Emittance measurements in RHIC.

• Beam intensity profile measurements with the RHIC p-C CNI polarimeters.

• Cross-calibration with the other techniques.• Bunch-by-bunch emittance measurements.• Emittance measurements at injection energy.• Emittance growth on the energy ramp.

APEX Workshop, December 5, 2008

A.Zelenski, A. Bazilevskiy, G. Bunce, R.Gill, H.Huang, Y. Makdisi,B. Morozov, S.Nemesure, T.Russo, D.Steski, M. Sivertz, K.Yip

Emittance measurements in RHIC.

AGS - IPM, CNI polarimeter scans, ATR-flags.

RHIC - Ionization Profile MonitorspC CNI polarimeter scansShottke-cavityH-jet luminescence monitorVernier scansBack estimation from luminosity

Emittance measurements in RHIC.

Emittances degradation during the store.

20pi

APEX proposal• Experiment Goals:• Accurate, absolute emittance measurements in RHIC, cross-calibration

with the other techniques. • Emittance growth on the ramp.• Bunch-by-bunch emittance measurements.

• Benefits: RHIC luminosity increase.

Experiments description:

• Cross-calibration with IPMs, Vernier scans, Shottke-cavity, H-jet luminescence monitor.

• Measurements with different targets, both planes, both rings. • Measurements at injection and store. Bunch-by-bunch measurements.• Emittance growth on the ramp ( take multiple measurements during the

energy ramp time).

The RHIC p-Carbon CNI polarimeter.

Ultra thin Carbon ribbon Target(5 μg/cm2)

1

34

5

6

2

Si strip detectors(TOF, EC)

18cm

Polarized proton

Recoil carbon

Carbon target

↓↑LL NN or

↓↑RR NN or

↓↑ or

Elastic scattering: interference between electromagnetic and hadronic amplitudes in the Coulumb‐Nuclear Interference (CNI) region.

RL

RLN

pCN

Nbeam

NNNN

AP

+−

=

−=

ε

εAN(pC)~1%

P-Carbon CNI polarimeter.

Target speed

200 steps/sec → 25 mm/sec

linear speed.

~ 100 mmRHICbeam

180 mm

10 mm-SSD

Scattering angle ~0.5 deg~1.6 mm

Carbon recoil nuclei~50-70ns delayEvent rate ~106/s

Horiz. Emittances at injection after the ATR tune was corrected consistent with numbers measured in AGS.

BLUE Yellow

Measurements at Store, Feb. 7

• Very thin target , practically non-destructive.• Very high rate.• Very good signal/noise ratio. Delayed Carbon-ion

detection.• Single bunch measurements.

• Remaining problems :• Carbon strips are not straight. Target lifetime.

P-CNI polarimeter can be an ideal wire-scanner.

P-CNI polarimeter as a wire scanner.

AGS Vertical emittance CNI scan (horizontal target).

Intensity=1.6·1011.γβ=25.3

β*=21.7m

Ev=6π(1.44)2·25.3/21.7=14.5 π.

Emittance measurement in AGS, single pulse at flattop.

Sigma 0.96 mm~15 piHoriz emittance

Ev=6π(0.96)2·25.3/10.0=14.0 π.

σh=096 mm

AGS Emittances at Extraction (2006 setup).

15 pi

Horiz. CNI

1.5·1011

Vert. IPM

Horiz IPM

Effective emittances calculatedback from luminosity.

20 pi

Yellow vertical emittance measurement by luminescence monitor in the H-jet polarimeter.

Yellow vert IPM-26.9pi.

Yellow horizontal bunch-by bunch emiitances.Fill 9992.106.

hmnEntries 120

Mean 55.39

RMS 32.15

0 20 40 60 80 100 12027.69

27.695

27.7

27.705

27.71

27.715

27.72

27.725

27.73

27.735

hmnEntries 120

Mean 55.39

RMS 32.15

Mean vs bunch, mm hmndEntries 120

Mean 27.71

RMS 0.006673

27.6927.69527.727.70527.7127.71527.7227.72527.7327.7350

1

2

3

4

5

6

7

8

9

hmndEntries 120

Mean 27.71

RMS 0.006673

Mean, mm

hsgEntries 120

Mean 55.29

RMS 32.21

0 20 40 60 80 100 120

1.05

1.1

1.15

1.2

1.25

1.3

hsgEntries 120

Mean 55.29

RMS 32.21

Sigma vs bunch, mm hsgd

Entries 120

Mean 1.171

RMS 0.044

1.05 1.1 1.15 1.2 1.25 1.30

2

4

6

8

10

12

hsgd

Entries 120

Mean 1.171

RMS 0.044

Sigma, mm

Sigma=1.18mmEx=26.4 pi

Sigma=1.07mmEx=21.7 pi

25 um

Fill 9992.109, 6 hr later.

