CLIC Decelerator Instrumentation CLIC Decelerator Instrumentation - Ideas and outlooks – non exhaustive -- Ideas and outlooks – non exhaustive -

Erik Adli, July 9, 2008Erik Adli, July 9, 2008

Intro: Beam dynamics and requirementsIntro: Beam dynamics and requirements

What are we interested in?What are we interested in? Do we produce the correct power?Do we produce the correct power? Do we transport the beam well?Do we transport the beam well?

If not: why not? What and where is the problem?If not: why not? What and where is the problem? Commissioning: special needsCommissioning: special needs

r=11.5 mm

~ 1000 units per decelerator sector

Intro: CLIC drive beam parametersIntro: CLIC drive beam parameters

Initial beam parameters:Initial beam parameters: EE0 0 2.4 GeV 2.4 GeV I I 100 A 100 A d = 25 mm (bunch spacing, fd = 25 mm (bunch spacing, fbb = 12 GHz) = 12 GHz) 240 ns (2900 bunches) 240 ns (2900 bunches) Gaussian bunch, Gaussian bunch, z z 1 mm 1 mm

m m x,y x,y 0.3 mm (at 0.3 mm (at maxmax))

11stst particularity of the decelerator beam: huge current particularity of the decelerator beam: huge current

22ndnd particularity of the decelerator beam: large energy spread particularity of the decelerator beam: large energy spread

Along lattice: BPMsAlong lattice: BPMsThe need for beam-based alignment implies:The need for beam-based alignment implies:

One BPM per quadrupoleOne BPM per quadrupole Total number of BPMs: ~ 24 * 2 * 900 = ~ 40000Total number of BPMs: ~ 24 * 2 * 900 = ~ 40000 Production beam: ~ 100 AProduction beam: ~ 100 A

BPM (abs. pos.) precision: ~ 20 um (incl. static misalignment)BPM (abs. pos.) precision: ~ 20 um (incl. static misalignment) BPM diff. precision: 2 um ( <-> accuracy of 1 um ?)BPM diff. precision: 2 um ( <-> accuracy of 1 um ?)

Commission beam: ~ 100/N A, (N ~ 10)Commission beam: ~ 100/N A, (N ~ 10) BPM (abs. pos.) precision: ~ 20 umBPM (abs. pos.) precision: ~ 20 um BPM differential precision: up to 10 um probably ok (with gradually better BPM differential precision: up to 10 um probably ok (with gradually better

resolution for higher currents)resolution for higher currents) Expected centroid displacement:Expected centroid displacement:

< 5 mm (uncorrected machine)< 5 mm (uncorrected machine) Expected rms sizeExpected rms size

< 4 mm (uncorrected machine)< 4 mm (uncorrected machine) Available length for BPMs: Available length for BPMs: 10 cm 10 cm Time resolution: ~ 10 ns Time resolution: ~ 10 ns

(fraction of train length)(fraction of train length)

(exact values to be studied further! )

Along lattice: loss monitorsAlong lattice: loss monitors Important for tune up and failure monitoring Important for tune up and failure monitoring High sensitivity (could risk small but steady losses High sensitivity (could risk small but steady losses

along the lattice). Sensitivity: 1% of one bunch: 80 pCalong the lattice). Sensitivity: 1% of one bunch: 80 pC Precise time resolution: probably not needed? (TBD) Precise time resolution: probably not needed? (TBD)

[for TBL yes, but for CLIC no][for TBL yes, but for CLIC no]

Along lattice: transverse profile Along lattice: transverse profile monitorsmonitors

At selected positions along the latticeAt selected positions along the lattice 10-20 per decelerator would give good picture of 10-20 per decelerator would give good picture of

envelope growthenvelope growth Important for tune up and failure monitoringImportant for tune up and failure monitoring 1 sigma transverse size:1 sigma transverse size:

uncorrected machine : 0.3 mm at start up to 3 mm at enduncorrected machine : 0.3 mm at start up to 3 mm at end Corrected machine: 0.3 mm at start up to 1 mm at endCorrected machine: 0.3 mm at start up to 1 mm at end

Range: desired to observe 3 sigma sizeRange: desired to observe 3 sigma size Accuracy: 50 um adequateAccuracy: 50 um adequate

At lattice start and end: I and FFAt lattice start and end: I and FF

Power production depends mainly on PETS Power production depends mainly on PETS parameters, bunch frequency + I / Form Factor :parameters, bunch frequency + I / Form Factor :

PrecisionPrecision measurement of these parameters at the measurement of these parameters at the start of the lattice:start of the lattice: Current measurement, precision: <= 0.1%Current measurement, precision: <= 0.1% Form factor / bunch-length measurement, precision: <= Form factor / bunch-length measurement, precision: <=

0.1 % (one-shot measurement is probably ok)0.1 % (one-shot measurement is probably ok)

( Current monitors: also along lattice, but maybe not ( Current monitors: also along lattice, but maybe not needed with as high precision )needed with as high precision )

P P (1/4) I (1/4) I2 2 LLpetspets2 2 F(F())2 (2 (R’/Q) R’/Q) bb / v / vgg

Dump: energy measurementDump: energy measurement

Spectrometer dump Spectrometer dump

Desirable: one fast (12 GHz) BPM to Desirable: one fast (12 GHz) BPM to verify time-resolved centroid energy of verify time-resolved centroid energy of each buncheach bunch Close to the bendClose to the bend

Desirable: total beam energy Desirable: total beam energy measurement in dump (cross-check measurement in dump (cross-check with power production)with power production) Precise time resolution: probably not Precise time resolution: probably not

needed? (TBD) [for TBL yes, but for CLIC needed? (TBD) [for TBL yes, but for CLIC no]no]

Dump: transverse phase-spaceDump: transverse phase-space

Transverse phase-spaceTransverse phase-space Useful for tune-upUseful for tune-up Useful for verification of beam dynamicsUseful for verification of beam dynamics Set of profile monitors better than quad-scan, due to Set of profile monitors better than quad-scan, due to

energy spread :energy spread : See the transverse screens slide (need to have at See the transverse screens slide (need to have at

least 3 profiles towards the end of the decelerator) least 3 profiles towards the end of the decelerator)