1. CLIC Drive beam BPM Requirements and cost estimate

2. CLIC module, Type 1 Main Beam Drive Beam DB-BPM MB-BPM Beams Wake Field Monitors*8 DB-BPM

3. Module types 78 0? 4 5 1 BPM per quadrupole 1WFM per accelerating structure In total 10462 modules per Linac 8374 154 634 477 731

4. Drive beam parameters Bunch spacing83ps (12GHz) Bunch length1.0mm / 3.3ps Charge per bunch8.4nC (5.2*10 10 ) Bunch peak current~1015A Nb of bunches2922 Pulse length243.7ns Pulse current101A Energy (Inj.)2.37GeV Beam pulse power240GW Average power, 50Hz3MW Standard BPM coupling impedance of -40dB would pump 300W! 40000 BPMs would dissipate 12MW!!

5. Specifications AccuracyResolutionStabilityRangeBandwidth Short range wake field Long range wake field Beam tube aperture Available length Intercepting device? How many? Used in RT Feedback? Machine protection Item? BPM 20µm2µm2um<5mm35MHz W L (s)<??V/pC W T (s)<??/pC/mm W L (s)<??V/pC W T (s)<??V/pC/mm 23mm104/74mmNo41480NoYes Nominal beam parameters : Charges/bunch: 5.2*10 10 ; Nb of Bunches: 2922; Bunch length: 1mm; Train length: 243.7ns ; Bunch spacing: 0.0833ns AccuracyResolutionStabilityRangeBandwidth Short range wake field Long range wake field Beam tube aperture Available length Intercepting device? How many? Used in RT Feedback? Machine protection Item? BPM20µm5µm ±12.5mm35MHz W L (s)<??V/pC W T (s)<??V/pC/mm W L (s)<??V/pC W T (s)<??V/pC/mm 23mm104/74mmNo41480NoYes Commission beam parameters : Nominal bunch-charge, with 9/10 buckets empty ( 10% of nom. Current); Bunch length: 1mm; Max train length: 243.7ns; Bunch spacing: 0.0833ns 80dB Feasible Difficult / Expensive

6. Beam spectrum Chamber cutoff frequency 7.6GHz!!!HOM from PETS with several kilo Watt’s Current modulation? 1)Introduce current modulation at e.g. 2GHz? 2)Measure with button, strip line or inductive BPM at baseband 3)Use other (unknown) spectral lines HOM

7. Cost estimation Button BPM, simple and cheapest. LHC prices ~ 1000pc Body, support, Buttons5kCHF Cables: Fiber + Coax6kCHF Analogue electronics2kCHF Digital electronics (ADC)2kCHF Infra structure, crates, racks3kCHF TOTAL18kCHF Do not expect a 50% price reduction going from 1000 to 10000 pc!!. Cable costs should/can be reduced by ~50%, but precise machining of BPM will compensate this increase. Radiation hardness of cables and electronics could increase the costs.

8. Conclusion Drive beam BPM very complicated and study needed. Performance + cost. There is a lot of power in the drive beam. 40000 BPMs of 15KchF each: ~600MCHF Reduction in total numbers is essential.