1.Beam Tuning Simulation 2.IP Beam Position Stability 2-1 ) Magnet Vibration 2-2 ) IP position jitter subtraction for 2 nd bunch with FONT feedback 2-3 ) Stability of cooling water temperature 3. Lower betaY* optics Status of ATF2 Goal 1 study and beyond to 20nm Toshiyuki OKUGI, KEK 2015/ 2/ 24 ATF Technical Board & SGI meeting LAPP (Annecy, France) ( based on the Goal 1 session of ATF2 project meeting )

IP Beam Tuning Simulation

Emittances (  x /  y ) 2nm /12pm Beta Functions (  x */  y * ) 40mm / 0.100mm Momentum Spread (  p /p) 0.08% Optics to be used for IP beam size tuning simulation No SF5FF ( Present sextupole setting ) No SF5FF ( Optimized to make large bandwidth ) with SF5FF ( Optimized to make large bandwidth ) The bandwidth for present sextupole setting was very narrow. When we use SF5FF, the acceptance of horizontal IP angle makes wide for X66 correction. All magnets errors were OFF. Momentum Offset Momentum Spread IP Horizontal Angle

Procedures of IP beam tuning simulation 1. Put the following errors in Magnets as follows. QuadrupoleSextupole Quadrupole error0.001N.A. Sextpole error0.001 at R=1cm0.001 Rotation Error0.1mrad BBA offsetN.A.50um 2. Tune the beam by the following steps Carbon Wire QF1FF strength (H) QD0FF strength (V) QD0FF rotation (V) Sextupole ON AX knob (H) EX knob (H) AY knob (V) EY knob (V) Coup2 knob (V) IP-BSM 8degree AY knob (V) EY knob (V) Coup2 knob (V) IP-BSM 30degree Y24 knob (V) Y46 knob (V) AY knob (V) EY knob (V) Coup2 knob (V) IP-BSM 174 degree Y24 knob (V) Y46 knob (V) AY knob (V) EY knob (V) Coup2 knob (V) Y22 knob (V) Y26 knob (V) Y66 knob (V) Y44 knob (V) AY knob (V) EY knob (V) Coup2 knob (V) M 008 > 0.30M 030 > 0.30M 174 > times 3. Simulate the IP beam size for various momentum spread.

with SF5FF ( Optimize to large bandwidth ) No SF5FF ( Present sextupole setting ) No SF5FF ( Optimize to large bandwidth ) Results of beam tuning simulation for ATF2 10x1 optics

No SF5FF ( Present sextupole setting ) No SF5FF ( Optimize to large bandwidth ) Model calculation, when no multipole errors Momentum spread dependence for “NO” SF5FF When momentum spread was increased after IP beam tuning with small momentum spread, - momentum spread dependence are almost same for present and optimized optics without SF5FF. - momentum spread dependence was in between model calculation for present and optimized optics.

Momentum spread dependence “with” and “without” SF5FF without SF5FF with SF5FF When momentum spread was increased after IP beam tuning with small momentum spread, momentum spread dependence of the optics with SF5FF was larger than that without SF5FF. The strength change of same knob amplitude for 4 sextupole optics is smaller than that for 5 sextupole optics. This is the special case for 10x1 optics. The optics with smaller IP horizontal beta functions were different situations.

with SF5FF ( Optimize to large bandwidth ) No SF5FF ( Present sextupole setting ) No SF5FF ( Optimize to large bandwidth ) IP tuning performance of 10x1 optics for different IP-BPM monitor resolution There are no clear difference for 3 beam optics. The IP-BSM resolution is sensitive to the final IP beam size. We should use the IP beam size monitor less than 5% modulation errors.

Summary of Beam Tuning Simulation When we apply the enough number of the iteration of knob tuning, the final sextupole setting after the beam size tuning is automatically optimized for the momentum spread of the beam. Therefore, it is small impact for the initial sextupole setting. The final sextupole setting of 10x1 optics for  p/p=0.08% has small momentum bandwidth, and small IP horizontal angle acceptance. The simulation said the momentum spread after tuning with 4 sextupoles were larger than that with 5 sextupoles for 10x1 optics. We need less than 5% of modulation accuracies for IP-BSM in order to achieve optimum IP beam size. We should check the energy bandwidth of IP beam size. (Kubo-san proposed at the end of 2014) IP-BSM resolution is not only important to measure the IP beam size, but also important for IP beam size tuning.

