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Moriond Meeting 17-21/3/2003. Contents. Acceleration of RIB using linacs. Introduction Technological highlights in superconducting low-  l inacs Superconducting linacs for RIB acceleration Example of multicharge transport in EURISOL SRL Conclusions. Alberto Facco

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  1. Moriond Meeting 17-21/3/2003 Contents Acceleration of RIB using linacs • Introduction • Technological highlights in superconducting low- linacs • Superconducting linacs for RIB acceleration • Example of multicharge transport in EURISOL SRL • Conclusions Alberto Facco INFN-Laboratori Nazionali di Legnaro

  2. Moriond Meeting 17-21/3/2003 Ideal RIB accelerator requirements • Acceleration of all possible radioactive beams • All possible final energies up to ~ 100 MeV/u, finely tuneable • Capability of acceleration of singly charged ions • Very good beam quality up to at least 10 MeV/u • Affordable construction and operation cost • reliability, easy maintenance, easy beam set-up and operation, etc.

  3. Moriond Meeting 17-21/3/2003 RIB accelerators special constraints • Variable q/A beams • Efficiency in a wide range of q/A • Wide acceptance in : acceleration with variable velocity profiles is desirable • Very low current beams • negligible beam loading: Rf power efficiency • Stability and large acceptance • Very high transmission efficiency, aiming to 100%

  4. Moriond Meeting 17-21/3/2003 Independently-phased Superconducting Cavity Linacs virtues • Wide velocity and q/A acceptance • Modularity: all final energies can be reached, with fine tunability • Excellent beam quality • Transmission efficiency limited only by charge selection after stripping Recent achievements in the field: high transmission efficiency after stripping Competitive construction and operation cost Multicharge beam transport High acceleration gradient

  5. Moriond Meeting 17-21/3/2003 Technological highlights in superconducting low- linacs

  6. Moriond Meeting 17-21/3/2003 Superconducting QWR’s (optimum range 0.03<<0.3 and 50<f<200 MHz) Mechanical damper LNL 80 MHz, =0.055 cryostat Best ALPI and PIAVE low beta cavities results LNL PIAVE 80 MHz,  =0.047 QWR

  7. Moriond Meeting 17-21/3/2003 ISAC-II =0.072 cavity • Design gradient: 6 MV/m @7W • reached 7 MV/m with <10W TRIUMF ISAC-II 106 MHz, =0.072 prototype 4.2 k test results

  8. Moriond Meeting 17-21/3/2003 Superconducting Spoke resonators (optimum range 0.2<<0.5 and f350 MHz) ANL =0.3 and = 0.4 prototypes LANL =0.2 prototypes

  9. Moriond Meeting 17-21/3/2003 Superconducting RFQ’s • Compactness • CW operation • High efficiency LNL Superconducting SRFQ2 A/q=8.5, 0.0255<b<0.0355

  10. Moriond Meeting 17-21/3/2003 6 MV/malready achieved in existing linacs7 MV/mseems very realistic for future accelerators Low - SC linacs design gradient

  11. Eurisol Town Meeting, Abano 24-25/1/2002 EM steering in QWR’s • The steering is proportional to the energy gain • The magnetic contribution is dominant

  12. A. Facco - SPES meeting –LNL 11-3-2003 Quarter Wave Resonatorswith dipole correction • ANL QWR 115 MHz for RIA • MSU QWR 161 MHz for RIA • (MSU-LNLcollaboration) QWR steering : 161 MHz standard shape (top) 161 MHz corrected

  13. Moriond Meeting 17-21/3/2003 Multicharge beam transport • Proposed and demonstrated at ANL (in ATLAS) • Studied at • ANL and MSU for RIA (driver and reaccelerator linacs) • TRIUMF for the ISAC-II reaccelerator • LNL for the Eurisol reaccelerator • Important tool to achieve high efficiency in both transmission and acceleration

  14. W q1 q2 q3 q4 f Moriond Meeting 17-21/3/2003 Multicharge beam transport • Ions with different charge state receive the same acceleration if their synchronous phase is properly chosen • Many different charge states can be transported simultaneously • Most of the beam particles can be captured after stripping DW=qEaLT(b)cosf