hmnEntries 120

Mean 55.39

RMS 32.15

0 20 40 60 80 100 120

26.08

26.085

26.09

26.095

26.1

26.105

26.11

26.115

26.12

hmnEntries 120

Mean 55.39

RMS 32.15

Mean vs bunch, mm hmndEntries 120

Mean 26.1

RMS 0.006701

26.0826.08526.0926.09526.126.10526.1126.11526.120

1

2

3

4

5

6

7

8

hmndEntries 120

Mean 26.1

RMS 0.006701

Mean, mm

hsgEntries 120

Mean 55.29

RMS 32.2

0 20 40 60 80 100 120

1.1

1.15

1.2

1.25

1.3

1.35

hsgEntries 120

Mean 55.29

RMS 32.2

Sigma vs bunch, mm hsgd

Entries 120

Mean 1.241

RMS 0.0394

1.1 1.15 1.2 1.25 1.3 1.350

2

4

6

8

10

12

hsgd

Entries 120

Mean 1.241

RMS 0.0394

Sigma, mm

30.6 pi

Emittance mode measurement, Run06

Measurements with p-Carbon CNI polarimeter

• Polarization measurements:• Polarization, polarization profile measurements in the scanning mode.• Polarization losses during acceleration and store.• Polarization decay during store.

• Emittance measurements:• Beam intensity profile (emttance) including bunch-by-bunch.• Emittance measurements cross-calibrations.• Emittance measurents on the ramp.

• Problems:• Targets lifetime.• Measurements in both plane take too much time for target activation.• Carbon targets quickly degraded (loosed) after the beam exposure.

The ongoing CAD polarimeter upgrade project will address these problems for the

2009 polarized run.

The plan is two build and install the second polarimeter ineach RHIC ring. These two polarimeters will be installed in newvacuum chambers with more powerful vacuum system toimprove RHIC vacuum conditions. Two identical Carbon targetmotion mechanisms and detectors assembly will be installed ineach chamber (both ring).

One polarimeter can be used for the vertical polarizationand intensity profile measurements and the second can be usedfor the horizontal profile measurements. It will minimize numberof target motions, speed up the measurements (increaseefficiency of the stored beam use for about 5-10%) and reducethe risk of the target damages.

The RHIC p-Carbon CNI polarimeter upgrade for the beam polarization and intensity profile measurements

December 4

Operation modes.

• Polarization measurement scan (main mode).Polarization, polarization profiles, beam intensity profile (including bunch-by bunch).

• Emittance measurements and calibration in fast scan mode, with dedicated targets (which will be used initially only for emittance measurements to reduce beam exposure and target degradation).

• There will be more targets in polarimeter after upgrade.

Target Drives upgrades

A new target drive design to improvepositioning accuracy (low backlash)Improve reliability, reduce vibrations.

Target drives installationDecember 4

Beam request.

• Cross-calibration with IPMs, Vernier scans, Shottke-cavity, H-jet luminescence monitor.

• Meaurements with different targets, both planes, both rings.

• Measurements at injection and store.• Emittance growth on the ramp.

• Beam request - 2 hrs.

Backup slides.

