This meeting was devoted to 2mrad extraction design

Summary:

 Y.Nosochkov, A.Seryi, B.Parker, C.Spencer, L.Keller, T.Maruyama:  
Toward 0th design of 2mrad extraction IR

• We used new approach to design FD and extraction line for 2mrad case:
• This approach consists of:
  • Optimizing Final Doublet BOTH for incoming beam AND for extracted beam
  • With a "correct sign" of crossing angle the SD0 is providing focusing and is facilitating extraction
  • Analysis is done both with MAD and with tracking by TURTLE
  • Shapes of magnets, field and apertures are determined from the tracked beam and immediately verified for feasibility
  • The beamline is optimized for beam with 65% energy spread
  • The design process is Matlab driven and allow automatic optimization of tracked beam at many locations in FD and extraction line
• This approach allowed to design three versions of 2mrad extraction line which all exhibit good behavior of the extracted beam for all energies from -65% to full energy.
• The Version of February 13 has QF1 and SF1 fields zeroed for the extracted line. This was distributed a week ago and discussed via e-mail.
• Some of the lessons from the Version Feb.13 discussion:
  • Optics can indeed be optimized both for the incoming and extracted beam, and this allows considerable improvements for the extracted beam
  • The “correct sign” of crossing angle (which give focusing by SD0) is the one less favorable for the overall layout (the length to the beam dump needs to be longer and the IP1 and IP2 separation is reduced by several meters)
  • Large bore SC sextupole SD0 is on the limit
  • It is difficult to make the extraction magnets to be the iron pocket coil, since it is difficult to shield the incoming beam
  • SC Super Septum Quad was suggested by Brett
• Considered the magnets needed for this version, Brett Parker suggested super conducting super septum quadrupoles (SC SSQ) that could provide minimum separation between the extracted quad aperture and field free region for the incoming beam
• The Version of February 18 uses Brett's SC SSQ, includes additional dipole, vertical chicane and doublet. The nonlinear QF1 field between the poles is used. The SF1 is assumed to be pocket coil sextupole. The final outgoing angle of the extracted beam is 5.4mrad.
• The Version of February 20  is a variation of the previous, where it is assumed that SF1 is not the pocket coil iron sextupole, but the large bore SC sextupole. Thus, SF1 will somewhat reduce focusing giving by SD0, but will increase the total kick (to 7.5mrad). This version seem to be the favorite so far.
• The Version of February 20 will be used to create Geant model of the IR and extraction. One of the important questions that Geant study should answer, in addition to the detector background analysis, is to show what is the synchrotron radiation power loads on the SC magnets.
  
  
   

Cherrill Spencer:  Details of QF1 and SF1 and ideas of Panofsky septum quad 

• Cherrill (being on vacations today) gave us files which describe details of QF1 and SF1 pocket coil magnets for the 2mrad FD, as well as described an idea of Panofsky quad for extraction line. This idea should be further investigated.

Andrei Seryi, 02/23/05