  15. F=-150 F=-150 F=-1000 F=-200 beam Phase synchronization after the first stripper, at the beginning of the SRL ME section. Top: first cryostat (see fig 3) and the reference acceleration phase at each of the cavities. Bottom: longitudinal phase space, in energy spread (%) as function of phase (deg) in different position along the cryostat. The cavities frequency is 160 MHz. The 5 charge states of the beam particles are represented by different colors. Moriond Meeting 17-21/3/2003 Multicharge beam transport

  16. Moriond Meeting 17-21/3/2003 Examples of superconducting linacs for RIB acceleration

  17. Moriond Meeting 17-21/3/2003 ISACpost-accelerator at TRIUMF(operating, under completion) • ISAC-I, in operation • NC Linac up to 1.5 MeV/u • ISAC-II, under construction • SC linac ~43 MV • Rib energy up to ~6 MeV/u • A150 • 1 or 2 carbon foil strippers • Multicharge transport • Charge breeder for A>30

  18. Moriond Meeting 17-21/3/2003 ISACpost-accelerator special components • 35.3 MHz RFQ A/q 30 (8m long) • 106 MHz Separate function DTL • SC QWRs • 70.7 MHz =0.042 • 106 MHz, =0.072 (under construction) • 106 MHz =0.105 ANL-RIA type SC solenoids Inside cryostats

  19. Moriond Meeting 17-21/3/2003 The RIA RIB facility • RIA Driver SC linac: • Ion beams of all masses • 400 MeV/u Uranium RIA driver superconducting cavities under development at ANL RIA (MSU version)

  20. Moriond Meeting 17-21/3/2003 The ANL-RIA post-accelerator(proposed as injector of the existing ATLAS SC linac) • No charge breeder, accepting q=1+ • Masses 66<A< 240 need He gas stripper at ~10 keV/u to reach A/q66 • Carbon foil stripper at 600 keV/u to reach A/q8.3 • 3 NC RFQs (2 on a 400 kV platform) • 62 SC cavities + SC solenoids • Output energy 1.4 MeV/u • Very efficient in transmission, >30% up to the 2nd stripper • Good emittance • Very conservative design gradient • Beam injected into ATLAS ( ~50 MV)

  21. Moriond Meeting 17-21/3/2003 RIA post-accelerator special components • R&D in an advanced stage for RFQ and SC solenoids • 4-gap SC cavity technology well established • ATLAS working since 20 years 15 T superconducting solenoid with steerers 4 gap superconducting QWR 12 MHz Hybrid rfq

  22. Moriond Meeting 17-21/3/2003 EURISOL SRL(preliminary project) • 2 intermediate stripping stations to increase linac efficiency and reduce linac length • 3 main extraction lines for low, medium and high energy experiments • Multicharge beam transport to maximize transmission up to 100 MeV/u • Acceleration with no stripping and full intensity up to 60 MeV/u

  23. Cavity type QWR QWR QWR QWR HWR units f 80 80 160 240 320 MHz b0 0.047 0.055 0.11 0.17 0.28 Ep/ Ea 4.89  4.81  4.93  5.17  3.7 Hp/Ea  103  101  108  110 106 Gauss/(MV/m) G= Rs Q  14.9  14.9  28.3  38.4  61.7 W Rsh/ Q  1640 1660 1480  1470 1200 W/m U/ Ea2 0.121 0.120  0.0670  0.0452  0.093 J/(MV/m)2 Eff. length 0.18 0.18 0.18 0.18 0.223 m Design Ea 7 7 7 7 7 MV/m Cryo power allowed 10 10 10 10 10 W n. required 3 15 24 37 160 Moriond Meeting 17-21/3/2003 SRL cavity parameters QWR HWR • * Calculated by means of the code HFSS

  24. Moriond Meeting 17-21/3/2003 SRL modules Schematic of RFQ section and first QWR module SRFQ section • 3 LNL type superconducting RFQ’s in 2 cryostats • Design A/q  10 (up to 132Sn13+) • Ein =2.3 keV/u, Eout =670 keV/u QWR-HWR modules • Cryostat • 4 QWR’s (section I and II) at 7 MV/m • 8 HWR’s (section III) at 7 MV/m • 1 superconducting solenoids at B<15 T • Diagnostics box

