Overview of Beam Diagnostics from the Advanced Accelerator

Concepts Workshop (AAC06)

Vic ScarpineInstrumentation Meeting

20 Sept 2006

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Outline:– Brief description of working groups– Overview of beam diagnostic talk mostly

from working group #5Out of ~170 participants only 3 were from

Fermilab (not counting A0/Nicadd)• Myself, Shiltsev and Yoon

Disclaimer – Any confusion, mis-information, half-baked explanations are solely the fault of the speaker. Any interest in presented topics should be followed up thoroughly by audience members (or else you get what you deserve).

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Working Groups

WG1 - Computational Accelerator PhysicsWG2 - High-Gradient StructuresWG3 - High Energy Density Physics and Exotic

Acceleration SchemesWG4 – e-Beam Driven Accelerators WG5 – Beam Generation, Monitoring, and Control WG6 – Laser Plasma Acceleration GroupWG7 - EM Structure Based Accelerators

– Vladimir Shiltsev has give a highlights talk at a previous Tuesday accelerator seminar on the accelerator topics from AAC06 (in Doc DB)

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WG5 – Beam Generation, Monitoring, and Control

Mission Statement:The working group "beam quality" will concentrate on three aspects of

advanced accelerators: (1)    the production of high quality beams with "conventional"  sources, (2)    the characterization and control of high quality beams, and(3)    synchronization with external systems.• The ultimate goal of a diagnostic is to characterize the beam properties

in the 6-dimensional phase space, ideally providing the beam distribution.  

• Diagnostics are also used as inputs for feedback system aimed to regulate one of the beam properties (e.g. energy, time of arrival, transverse position, etc.), typically based on a zeroth-moment (e.g. energy, arrival time, transverse position) or first-moment (e.g. energy spread, bunch length, spot size) measurement.

• Finally it is now common to require an external source (e.g. another beam source, external laser, synchrotron radiation pulse, etc.) to be synchronized with the beam.  For instance the synchronization at the sub-picosecond level is a challenging problem needed for certain pump-probe experiment or diagnostics (e.g. electro-optical sampling for bunchlength measurement).  

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Typical Electron Machine Diagnostics?

• Heavy on the optical techniques• Similar to A0 diagnostics• Future for us in ILC-land?

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Final Focus Test Beam at SLAC using interferometry to measure beam size

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Ultrafast Diagnostic Techniques Used In STELLA-LW Experiment - W. D. Kimura

- Translating interferometer mirror yields autocorrelation- Analysis of autocorrelation signal gives information about bunch

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Ultrafast Diagnostic Techniques Used In STELLA-LW Experiment - W. D. Kimura

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Measurements of Longitudinal Electron Bunch Shape WithCoherent Transition Radiation - Daniel Mihalcea, NIU+FNAL

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Coherent Transition and Smith- Purcell Radiation Experiments on the HRC MIT 17 GHz Linac - Roark A.

Marsh, MIT

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From Beam Diagnostics Summary Page

Longitudinal measurements are maturing– CTR is almost “routine” for bunch length– Advanced methods for profile reconstruction

with CTR, phase-space projection with deflector cavities + dipoles

– Working towards “single-shot” CTR-based meas.

Transverse measurements– Tomographic reconstruction is now widely used– New BPM designs for position and moment

extraction– Ideas for full phase-space projections to a screen

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Some Upcoming Non-InterceptingTechniques

• Quad cavity BPMs to extract beam moments, measure rms emittance

• Optical diffraction radiation to monitor high-energy beam size

• Metallic post BPMs• Photonic bandgap structures• Coherent edge radiation

Questions: wakefields? beam-to-structure clearance?

(Not discussed in WG5: laser wire, EO techniques)

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S. Banna, L. Ludwig and L. Schächter, NIMA, 555, p. 101 (2005).

Power Spectrum for 6x6 Posts Array

• For zero offset the radiation pattern is symmetric.• The intensity of the backward radiation increases with the increase of the offset.• The radiation pattern is highly directional and has narrow angular range

Array of Metallic Posts as a BPM Pick-Up

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Alex Lumpkin, APS, Argonne

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Alex Lumpkin, APS, Argonne

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Alex Lumpkin, APS, Argonne

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Bunch compression and coherent radiation measurements experiment at UCLA-ATF chicane- J. Rosenzweig, UCLA

Autocorrelation of CTR used to measure bunch length.CTR generated by foil.

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Phase Space Mapping and Emittance Measurement Of Intense Particle Beams Using A Tomography Technique

Measure the beam phase space by combining asimple quadrupole-scan with tomography

Diktys StratakisUniversity of Maryland

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Possibilities...

Lots of interesting diagnostic techniques for the electron world

R&D available at FNAL? – A0 lab (and it’s future incarnation)

Electro-optic world dominate in e-accelerators and have potential for unique and non-interacting techniques