Status Report of the LISOL Laser Ion Source Yu.Kudryavtsev, T.Cocolios, M.Facina, J.Gentens,...

Status Report of the LISOL Laser Ion Source

Yu.Kudryavtsev, T.Cocolios, M.Facina, J.Gentens, M.Huyse, O.Ivanov, D.Pauwels, M.Sawicka, P.Van den Bergh, P.Van Duppen,

Instituut voor Kern- en Stralingsfysika, K.U. Leuven,

Celestijnenlaan 200 D, B-3001 Leuven, Belgium.

Yu.Kudryavtsev, SMI06, March 27-28, 2006 1/24

CYCLONE 30CYCLONE 110

CYCLONE 44

LISOL

LASERS

Louvain-la-Neuve Radioactive Beam FacilityLouvain-la-Neuve Radioactive Beam Facility

LASER ION SOURCE


LISOL laser ion source

Energy (eV)

0

4

laser

+ ++

separator

primarybeam

SPIG

gas cell

Ar

target

3-10mg/cm2

40 kV

Time profiles of laser-ionized stable

Ni-58 from a filament

~1994

We need to provide:

1. Efficient laser ionization

2. Survival of laser-produced ions in a small volume around the exit hole

Weak beam, 1nA, 1ms

Strong beam, 1uA,20ms


Yu.Kudryavtsev, SMI06, March 27-28, 2006

LISOL Laser Ion Source is used since 1994 in

1. Light ion-induced fusion evaporation reactions (Co,Ni,Mn)

2. Heavy ion-induced fusion evaporation reactions (Rh,Ru,Ti)

3. Proton-induced fission of U-238 (Ni,Co,Fe,Cu)

4. Stopping of 185 MeV Ni beam in a gas cell

5. Products from spontaneous fission Californium-252 (Rh,Ru,Mo,Pd)

4/24

Lay out of the gas cell and ion extraction

filament

Fusion cell

Fission cell


500mbar Ar

1e-5mbar

1e-2 mbar

Dye Laser 2

Dye Laser 1

SHG

Synchron. Unit

Telescope

Telescope

Laser Ion Source at the LISOL front end

Reference Cell

Energy meters

15 m

1

2

TOF SEM

Laser System

Excimer laser 1

LPX240, 200Hz, 15ns

Excimer laser 2

LPX240, 200Hz, 15ns

Tunable range

225 - 800 nm


Atomic beam

Autoionizing stateEnergy (eV)

0

4

I.P.


Laser System


Excimer lasers

Dye lasers

SHG

Reference cell

towards LIS

7/24

Two-step laser ionization schemes

at LISOL

- found @ tested on-line

- found @ tested off-line


80% of all elements can be ionized by the LISOL laser system in two steps

The aim – refractory elements (thin target and fast extracion)

8/24


Calculated fission cross section

1.00E-06

1.00E-05

1.00E-04

1.00E-03

1.00E-02

1.00E-01

1.00E+00

60 62 64 66 68 70 72 74 76 78mass number

cros

s se

ctio

n [m

b] Fe

Co

Ni

p oly eth y len + b o rax

L ea d b rick s

C u + Z n

beam

im p lan ta tion tap e

p lastic d etectorsβ

MINIBALL

MINIBALL

DETECTOR

DETECTOR

γ γ

Detection set-up

9/24

Z

29

28

27

26

Proton-induced fission of U-238 Proton-induced fission of U-238

- Studied isotopes

- Isotopes measured in 2005


66Fe176 keV

66Fe807 keV

66Fe881 keV

6 6 F e9 1 8 k eV

66Fe930 keV

66Fe471 keV

66C o1246 keV

66C o1425 keV

66Fe1022 keV

66Fe176 keV

66Fe807 keV

66Fe881 keV

6 6 F e9 1 8 k eV

66Fe930 keV

66Fe471 keV

66C o1246 keV

66C o1425 keV

66Fe1022 keV

F e ß -g a te d sp e c tr a O n (r e d )/O ff (b lu e ) -r e so n a n c e 66

6 7 F e1 8 9

6 7 F e1 2 5 1 k e V

67Fe2054 keV

67Fe2080 keV

67Fe2087 keV6 7 F e

1 8 9 k e V

k e V6 7 C o

6 9 4

6 7 F e1 2 5 1 k e V

67Fe2054 keV

67Fe2080 keV

67Fe2087 keV

F e ß -g a te d sp e c tr a O n (r e d )/O ff(b lu e )-re so n a n c e 6 7

p oly eth y len + b o rax

L ea d b rick s

C u + Z n

beam

im p lan ta tion tap e

p lastic d etectorsβ

MINIBALL

MINIBALL

DETECTOR

DETECTOR

γ γ

Gamma spectroscopy of neutron-reach Fe isotopes

In June 2006 – 192 hours of beam time (protons 30 MeV)

10/24


Isospin symmetry test

54Fe(3He,3n) 54NiN=Z

Accurate comparison of Gamow -Teller transitions for A=46, 50 and 54 in beta decay and in (3He,t) reactions

11/24

180


I937=250(35), Pk/B = 2.3

922 keV:411+511

keV

Half-life fit:

Beam ON Beam OFF

T1/2 = 109 (13) ms

I937=177(16), Pk/B = 11.3

P = 12 at/C

P = 17 at/C

Production of proton-reach nickel-54 isotope

3He2+

In April 2006 – 168 hours of beam time (3He 45MeV)

54Fe(3He,3n) 54NiTest experiment in 2005

12/24


Spontaneously fission of Californium-252

0

0.5

1

1.5

2

2.5

3

3.5

4

80 90 100 110 120 130 140 150 160

Mass, a.u.

