Present and Future Effort in ACFA-FFIR group

Interaction Region

• Optimization of IR-layout ( L*, innermost layer of VTX, crossing angle, extraction line, FEATHER, pair monitor ( Tohoku univ., minutes ) and background)
  • Physics and detector
  • Acclerator
• First optimization was completed in 2000; B=2 and 3 Tesla, L*=2m, 4.3m.
• Recent background estimation; talk(pdf, 2.9MB) presented at LCWS04, 19 April,2004, and talk (pdf, 90KB) presented at the 6th ACFA-LC video conference, December 12, 2003, by T. Aso (Toyama National College of Maritime Technology).

Support Tube R&D

• short history
  • 2000, ANSYS calculations of the support tube in the JLC detector,
    fabrication of support tube prototype was started.
  • 2001, sensor,software improvement and measurements of vibration properties.
  • 2002, fabrication of the 1/10 model (cantilever with 4 segmentions, flat and taper flanges)
  • 2003, plan (test of the 1/10 model, optimization of the CFRP central tube thickness, etc. )
  • 2004, plan
• measurement of oscillating amplitude with different phases at both ends,
• manufacturing of 1/10 model with realistic structures
  photo:1/10 model ( 80mm outer diameter, 10mm thick, Al tube ), Taper Flange
• stiffness test of the model and study of a vibration isolation system.
• active feedback system at sub-nanometer level.
• Optimization of thickness of central connection tube, which shall be thinnest keeping stability of oscillation properties of the tube.
• Recent progress report can be found here : tube with taper flanges, flat flanges, and loads.
• Frequency response analysis

Collimation System

• calculation of synchrotron radiations by SAD (new implementation in SAD) : 1, 2
• JLC scheme with muon attenuators ( presented at APPI03 by Ohgaki ) : 1
• estimation of muon background by MUCARLO in cooperation with Namito-san, short muon attenuator?
• understanding of TFO (Tail Folding Octupoles) -role quantitatively and optimization of the collimation system
  • First estimation
• collimator design
  • collimation depth -- innermost layer of a vertex detector
  • calculation of wake field at the spoilers and absorbers; Yokoya's calculations and a short review,
• beam halo
  • gas scattering ; brief review, NLC, 1, 2, 3 and Yamamura's master thesis, Tokyo univ., 2004.3 Japanese, pdf,8,4MB
  • dark current ; 1, 2, 3, 4, 5, 6, 7
  • longitudinal tail, to be collimated at pre-LINAC collimation.
• Possibility of shorter collimation: 1

BDS Simulation

• estimation of beam halo and dark current at LINAC; beam gas scattering, wake field etc; project, 1
• estimation of backgrounds at detectors; results of 1 , 2.
  • synchrotron radiations from final doublet and others
  • muons (collimators)
  • neutrons (dump line) : 1, 2, 3
  • pairs (IP), primary in VD and secondary in CDC
• energy loss along the beam line -- radiation loss

Final Focus System

• New Final Focus with large L*

  • New optics interest : 1, 2, 3, 4, 5
  • Optimization of L*; L*=3.5m (roadmap) or 4, 5m? (3.5/4.3m, 4.3m, chromaticity;1, 2, 3:ATF2 ) from physics/detector
  • Assessment of effects due to errors in strength (Q , SEXT), positions ( Q, SEXT ) and rotations/longitudinal position ( Q , SEXT ) of each magnet at the FF system
  • Beam stabilization ; study on feedback method with orbit corrections
  • Estimation of momentum acceptance in terms of luminosity and background

• Q/A of errors and L* at the old design (by Oide)

• Crab Crossing

  • 7mrad or 20 mrad? | discussion
  • Crossing Angle of GLC(pdf), presented at the JLC-KEK weekly meeting by K.Yokoya, 18 July,2003.
  • Review of NLC crab cavity by H. Hayano,23 April, 2003
  • Crab cavity at KEKB by K.Akai

• Superconducting final doublet (large aperture with 7 mrad crossing)

  • design: 1, 2, 3, 4, 5, 6, 7, 8
    • L*=4.3m
  • Estimation of background at the dump line, specially synchrotron radiations generated by extractede beam in the final Q, by the BDS simulation

• Permanent final doublet

  • R&D issues
  • method of varying the strength ( for Ebeam=45GeV ~ 250GeV) -- rotation of segmentations?
  • tolerances of various errors for the design: strength
  • recent progress report can be found here (pdf), which was presented at the ISG11, December 16-19, 2003, by T. Mihara (Kyoto university).

