M. Steck, RUPAC 2006, Novosibirsk

Cooling of Rare Isotope Beams in the ESR

Cooling by:• Stochastic cooling (pre-cooling)• Electron cooling (final cooling)

M. Steck, for the FSR team:K. Beckert, P. Beller †, C. Dimopoulou, A. Dolinskii, V. Gostishchev, I. Nesmiyan, F. Nolden, C. Peschke

Injection of:• Highly charged heavy ions from SIS18• Rare isotope beams via fragment separator FRS

M. Steck, RUPAC 2006, Novosibirsk

The Existing GSI Accelerator Facility

M. Steck, RUPAC 2006, Novosibirsk

Stochastic Cooling at the ESR

energy 400 (-550) MeV/ubandwidth 0.8 GHz (range 0.9-1.7 GHz) p/p = p/p = m m

electrodes installed inside magnets

combination of signals from electrodes

power amplifiersfor generation ofcorrection kicks

Fast pre-cooling of hot fragment beams

M. Steck, RUPAC 2006, Novosibirsk

The ESR Electron Cooler

electron beam parameters

energy 1.6 – 250 keVcurrent 0.001 – 1 Adiameter 50.8 mmgun perveance 1.95 Pcollection efficiency > 0.9998temperature transverse 0.1 eV longitudinal ~ 0.1 meV

magnetic fieldstrength 0.015 – 0.2 Tstraightness 1×10-4

vacuum 2×10-11 mbar

M. Steck, RUPAC 2006, Novosibirsk

Stochastic Cooling

Longitudinal cooling

Transverse cooling

Cooling time

dependent on beam intensity

(Schottky noise)

(beam profile)Ar18+

cooling time for U92+ (N=106):longit., vert.: 0.5 s, horiz.: 2.5 s

5 s

5 s

Ar18+

Ar18+

M. Steck, RUPAC 2006, Novosibirsk

Stochastic Cooling of U92+ Beam

Minimum longitudinal cooling time (for N = 8106): 0.3 spreviously (not optimized): vertical 0.5, horizontal 2.5 s

reduction by factor 3 compared to Ar18+

optimization of system gain

U92+

400 MeV/u

mo

me

ntu

m s

pre

ad

p

/p

time t [s]

M. Steck, RUPAC 2006, Novosibirsk

Equilibrium Beam Parameters of Cooled Beams in the ESR

[mm

mra

d]

106limited by intrabeam scattering

Electron cooling results insmaller momentum spread and smaller emittancecompared to stochastic cooling.

The equilibrium is a balance between the cooling rate and the heating rate by intrabeam scattering.

calculated IBS-heating/cooling rate [s-1]

longit. transv.

stoch. cool. 0.9 - 2.2 0.5 - 1.3 el. cool. [25 mA] 2.0 - 6.0 1.4 - 3.3el. cool. [250 mA] 18 - 58 7 - 10

Electron cooling is more powerful for cold beams.

M. Steck, RUPAC 2006, Novosibirsk

0

50

100

150

200

250

-0.25% -0.15% -0.05% 0.05% 0.15% 0.25%

p/p

Pow

er [

dB/H

z]

Fast stochastic pre-cooling

One trace every 120 ms5.52 s in total

Subsequent electron cooling

Inj.

3 s

5 s

Primary Uranium beamheated in thick target

stochastic pre-cooling + final electron coolingimmediately after injection

Combination of Stochastic and Electron Cooling

Stochastic pre-cooling reduces thetotal cooling time to a few seconds,electron cooling only takes 10 - 60 s

Accumulation of secondary beams

1) s.c. on injection orbit2) rf stacking3) electron cooling of stack

Ion

cu

rren

t [m

A]

time [s]

Intensity increase for secondary beams

M. Steck, RUPAC 2006, Novosibirsk

Electron Cooled Beams in Equilibriumwith Intrabeam Scattering

Phase space volume increases with: ion beam intensity and ion charge

by non-destructive methods(particle detectors, profile monitor)

by destructive scraping

p/p N0.3

x,y N0.5-0.6

x [

mm

mra

d]

vert

ical

rad

ius

[mm

]

y [

mm

mra

d]

hori

zont

al r

adiu

s [m

m]

E = 400 MeV/u

M. Steck, RUPAC 2006, Novosibirsk

Observation of Ultra-cold Beam

temporal evolution of Schottky noise allows independent determination of particle number

decay time due to REC

sudden reduction of the momentum spread for less than about one thousand stored ions

linear ordering in ion string storage time [min]

p/p

Scho

ttky

noi

se p

ower

[a.

u.]

