1. First investigations of ATF2 at SLAC Axel Brachmann, Thomas Himel, Tom Markiewicz, Janice Nelson, Toshiyuki Okugi, Mauro Pivi, Tor Raubenheimer, Marc Ross, Robert Ruland, Andrei Seryi, Peter Tenenbaum, Mark Woodley, Mike Woods December 11, 2004

2. 2 Content and plans Design and study of various optics versions  Toshiyuki Okugi, Mauro Pivi, Tor Raubenheimer, Andrei Seryi Extraction line correction and orthogonal knobs  Peter Tenenbaum, Mark Woodley Also working on (to be discussed on January 5) : How to quantify risk reduction  Tom Himel ILC train extraction options  Janice Nelson, Tom Markiewicz, Marc Ross, Mark Woodley Application of Shintake style beam size monitor  Axel Brachmann, Mike Woods ATF2 alignment  Robert Ruland

3. 3 Final focus optics status Optics of Shigeru Kuroda  was converted from SAD to MAD format and investigated with DIMAD, TRANSPORT and TURTLE  was combined with existing extraction line  found that additional sextupoles in the extraction line help to increase the bandwidth Scaled NLC version  was first designed as stand alone, then combined and tuned together with the existing extraction line  also assume that additional sextupole correction in the extraction line can be made Two more versions need to be produced  new extraction line going to South + diagnostics area + FF  Is it still interesting, given possibility of the North location?

4. 4 Survey: Blue dashed- existing extraction line Red – new final focus Existing extraction + final focus of Shigeru Kuroda

5. 5 Existing ATF extraction line (converted from SAD to MAD by Mauro Pivi) Note a need to include sextupole errors in bends (M.Woodley)

6. 6 Extraction + FF FF optics: with IP  x,y = 13.5,0.1mm,  x ’ = 0.072 rad, L*=2m.

7. 7 Bandwidth, etc., shown on the next slides obtained with MAD and tracking done with TURTLE We found that bandwidth is much less than 1% and that it further decrease when combined with the extraction line Then we found that bandwidth of the combined system can be improved with sextupoles in the extraction line Then confirmed this improvement with SAD Note that the extracted dE/E is 0.8E-3 and the optics of S.Kuroda was optimized for this energy spread

8. 8 Optics of Shigeru Kuroda no additional sextupoles in the extraction line Final focus only Existing extraction + final focus

9. 9 Existing extraction + final focus of Shigeru Kuroda no additional sextupoles in the extraction line

10. 10 2 nd order dispersion zeroed & y- chromaticity minimized at the exit of extraction line (see further below) Existing extraction + final focus of Shigeru Kuroda

11. 11 Since we were worrying that the narrow bandwidth may be explained by differences of the codes, we tried to use SAD for these studies => Bandwidth obtained by TURTLE tracking of (extraction+FF) when 2 nd order dispersion & y-chrom. zeroed at the exit of extraction line All apertures were fictitiously increased to eliminate beam losses up at 1% Luminosity equivalent IP beam sizes

12. 12 FF optics in SAD run at SLAC (M.Pivi is an official SAD user) MAD Compare SAD & MAD Rather good agreement

13. 13 Compare SAD & MAD SAD FF of S.Kuroda Bandwidth at IP, FF only MAD MAD shows better bandwidth, but it is known that MAD does not include cross- plane aberrations

14. 14 DX (m) BX BY  1/2 (m) SAD: Combined extraction line and final focus Extraction line + FF of S.Kuroda

15. 15 Beam tracking with SAD Not yet combined: only final focus of S.Kuroda dispersion-prime at IP as expected

16. 16 Beam tracking with SAD DP (%)  x (  m)  y (nm)  x/  0  y/  0 0.0 3.85 34.6 1.00 1.00 0.1 4.83 41.5 1.25 1.19 0.15 17.7 63.5 4.6 1.8 0.2 91.8 108.2 24.1 3.17 Extraction line + FF of S.Kuroda

17. 17 Okugi-san adjusted FF sextupoles to minimized beam size for the optics with sextupole in ATF extraction line (studies with SAD) This seem to confirm that additional sextupole(s) in extraction line are useful to increase the bandwidth

18. 18 Blue dashed- existing extraction line Red – new final focus FF optics is NLC-like

19. 19 Existing extraction line Final bend is not used

20. 20 2 nd order dispersion in the existing extraction line 2 nd order dispersion zeroed & y-chromaticity minimized at the exit of extraction line with three sextupoles (marked with red)

21. 21 FF optics with IP  x,y = 4,0.1mm,  x ’ = 0.14 rad, L*=1m. Existing extraction + NLC-like FF

22. 22 Existing extraction + NLC-like FF

23. 23 Note that extraction line apertures were increased. Extraction line probably would not pass the beam with 1% without losses (due to large dispersion). Bandwidth of (extraction+ff) obtained by TURTLE tracking Existing extraction + NLC-like FF

24. 24 Further work on optics Tracking of Extraction + NLC-like FF with SAD Tolerances & Tuneability tests of FF Further optics optimization Understand performance (e.g. length needed) of S.Kuroda style optics at 1TeV Include field errors in the quads, in particular extraction line bends South extraction line + FF Design diagnostic section of south line Studies of tuning and diagnostics of complete beamline

25. 25 Extraction line correction Discussed studies of vertical dispersion correction made in 2000 in the ATF extraction line In that case, vertical dispersion was detected in the wire scanner area and corrected using vertical bump in the dispersion area Further modeling has shown that correctors could not produce the observed amount of vertical dispersion, unless a sextupole error is present in the bends This was later confirmed, that the bends indeed have sextupole component close to the limit of manufacturing specs  Described in the report ATF-00-06 These sextupole components need to be taken into account when any correction of the second order dispersion is considered in the ATF extraction line  Presently, there are two skew quads installed in the high dispersion points, for vertical dispersion correction, and other four in the wire scanner area

26. 26 South option for the extraction line South option (GLCTA area) for the extraction line  Design by Okugi-san for bunch compressor  Second order dispersion correction need to be checked  This optics does not have instrumentation section, and this section needs to be added to the beamline before the final focus The plan is to match both FF versions to the South extraction line optics and study it

27. 27 Comments from PT on tuneability, etc. Based on FFTB experience, PT brought up a question about coupling correction:  In FFTB we were unable to design the optics with proper coupling correction. We struggled with this problem, and never resolved whether we were perhaps limited in our beam size by an xy rotation at the IP (though the Orsay monitor would in principle have shown if such a problem was present). The SLC FF also had incomplete control of its coupling, and I seem to recall that they had some problems as a result (Nan or Panta may remember better than I do). I think there could be a lot of benefit to Tail folding comment from PT:  Tail-folding octupoles and bandwidth octupoles and decapoles. There remains some nervousness about these features for ILC. Also, we always found with the Shintake monitor that background control was very important, and rather hard to achieve. Having an additional tool for this process (over and above the collimators) would be beneficial. Come to that, the design should probably include adequate collimation (in FFTB we had the large # of main linac collimators, and we needed them).

28. 28 58 people so far on the list, and the list, and the collaboration, are open

29. 29 just a possible name