BGIP Beam Gas Ionization Profile Monitor

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BGIPBeam Gas Ionization Profile Monitor

• Ana Arauzo, C. Bovet, J. Koopman, A. Variola

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Outline

• 1. Device Description
• 1.1 Working principle
• 1.2 Prototype
• 2. LHC Beam Diagnostics
• 2.1 Spectrum analysis Beam Emittance
• 2.2 Expected Performance
• 2.3 Additional Features
• 3. SPS tests
• 3.1 Beam conditions
• 3.2 Performances achieved, examples
• 4. Conclusions

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1.1 Working principle

• Residual gas ionization acceleration by the
  beam (no additional fields)
• Ions spectrum Analysis ions are collected and
  spatially resolved in energies.
• Great accuracy non-destructive method

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1.2 Prototype
B
H
vfm
Dm
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Prototype
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2. LHC Beam Diagnostics2.1 Spectrum Analysis

• Edge ? M vfm2 a bln(? r )
• (a,b ? Beam Intensity)
• Width ? Beam ellipticity
• (flat beam ? 2 Detectors)

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(No Transcript)
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Beam Emittance

• Gaussian Density Profile rms ?r
• ?
• vfm
• M vfm2 a bln(? r )
• ?
• B
• vfm c B

a,b ? I c ? Dm/M
Error Transmission I , B, Dm
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2.2 Expected Performance

• Non-perturbing
• Beam size monitoring whole Energy range 450 GeV
  - 7 TeV
• low energy residual gas ions, H, H2
• high energy injected gas ions, He, N2
• Great Accuracy better than 1
• ?r ? 1 Detector H or V
• ?x and ?y ? 2 Detectors H and V
• Great Resolution up to 0.1

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2.3 Additional Features

• Spectrum from different species is spatially
  resolved sweeping B
• Amplitude ? ionization rate Pgas, ?ion
• Study of the beam density profile
• Information stored in the ion energy spectrum
  shape

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3. SPS Tests Beam conditions

• 26 GeV LHC type beam
• 84 proton bunches
• Intensity Np 0.7- 0.81011 p/bunch
• Vacuum 10-8 torr 2.3105 ions/s
• ?M ( ? r) 4.6 0.5 mm
• ?
• test limitations energy range or/and emittance
  range, limits in precision and resolution

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3.2 Performances Achieved

• Ion detected H2
• Measurement Dm(B) for almost the same beam size
• Signal for B 100 to 250 gauss

Accuracy in beam size determination
16 wire-scanner cross-checked
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174.3 G
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H-Profile ? Exp. Data ? Simulation
Dm fit ? Exp. Data ? Simulation (Dm limits
CCD)
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Errors in Beam conditions Emittance
?m 8 Intensity I 10
Error in simulated Dm 8 ??m ? 2 Dm 10 I ?
7 Dm
Results vs. simulations 4 rms deviations Dm data
Error in ??m determination 16
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4. CONCLUSIONS

• BGIP predicts good performance for the LHC beam
  parameters
• Successful results obtained in the first tests
  for a LHC-type beam

Advantages Non-perturbing high accuracy control
of the beam size over the whole LHC energy range
Disadvantages No physical measurement of the beam
density profile
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References

• 1. Buon J. et al., NIM A306, 93-111 (1991)
• 2. Puzo P. et al., NIM A425, 415-430 (1999)
• 3. Arauzo A. et al., LHC Project Note 198 (1999)

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Acknowledgments

• J. Buon and P. Puzo for their support in the
  theoretical calculations and detector design.
• R. Perret, J. Camas, M. Sillanoli, J. Colchester
  for the practical realization and installation.
• R. Jung for the general support
• J.J. Gras for the software support
• Gijs de Rijk for the dipole magnet measurements