June 13, 2016

Overview ofLatticeY. Ohnishi
The 21th KEKB Accelerator Review Committee

Outlook of Lattice"IP"

No QCS, No Solenoid
No Local Chromaticity
Correction

LER"IP"

HER
Beast II

LER wiggler
HER wiggler

The vertical emittance is very importantin the "nano-beam".
LER Arc Cell

HER Arc Cell
LER abort
injection
SF -I' SF SD-I' SD

HER abort (sext.)
injection
SF -I' SF SD-I' SD2

Strategy of Optics Tuning at Phase-1
HER

LERwiggler OFFΔz = -0.4 mm

wiggler OFFΔz = -6.32 mm

3-BPM/Local Bump
Gain Mapping
Quad BPM

Orbit
Correction

Yes

No

εy < 5-10 pm ?

HER Ready

Orbit
Correction

Adjust Adjust circumference wiggler ON
fRF
Δz = 0 mm

wiggler ON
Δz = 0 mm

OpticsCorrection

3-BPM/Local Bump
Gain Mapping
Quad BPM

X-Y coupling
Dispersion
Beta-function

OpticsCorrection

We are Here. Yes

Adjustchicane

No

OK

X-Y coupling
Dispersion
Beta-function

εy < 5-10 pm ?

LER Ready3

Vertical Beam Size
Target εy is less than 10 pm, hopefully 5 pm.
X-ray Beam Size Monitor
LER

βy = 67 [m]@X-rayHER
20 pm
10 pm

βy = 7.64 [m]@X-rayεy = 120 pm

εy = 5 pm
Beam Current [mA]
Red: before installing permanent
skew quad to correct leakage
skew quad. field fromLambertson.
Blue: after installing permanent
skew quad

Beam Current [mA]εx = 4.6 nm
εy/εx = 2.6 % ?
Is εy relally big in HER ?
4

Estimation of Vertical EmittanceTarget value is less than 10 pm, hopefully 5 pm.
6 kinds of steerings are used to induce orbits
for each x and y.

β measurement
based on orbit distortion(x, y)

physical dispersionmeasurement(ηx, ηy)M6x6

Twiss parameters M11(βx, βy, φx, φy)αxX-Y coupling X-Y coupling(r3,r4)u-mode (r1,r2)
M(ηx, ηpx, ηy, ηpy)(ηu, ηpu, ηv, ηpv)
integration in dipoles

for 440 - 460 BPMs
5

X-Y Coupling in LER
r1

after installing permanent magnet

beforer2
r3
r4
Lambertson(skew quad)

q1
q2
q3
q4

6

Normal Dispersions in LER
before installing permanent magnet

after installing permanent magnet

Lambertson(skew quad)

normal dispersion

physical dispersion(measurement)

7

Estimation of Vertical Emittance in LER

wiggler

wiggler

Lambertson
septumεy = 7.2 pm

8

X-Y Coupling and Normal Dispersions in HER
r1r2
r3
r4

q1

wigglerq2

Lambertson(skew dipole)q3

ηy should be corrected.

q4
X-Y coupling is well corrected.
9Estimation of Vertical Emittance in HER

wiggler

εy = 9.1 pm
Lambertson
septum10

Summary

The vertical emittance is the most important parameter in the nanobeam scheme. The target is less than 10 pm (desired value is 5 pm).
Lambertson leakage skew quad. field is successfully corrected byinstalling the permanent skew quad. in LER.
The vertical emittance is estimated by the optics measurement data;εy = 7.2 pm in LER, εy = 9.1 pm in HER
The vertical emittance is also obtained from X-ray beam size monitor;
εy = ~10 pm in LER, εy = ~120 pm in HER
The vertical emittance in LER is almost consistent with X-raymonitor, however the big discrepancy in HER is found. How toconfirm ?
11

Appendix

12

Machine Parameters at Phase-1
Parameter
E [GeV]I [mA]
nbεx [nm]αpσδ
Vc [MV]U0 [MeV]τs [msec]σz [mm]
νsνx
νyLER

HER

4

7890

810

1576

1576

1.8

4.6

2.45x10-4

4.44x10-4

7.72x10-4

6.30x10-4

7.56

12.61

1.76

2.43

23

29

4.6

5.3-0.0192-0.0251

44.55545.57246.59543.58913

Orbit at Lambertson Septum
LER

Lambetson

0.475 mrad

HER

Lambertson

0.350 mrad

14

Lambertson in LER

LER

Lambertson septum
leakage skew quad. field-I' transformation

skew quad. coil(corrector)

skew quad. coil(corrector)
15

Dynamic Apertrue

LER
30 minεy/εx = 0.4 %(εx = 1.8 nm, εy =7.2 pm)
Ib = 0.34 mA

HER
76 minεy/εx = 0.2 %(εx = 4.6 nm, εy =9.1 pm)
Ib = 0.34 mA

16