jyfl ion cooler and buncher
DESCRIPTION
JYFL ION COOLER AND BUNCHER. The JYFL IGISOL facility. High Voltage. Cyclotron beam. Ion guide. Separator magnet. Beam switchyard. Ion Beam Cooler. 90 bend. High Voltage. Penning Trap. 2 m. 0. 1. Cooler layout. Ion beam cooler. Central beam line. Cooler beam line. - PowerPoint PPT PresentationTRANSCRIPT
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)