August 27, 2006R. Garoby Introduction 5 GeV version of the SPL Scenarios for accumulation and compression Conclusion SPL-BASED 5 GeV PROTON DRIVER

27/08/2006R.G.2 Introduction (1/5) Today’s characteristics and design of the SPL have been summarised in a recent publication [CERN available on the CERN Document Server] Conceptual design of the SPL II : A high-power superconducting H - linac at CERN Baylac, MBaylac, M; (LPSC Grenoble) Gerigk, F (ed.); Benedico Mora, E; Caspers, F; Chel, S (CEA Saclay) ; Deconto, J M (LPSC Grenoble) ; Duperrier, R (CEA Saclay) ; Froidefond, E (LPSC Grenoble) ; Garoby, R; Hanke, K; Hill, C; Hori, M (CERN and Tokyo Univ.) ; Inigo-Golfin, J; Kahle, K; Kroyer, T; Küchler, D; Lallement, J B; Lindroos, M; Lombardi, A M; López Hernández, A; Magistris, M; Meinschad, T K; Millich, Antonio; Noah Messomo, E; Pagani, C (INFN Milan) ; Palladino, V (INFN Maples) ; Paoluzzi, M; Pasini, M; Pierini, P (INFN Milan) ; Rossi, C; Royer, J P; Sanmartí, M; Sargsyan, E; Scrivens, R; Silari, M; Steiner, T; Tückmantel, Joachim; Uriot, D (CEA Saclay) ; Vretenar, M;Gerigk, FBenedico Mora, ECaspers, FChel, SDeconto, J MDuperrier, R Froidefond, EGaroby, RHanke, KHill, CHori, MInigo-Golfin, JKahle, KKroyer, TKüchler, DLallement, J B Lindroos, MLombardi, A MLópez Hernández, AMagistris, MMeinschad, T K Millich, AntonioNoah Messomo, EPagani, CPalladino, VPaoluzzi, MPasini, MPierini, PRossi, CRoyer, J P Sanmartí, MSargsyan, EScrivens, RSilari, MSteiner, TTückmantel, Joachim Uriot, DVretenar, M 2006 Geneva : CERN, p

27/08/2006R.G.3 Introduction (2/5) Ion speciesH-H- Kinetic energy3.5GeV Mean current during the pulse40mA Mean beam power4MW Pulse repetition rate50Hz Pulse duration0.57ms Bunch frequency352.2MHz Duty cycle during the pulse62 (5/8)% rms transverse emittances0.4  mm mrad Longitudinal rms emittance0.3  deg MeV Length430m SPL (CDR2) main characteristics

27/08/2006R.G.4 Introduction (3/5) SectionT out [MeV] Nb. of cavities P RF peak [MW] Nb. of klystrons Length [m] Source RFQ31116 Chopper (MEBT) DTL CCDTL SCL Superconducting  = Superconducting  = Total SPL (CDR2) accelerating sections

27/08/2006R.G.5 Introduction (4/5) The low energy part (up to 160 MeV) of the SPL is the subject of the “Linac4” project. A decision is expected by the end of the year.

27/08/2006R.G.6 Introduction (5/5) The SPL is part of a global strategy outlined by the PAF working group for the upgrade of the proton accelerator complex at CERN.

27/08/2006R.G.7 5 GeV version of the SPL SPL (CDR3) characteristics Ion speciesH-H- Kinetic energy5GeV Mean current during the pulse40mA Mean beam power4MW Pulse repetition rate50Hz Pulse duration0.4ms Bunch frequency352.2MHz Duty cycle during the pulse62 (5/8)% rms transverse emittances0.4  mm mrad Longitudinal rms emittance0.3  deg MeV Length535m Increasing the energy of the SPL (CDR2) is obtained by adding 105 m of  =1 superconducting accelerating structures and 14 klystrons [704 MHz – 5 MW].

27/08/2006R.G.8 Scenario for accumulation and compression (1/13) ParameterBasic valueRange Beam energy [GeV] Burst repetition rate [Hz]50? Number of bunches per burst (n)41 – 6 ? Total duration of the burst [ns]~ Time interval between bunches [  s] (t int ) – 16 ? Bunch length [ns] Specifications (from R. Palmer’s conclusion at ISS meeting in RAL on Thursday 27, April 2006) ~ 50/(n-1)

27/08/2006R.G.9 Scenario for accumulation and compression (2/13) Accumulation Duration = 400  s Compression t = 0  s t = 12  s t = 24  s t = 36  s etc. until t = 96  s Accumulator [120 ns pulses - 60 ns gaps] SPL beam [42 bunches - 21 gaps] Compressor [120 ns bunch - V(h=3) = 4 MV] Target [2 ns bunches – 6 times]

