Linear Collider For Japan-US HEP Program Committee May, 2003 Nobu Toge (KEK, Accelerator Lab)

Japan-US HEP Program Comm Mtg2 May 30, 2003 Participants and Activities KEK (Accel. Lab., IPNS), Nagoya, Tohoku Gakuin, Yokohama National, Tokyo Metr., Kyoto, Tokyo, Saitama, NIRS) SLAC, LBNL, LLNL, FNAL, BNL LC ISG (International Study Group) Meeting twice a year.  One at KEK, the other at SLAC Visits to US: ~ 35 person-weeks Visits from US: ~ 25 person-weeks Research subjects:  ATF (low emittance beam production)  X-band RF R&D

Japan-US HEP Program Comm Mtg3 May 30, 2003 ATF in JFY 2002 Beam Emittance in Single-bunch mode operation   x = 1.7 x  x = 4.1 x [LC-spec: 3x10 -6 ]   y = 5.2 x   y = 1.3 x [LC-spec: 2x10 -8 ] Multi-bunch Photocathode RF gun:  New construction, installation and commissioning. Beam monitors and Electronics:  Improvements Beam emittance in multibunch operation:  Start-up of systematic surveys

Japan-US HEP Program Comm Mtg4 May 30, 2003 ATF Layout E=1.28GeV Ne=1x10 10 e-/bunch 1 ~ 20 bunches Rep=1.5Hz X emit=2.5E-6 ( at 0 intensity) Y emit=2.5E-8 ( at 0 intensity)

Japan-US HEP Program Comm Mtg5 May 30, 2003 RF Electron Gun with Multibunch Capability - 20 bunches, 2.8 ns spacing with high quality beam - BNL-style S-band cavities built within KEK - Cs2Te cathode - Nd:YV04 357MHz mode-lock laser ← Beam

Japan-US HEP Program Comm Mtg6 May 30, 2003 Multibunch e- beam at 80 MeV point Beam Intensity ~1x10 10 /bunch Normalized Emittance  y= 28x10 -6 rad.m Bunch length  z= 6.4 ~ 7.9 ps Energy spread dE/E = 4.9% full-width Q.E. of CsTe cathode 16% initial, 2~3% with RF ON & constant over a week

Japan-US HEP Program Comm Mtg7 May 30, 2003 Improved Beam Instrumentation at ATF (JFY 2002) DR Laser-Wire Monitor  Measurement capability for X (horizontal) beam sizes in addition to the Y (vertical). DR Beam Profile Mon with X-ray SR  Resolution ~ 1.9  m DR BPM Readout Electronics  Improved resolution: 20 – 30  m  3  m  Online calibration capability Optical Diffraction Radiation (ODR) Monitor RF Cavity BPM  Possibly expanded collab with UK in addition to USA.

Japan-US HEP Program Comm Mtg8 May 30, 2003 ATF: Goals for JFY 2003 RF Electron Gun:  Establish stable, routine operation  Improved laser stability and alignment w.r.t. the inj linac system DR Beam Emittance in Multibunch Opeation  Signatures of Longitudinal Coupled Bunch Instability exist, Need to identify the cause(s) and fix so as to proceed with MB emittance studies in the extraction line.  Store up to 5 bunch trains in DR. Application of High-Resolution Beam Monitor Systems  High resolution BPMs  Improved optics tuning / alignment  High resolution beam profile mons  Emittance meas and tuning

Japan-US HEP Program Comm Mtg9 May 30, 2003 Resurrected in 2001 under ICFA, reorganizing the 1 st TRC Group.  Review the LC R&D status and assess the technological prospects for achieving E CM ~ 500 GeV and/or higher.  Assess the R&D focus items for the next several years.  Recommend collaborative research programs. Top-Ranking R&D items (R1) identified for X-band LCs.  Acc. Structures: Stable high-field operation of strucs with LC-grade implementation of a/, HOM detuning and damping.  Pulse compression: Demonstrate power production and handling with 2-mode SLED-II. TRC-II -- ICFA ILC Technical Review Committee

Japan-US HEP Program Comm Mtg10 May 30, 2003 X-band RF Systems R&D in JFY 2002 PPM Klystrons Revised scheme for RF pulse Klystron modulator with semiconductor switching devices Study of high-field operation of accelerator structures Sharpened focus on top-ranking R&D items, in response to ILC-TRC reporting.

