jyfl ion cooler and buncher
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JYFLION COOLER
ANDBUNCHER
The JYFL IGISOL facilityThe JYFL IGISOL facility
Cyclotron beam
Ion guide
Separator magnet
Beam switchyard
Ion Beam Cooler
Penning Trap
0 1 2 m
90 bend
High Voltage
High Voltage
Buffer gas cell, pHe ~ 0.1 mbar
DecelerationCollisional cooling in an
RF-quadrupole Acceleration
Beam in Beam out
40 kV
Turbo pump500 l/s
Turbo pump1300 l/s
Turbo pump900 l/s
High vacuum 10-6 mbar
Intermediate vacuum 10-4 mbar Electrodes
HV isolator
Cooler layoutCooler layout
Central beam line
Beam switchyardCooler beam line
Ion beam cooler
0.00 0.05 0.10 0.15 0.20 0.250
100
200
300
400
500
600
I (p
A)
pHe
[mbar]
89Y
2 4 6 8 100
1
2
3
4
5
6
I (n
A)
Vbias (Volts)
2 4 6 8 10
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Energy spreadEnergy spread
Beam intensity cut off vs. bias voltage.Intensive beams (129Xe, few nA) EFWHM = 1.5 eV
On-line beams 105 ions/s EFWHM = 0.7 eV
Collinear laser spectroscopy setupOff-line Barium beamEFWHM < 4 eV 20 MHz doppler broadening
Off-line 129Xe+
400 410 420 430 4400
200
400
600
800
1000
1200
V (Volts)
IGISOLV
sk = 12 V,
PHe
= 22 mbar
MRP = 615
COOLERP
He 0.1 mbar
Vrf = 140 V
f = 420 kHz
9.2 ± 0.3 V
PMT
Cou
nts
400 410 420 430 440
100
200
300
400
500
600
PMT
Cou
nts
IGISOLV
sk = 250 V,
PHe
= 22 mbar
MRP = 220
COOLERP
He 0.18 mbar
Vrf = 140 V
f = 420 kHz
9.2 ± 0.5 V
V (Volts)
Delay timeDelay time
IGISOL delay time ~msWithout axial field: diffusion, space chargeDepends on:
- Einj
- Einj
- pHe
Without axial field up to hundreds of msShorter by axial electric field (down to ms region)Longer beam bunching
slowfast
t
slow
t
fast eIeII
fastslow
fastfastslowslow
II
II
500 1000 1500 2000 25000
50
100
150
200
250
300
350
pHe
= 0.05 mbar
Cou
nts
t (ms)
pHe
= 0.08 mbar
pHe
= 0.1 mbar
Beam offBeam on
pHe
= 0.13 mbar
0 50 100 150 200 250 300 350 400
0
2
4
6
rf-quadrupoleexit
rf-quadrupoleentrance
z (mm)
Seg
men
tatio
n sc
hem
e
DC
leve
l (V
olts
)
i
iv
iiiii
0.09 0.10 0.12 0.13 0.14 0.150
1
2
3
4
10
20
30
40
50
60
70
iv
iii
ii
i
(
ms)
pHe
(mbar)
0.08 0.10 0.12 0.14 0.1620
40
60
80
100
120
140
160
180
200
220
Fission ptc = 200 mbar
Fission ptc = 50 mbar
HIGISOL
(m
s)
pHe
(mbar)
0.00 0.05 0.10 0.15 0.20 0.250
100
200
300
400
500
600
I (pA
)
pHe
[mbar]
0 50 100 150 200 250 3000
1x105
2x105
3x105
4x105
cts before
cts after cooler
transmission
cou
nts
/ 120
s
Skimmer voltage (volts)
0
20
40
60
80
100
Tra
nsm
issi
on %
TransmissionTransmission
- 29 MeV proton induced fission of 238U- Normal ion guide pressure 250 mbar- Skimmer voltage varied- A = 112 IGISOL beam (mostly 112Rh)- Beta count rate in two Si-detector setups, before
and after the cooler- Transmission > 60 %
-1
0
1
2
3
4
DC
leve
l (V
)
0 500 1000 1500 2000 2500 3000 3500 40001
10
100
1000
10000
Cts
t (s)
3300 3320 3340 3360 3380 3400 3420 3440
2000
4000
6000
8000
10000
12000
Cts
t (s)
- Separator beam on t = 0 - 1000 s- Cooler end plate voltage down t = 3300-4000 s
Z
+2 V +1 V +0.5 V
-1V
+70 V (collect)0 V (release)
Potential along z - axis
BunchingBunching
0 10 20 30 40 500
2
4
6
8
10
12
14
0 10 20 30 40 500
1000
2000
3000
4000
5000
6000
7000
LCRLASERIONS
Singles photonsPhotons gated onthe ion bunch
Delayed Ion-photon coincidence method
Bunched beam method
Photons gated onthe ion bunch
Ion Beam Energy Tuning (eV)
Cou
nts
174Hfttrap = 0.5 sGate1 = 15 sGate1 = 30 sGate1 = 75 s
Hf 15(1) sTi 10(1) s (with <10 000 ions/bunch)
0 10 20 30 40 500
2
4
6
8
10
12
14
16
18
Cou
nts
Ion Beam Energy Tuning (eV)
Gate3 Gate2 Gate1
Gate3
Gate2
Gate1
Ion bunch
Trigger
1000 10000 1000000
5
10
15
20
25
30
35
Ti Hf
Bun
ch w
idth
(s
)
Ions/bunch
Bunch width - Mass and Space charge effectsBunch width - Mass and Space charge effects
0 2 4 6 8 10 120
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
178mHf T½ = 4.0 s
Meas. Calc.
I(17
8mH
f) (
Ions
/min
)
Trapping time (s)
1 2 3 4 5 6 7 8 9 10 110.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
144
Ba++
144
La++
72
Cu+
I (a
.u.)
Accumulation time (s)
Ion survival in the BuncherIon survival in the Buncher
P. Campbell et al. Hypf. Int. 127 (2000)
On-line photon efficiency in collinear On-line photon efficiency in collinear laser spectroscopy (ion survival)laser spectroscopy (ion survival)
Without the buncher- Metastable population- IGISOL pressure
With the buncher- Off-line efficiencies hold metastables reduced- No IGISOL pressure effects (below fig. pIG=450 mbar)
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