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

2. Ideal RIB accelerator requirements
Moriond Meeting /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. RIB accelerators special constraints
Moriond Meeting /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. Independently-phased Superconducting Cavity Linacs virtues
Moriond Meeting /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. Technological highlights in superconducting low- linacs
Moriond Meeting /3/2003
Technological highlights in superconducting low- linacs

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

8. Superconducting Spoke resonators
Moriond Meeting /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. Superconducting RFQ’s
Moriond Meeting /3/2003
Superconducting RFQ’s
Compactness
CW operation
High efficiency
LNL Superconducting SRFQ2
A/q=8.5,
0.0255<b<0.0355

10. Low - SC linacs design gradient
Moriond Meeting /3/2003
Low - SC linacs design gradient
6 MV/m already achieved in existing linacs 7 MV/m seems very realistic for future accelerators

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

12. Quarter Wave Resonators with dipole correction
A. Facco - SPES meeting –LNL
Quarter Wave Resonators with 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. Multicharge beam transport
Moriond Meeting /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. Multicharge beam transport
Moriond Meeting /3/2003
Multicharge beam transport q1 q2 q3 q4 f W
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. Multicharge beam transport
Moriond Meeting /3/2003
Multicharge beam transport
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.

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

17. ISAC post-accelerator at TRIUMF (operating, under completion)
Moriond Meeting /3/2003
ISAC post-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. ISAC post-accelerator special components
Moriond Meeting /3/2003
ISAC post-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. The RIA RIB facility RIA Driver SC linac: Ion beams of all masses
Moriond Meeting /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 /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. RIA post-accelerator special components
Moriond Meeting /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. EURISOL SRL (preliminary project)
Moriond Meeting /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. SRL cavity parameters QWR HWR * Calculated by means of the code HFSS
Moriond Meeting /3/2003
SRL cavity parameters
QWR
HWR
Cavity type
QWR
HWR
units f 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
 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
0.223 m
Design Ea 7
MV/m
Cryo power allowed 10
n. required 3 15 24 37
* Calculated by means of the code HFSS

24. SRL modules SRFQ section QWR-HWR modules
Moriond Meeting /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. Example of multicharge beam transport in EURISOL SRL
Moriond Meeting /3/2003
Example of multicharge beam transport in EURISOL SRL

26. Beam dynamics simulations in SRL* using realistic EM fields of QWR’s
Moriond Meeting /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 MeV/u
1 stripper
2 strippers
* performed using the code LANA (courtesy of D. Gorelov, MSU-NSCL)

27. Linac Beam Envelopes with no strippers
Moriond Meeting /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 q
Eff. (%)
Cav./prd. I 25
100 4 II
III 8
N.B. simulation performed with an input transverse emittance 2 times larger than the nominal value

28. High Energy Section-160 HWR’s (1 stripper mode)
Moriond Meeting /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. Linac Beam Envelopes with 2 strippers
Moriond Meeting /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 q
Eff. (%)
Cav./
prd. I 25
100 4 II
36,37,38,39,40 78
III
46,47,48,49 95 8
N.B. simulation performed with an input transverse and longitudinal emittance 2 and 5 times larger than the nominal value, respectively

30. High Energy Section-160 HWR’s (2 stripper mode)
Moriond Meeting /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. SRL simulations results for different modes of operation
Moriond Meeting /3/2003
SRL simulations results for different modes of operation
No stripping (prob. most experiments)
E max 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. Acceleration of different q/A beams with 2-gap cavities
Moriond Meeting /3/2003
Acceleration of different q/A beams with 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. SC linacs can be excellent RIB accelerators
Moriond Meeting /3/2003
Conclusions
Recent developments in SC linac technology
multiple charge beam transport beam 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