BEAM EMITTANCE MEASUREMENTS IN RHIC A.Zelenski, A. Bazilevskiy, G. Bunce, R.Gill, H.Huang, Y. Makdisi, B. Morozov, T.Russo, D.Steski, M. Sivertz, K.Yip, Collider

Accelerator Department, Brookhaven National Laboratory,

Upton, New York 11973, USA

Abstract. The proton polarization measurements in AGS and RHIC are based on proton-carbon and proton-proton elastic scattering in the Coulomb Nuclear Interference (CNI) region. Polarimeter operation in the scanningmode gives polarization profiles and beam intensity profile (beam emittance) measurements. This polarimeter isan ideal wire-scanner due to: extremely good signal/noise ratio and very high counting rate, which allows accuratebunch by bunch emittance measurements during 100 ms time of the beam crossing. The use of a very thin carbontarget makes these measurements practically non-destructive. The consistence of these measurements with theIonization Profile Monitor, H-jet Luminescence Monitor, Vernier scan, luminosity measurements will bediscussed. Bunch by bunch emittance measurements is very powerful tool for the machine set-up and for the proton beams can be measured only by CNI polarimeter scans. The complete set of polarization and beamintensity profile measurements (in both vertical and horizontal planes) are limited at present by the long targetswitching time and possible target destruction during this complicated motion. The systematic measurements ofthe beam emittance in both vertical and horizontal planes will be possible after polarimeter upgrade for the 2009 polarized run. Two new vacuum polarimeter vacuum chambers will be installed in the RHIC rings. Two identicaltarget motion mechanisms and detectors assembly will be installed in each chamber (each ring). One polarimeter can be used for the vertical polarization and intensity profile measurements and the second can be used for thehorizontal profile measurements. It will minimize number of target motions, speed up the measurements and reduce the risk of the target damages. The emittance measurements at injection during the energy ramp and atstore will be used to study emittance evolution in RHIC. The absolute accuracy limitations and cross-calibration of different techniques will be also discussed.

Abstract. The proton polarization measurements in AGS and RHIC are based on proton-carbon andproton-proton elastic scattering in the Coulomb Nuclear Interference (CNI) region. Polarimeteroperation in the scanning mode gives polarization profiles and beam intensity profile (beamemittance) measurements. This polarimeter is an ideal wire-scanner due to: extremely goodsignal/noise ratio and very high counting rate, which allows accurate bunch by bunch emittancemeasurements during 100 ms time of the beam crossing. The use of a very thin carbon targetmakes these measurements practically non-destructive. The consistence of these measurementswith the Ionization Profile Monitor, H-jet Luminescence Monitor, Vernier scan, luminositymeasurements will be discussed. Bunch by bunch emittance measurements is very powerful tool forthe machine set-up and for the proton beams can be measured only by CNI polarimeter scans. Thecomplete set of polarization and beam intensity profile measurements (in both vertical and horizontalplanes) are limited at present by the long target switching time and possible target destruction duringthis complicated motion. The systematic measurements of the beam emittance in both vertical andhorizontal planes will be possible after polarimeter upgrade for the 2009 polarized run. Two newvacuum polarimeter vacuum chambers will be installed in the RHIC rings. Two identical targetmotion mechanisms and detectors assembly will be installed in each chamber (each ring). Onepolarimeter can be used for the vertical polarization and intensity profile measurements and thesecond can be used for the horizontal profile measurements. It will minimize number of targetmotions, speed up the measurements and reduce the risk of the target damages. The emittancemeasurements at injection during the energy ramp and at store will be used to study emittanceevolution in RHIC. The absolute accuracy limitations and cross-calibration of different techniques willbe also discussed.

Beam emittance measurements in RHICA.Zelenski, A. Bazilevskiy, G. Bunce, R.Gill, H.Huang, Y. Makdisi, B. Morozov, S.Nemesure, T.Russo, D.Steski, M. Sivertz,

K.Yip, CAD, Brookhaven National Laboratory, Upton, New York 11973, USA

PAC 2009, Abstact

Vacuum system upgrade.

• Polarimeter will be pumped by two pumps (ion pump and NEG cartridge) isolated by vacuum valves.

• Diam. 8.0” (ID) nipples will provide sufficient conductance to utilize full pump capacity.

• Isolation valves will allow proper pump conditioning and faster turn around time after the venting.

• In future we plan to setup some moderate chamber baking after testing of polarimeter components (targets, detectors, Am-sources) tolerances to temperature.

Yellow polarimeter baking, Dec.4

Target drives installation, Dec.4

Event Selection

Carbonα

400<E<900keV

Very clean Carbon event extraction!

3σ

Horiz. Emittances at injection after the ATR tune was corrected consistent with numbers measured in AGS.

BLUE Yellow