Japan-US HEP Program Comm Mtg11 May 30, 2003 X-band PPM Klystrons At KEK:  PPM#3 at KEK March -June MW, 1.5  s, 50 Hz achieved （ goal was 75NW, 1.6  s, 150Hz ）  New RF window ： good performance  Improved body cooling: estimate  T < 30 deg 100Hz At SLAC:  Built XP3#3 and #4. Joint agenda for JFY 2003 ：  Cooling for Hz operation with good margins.  Demonstrate stable operation at Hz.

Japan-US HEP Program Comm Mtg12 May 30, 2003 RF Pulse Compression What needs to be done ： Combine output power of 75MW, 1.6  s klystrons, Create RF pulses with 450 – 600 MW, 400ns, Feed them to acc. Structures with shunt Impedance ~ 80 M  /m, Then acc field of ~ 65MV/m can be created over ~ 5m. Comparison SLED-II  DLDS #klys 2 8 L(vac) ~ 30m 30-50m Eff 75 % 85 % #yrs ~ 1 ~3 To demo

Japan-US HEP Program Comm Mtg13 May 30, 2003 Revised Scheme for RF Pulse Compression Focus on high power demonstration of SLED-II at least during Decision based on discussions + studies in Summer/Fall of Basic proof of principle exists with low-power testing in 2002 at SLAC. Numerous applications of ideas from DLDS R&D (i.e. this is not entirely a “zero resetting” of R&D). SLED-II results likely to be applicable for “future upgrades” with DLDS. Aiming at making a timely response to “Critical R&D List” quoted in the ILC-TRC Report. Full integration of JA – US efforts on X-band linac tehnologies.

Japan-US HEP Program Comm Mtg14 May 30, 2003 SLED-II Test Site at NLCTA (SLAC) Goal: Demonstrate production of ~ 500MW, 400ns X-band RF power within 2003.

Japan-US HEP Program Comm Mtg15 May 30, 2003 SLED-II ： Top Priority in JFY 2003 SLAC: Complete one set of SLED-II system in (Note: Figure shows two sets). Use XL4 first. May use KEK PPM tubes Later. KEK ： Replacement taper in June, 2003 Replacement hybrid components to co- develop by SLAC- KEK in In 2003 In 2004

Japan-US HEP Program Comm Mtg16 May 30, 2003 X-band Accelerator Structures Mostly high-field issues New observations: Likely damages due to high surface currents, in addition to breakdowns at high surface field points.  Verification of solution candidates for the coupler area.  Beginning application of solutions for regular cells with HOM damping slots. In addition, Relation between surface treatment methods and high-field performance. Fabrication and assembly techniques development.

Japan-US HEP Program Comm Mtg17 May 30, 2003 Continue Cut-away view of an Accel. Structure (Upstream end)

Japan-US HEP Program Comm Mtg18 May 30, 2003 Damages ascribed to Surface Current Estimated Instantaneous temp rise ~ 100 deg C / pulse

Japan-US HEP Program Comm Mtg19 May 30, 2003 Example Solution “Mode-Convertor” type I/O couplers Note: spin-off from DLDS R&D Pulsed temperature rise ： estimated to be ~ 20deg C. Tested in Summer/Fall of 2002

Japan-US HEP Program Comm Mtg20 May 30, 2003 Goal for Eacc ： 65MV/m Summer/Fall 2002 Test Structure with New I/O Couplers

Japan-US HEP Program Comm Mtg21 May 30, 2003 New designs of regular cells with HOM damping (Highest priority item for ) Encouraging results from a test struc which partially includes this type of damped cells  Ongoing test at NLCTA. BD rate ~ 0.25 / hr at 65MV/m, 400ns pulses. Test strucs made entirely with this type of cells:  #1: No HOM extracted to loads. Test to begin in June,  #2: No HOM extracted to loads. Test to begin in Aug.,  #3:HOM fully extracted to loads. Test to begin in Early 2004.

Japan-US HEP Program Comm Mtg22 May 30, 2003 Processing History of Test Struc including 6 DDS cells with rounded HOM openings April, MV/m

Japan-US HEP Program Comm Mtg23 May 30, 2003 GLCTA at KEK KEKB Crab Cavity Lab ATF beam line extension JFY 2004 or later Bunch compressor (JFY 2004 or later) X-band High Gradient Test Station within JFY 2003 (Reference info. This efforts will befunded by sources other than US-Japan)

Japan-US HEP Program Comm Mtg24 May 30, 2003 Summary of 2003 Activity Plans

Japan-US HEP Program Comm Mtg25 May 30, 2003 Proposed Budget Composition JFY 2003 JAUSSum Klystron85,000KY20,000KY105,000KY SLED-II40,000KY50,000KY90,000KY Acc.Struc65,000KY30,000KY95,000KY Office / GA20,000KY Sum190,000KY120,000KY310,000KY