#3224 Sat 17th November

• Restored an “AP” set-up with some measurement of Twiss. – The idea was to take some BPM data with a

known twiss set-up to see how the bunch-to-bunch position variation correlates with the Twiss.

• Took BPM data in AR1.• Scanned AR1-Q1/4 to close dispersion • Scanned AR1-Q1/4 to make isochronous.

#3224 Twiss

• AP set up from #3139• See \\Dlfiles03\alice\Analysis\Period 14

data\AP_period13and14\transversemodel\3139

• Repeated the same scans to compare Twiss repeatability.

• ST1-Q1 scan Q2 = 0.6 A Q3/4 = 0 A• ST1-Q2 scan (0-1.4A) with Q1 = 0.40A.

ST1-Q1 scan Q2 = 0.6 A Q3/4 = 0 A, beamsize measured on ST1-4

0 0.1 0.2 0.3 0.40

1

2

3

43.471

0.228

I1( )

Ai 2

0.40 I1 Ai 1

Yuri original meas’t on #3139

0 .0 0 .1 0 .2 0 .3 0 .40

1

2

3

4

I ST 1Q 1Guassianfitsigmamm

#3224. Position of minimum looks similar but curve much shallower

0 .0 0 .1 0 .2 0 .3 0 .40

1

2

3

4

I ST 1Q 1Guassianfitsigmamm

My analysis of #3139

ST1-Q2 scan (0-1.4A) with Q1 = 0.40A. beamsize measured on ST1-4

No plot available from Yuri’s file

0 .0 0 .2 0 .4 0 .6 0 .8 1 .0 1 .2 1 .40

1

2

3

4

I ST 1Q 2Guassianfitsigmamm

0 .0 0 .2 0 .4 0 .6 0 .8 1 .0 1 .2 1 .40

1

2

3

4

I ST 1Q 2Guassianfitsigmamm

My analysis of #3139

My analysis of #3224

Twiss Calculationγ.εx (μm)

αx(m) βx (m) γ.εy (μm)

αy(m) βy(m)

#3149 YMS evaluation

8.5 21.0 77.4 3.1 -2.31 22.3

#3149 My evaluation

9.5 19.0 75.7 Not done Not done Not done

#3224My Evaluation

6.5 11.4 40.7 Not done Not done Not done

Uses parabolic fit to σ^2 vs k.lConstrain parabola vertical offset to smallest beamsize measurement

Twiss Conclusions

• NB: I didn’t go to divisor 20 like Yuri did. But I would expect the result (if any) of this would be to make my beamsizes on #3224 larger due to increased beam loading. However, my beamsizes are smaller.

• I set up phases “accurately” to match #3224 60pC; BC=-10/+15deg; Lc = crests. Pb=1.2kW.

• Comparison of the quad scan data suggests optics are not highly repeatable. Two months gap between measurements being compared. Maybe this is too long a gap.

Model vs Measure #3224

ST1-3 AR2-1

ST2-1

ST2-2

Model/measure agreement not too bad

Bunch intra-train variation/jitter compared with β function

x-plane

AR1-BPM-01 AR1-BPM-03 AR1-BPM-04 AR1-BPM-06

Plot sqrt(β) (~ beamsize) vs rms x position with the train, for each BPM trace. The β at each BPM comes from model on previous slide.

There does seem to be strong correlation, perhaps expected. AR1-BPM-06

AR1-BPM-01

AR1-BPM-03

AR1-BPM-04

AR1 STUDIES

After Twiss evaluation, restore the #3139 “AP” set up and study dispersion and R56 of AR1

AR1 Dispersion Measured on AR1-BPM-06

Each plot is BPM x position vs beam energy

Vary AR1-Q1/4 from 1.9 to 2.4 in 8 steps

2.0 2.1 2.2 2.3 2.4

100

50

50

Dispersion (mm) vs AR1-Q1/4 current

AR1 R56 measured on AR1-BPM-06 Each plot is BPM relative path length vs beam energy

Vary AR1-Q1/4 from 1.9 to 2.4 in 8 steps

R56 (mm) vs AR1-Q1/4 current

2.0 2.1 2.2 2.3 2.4

300

200

100

100

200

300

AR1-Q1/4 current

Summary

2.0 2.1 2.2 2.3 2.4

100

50

50

2.0 2.1 2.2 2.3 2.4

300

200

100

100

200

300

R16 R56

Isochronous + zero dispersion condition at AR1-Q1/4 = 2.18 A

AR1-Q1/4 current AR1-Q1/4 current