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PRISM experiment on EMMA• Test Non-Scaling optics for PRISM• ¼ of the synchrotron oscillation takes ~3 turns in

EMMA and ~6 turns in PRISM.• Experimental steps (version I):– Inject into EMMA at fixed energy from ALICE with

different conditions (transverse amplitudes)with RF on (voltage and phase set to stationary bucket).

• Extract after ¼ (3/4) of synchrotron oscillation and measure energy and ToF.

• Analyse the data and reproduce the longitudinal phase space as a function of the transverse amplitude J. Pasternak, R. D’Arcy, bdm

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PRISM experiment on EMMA• Experimental steps (version II):– Inject into EMMA at different equivalent energies

with different conditions (transverse amplitudes) with RF on (voltage and phase set to stationary bucket).

• Extract after ¼ (3/4) of synchrotron oscillation and measure energy and ToF.

• Analyse the data and reproduce the longitudinal phase space as a function of the transverse amplitude.

• Can we measure the emittance growth ?• Do we need more initial RF phases or energies ?

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PRISM experiment on EMMA• Not much progress made in the last run … • Only really had ~ 6 hours and remember– Need to extract the beam & measure energy– Everything before extraction has to work …

• Only have pencil beam – cannot model directly– Take 3 or more bunches to represent PRISM beam– Show rotation that way by changing RF phases

• Find stable fixed point of RF bucket• Vary phase & extract ‘beamlets’ (small bunches)– Lower energy / higher energy

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PRISM experiment on EMMA• Have established extraction reliably after n turns– Good transport (though intensity not sufficient to get

to Faraday cup at the end of line …)– Beam centred down extraction line

• However n was small (only 1/2, 3/2, 5/2 turns)– Did not have RF capture of beam which would have

been ideal for this experiment• Saw beam on YAG01 & YAG03 in extraction– Have script to scale all magnets in extraction line

according to energy by Jaroslaw– Make images on YAGs identical

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BPMs at dipole entrance Wall current monitor

YAG screens x 3

YAG screen, vertical slit

Combined horizontal and vertical steering magnets x 3

Faraday Cup

YAG screen

BPM

EO diagnostic

Vertical steering magnets x 2Combined horizontal and vertical steering magnet

Spectrometer dipole,BPM, YAG screen

Tomography, EO and spectrometer sectionFirst dispersive section

Matching section and possible TDC location

• YAGs used highlighted with red circles

PRISM experiment on EMMA

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PRISM experiment on EMMA• Can use ‘overlay’ function with images to do this– Images do look very similar but reduced intensity– Should be able to ‘match’ centroids easily– This should increase accuracy of results …

YAG01 – 1/2 turn, no RF YAG03 – 1/2 turn, no RF

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PRISM experiment on EMMA

YAG01 – 3/2 turns, no RF YAG03 – 3/2 (top), 5/2 turns, no RF

• Can now turn RF on• Scale magnets• Try to restore beam to

the same position

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PRISM experiment on EMMA

YAG01 – 1/2 (top), 3/2 turns, RF on YAG03 – 1/2, RF on

• All images without correction (no YAG3 for 3/2 turns - acceleration)

• Behaviour as expected• Now use scaling program

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PRISM experiment on EMMA

YAG01 – 3/2 (top), 5/2 turns, RF on, scaling YAG03 – 3/2 (top), 5/2 turns, RF on, scaling

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PRISM experiment on EMMA• Conclusions– Need RF capture of beam to do this well but EMMA

was not cooperating on this …– Extraction line difficult to use as beam has been

extracted pragmatically so far …– Need precise model for this so as to know initial

parameters in better detail– Have good idea what needs to be done (I think)– Feedback to Jaroslaw or myself– Next run hopefully ~ March 2012– Many things will have changed by the time we come

up again – hopefully this does not hinder us but …