1. WP4-CHOPPER coordinated by A. Lombardi HIPPI yearly meeting, sep28-sep30 2005 COSENERS HOUSE- Abington Hosted by CCLRC

2. General info  Contributors : RAL : C. Prior, M. Clarke-Gayther, G. Bellodi, C. Plostinar RAL : C. Prior, M. Clarke-Gayther, G. Bellodi, C. Plostinar CERN : M. Paoluzzi, F. Caspers, M. Morvillo, L. Bruno, K. Hanke, E. Sargsyan, J.B. Lallement, M. Hori, A. Lombardi CERN : M. Paoluzzi, F. Caspers, M. Morvillo, L. Bruno, K. Hanke, E. Sargsyan, J.B. Lallement, M. Hori, A. Lombardi  WEB site : http://lombarda.home.cern.ch/lombarda/WP4/WP4main.htm  Yearly meeting : 13-15 april 2005 joint with WP5

3. Publications CARE Conf-05-015- HIPPI (PAC05) Michael A. Clarke- Gayther “Fast-Slow” Beam Chopping for Next Generation High Power Proton Drivers CARE/HIPPIDocument-05-003 M. Paoluzzi Status of cern chopper driver and the solid state alternative CARE/HIPPI Document-05-008 M. A. Clarke- Gayther HIPPI Work Package 4 (WP4): The RAL†Fast Beam Chopper Development Programme Progress Report for the period: January 2004 – June 2005

4. Task (original)  compare two different approaches to building and integrating in a matching line a device able to remove micro-bunches with a time duration of few nsec  both approaches make use of electrostatic field across two parallel plates placed longitudinally in the beam line and driven by a fast amplifier  the difference between the two approaches is in the amplifier design, in the range of duty cycle that it can cover and in the integration of the chopper in the beam line.

5. Tasks

6. WBS #Title Original begin date (Annex 1) Original end date (annex1) Estimated Status Revised end date 4.1Chopper structure A (CERN) 4.1.1Pre-prototype constructionJanuary 2004June 2004FinishedJune2005 4.1.2Pre-prototype testingJuly 2004November 2004 Combined with task 4.1.5 December 2005 4.1.3Driver construction & testingJanuary 2004December 200580 % 4.1.4Full scale prototype designJanuary 2005June 2005Finished 4.1.5Full scale prototype constructionJanuary 2005December 200590% 4.2Chopper line (CERN) 4.2.1Dump designJanuary 2004June 2004Finished 4.2.2Dump constructionJanuary 2005June 200520%December 2005 4.3Chopper structure B (RAL) 4.3.1Pre-prototype design and testJanuary 2004June 2005Finished 4.3.2Prototype designJanuary 2005December 200540 %

7. changes  CERN : Driver conceptionDriver conception Skip the phase of pre-prototypeSkip the phase of pre-prototype  RAL : Beam dynamics (frequency,energy)Beam dynamics (frequency,energy) Chopping mechanism (localised dump, quad)Chopping mechanism (localised dump, quad)

9. Achievements

10. the deliverables WBS #TitleDue date in Annex 1StatusRevised delivery date 4.1.1Chopper A design reportJune 2005delayedDecember 2005 4.1.2Intermediate test reportMarch 2005 Waiting for task 4.1.5 March 2006 4.2.2Dump design reportJune 2005pendingOctober 2005 4.3.1Chopper B intermediate reportJune 2005Delivered July2005

11. Collaboration  1. Activity at RAL re-design of the chopper line optics - based on the idea of ‘amplification’ of chopper beam deflection with a downstream defocusing quadrupole. This is an example of a CERN based idea influencing the RAL design effort.  2. Activity at RAL regarding the modification to the design of RAL slow wave structure C, to enable it to fit into the bore of a quadrupole - prompted by the possibility of testing on the CERN front-end test facility. An example of a CERN based requirement influencing RAL design.  3. Activity at CERN regarding the design of the new FET based bipolar pulser. This approach came about as a result of the cross fertilisation of ideas between CERN and RAL. Example of RAL helping the CERN effort.  4. Activity during the last HIPPI meeting at Abingdon (and subsequently), regarding a meeting between J. Hares (Director & Chief Designer, Kentech Instruments Ltd, UK), CERN and RAL representatives with the purpose of discussing the possibility of alternative pulse generator designs for the CERN chopper. This activity has also (subsequently) involved discussions with Bill Foster regarding a Fermilab linac upgrade scheme. This is an example of a RAL based connection with a specialist manufacturer being utilised by a CERN based collaborator (and a FERMILAB based colleague).

12. Ingredients of the working package Chopper (plates and drivers) Chopper (plates and drivers) Beam dynamics Beam dynamics Beam lines Beam lines

13. today’s program  Status of the CERN chopper (25’+5’) - M.Paoluzzi  Status of the RAL ‘Fast-Slow’ beam chopper development programme (25’+5’) - M. Clarke-Gayther  The FETS: Front End Test Stand (15’+5’) – D. Findlay  Beam dynamics studies and design options for the RAL FETS chopper line (10’+5’) - G.Bellodi  Status of the CERN Chopper line (10’+5’) - A.Lombardi  Design of a rebunching cavity for the RAL FETS chopper line (10’) - C. Plostinar