Yie

ld,

%

34Se

35Br

36Kr

37Rb

38Sr

39Y

40 Zr

41 NB

42 Mo

43 Tc

44 Ru

45 Rh

46 Pd

47 Ag

48 Cd

49 In

50 Sn

51Sb

52Te

53I

54Xe

55Cs

56Ba

57La

58Ce

59Pr

60Nd

61Pm

Independent Yields of Spontaneous Fission for Cf-252

105 MeV 85 MeV

112Rh

Life time – 2.645 y252Cf decays: 96.9% to 3.1% to fission fragments

13/24


Cf-252 gas cell

Exit hole

Gas in

Water cooling

Filament

Laser beams

Heating

Length – 16 cmInner diameter – 7 cmExit hole diameter – 0.5 mmEvacuation time (Ar) – 0 - 10 s

14/24


Gas cell for production of radioactive ions from spontaneously fission Cf-252

Californium - 252 source:

Diameter – 3 mmActivity – 25 MBq, April 2004, (4 ) Transmission through degrader foil – 33%Fission fragments inside gas – 2 E5 at/s

Plasma density – 1e8 ion-el pairs/cm3

Recombination time – 0.1 s

500 mbar Ar

Laser beams

Cf-252

Movable holder

Al foil, 6u+

+

++

+

+

αα

α

α

αα

α

α

α

+ +

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.00

100

200

300

400

Distance from Cf source, cm

CsRh

-3

-2

-1

0

1

2

3

-3 -2 -1 0 1 2 3

Y, cm

Z, c

m

Rh

SRIM calculation

15/24

1. Survival of elements with different chemical properties can be studied

2. Absolute efficiency can be measured

500 mbar Ar


-gated gamma spectrum of Rh-112 from Cf-252 source

0.1

1

10

100

1000

0 20 40 60 80 100

distance (exit hole-Cf252), mm

pro

du

cti

on

Rh

-112m

, at/

s

lasers-ONlasers-OFF

Laser enhancement for Rh-112 isotopes from Cf-252 source

0

5

10

15

20

25

30

35

40

0 200 400 600 800 1000 1200

energy, keV

cou

nts

/ch

ann

el

0

100

200

300

400

500

600

0 200 400 600 800 1000 1200

energy, keV

cou

nts

/ch

ann

el

lasers - ON

lasers - OFF

560 keV

560 keV

252Cf

Ar- 500mbar

52 mm

Yield of 112Rh into gas – 2.6% -> 5000 at/sLaser ionized mass separated yield – 250 at/sEfficiency – 5 %Selectivity: – 160

16/24


Gamma spectroscopy using spontaneously fission Cf-252 source

114Rh

Lasers - ON

Lasers - OFF

10

100

1000

10000

105 110 115 120

Mass, A.U.

Calcu

lated

yield

, at/s

42 Mo

43 Tc

44 Ru

45 Rh

46 Pd

47 Ag

48 Cd

Spectroscopy 113Rh -116Rh

Branching ratios, life-times

17/24

252Cf

Ar- 500mbar

52 mm


1,0E+01

1,0E+02

1,0E+03

1,0E+04

137 138 139 140 141 142 143 144 145 146

Cesium isotope, A.U.

Yie

ld o

f ce

siu

m is

oto

pe,

ato

ms/

s Fed into Ar gas

Measured after mass-separation

Efficiency, %

Yield of Cesium isotopes from Californium source

40%

500 mbar Ar

SPIG transport eff. – 60%

Mass separator eff. – 90%

74% of Cs atoms stay in a single charge state

Ionization potential of Cesium - 3.9 eV

Distance to the exit hole-32 mm

252Cf

Ar- 500mbar

32 mm

18/24


0.01

0.1

1

10

0 20 40 60 80 100 120

Distance exit hole - Cf-252 source, mm

Nor

mal

ized

yie

ld o

f Cs-

140

and

Cs-

142

142Cs T1/2=1,7s

140Cs T1/2= 64s

Life-time corrected on an evacuation time inside the gas cell

Survival of Cesium Ions in Argon

Short-leaved isotope can be used to probe the evacuation time

inside the gas cell

252Cf

Ar- 500mbar

Distance

19/24


The problem to be solved:Ion source efficiency at high cyclotron beam current

20/24


10-1 100 101 102 103 104 105 106 107 108 109 1010 1011

10-8

10-7

10-6

1x10-5

1x10-4

10-3

10-2

10-1

100

Lasers off

40Ar

58Ni

Eff

icie

ncy

Cyclotron beam current (pps)

58Ni

Lasers onlasersgas

Laser Ion Source Efficiency for Rh-95

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

20%

1.0E+09 1.0E+10 1.0E+11 1.0E+12

I cyclo [part/sec]

LIS

Eff

icie

ncy

[%

]

Laser ion source efficiency for heavy ion-induced fusion evaporation reaction

Extraction efficiency as function of primary 58Ni beam intensity

40Ar + 58Ni => 98Pd* => Rh/Ru + xp yn

95Rh

Ni beam

40Ar

21/24

Lasers -offgas

58Ni beam

Recombination of laser-produced ions at high beam intensity


Time profile of extracted 40Ar ions

High plasma density in the laser ionization region

22/24

2.9E10ions/s

Lasersgas

58Ni beam

Collector plate

Collection of electrons after the cyclotron pulse


Collection of electrons before laser ionization increases ion signal

Laser beams

gas

Target

Stopping volume

Ionization volume

Cyclotron beam

Separation of stopping and ionization volumes


Evacuation time inside the cell

0,01

0,1

1

10

100

0 1 2 3 4 5 6 7 8 9 10 11 12

Distance from the exit hole, cm

Ev

ac

ua

tio

n t

ime

, s

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Status Report of the LISOL Laser Ion Source Yu.Kudryavtsev, T.Cocolios, M.Facina, J.Gentens,...

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