1 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam Design of a new Final Focus System with l* = 4,5 m J. Payet, O. Napoly CEA/Saclay

2 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam New Final Focus NLC (P.Raimondi, A.Seryi) Two optics with angular dispersion D x ’* at the IP 1) « Long doublet » : 3 cm radius aperture with 72 T/m, D x ’* = 5 mrad 2) « Short doublet » (not published) 1 cm radius aperture with 140 T/m, D x ’* = 9 mrad

3 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam New Final Focus NLC Chromatic correction For both optics, β-bandwidth > ±1% (TESLA parameters) β x * =15 mm β y * = 400 µm

4 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam New Final Focus NLC IP spot sizes energy offset short doublet long doublet 1 2 σ x * / 553 nm –1%+1% 1 2 σ y * / 5 nm –1%+1% energy offset

5 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam New Final Focus ‘à la NLC’ l* IP waist β* Advantages from the machine point-of-view: –Better chromaticity correction  larger l* – l* = 5m  final doublet moved out of the detector solenoid chromaticity : ξ = l* / β*

6 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam New Final Focus with l* = 5m Advantages from the detector point-of-view –Larger forward acceptance at low angles –Final doublet moved out of the calorimeter  less e.m. showers in the detector –Lighter Tungsten-mask and simpler support

7 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam Main issues of the Design 1.Extraction of Beam after the interaction 2.Extraction of Synchrotron Radiation from Final Doublet (i.e. check collimation requirements) 3.Final Focus Optics N.B. : First two issues, independent of the FF optics, depend only on l* and on the final doublet apertures Φ.

8 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam Beam Extraction φ*φ* Final doublet acceptance Θ* max (E, φ*) with l* = 5m Φ = 48 mm Solenoid B S = 4 T

9 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam Comparison of horizontal acceptances (φ*= 0) for l* = 3,4,5 m Differences are small. Tracking simulations are needed l*=5m acceptance : better for lower energies worse for high energies

10 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam Synchrotron Radiation Extraction Collimation requirements for l* = 5m Φ = 48 mm inner mask - s = 4 m - Φ = 24 mm

11 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam Collimation Requirements l* [m] s mask [m] NxNy TDR New FF New FF  new collimation section required with tail folding by octupoles

12 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam NLC type correction, l* =5m SF1, SD1 SF2 SD2 SF3 Beamstrahlung Dump IP angular dispersion D’ x * = 10 mrad

13 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam NLC type correction, l* =5m  400 GeV = m.rad Emittance growth minimized by fine tuning of dipoles

14 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam NLC type correction, l* =5m IP spot sizes

15 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam Correction type NLC, l* =5m IP spot sizes and luminosity L/L 0 = 0.86 for  E /E = 0.4 %,

16 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam Hybrid Correction, l* =5m SH SV1 SV2 Beamstrahlung Dump IP angular dispersion, D’ x * = 2.6 mrad

17 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam Hybrid correction, l* =5m  400 GeV = m.rad Emittance growth at 400 GeV

18 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam Chromatic Acceptance IP Spot sizes NLC short doublet NLC long doublet TDR, l* = 3m B789, l* = 5m energy offset σ x * / 553 nm 1 2 energy offset σ y * / 5 nm 2 1

19 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam Correction hybride, l* =5m Dimensions rms et IP L/L 0 = 0.70 for  E /E = 0.4 %

20 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam Optics Summary The ideal solution is surrounded, but not yet found

21 April 1 st, 2003 O. Napoly, ECFA-DESY Amsterdam Conclusions Design for l* = 4,5 m new optics is possible within the TDR length constraint, about 600 m Momentum bandwith already better than TDR Several optimisations are still needed (w.r.t. to dispersion, emittance growth, octupoles, …) Beam extraction through final doublet : OK Collimation requirements about a factor 2 tighter