Emittances Normalised r.m.s. Emittances at Damping Ring Extraction Horizontal Emittance (  m) Vertical Emittance (  m) SLC ILC TESLA 500 TESLA 800 ATF measured JLC/NLC CLIC DR 2005 !

CLIC Damping Ring I BEAM = 75 mA Wiggler typePMSC Peak on axis fieldT Period lengthcm105 Beam energyGeV2.42 Circumferencem Total length of wigglersm152 RF frequencyGHz1.875 RF peak VoltageMV Horizontal damping timems Vertical damping timems Longitudinal damping timems Horizontal IBS growth ratems Long. IBS growth ratems  x w/o IBS nm  x with IBS nm  y with IBS nm emittance coupling ratio%0.63  L with IBS eV m5000

CLIC damping ring regime Equilibrium emittance dominated by IBS (=Intra Beam Scattering) emittance growth. Wigglers are essential to shift equilibrium between combined IBS and SR quantum excitation heating and SR damping cooling to smaller emittance. The more the B W field of the wigglers can be raised, the lower the equilibrium emittance, provided the contribution of the wigglers to the 5 th SR integral can be kept small enough. Therefore, an increase of B w has to be associated with a decrease of the wiggler period at least like w ~ B w -3/2 This regime is different from ILC DR, where main purpose of wigglers is to shorten storage time between injection and extraction. Optimisation of B w and W (Maxim Korostelev)

Schematic view of the s.c. wiggler design Wiggler typeP.M. S.C. (NbTi) Period lengthcm105 Total height of beam aperture mm12 Peak field on axisT Length of wiggler module m22 Transverse field flatness at +/-1cm %<0.1 Operating temperature K Room temp. 4.2 K Wiggler parameters CLIC study has established a collaboration with BINP for wiggler issues. BINP has studied various wiggler options and problem of radiation absorption. Mid term goal (for 2007): BINP completes short prototype of S.C. wiggler for verification of design and field mapping.

Wiggler magnet technology  Try alternative designs / materials (Nb 3 Sn ?) to push performance in w – B w plane  Questions of resistive wall and radiation heating in small wiggler gaps  Full fledged prototype for test with beam  …

Theoretical studies on IBS  ad initio design of magnet lattice to get IBS+SR “TME lattice ”  Potential benefits from harmonic cavity to reduce particle density / IBS in bunch core  Computation of phase space density distributions in the presence of strong IBS (for beam core and beam halo)  Computation of wiggler field tolerances  Combined function wiggler with integrated transverse focusing  …

Instrumental developments  Static measurement of minuscule horizontal, vertical and longitudinal emittances in storage rings  Dynamic measurement of minuscule horizontal, vertical and longitudinal emittances in storage rings (damping rings have no need to keep beams at equilibrium emittance)  Improving BPM technology for orbit control  Alignment & vibration damping technologies  …

Measurements in existing storage rings  Find operational regime where emittance is dominated by IBS and damping by wigglers (ANKA at low energy ?) Comparison of measured and predicted emittances (H,V,L) measurement of transverse and longitudinal particle distribution (gaussian ?, tails ?) Effects of 3 rd harmonic cavity  Test advanced emittance measurement methods  Test prototype CLIC wiggler with beam  Find out what’s is the smallest acceptable wiggler gap during injection  …