Contents

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Contents
Moriond Meeting 17-21/3/2003
Acceleration of RIB using linacs
Alberto Facco INFN-Laboratori Nazionali di
Legnaro

• Introduction
• Technological highlights in superconducting low-?
  linacs
• Superconducting linacs for RIB acceleration
• Example of multicharge transport in EURISOL SRL
• Conclusions

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Ideal RIB accelerator requirements
Moriond Meeting 17-21/3/2003

• 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.

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RIB accelerators special constraints
Moriond Meeting 17-21/3/2003

• 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

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Independently-phased Superconducting Cavity
Linacs virtues
Moriond Meeting 17-21/3/2003

• 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
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Technological highlights in superconducting low-?
linacs
Moriond Meeting 17-21/3/2003
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Moriond Meeting 17-21/3/2003
Superconducting QWRs (optimum range 0.03lt?lt0.3
and 50ltflt200 MHz)
Mechanical damper
LNL 80 MHz, ?0.055 cryostat
Best ALPI and PIAVE low beta cavities results
LNL PIAVE 80 MHz, ? 0.047 QWR
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Moriond Meeting 17-21/3/2003
ISAC-II ?0.072 cavity

• Design gradient 6 MV/m _at_7W
• reached 7 MV/m with lt10W

TRIUMF ISAC-II 106 MHz, ?0.072 prototype
4.2 k test results
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Moriond Meeting 17-21/3/2003
Superconducting Spoke resonators (optimum range
0.2lt?lt0.5 and f?350 MHz)
ANL ?0.3 and ? 0.4 prototypes
LANL ?0.2 prototypes
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Moriond Meeting 17-21/3/2003
Superconducting RFQs

• Compactness
• CW operation
• High efficiency

LNL Superconducting SRFQ2 A/q8.5,
0.0255ltblt0.0355
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6 MV/m already achieved in existing
linacs7 MV/m seems very realistic for
future accelerators
Moriond Meeting 17-21/3/2003
Low -? SC linacs design gradient
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EM steering in QWRs
Eurisol Town Meeting, Abano 24-25/1/2002

• The steering is proportional to the energy gain
• The magnetic contribution is dominant

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Quarter Wave Resonatorswith dipole correction
A. Facco - SPES meeting LNL 11-3-2003

• ANL QWR 115 MHz for RIA

• MSU QWR 161 MHz for RIA
• (MSU-LNLcollaboration)

QWR steering 161 MHz standard shape (top) 161
MHz corrected
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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

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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

DWqEaLT(b)cosf
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Moriond Meeting 17-21/3/2003
Multicharge beam transport
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Moriond Meeting 17-21/3/2003
Examples of superconducting linacs for RIB
acceleration
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ISAC post-accelerator at TRIUMF (operating,
under completion)
Moriond Meeting 17-21/3/2003

• 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 Agt30

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ISAC post-accelerator special components
Moriond Meeting 17-21/3/2003

• 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
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The RIA RIB facility
Moriond Meeting 17-21/3/2003

• RIA Driver SC linac
• Ion beams of all masses
• 400 MeV/u Uranium

RIA driver superconducting cavities under
development at ANL
RIA (MSU version)
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The ANL-RIA post-accelerator (proposed as
injector of the existing ATLAS SC linac)
Moriond Meeting 17-21/3/2003

• No charge breeder, accepting q1
• Masses 66ltAlt 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, gt30 up to the
  2nd stripper
• Good emittance
• Very conservative design gradient
• Beam injected into ATLAS ( 50 MV)

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RIA post-accelerator special components
Moriond Meeting 17-21/3/2003

• RD 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
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EURISOL SRL (preliminary project)
Moriond Meeting 17-21/3/2003

• 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

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SRL cavity parameters
Moriond Meeting 17-21/3/2003
QWR
HWR
Calculated by means of the code HFSS
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SRL modules
Moriond Meeting 17-21/3/2003

• SRFQ section
• 3 LNL type superconducting RFQs in 2 cryostats
• Design A/q ? 10 (up to 132Sn13)
• Ein 2.3 keV/u, Eout 670 keV/u
• QWR-HWR modules
• Cryostat
• 4 QWRs (section I and II) at 7 MV/m
• 8 HWRs (section III) at 7 MV/m
• 1 superconducting solenoids at Blt15 T
• Diagnostics box

Schematic of RFQ section and first QWR module
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Example of multicharge beam transport in EURISOL
SRL
Moriond Meeting 17-21/3/2003
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Moriond Meeting 17-21/3/2003
Beam dynamics simulations in SRL

• Simulation of the accelerating sections
• using realistic EM fields of QWRs
• 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 60 MeV/u
• 1 stripper 93
• 2 strippers 100

performed using the code LANA (courtesy of D.
Gorelov, MSU-NSCL)
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Linac Beam Envelopes with no strippers
Moriond Meeting 17-21/3/2003
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
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Beam emittances with no strippers
Moriond Meeting 17-21/3/2003
INITIAL
FINAL
Simulated using the LANA code

• 132Sn
• Win 670 keV/u
• Wout 59.6 MeV/u
• -20 deg
• q 25
• Eacc 7 MV/m

N.B. simulation performed with an input
transverse emittance 2 times larger than the
nominal value
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High Energy Section-160 HWRs (1 stripper mode)
Moriond Meeting 17-21/3/2003
INITIAL
FINAL
Simulated using the LANA code

• 132Sn
• Win 16.3 MeV/u
• Wout 92.9 MeV/u
• -20 deg
• q45,46,47,48,49
• 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
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Linac Beam Envelopes with 2 strippers
Moriond Meeting 17-21/3/2003
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
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Medium Energy Section-60 QWRs
Moriond Meeting 17-21/3/2003
INITIAL
FINAL
Simulated using the LANA code

• 132Sn
• Win 4.2 MeV/u
• Wout 22.4 MeV/u
• -20 deg
• q36,37,38,39,40
• Eacc 7 MV/m

BUNCHED
After stripping in a 200 mg/cm2 carbon foil
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High Energy Section-160 HWRs (2 stripper mode)
Moriond Meeting 17-21/3/2003
INITIAL
FINAL
Simulated using the LANA code

• 132Sn
• Win 21.6 MeV/u
• Wout 100 MeV/u
• -20 deg
• q46,47,48,49
• Eacc 7 MV/m

BUNCHED
After one more stripping in a 3 mg/cm2 carbon
foil
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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

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Moriond Meeting 17-21/3/2003
Acceleration of different q/A beamswith 2-gap
cavities

• Virtually all RIBs that allow charge breeding
  can be accelerated by SRL with similar results.
• Examples
• 33Ar(8)
• E127 MeV/u
• 210Fr(25)
• E100 MeV/u

33Ar(8)
210Fr(25)
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Conclusions
Moriond Meeting 17-21/3/2003

• 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