02.11.1
A plan of ATF Final Focus Test BeamLine (A-FFTB)
1. Introduction
2. Optics
3. Summary
02.11.1
ACCELERATOR TEST FACILITY FOR LC
Jan.14, 1998 120m
50.
4m
16.
8m
1.54 GeV Damping ring
1.54GeV S-band LINACDamped cavities Wiggler magnets Positron source
Beam diagnostic system (EXT)
Wiggler magnetsWater cooling & Air condition facility
Water cooling & Air condition facility
ModulatorsKlystrons
RF gun
DC power supply for modulator
Polarized electron source
714MHz RF source
Magnet power supply
53.4m
27.
6m
13.8m
Aug.'93
Nov.'95
Jan.'97
Nov.'97
02.11.1
50.4m
L1 L2 L3 L4 L5 L6 L7 L8 L9 L10 L11 L12 Lec2 L13 L14 L15 L16Lec1
120m
X-band Section
Bunch Compressor
1.54 GeV S-band Linac
1.54 GeVDamping RingControl Room
Final Focus
ATF-II
(ATF2)(ATF1)
(30psec to 3psec)
02.11.1
KEK is discussing ATF-II as next R&D for LC’s.Proposal of ATF-II will be obtained within two months.
*High Gradient beam acceleration with compact X-bandSystem. (ATF1)
*Test of F.F. Optics (Proof of Principle Experiment). (ATF2)Stabilization, FD to realize 50nm even if 1.3GeV.
Shigeru Kuroda, K.Kubo, T.Okugi, T.Tauchi and me (J.Urakawa)
T.Tauchi : Leader of ATF2
02.11.1
ATF1:Simplest 2 single-mode DLDSATF1:Simplest 2 single-mode DLDSand high gradient acceleration withand high gradient acceleration with1.3GeV low 1.3GeV low emittance emittance beambeam
l DLDS Experiment with Two 75MW Klystronsl High Gradient Acceleration with 1.3GeV beam
ATF1 has higher priolity. This is not related to my talk.So, I will explain ATF2 for this workshop.
02.11.1
35m
P.Raimondi and A.Seryi Lattice: Test of New Optics
Scaling (FFTB and ATF2) by only PhysicalEmittance
60nm •46
1.543 ¥10-6
3 ¥10-8 = 33nm!
IP
From ATF
02.11.1
Ds * = xds 0*
d =Dpp
s0* :linear optics beam size
Sexta in Dispersion region for chromaticity correction.-I: Nonlinear Effect is cancelled.
02.11.1
P.Raimondi and A.Seryi (New FF Lattice)~1600m is reduced ~500m.
2nd order geometric aberration is cancelled by SF1 and SD1.
02.11.1
MP =
F 0 0 0F2 1 1/ F 0 00 0 F 00 0 F4 3 1/ F
Ê
Ë
Á Á Á
ˆ
¯
˜ ˜ ˜
QM =
D 0 0 0D2 1 1/ D 0 00 0 D 00 0 D4 3 1/ D
Ê
Ë
Á Á Á
ˆ
¯
˜ ˜ ˜
K2SF1 = -F3K2SF 2
K2SD1 = -D3K2SD2
Remain 3rd order geometric aberration.
02.11.1
Thin lens approximation:
K2SF1 = -F3K2SF 2
K2SD1 = -D3K2SD2
U3444 µ N3 42 Q1 2 N2 3Q3 4 + N3 4Q4 4( )2
U1244 = U3224 µQ1 2N3 42 NQ( )1 2
2 + Q1 2N1 22 NQ( )3 4
2 - 4Q3 4N1 2N3 4 NQ( )1 2 NQ( )3 4
1,2,3 and 4 correspond to x, px, y and py
U1244 = U3224 = 0U3444
By final quads: make small.
02.11.1
Computer Program SAD:(http://acc-physics.kek.jp/SAD/sad.html1.54GeV, 3x10-6, 3X10-8, Dp/p=0.1%(Gaussian Distribution)*Large Geometric Aberration due to large physical emittance*Smaller nonlinear effect due to 0.1% energy spreadComparing LC’s design.Required Condition:
L* = 2m(IP - QD), (QF - SD2) = 2m(SF2 - QF) = (SD2 - QD) = 0.3m
KQD = -0.67m-1, KQF = 0.31m-1
U3444 = 9.57 (not minimum but optimum choice considering x)
P-Lattice and Q-Lattice are identical. F=-1.12 and D=-0.893
KQuad £ 0.2m-1
02.11.1
SF1 SD1 SF2 SD2
IP
02.11.1
Matching atMatching atIP:IP:aaxx==aayy=0,=0,bbxx=0.01m,=0.01m,bbyy=100=100mmm,m,hhxx=0 for=0 fordd=-0.2%,-0.1%,0%,0.1% and 0.2%=-0.2%,-0.1%,0%,0.1% and 0.2%
DP -0.2% -0.1% 0% 0.1% 0.2%
ax -0.089 -0.019 0.008 -0.010 -0.074
bx[cm] 1.01 1.01 1.01 1.02 1.03
ay -0.063 0.003 0.007 -0.024 -0.058
by[mm] 102 102 101 101 101
hy[mm] -110 -20 12 -28 -153
K2SF 2 = -1.2m -2 , K2SD2 = 3.5m-2
02.11.1
Accidentally, the dispersion at the final sextupole magnets isAlmost zero. This means the chromatic correction is done byThe sextupole pair upstream and downstream sexta play theRole of the geometric aberration cancellation.--->h=h’=0
Tracking Simulation: 1000 particles, No Errorsx*=3.42mm, sy*=36.8nmError : 100 seedsDsrot=0.1mrad, Dsz=500mm, Dsx=100mm, Dsy=50mm,DsDB/B=0.01% one s cut distributionAfter correction with ideal BPM and spot size monitor,Orbit Correction, Skew Correction, Position Correction ofSexta and FD.sy*=47nm (90% C.L.)If Dsrot=0.02mrad, Dsz=50mm, Dsx=30mm, Dsy=30mm,sy*= 37nm??
02.11.1
Tuning Method1. Orbit Correction with ideal BPM’s (15 Quads), Longitudinal Movement of 2 Final Quads and 4 Sexta on Movable girders with ideal beam size monitor at IP.2. (Orbit + Dispersion at 2 sexta near IP and IP): MinimizeFQ, Sexta on Movable girder: tuning3. 1-2 tuning : 4 times
First dispersion correction requires strong steerings. So, we donot correct the dispersion due to error of quad-rollBy steering magnets at first.
From ATF Alignment experience, Initial alignment of roll and pitch are +/-0.02mrad is possible by peak-to-peak.However, the diffusion of the alignment is fast and 0.15mradpeak-to-peak is diffused after about half year.
02.11.1
50nm
02.11.1
Shigeru Kuroda asked me to say following “Words”;“これは、とっても難しい ” It’s so challenging becauseof low energy 1.5GeV.This is preliminary results. However, proposal for ATF-IIwill be completed by Tauchi (Group leader of ATF-FFTB).
SummaryIt is very important to test experimentally the principle of thenew final system. The beam size is expected as sx=3.4mmand sy=37nm.R&D for some hardware is required.
Top Related