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LEP Energy WG Report

October 13th, 2001 WWMMI Cetraro, Italy Eric Torrence University of Oregon

Eric Torrence

WWMMI Cetraro

October 2001


Overview

Work Continues in several areas · Flux Loop analysis · Qs vs. fRF analysis · Spectrometer magnet mapping · Spectrometer BPM analysis

More general overview available here:
http://www.cern.ch/LEPECAL/talks/CERN_01Apr

Eric Torrence

WWMMI Cetraro

October 2001


Flux Loop Studies
30 20 10 0 -10 -20 -30 -40 30 20 10 0 -10 -20 -30 -40 Apr

[ MeV ]

1997 data

1998 data

- EN

MR

Eb= 92 GeV

Eb= 94 GeV

ux Loop

1999 data

2000 data

EFl

Eb= 98 GeV

Eb= 100 GeV

Jul

Jun

Aug

Jun

Jul

Aug

Oct

Sep

May

Extensive cross-checks · Analyze all data combined · Check against octant, NMR, year, etc. · Documentation underway
ї

Stable results for all years

Eric Torrence

WWMMI Cetraro

May

October 2001

Sep

Apr

Oct


Flux Loop Checks

versus Beam Energy

EFL - ENMR [ MeV ] at 196

80 60 40 20 0

versus NMR Probe

-20 -40 -60
NMR

-80

0

2

4

6

8

10

12

14

16

Eric Torrence

WWMMI Cetraro

October 2001


Synchrotron Oscillations
0.2

Q

s

0.18 0.16 0.14 0.12 0.1 0.08 0.06 250

Enom = 50.005 GeV Enom = 55.293 GeV

Enom = 60.589 GeV Enom = 80.000 GeV

500

750 1000 1250 1500 1750 2000 2250 2500

V

RF

/ MV

Momentum Compaction

RF Voltage Calibration

Realistic RF Distribution

Dipole Losses

Other Losses

2000 Data · Three energy measurements · Additional parameter calibrations · Energy dependence of g
Eric Torrence WWMMI Cetraro October 2001


Voltage Calibration

2000 Data
without damping

· Enhanced damping · Need to excite Qs
with damping

· Frequency shifts
Qs

Additional Calibration
3

realtive change in g in permille

2 1 0 -1 -2 -3

Measurement in 2000

Measurement in 1999

45

50

55

60

65

E
ї

nmr

/ GeV

Does not effect 1999, precision possibly reduced
WWMMI Cetraro October 2001

Eric Torrence


Spectrometer Mapping
NMR Probe Hall Probe

Steel Dipole

Marble Bench

1m

Precision Stage Carbon Fiber Arm

Hetrodyne Ruler

Need B dl as f ( B

°

Ref

)

Field (kG)

3 2 1 0

NMR Probe Locks

-4

-3

-2

-1

0

1 2 3 Position (meters)

Magnet remapping essentially finished!
Eric Torrence WWMMI Cetraro October 2001


2001 Mapping Results
x 10
-4

Maps 2001, Fit to the ISR

Relative Residual

0.9 0.8 0.7 0.6 0.5 40 50 60 70 80 90 100

2001/07/24 19.48

Energy [GeV]

7 в10
Ratios Residuals
x 10
-4

­5

offset from 1999!
Multipoint Cycles

0.8 0.6 0.4 0.2 0 -0.2 40 50 60 70 80 90 100 Energy [GeV]

Only 3 в10
Eric Torrence

­5

in B dl

°

E2

/ B dl

°

E1

residual
October 2001

WWMMI Cetraro


Spectrometer BPMs
Left X triplet Left Y triplet

Right X triplet

Right Y triplet

· 1 micron ~ 10 MeV · Systematic shifts, not random · Possible to correct?

Eric Torrence

WWMMI Cetraro

October 2001


Bunch Length? Example Wiggler Experiments Wigglers
on (7667) off (7667) on (7676) off (7676)

8.4 4.7 8.4 4.7

z

LHS x LHS y RHS x RHS y 0 -4.8 0 -4.4 0 -1.2 0 -0.1 0 +2.3 0 +1.0 0 +0.5 0 +2.2

mm mm mm mm

Qs Experiments z = 4.4 3.7 4.4 mm

Bench BPM Test · Recreate in lab · Results in spring

Eric Torrence

WWMMI Cetraro

October 2001


Timeline

Flux Loop · Nearly final · Documentation started Qs vs. fRF · Additional damping seen in 2000 · Analysis finished by end of year Spectrometer mapping · Differences found · Nothing serious for spectrometer BPM analysis · Clear systematic trend · Correction possible, but explanation? · Lab test to verify beam measurements Start writing this Winter Final document(s) by Summer?

Eric Torrence

WWMMI Cetraro

October 2001