Measurement of Transverse Emittance in ASTA John Nocita

  • Slides: 16
Download presentation
Measurement of Transverse Emittance in ASTA John Nocita Amber Johnson John Diamond August 8,

Measurement of Transverse Emittance in ASTA John Nocita Amber Johnson John Diamond August 8, 2013

Overview Emittance • Hardware • • • Vacuum equipment Imaging • • • Software

Overview Emittance • Hardware • • • Vacuum equipment Imaging • • • Software • • Scintillation OTR ACNET Existing tools Emittance. Calculator Conclusions, Future Direction

Emittance • Emittance is beam size in phase space • Εn = ΥβE is

Emittance • Emittance is beam size in phase space • Εn = ΥβE is conserved through acceleration • Monitor beam, design components • Gaussian approximation of beam RMS emittance http: //www-pnp. physics. ox. ac. uk/~delerue/

Emittance •

Emittance •

Hardware Need to test angular acceptance, field of view: reading in pixels, computing in

Hardware Need to test angular acceptance, field of view: reading in pixels, computing in microns. - 27. 8 microns / pixel Alex Lumpkin

Targets / Slits Beam cage : prevent wakefield effect Scintillator crystal OTR foil

Targets / Slits Beam cage : prevent wakefield effect Scintillator crystal OTR foil

Slit imaging Slit spacing for divergence measurements • Tungsten blocks with 50 um spacing

Slit imaging Slit spacing for divergence measurements • Tungsten blocks with 50 um spacing • Known slit size measurable divergence •

Imaging techniques • Scintillation § • OTR § • Higher output; limited by crystal

Imaging techniques • Scintillation § • OTR § • Higher output; limited by crystal effects Better spatial, temporal resolution Both destructive

Scintillation Decay time = 70 ns 8 photons per Ke. V

Scintillation Decay time = 70 ns 8 photons per Ke. V

Optical Transition Radiation Angle of peak electron emission is 1/γ • A charged particle

Optical Transition Radiation Angle of peak electron emission is 1/γ • A charged particle transitioning between media with different dielectric constants must rearrange electric fields • § Photons emitted on subpicosecond timescale From Alex Lumpkin

ACNET Image. Tool Emittance Calculator Cameras Background Subtraction Target steppers

ACNET Image. Tool Emittance Calculator Cameras Background Subtraction Target steppers

A 0 PI Emittance calculator Image. Tool

A 0 PI Emittance calculator Image. Tool

Fitting multiple Gaussians Iterative methods need good initial condition • Peak selection – ease

Fitting multiple Gaussians Iterative methods need good initial condition • Peak selection – ease of use • Simulated phase space image •

Emittance. Tool Interface for cameras (ACNET) • Manual peak selection • Fits to data

Emittance. Tool Interface for cameras (ACNET) • Manual peak selection • Fits to data • Calculation of phase space ellipse •

Conclusions and Future Directions Adaptation of A 0 PI functions to ACNETcompatible format •

Conclusions and Future Directions Adaptation of A 0 PI functions to ACNETcompatible format • Specific to ASTA • § § Camera signatures beam energy, drift length More automated calculation Flexible – optimized to present hardware, software conditions but will adapt to beam • Hopefully, a useful tool through construction •

Thanks to: • • • Amber Johnson for guidance and support. John Diamond for

Thanks to: • • • Amber Johnson for guidance and support. John Diamond for countless good ideas and advice Alex Lumpkin for great explanations The Fermilab Accelerator Division for creating a welcoming and helpful atmosphere Eric Prebys, Linda Spentzouris, and Carol Angarola for all their work to make things go smoothly