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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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Contents

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


Ideal rib accelerator requirements

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.


Rib accelerators special constraints

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%


Independently phased superconducting cavity linacs virtues

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


Technological highlights in superconducting low l inacs

Moriond Meeting 17-21/3/2003

Technological highlights in superconducting low- linacs


Contents

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


Contents

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


Contents

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


Contents

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


6 mv m already achieved in existing linacs 7 mv m seems very realistic for future accelerators

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


Em steering in qwr s

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


Quarter wave resonators with dipole correction

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


Contents

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


Contents

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


Contents

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


Contents

Moriond Meeting 17-21/3/2003

Examples of superconducting linacs for RIB acceleration


Isac post accelerator at triumf operating under completion

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


Isac post accelerator special components

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


The ria rib facility

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)


The anl ria post accelerator proposed as injector of the existing atlas sc linac

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)


Ria post accelerator special components

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


Eurisol srl preliminary project

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


Srl cavity parameters

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


Srl modules

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


Example of multicharge beam transport in eurisol srl

Moriond Meeting 17-21/3/2003

Example of multicharge beam transport in EURISOL SRL


Contents

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)


Contents

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


High energy section 160 hwr s 1 stripper mode

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


Linac beam envelopes with 2 strippers

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


High energy section 160 hwr s 2 stripper mode

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


Contents

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


Contents

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+)


Conclusions

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