Reduction of momentum spread

M. Steck, RUPAC 2006, Novosibirsk

Transverse Beam Size of Ultra-cold Beam

lowest temperaturefor C6+ at 4800 MeV

kT= 0.26 meV

kTX= 0.14 meV[m

m]

[mm

]

minimum ion temperature of the order of the longitudinal electron temperature

magnetized cooling

[a.u

.]

high precision measurementemploying a scraper in a dispersive section ( D 1 m )

scraper position [mm]

M. Steck, RUPAC 2006, Novosibirsk

Detection of Single Ions

decay of an unstable nucleus

measurement of excited states in unstable nuclei

resolution m/m up to 1×106

M. Steck, RUPAC 2006, Novosibirsk

p-bar target

p-linac

Super- FRS

SIS100 SIS300

HESR

CR

RESR

Unilac

SIS 100

PANDA

Atomic Phys.

Plasma Phys.

NESR

HESR

Low Energy Exp.

High Energy Exp.

NESR Exp.

Antiproton Prod. Target

SIS18 Upgrade

CR

FAIR Baseline Layout

SuperFRS

FLAIR

RESR

p-linac SIS 300

Atomic Physics

HADES & CBM

Accelerator

Experiment

M. Steck, RUPAC 2006, Novosibirsk

Cooling of Secondary Beams

at the FAIR Storage Rings

HESR

CR complex(CR, RESR)

NESR

NESR Electron Cooling

CR Stochastic Cooling

RI beamspbars

HESR Electron Cooling

in collaboration withBINP Novosibirsk

5 (8) MeV 2 A

450 keV

2 A

B = 0.5 T

B = 0.2 TRESRpbar accumulation

M. Steck, RUPAC 2006, Novosibirsk

Cooling Systems at FAIR

CR: stochastic pre-cooling of 1) RIBs at 740 MeV/u (cooling time 1.5 s )2) antiprotons at 3 GeV (cooling time 10 (5) s )

RESR: accumulation of antiprotons at 3 GeV(electron cooling of antiprotons at 400 MeV)

NESR: electron cooling of1) ions at 4 - 800 MeV/u (accumulation at 100 - 740 MeV/u)2) antiprotons at 30 / 800 MeV (during deceleration)

HESR: electron cooling of antiprotons at 0.8 - 8 (15) GeV

FLAIR: electron cooling of ions and antiprotons below 30 MeV/u

M. Steck, RUPAC 2006, Novosibirsk

The Collector Ring CR

circumference 212 mmagnetic bending power 13 Tm

RIB pbar

energy 740 MeV/u 3.0 GeV tunes Qx/Qy 3.17/3.18 4.42/4.24 mom. accept. 1.5 % 3.0 % transv. accept. 20010-6 m 24010-6 m transition energy 2.9 3.54

isochronous (RIB) 790 MeV/u 2.55/3.17 0.7 % 70/5010-6 m 1.84

• fast stochastic cooling of antiprotons and rare isotope beams

fast bunch rotation with rf voltage 200(400)kV adiabatic debunching

stochastic pre-cooling system 1-2 (1-4) GHz

optimized ring lattice for proper mixing large acceptance superconducting dipoles

isochronous mass measurementsof rare isotope beams

operation at transition energy

M. Steck, RUPAC 2006, Novosibirsk

Techniques for Fast Cooling in CR

Fast bunch rotation of SIS100 bunchrf voltage 200 (400) kV at h=1after passage of production target to reduce momentum spread (2.5 0.5 %)

