m. steck, rupac 2006, novosibirsk cooling of rare isotope beams in the esr cooling by: stochastic...
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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