  25. Moriond Meeting 17-21/3/2003 Example of multicharge beam transport in EURISOL SRL

  26. Moriond Meeting 17-21/3/2003 Beam dynamics simulations in SRL* • Simulation of the accelerating sections • using realistic EM fields of QWR’s • Aims: • Check multiple charge beam transport at high gradient • Check the effect of QWR steering in MCBT • Evaluate SRL performance in different operation modes • No stripper up to 60MeV/u • 1 stripper 93 • 2 strippers 100 • * performed using the code LANA (courtesy of D. Gorelov, MSU-NSCL)

  27. Moriond Meeting 17-21/3/2003 Linac Beam Envelopes with no strippers Simulated using the LANA code 132Sn Win= 670 keV/u Wout= 59.6 MeV/u f = -20 deg Eacc= 7 MV/m N.B. simulation performed with an input transverse emittance 2 times larger than the nominal value

  28. Moriond Meeting 17-21/3/2003 High Energy Section-160 HWR’s (1 stripper mode) INITIAL* FINAL Simulated using the LANA code • 132Sn • Win= 16.3 MeV/u • Wout= 92.9 MeV/u • = -20 deg q=45,46,47,48,49 • Eacc= 7 MV/m • Eff.= 94% BUNCHED * After stripping in a 2 mg/cm2 carbon foil N.B. simulation performed with an input transverse emittance 2 times larger than the nominal value

  29. Moriond Meeting 17-21/3/2003 Linac Beam Envelopes with 2 strippers Simulated using the LANA code 132Sn Win= 670 keV/u Wout= 100 MeV/u f = -20 deg Eacc= 7 MV/m N.B. simulation performed with an input transverse and longitudinal emittance 2 and 5 times larger than the nominal value, respectively

  30. Moriond Meeting 17-21/3/2003 High Energy Section-160 HWR’s (2 stripper mode) INITIAL* FINAL Simulated using the LANA code • 132Sn • Win= 21.6 MeV/u • Wout= 100 MeV/u • = -20 deg q=46,47,48,49 • Eacc= 7 MV/m BUNCHED * After one more stripping in a 3 mg/cm2 carbon foil

  31. Moriond Meeting 17-21/3/2003 SRL simulations results for different modes of operation • No stripping (prob. most experiments) • E max 60 MeV/u • Transmission 100% Single charge beam • exey  0.5(0.25)p mm mrad, ez  0.7 p keV/u ns (5 rms) • Stripper 2 only • E max 93 MeV/u • transmission 94% Multiple charge beam • exey  0.6(0.3)p mm mrad, ez  1.4 p keV/u ns (5 rms) • Strippers 1 and 2 • E max 100 MeV/u • Transmission 74% Multiple charge beam • exey  1(0.5)p mm mrad, ez  10(2)p keV/u ns (5 rms) • N.B: 2 Strippers make the linac relatively insensitive to the charge breeder performance: with initial charge of 13+ instead of 25+, the final energy would be 95 MeV/u

  32. Moriond Meeting 17-21/3/2003 Acceleration of different q/A beamswith 2-gap cavities Virtually all RIB’s that allow charge breeding can be accelerated by SRL with similar results. Examples: • 33Ar(8+) E=127 MeV/u • 210Fr(25+) E=100 MeV/u 33Ar(8+) 210Fr(25+)

  33. Moriond Meeting 17-21/3/2003 Conclusions • Recent developments in SC linac technology multiple charge beamtransportbeam stripping and high transmission Superconducting cavites high gradients, wide b acceptance • High charge breeding is not strictly necessary • (but some charge breeding saves a lot of money) • SC linacs can provide • RIB acceleration with finely tuneable energy and good beam quality • High acceleration and transmission efficiency • Large acceptance in q/A low mass selectivity, but also low sensitivity to charge breeder performance • flexibility in the modes of operation • competitive construction and operation cost SC linacs can be excellent RIB accelerators

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