50 ns

2.5 %

0.5 %

0.75 %

bunch rotation

adiabatic debunching

SIS100 bunch

after bunch rotation anddebunching in CR

providing optimum initial parametersfor stochastic cooling

Fast stochastic pre-coolingsystem band width 1-2 (1-4) GHzmatched to velocities = 0.83 - 0.97rf power ~ 1 - 2 kW per system

electrode prototype

front and back side

CERN AC, band 158 mm horizontal

GSI 6 mm air gap92 mm horizontal

Increase of impedance (factor of 4)

Frequency [GHz]

analysis byL. Thorndahl

M. Steck, RUPAC 2006, Novosibirsk

RESRThe Antiproton Accumulator Ring RESR

• accumulation of antiprotons by stochastic cooling max. accumulation rate 7 1010/h (first stage 2.6 1010/h)

circumference 245.5 mmagnetic bending power 13 Tmtunes Qx/Qy 3.8/3.3momentum acceptance 1.0 %transverse accept. h/v 80/3510-6 mtransition energy 3.62

Additional mode: fast deceleration of RIBs

M. Steck, RUPAC 2006, Novosibirsk

NESRVersatile Storage Ring for Physics Experiments

Ions

storage and cooling of ion beams in the energy range 740 4 MeV/umaximum deceleration rate 1 T/s

experiments with internal target luminosity up to 1029 cm-2s-1 RIB accumulation by electron cooling

collider mode 1) with electrons luminosity up to 1028 cm-2s-1 2) with antiprotons luminosity up to 1023cm-2s-1

electron target

Antiprotons

deceleration 3000 800 30 MeV

electron cooling at 800 MeV

circumference 222.11 mmagnetic bending power 13 Tmtunes Qx/Qy 3.4 / 3.2momentum acceptance 1.75 %transverse accep. h/v 160/10010-6 mlength of straight section 18 m

M. Steck, RUPAC 2006, Novosibirsk

NESR Electron Cooler

design by BINP, Novosibirsk

Cooler Parameters

energy 2 - 450 keVmax. current 2 Abeam radius 2.5-14 mmmagnetic field gun up to 0.4 T cool. sect. up to 0.2 T straightness 2×10-5

vacuum 10-11 mbar

• high voltage up to 500 kV• fast ramping, up to 250 kV/s• magnetic field quality

Issues:

M. Steck, RUPAC 2006, Novosibirsk

0 20 40 60 801E-4

1E-3

0,01

0,1

1

10

vertical horizontal

Em

ittta

nce,

mm

mra

dt, sec

0 20 40 60 801E-6

1E-5

1E-4

1E-3

Mo

me

ntu

m s

pre

ad

p

/p

t, sec

BETACOOL Simulations of Electron Cooling in NESR

Antiprotons E = 800 MeVIe= 2 A, re= 1 cm, B = 0.2 T

0 1 2 3 4 5 60

30

60

90

120

150

180

initial momentum spread:

p/p = 5 x 10-4

p/p = 1 x 10-3

p/p = 1.5 x 10-3

coo

ling

tim

e, s

ec

initial emittance, mm mrad

Cooling timedependence onbeam quality

0,0 0,1 0,2 0,3 0,41E-3

0,01

0,1

1

em

itta

nce

, m

m m

rad

time, sec

horizontal vertical

0,0 0,1 0,2 0,3 0,410-6

10-5

10-4

10-3

p /

p

time, sec

RIB 132Sn50+, E = 740 MeV/uIe= 1 A, re= 0.5 cm, B = 0.2 T

M. Steck, RUPAC 2006, Novosibirsk

Final Remarks

Aspects of Antiproton Cooling in the HESR were givenin a separate presentation on Monday by D. Prasuhn

We appreciate the long standing collaboration with many cool Russians, particularly from

BINP Novosibirsk:I.A. Koop, P.V. Logatchov, V.V. Parkhomchuk, P.Yu. Shatunov, Yu.M. Shatunov, A.N. Skrinsky, P. Vobly

JINR Dubna:I.N. Meshkov, R.V. Pivin, A.O. Sidorin, A.V. Smirnov,G.V. Trubnikov ………….. and many others

hope to see you at:COOL07, Bad Kreuznach, Germany

September 10-14, 2007