sensors to measure the movement of BPM due to thermal deformation of a chamber. Electrode

Beam Instrumentation: Feedback H. Fukuma Bunch by bunch feedback system • Longitudinal feedback system will be required in LER. • Noise in transverse feedback system should be minimized to reduce the blowup of the beam size during collision. • Vacuum components such as kickers, power cables, feedthroughs and BPM electrodes should withstand large beam current. i. Gp digital signal processing system ◊Developed under US-Japan collaboration (KEK-SLAC). Firmware is supplied by Dim. Tel. ◊Adaptable to almost any harmonic number. ◊Operation at 509 MHz is possible for KEKB. ◊8 tap FIR(KEKB) to 32 Tap FIR (DAFNE) are available. ◊Down sampling function for Longitudinal feedback. ◊Bunch-selected FB ON/OFF and excitation. ◊Transient-domain analysis for study of instability. ◊Capable to monitor a feedback signal without disturbing feedback. ◊Tested successfully for the transverse and longitudinal system at KEKB. • Next generation system with a digital filter working at ~1. 3 GHz using new FPGA, and ADC and DAC with higher resolution is under development.