• Conventional final doublet

  • Design for the optics of L*=3.5m or 4.3m

Extraction Line and beam dump

• Design of extraction line : 1, 2, 3, 4, 5, 6, 7, 8, SQ: 9, 10, 11, 12, 13
• Dump design: water dump ( 1 , 2 ) , beamstrahlung photons
• Optimization of optics ( the second IP through the beam dump ); two dumps and single dump
• Design of magnets considering neutron background
• Estimation of neutron background from a single or two dumps for beamstrahlung photons and electron(positron) beam

• Interface to SAD and CAIN for a unified program routine : SLEPT
• Effect of missing quad-movers and BPMs
• Various BNS damping and low &beta optics
• Assessment of Ground motion effect on main linac and BDS ; studies of 1, 2, 3 .
• References
  • Manual(PDF,732KB), K.Kubo, K.L.F.Bane, T.O.Raubenheimer and K.A.Thompson, Phase space simulation program for main linacs of future linear colliders, NLC-Note 14, May 1995.
  • Correction Strategy ( PDF, 46KB), html(Japanese) ) , K.Yokoya, written in Japanese, 5 March 2003.
  • Requirements for movers at LINAC

• Poster presented at the ITRP meeting (KEK) ; gif, 951KB
• Preliminary results of KEK GM measurements, talk (pdf,52.9MB) presented at the ISG10, June 17-20 2003, by T.Tauchi.
• Measurements; KEK, Konoike-Tsukuba, F-net etc.
  • Preliminary Results (PDF, 2.3MB) presented at the ISG video meeting, 8 May, 2003, by T.Tauchi, K.Fujii, T.Matsuda, H.Yamaoka and N.Uchida.
  • Uchida's master thesis, Tsukuba univ., 2003.2, Japanese, pdf
• Measurements at TRISTAN ring, KEK
• GM models
  Brief review of GM model and talk(PDF, 2.5MB)

Fast feedback system:FEATHER

• Simulation by using CAIN -- evaluation of feedback performance
• Performance with beam blow up for 7 mrad crossing and L*=3.5m
• Design of the fast feedback system (simple, delayed, improved models, etc.)
• Construction of prototype system (Kicker, BPM etc. ) at the ATF extraction line for beam test
• Schedule, 2004-2007
• Link to FONT

Nanometer BPM ; collaboration with SLAC, LLNL and UK groups

• Demonstration of nanometer beam position resolution by cavity-type BPM
• Schedule, 2004-2007
• Future Plan, December, 2003

Laserwire ; collaboration with UK, DESY and SLAC groups

• Laser Based Beam Diagnostics at the ATF
• Beam profile measurement
• Beam energy distribution measurement at the 2nd IP of the GLC extraction line.

• Upstream Compton polarimetry; before collisions at sources, DR, LINAC etc.
• Downstream Compton polarimetry after collisions at the dump/extraction line.
  • Polarimetry; Important role of polarized positron beams for future linear collider, ( full file of pdf and tif ), T. Hirose (Tokyo Metropolitan), presented at LCWS95, proceedings of "Workshop on Physics and Experiments with Linear Colliders (LCWS95)", edited by A, Miyamoto et.al., 8-12 September 1995,Morioka-Appi, Iwate, Japan, World Scientific, p.748-755.
• Physics events; WW scattering
• Depolarization during collisions
  • ref 1) Depolarization due to beam-beam interaction in electron-positron Linear Colliders, Kaoru Yokoya, Pisin Chen. SLAC-PUB-4692, Sep 1988
  • ref 2) Spin depolarization due to beam-beam interaction in NLC, Kathleen A. Thompson. SLAC-PUB-8716, Jan 2001.

• Luminosity measurement as a function of the center-of-mass energy
  • Energy spread before collisions and beamstrahlung effects as well as initial state radiation
  • Bhabha scattering; acollinear angle
• Luminosity monitor (forward calorimeter) and active mask: first study results
• Beamstrahlung monitor: studies of 1, 2, 3