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APEX Schedule January 20, 2010

11pm

12x12 store

7pm

12x12 store

Nonlinearchromaticity Luo

Beta* squeeze+s* adjustment R-Demolaize

12x12 storeAC dipole

2am8pm

OpticsMeasureAC dipole

BaiWang

ramps

OpticsMeasureAC dipole

BaiWang

10pm

12x12 store

IR correctionsoctupole Zimmer

5am

Orbitfeedback MintyMarusic

7am

Start maintenance

6 amAGS OFF

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High Lights of APEX Studies

Failed first ramp with Blue beam only Yellow main dipole stopped ramping at 60 seconds after

accramp, feature of Yellow dipole feedback

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High Lights of APEX Studies

Beta* squeeze + s* adjustment + optics(Blue): Guillaume, Gang, Mei Main goal: use the effect of SC on emittance changes

along a store to increase luminosity by dynamically reducing β* (i.e. keep the ratio ε/β* constant).

Tested dynamic beta* squeeze at STAR in both rings. Optics in Blue were measured before and after beta*

squeeze Didn’t have chance to test s* adjustment

Lattice IR6 as of Model IR6 as of Loptics

Blue Au104 Blue Au104 squeezedsqueezed 0.6353020.635302 0.790.79

Blue Au104Blue Au104 0.698590.69859 0.830.83

APEX

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High Lights of APEX Studies

Blue IR6, Beta* = Blue IR6, Beta* = 0.675m0.675m

Yellow IR6, Beta* = Yellow IR6, Beta* = 0.68m0.68m

Blue IR6, Beta* = Blue IR6, Beta* = 0.625m0.625mYellow IR6, Beta* = Yellow IR6, Beta* = 0.6m0.6m

DECAYDECAY

BACKGROUNDBACKGROUND

ZDC RATEZDC RATE

IR STEERINGIR STEERING

From GRD

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High Lights of APEX Studies

2nd order chromaticity correction Au104: Yun, Dejan able to bring | Q'' | ~ 500 for both rings in the

measurement range. Blue radial shift went up to 2mm while yellow around 0.5

mm. small Q'' didn't give small beam decay during

measurement for yellow. Yellow vertical dispersion is about 2m in IR6. Blue maximum vertical dispersion about 0.8m in IR8. Blue loss during Q'' measurement located at IP Yellow loss during Q'' measurement located at IP4

( s=3195m ). Horizontal and vertical dispersion in IR6 and IR8 can be effectively corrected with small orbit angle bumps in those regions. But it did not provided obvious improvement in the momentum aperture

APEX

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High Lights of APEX Studies

High order non-linear resonance correction: Chris, Fulvia Only had ~ one hour beam time Minimized the horizontal tune shift from 10mm horizonatl

bumps by adjusting IR octupoles. This helped to reduce the beam decay in each ring. Max beam decay for a horizontal 10mm bump now seems to be about ~20 percent.

Observed the increase of beam decay being by further minimization of the horizontal tune shift in some instances; needs more investigation

Didn’t get time to investigate vertical bumps to confirm that the major octupole effects have been minimized already.

Still more work to do to automate the technique of non-linear resonance correction using IR bumps

APEX

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High Lights of APEX Studies

Orbit correction feedback: Michiko, Al, Vadim, Rob, …

verified convergence of feedback at injection energy in all 4 planes

devoted some time to eliminating suspect BPMs – in particular discovered

model/application error concerning one dual-plane in the yellow ring

executed 2 ramps with feedback on in blue and yellow and in both planes

Worked! Vertical orbit rms went down from ~0.5mm to ~0.15mm

Very good reproducibility between the two ramps with feedback on

Beam was aborted late part of the ramp due to a sextupole trip

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Convergence Tests

blue, X blue, X / Y

yellow, X yellow, Y

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Ramp w. Orbit Feedback

w.o. orbit feedback

w orbit feedback

w.o. orbit feedback

w orbit feedback

Manual orbit correction between ramps

Per

mit

pull

due

to s

extu

pole

trip

, un

know

n re

ason

APEX

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APEX Schedule February 3, 2010

noon

12x12 store

7am

ramps

BBA Satogata

Orbit feedback

MintyMarusicPtitsyn

12x12 storeAC dipole

Tune scanMomentum apertureChromatic correctionsLuoSchoeferTrbojevic

4pm11am

OpticsMeasurementsChromatic beta functions BaiWang

injection

7pm

Back2Physics

6pm

APEX

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Coming APEX Studies: Tune Scan

Tune scan+momentum aperture and chromatic correction in Yellow: Yun, Dejan

Ramp both beams to store with separation bumps

confirm the correction strengths found in last APEX session

dump blue beam, remove separation bumps

scan yellow working point along diagonal while checking Q'' with radial wiggling and observing the beam decay

if time permits, try Dejan's local sextupole correction ramp both beams to check rebucketing to see if it improves,

i.e. less yellow losses

APEX

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High Lights of APEX Studies