27/08/2006R.G.10 Scenario for accumulation and compression (3/13) Mean radius [m] (L A = 74/73 L C )  < 0.02 2T2T ~ 49 f REV [MHz] V RF [V]0 Number of bunches6 Bunch length / gap between bunches [ns]120 / 59 Number of protons per bunches Accumulator Mean radius [m] (L C = 73/74 L A )50 2T2T 5.29 f REV [MHz] h RF 3 f RF [MHz] V RF [MV]4 Number of protons per bunches Compressor

27/08/2006R.G.11 Scenario for accumulation and compression (4/13) Kinetic energy [GeV]5  E Total [MeV] 10 l bunch total [ns] at injection120 Time interval between centres of consecutive bunches [ns] ~ 354 Time interval between transfers [  s] ~ 12 Duration of bunch rotation for 1 bunch [  s] ~ 3 x 12 Number of protons per bunches Bunch characteristics at injection in the compressor Kinetic energy [GeV]5  E Total [MeV] ~ 170 MeV  bunch [ns] at ejection ~ 2 ns Time interval between ejection [  s] ~ 12 Number of bunches6 Duration of full burst to the target [  s] ~ 60 Number of protons per bunches Bunch characteristics at ejection to the target

27/08/2006R.G.12 Scenario for accumulation and compression (5/13) PDAC 2.2 GeV PDAC 5 GeV Improvement factor  Total number of protons per pulse Ring circumference [m] 2  1502  50 3 Number of bunches14461/24 Product1.05 ! Scaling for space charge induced  Q with respect to PDAC (2.2 GeV) Number of bunches Number of protons Beam energy Ring circumference

27/08/2006R.G.13 Scenario for accumulation and compression (6/13) Longitudinal phase space at injection in the compressor Space charge voltage Simulations: C. Carli

27/08/2006R.G.14 Scenario for accumulation and compression (7/13) Longitudinal phase space after 25  s in the compressor Space charge voltage Simulations: C. Carli

27/08/2006R.G.15 Scenario for accumulation and compression (8/13) Longitudinal phase space after 38  s in the compressor Space charge voltage Simulations: C. Carli

27/08/2006R.G.16 Scenario for accumulation and compression (9/13) Longitudinal phase space after 38  s in the compressor Line density  = 1.9 ns Simulations: C. Carli

27/08/2006R.G.17 Scenario for accumulation and compression (10/13) Longitudinal phase space after 38  s in the compressor Line density  = 1.5 ns Tentative use of 2nd harmonic RF (700 kV) Simulations: C. Carli

27/08/2006R.G.18 Alternative scenario for 5 bunches (11/13) Accumulation Duration = 400  s Compression t = 0  s t = 12  s t = 24  s t = 36  s etc. until t = 84  s Accumulator [120 ns pulses - 95 ns gaps] SPL beam [42 bunches - 33 gaps] Compressor [120 ns bunch - V(h=3) = 4 MV] Target [2 ns bunches – 5 times]

27/08/2006R.G.19 Alternative scenario for 5 bunches (12/13) Mean radius [m] (L A = 185/183 L C )  < 0.02 2T2T ~ 49 f REV [MHz] V RF [V]0 Number of bunches5 Bunch length / gap between bunches [ns]120/95 Number of protons per bunches Accumulator Mean radius [m] (L C = 183/185 L A )50 2T2T 5.29 f REV [MHz] h RF 3 f RF [MHz] V RF [MV]4 Number of protons per bunches Compressor

27/08/2006R.G.20 Kinetic energy [GeV]5  E Total [MeV] 10 l bunch total [ns] at injection120 Time interval between centres of consecutive bunches [ns] ~ 354 Time interval between transfers [  s] ~ 12 Duration of bunch rotation for 1 bunch [  s] ~ 3 x 12 Number of protons per bunches Bunch characteristics at injection in the compressor Kinetic energy [GeV]5  E Total [MeV] ~ 170 MeV  bunch [ns] at ejection ~ 2 ns Time interval between ejection [  s] ~ 12 Number of bunches5 Duration of full burst to the target [  s] ~ 50 Number of protons per bunches Bunch characteristics at ejection to the target Alternative scenario for 5 bunches (13/13)

27/08/2006R.G.21 Conclusion Although very preliminary, this analysis gives hope that a scenario can be set-up for meeting the ISS specifications with an SPL based 5 GeV proton driver. A refined analysis is needed that will take into account collective effects. Absolute comparison with other proton drivers will have to take into account:  Pion production and muon capture using the HARP results. The SPL energy could be marginally increased if necessary.  Change of muon capture efficiency with bunch length.  Construction and operation cost.  Technological risk. Relative (“site specific”) comparison will have to include:  Interest for other uses, flexibility, upgrade potential.  Match with local competences, industrial interest, real-estate availability.  Synergy with other work programmes.

27/08/2006R.G.22