CLIC Decelerator Instrumentation - Ideas and outlooks – non exhaustive - Erik Adli, July 9, 2008

Intro: Beam dynamics and requirements 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 needs Commissioning: special needs r=11.5 mm ~ 1000 units per decelerator sector

Intro: CLIC drive beam parameters Initial beam parameters: Initial beam parameters: E 0  2.4 GeV E 0  2.4 GeV I  100 A I  100 A d = 25 mm (bunch spacing, f b = 12 GHz) d = 25 mm (bunch spacing, f b = 12 GHz)  240 ns (2900 bunches)  240 ns (2900 bunches) Gaussian bunch,  z  1 mm Gaussian bunch,  z  1 mm    m   x,y  0.3 mm (at  max )    m   x,y  0.3 mm (at  max ) 1 st particularity of the decelerator beam: huge current 1 st particularity of the decelerator beam: huge current 2 nd particularity of the decelerator beam: large energy spread 2 nd particularity of the decelerator beam: large energy spread

Along lattice: BPMs The need for beam-based alignment implies: One BPM per quadrupole One BPM per quadrupole Total number of BPMs: ~ 24 * 2 * 900 = ~ Total number of BPMs: ~ 24 * 2 * 900 = ~ Production beam: ~ 100 A Production 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 um BPM (abs. pos.) precision: ~ 20 um BPM differential precision: up to 10 um probably ok (with gradually better resolution for higher currents) BPM differential precision: up to 10 um probably ok (with gradually better resolution for higher currents) Expected centroid displacement: Expected centroid displacement: < 5 mm (uncorrected machine) < 5 mm (uncorrected machine) Expected rms size Expected rms size < 4 mm (uncorrected machine) < 4 mm (uncorrected machine) Available length for BPMs:  10 cm Available length for BPMs:  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 monitors Important for tune up and failure monitoring Important for tune up and failure monitoring High sensitivity (could risk small but steady losses along the lattice). Sensitivity: 1% of one bunch: 80 pC High sensitivity (could risk small but steady losses along the lattice). Sensitivity: 1% of one bunch: 80 pC Precise time resolution: probably not needed? (TBD) [for TBL yes, but for CLIC no] Precise time resolution: probably not needed? (TBD) [for TBL yes, but for CLIC no]

Along lattice: transverse profile monitors At selected positions along the lattice At selected positions along the lattice per decelerator would give good picture of envelope growth per decelerator would give good picture of envelope growth Important for tune up and failure monitoring Important 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 end uncorrected machine : 0.3 mm at start up to 3 mm at end Corrected machine: 0.3 mm at start up to 1 mm at end Corrected machine: 0.3 mm at start up to 1 mm at end Range: desired to observe 3 sigma size Range: desired to observe 3 sigma size Accuracy: 50 um adequate Accuracy: 50 um adequate

At lattice start and end: I and FF Power production depends mainly on PETS parameters, bunch frequency + I / Form Factor : Power production depends mainly on PETS parameters, bunch frequency + I / Form Factor : Precision measurement of these parameters at the start of the lattice: Precision measurement of these parameters at the start of the lattice: Current measurement, precision: <= 0.1% Current measurement, precision: <= 0.1% Form factor / bunch-length measurement, precision: <= 0.1 % (one-shot measurement is probably ok) Form factor / bunch-length measurement, precision: <= 0.1 % (one-shot measurement is probably ok) ( Current monitors: also along lattice, but maybe not needed with as high precision ) ( Current monitors: also along lattice, but maybe not needed with as high precision ) P  (1/4) I 2 L pets 2 F(  ) 2 ( R’/Q)  b / v g

Dump: energy measurement Spectrometer dump Spectrometer dump Desirable: one fast (12 GHz) BPM to verify time-resolved centroid energy of each bunch Desirable: one fast (12 GHz) BPM to verify time-resolved centroid energy of each bunch Close to the bend Close to the bend Desirable: total beam energy measurement in dump (cross-check with power production) Desirable: total beam energy measurement in dump (cross-check with power production) Precise time resolution: probably not needed? (TBD) [for TBL yes, but for CLIC no] Precise time resolution: probably not needed? (TBD) [for TBL yes, but for CLIC no]

Dump: transverse phase-space Transverse phase-space Transverse phase-space Useful for tune-up Useful for tune-up Useful for verification of beam dynamics Useful for verification of beam dynamics Set of profile monitors better than quad-scan, due to energy spread : Set of profile monitors better than quad-scan, due to energy spread : See the transverse screens slide (need to have at least 3 profiles towards the end of the decelerator) See the transverse screens slide (need to have at least 3 profiles towards the end of the decelerator)