CARE07, 29 Oct Alexej Grudiev, New CLIC parameters. The new CLIC parameters Alexej Grudiev

CARE07, 29 Oct Alexej Grudiev, New CLIC parameters. energy loss by beamstrahlung center-of-mass energy Vertical emittance wall-plug power wall-plug to beam efficiency Linear Collider major parameters High Beam Power (several MWatts) Wall-plug to beam transfer efficiency as high as possible (several %) Generation & preservation of beam emittances at I.P. as small as possible (few nmrad) Beam focusing to very small dimentions at IP (few nm) Beamstrahlung energy spread increasing with c.m. colliding energies Luminosity: Energy reach High accelerating gradient

CARE07, 29 Oct Alexej Grudiev, New CLIC parameters. CLIC overall layout 3 TeV Main Beam Generation Complex Drive Beam Generation Complex

CARE07, 29 Oct Alexej Grudiev, New CLIC parameters. Old and new CLIC main parameters Old (2005)New (2007) Center-of-mass energy3 TeV Peak Luminosity6.5·10 34 cm -2 s -1 7·10 34 cm -2 s -1 Peak luminosity (in 1% of energy)3.3·10 34 cm -2 s -1 2·10 34 cm -2 s -1 Repetition rate150 Hz50 Hz Loaded accelerating gradient150 MV/m100 MV/m Main linac RF frequency30 GHz12 GHz Overall two-linac length28 km42 km Bunch charge2.56· ·10 9 Bunch separation0.267 ns0.5 ns Beam pulse duration58.4 ns156 ns Beam power/beam20 MW14 MW Hor./vert. normalized emittance660 / 10 nm rad660 / 20 nm rad Hor./vert. IP beam size bef. pinch60 / 0.7 nm40 / ~1 nm Total site length33 km48 km Total power consumption418 MW322 MW

CARE07, 29 Oct Alexej Grudiev, New CLIC parameters. CLIC main linac optimization model Bunch population Structure parameters Cell parameters Bunch separation BD, f, ∆φ,, da, d 1, d 2 N NsNs Q, R/Q, v g, E s /E a, H s /E a Q 1, A 1, f 1 BD η, P in, E s max, ∆T max L s, N b rf constraints Cost function minimization YES NO

CARE07, 29 Oct Alexej Grudiev, New CLIC parameters. Optimization constraints Beam dynamics (BD) constraints based on the simulation of the main linac, BDS and beam-beam collision at the IP: N – bunch population depends on / λ, Δa/, f and because of short-range wakes N s – bunch separation depends on the long-range dipole wake and is determined by the condition: W t,2 · N / = 10 V/pC/mm/m · 4x10 9 / 150 MV/m RF breakdown and pulsed surface heating (rf) constraints: Δ T max (H surf max, t p ) < 56 K E surf max < 250 MV/m P in /C in t p 1/3 < 18 MW·ns 1/3 X-band (frequency dependent)

CARE07, 29 Oct Alexej Grudiev, New CLIC parameters. Frequency scaling of power constraint Scaled structures Scaled structures show the same gradient at X-band and at 30 GHz: E a t p 1/6 = const P in /C in t p 1/3 f = const Experimental data at X-band and 30 GHz become available 2006

CARE07, 29 Oct Alexej Grudiev, New CLIC parameters. Optimization Cost functions 1. Luminosity per linac input power (performance): Collision energy is constant Figure of Merit (FoM) 2. Total cost parametric model (become available 2006) Investment cost + Exploitation cost for 10 years C t = C i + C e

CARE07, 29 Oct Alexej Grudiev, New CLIC parameters. Optimization parameter space All structure parameters are variable: = 90 – 150 MV/m, f = 10 – 30 GHz, Δφ = 120 o, 150 o, / λ = , Δa/ = 0.01 – 0.6, d 1 / λ = , d 2 > d 1 L s = 100 – 1000 mm. N structures:

CARE07, 29 Oct Alexej Grudiev, New CLIC parameters. CLIC performance and cost versus gradient Performance increases with lower accelerating gradient (mainly due to higher efficiency) Flat cost variation in 100 to 130 MV/m with a minimum around 120 MV/m E cms = 3 TeV L (1%) = cm -2 s -1 Previous New Optimum Performance Cost

CARE07, 29 Oct Alexej Grudiev, New CLIC parameters. CLIC performance and cost versus frequency E cms = 3 TeV L (1%) = cm -2 s -1 Maximum Performance around 14 GHz Flat cost variation in 12 to 16 GHz frequency range with a minimum around 14 GHz New Previous Optimum Performance Cost

CARE07, 29 Oct Alexej Grudiev, New CLIC parameters. CLIC Performance and Cost optimization Performance (a.u.) Total cost (a.u.) CLIC New parameters Accelerating field = 100 MV/m RF frequency = 12 GHz CLIC Old Parameters Accelerating field = 150 MV/m RF frequency = 30 GHz

CARE07, 29 Oct Alexej Grudiev, New CLIC parameters. Interplay between BD and RF RF optimum aperture: / λ = 0.1 ÷ 0.12 Why X-band ? Crossing gives optimum frequency FoM = L 1 /N · η BD RF BD optimum aperture: = 2.6 mm L 1 /N

CARE07, 29 Oct Alexej Grudiev, New CLIC parameters. Summary CLIC main linac optimization model taking into account complex interplay between beam dynamics and rf performance has been developed over the past few years In 2006, new experimental data both at 30 GHz and at X-band have been obtained CLIC total cost parametric model has become available Optimization of CLIC frequency and gradient has been done which (together with some other considerations) resulted in major change of CLIC parameters from 150MV/m at 30GHz to 100MV/m at 12GHz