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)