Magnet Vibration

2015 March -prepare the drawing (LAPP) 2015 April -start fabrication (KEK) - test the horizontal fixture 2015 May - Install the new support by the test result New support structure Vibration of QF1FF presented at ATF operation meeting on 2015/10/17 by A.Jeremie

Not only QD10AFF, but also other QEA magnets were vibrated. at ATF2 project meeting at 2015/2/24 by M.Ptecki and A.Jeremie Vibration of QEA magnets Difficult to reduce with shim ?? Height adjustment Mover

Magnet vibrationIP position jitter QF1FF30 nm 1) 12.6 nm QD0FF4.8 nm 1) 7.3 nm QEA magnets18 nm 2) nm 3) 1) Presented by A.Jeremie at ATF2 meeting at 8/30/ ) Presented by A.Jeremie and M.Patecki about QD10AFF at ATF2 project meeting at 2/24/ ) All QEA magnet vibrations were assumed to be same to QD10AFF and the correlation length were assumed to be less than 1.5m. Summary of Magnet Vibration nm with shim expected to reduce

Preparation of the IP beam size measurement after 2 nd Bunch Beam Jitter Subtraction with FONT

By using the Cherenkov detector, we can measure the beam size for individual bunch. But, we cannot read the beam position for 2 bunch mode now. - No orbit correction - No orbit feedback presented by Y.Kano at ATF2 project meeting on 2015/2/24. 2 nd Bunch Beam Size Measurement

2 nd Bunch Beam Position Reading ( C-band BPM ) presented by A.Lyapin at ATF2 project meeting on 2015/2/24.

Cooling Water Stability

DR Magnet ( 1000 l/m ) DR Magnet Sub ( 400 l/m ) DR Magnet DR Vacuum DR RF DR Klystron DR RF Cavity DR Cavity EXT&FF Magnet AUX LUCX LINAC LINAC RF Cooling Facilities Loads Schematic Figures of ATF Cooling Water System Replaced to Unit System at 2014 October Cooling Tower was outside of Assembly Hall

Linac Cooling Water System June and July Operation Outside temperature was increased. The floor of Assembly hall was expanded. The frequency of RF system was changed to match the circumference of DR. The frequency of RF system was mismatched to the resonant frequencies of Linac cavity. The injection energy to DR was reduced. Before 2014, we stopped the beam, or operated with mismatched DR circumference. From 2014, the temperature of linac RF system was changed to match the appropriate frequency by Naito-san. We could operate in June (We achieved the minimum beam size.) LINAC LINAC RF

DR Cooling Water Temperature (2014/12/01 – 2014/12/21) 2 degree C / div The DR horizontal orbit was oscillated with the DR cooling water temperature. The FF vertical orbit was also oscillated with DR cooling water temperature. - Since we operated with ultra-low beta optics at December 2014, we could clearly observed the oscillation in FF beamline. - Since the frequency of FF orbit oscillation was twice as DR cooling water temperature, DR horizontal orbit oscillation was converted to FF oscillation through skew sextupole field at septum. Naito-san adjusted the feedback parameters of the cooling water.

2014 March (03/03-03/07) 2014 April (04/14-04/18) AM 0: June (06/02-06/10) AM 0:00 AM 0:00 AM 0:00 AM 0:00 Maximum IP-BSM modulation was more than 50%. Maximum IP-BSM modulation was limited around 30%. Cooling Water Temperature in 2014 Spring Operation 2 ℃ / div 17.9 ℃ 21.7 ℃ 25.1 ℃ 21.0 ℃ 14.5 ℃ Maximum temperature at Tsuchiura city 8.9 ℃ 6.3 ℃ 9.1 ℃ 9.6 ℃ 7.0 ℃ Minimum temperature at Tsuchiura city by Japan Meteorological Agency 2 ℃ / div In 2014 January to March, the temperature of DR magnet cooling water was also fluctuated. In 2014 June, the temperature of DR magnet cooling water was stable.

Lower betaY* optics

IP tuning simulation for10x0.25 optics Same beam tuning simulation was done for 10x0.25 optics. Optics was used for “No SF5FF (Matched only with QM magnets )” 10x1 optics 10x0.25 optics 10x0.25 optics sometimes cannot go to 174 degree mode (dynamic range of Y44). Tuning result of 10x0.25 optics is also sensitive to monitor resolution.

presented by M. Patecki et al., 2015 CLIC workshop The IP vertical beam size at ATF2 low beta optics is sensitive to the fringe field of final doublet. The fringe field may be corrected by using octupole magnets. But, the following simulation, I will not use fringe field of FD and octupoles. Comment for low beta optics evaluation

Installation plan will be discussed tomorrow. presented by M. Patecki et al., 2015 CLIC workshop

Thank you for your attention