Y. Liu, C. Baktash, J.R. Beene, J.F. Liang, D.W. Stracener

C.C. Havener, H.F. Krause, D.R. Schultz, C.R. Vane

Physics Division, Oak Ridge National Laboratory

Oak Ridge, Tenneessee

in collaboration with the Larissa Group, Physics Department, Uni-Mainz, Germany

Christopher Geppert, Tina Gottwald, Thomas Kessler*, Ben Tordoff*, Katja Wies, Klaus Wendt

*borrowed from JYFL

Development of a Laser Ions Source for Development of a Laser Ions Source for

Beam Purification at HRIBFBeam Purification at HRIBF

• The Holy Field RIB facility at ORNL

• Off-line ion source test facilities at HRIBF

• Laser ion source developments

– Accessible elements and efficiency

– Atomic spectroscopy on excitation schemes

– Emittance and temporal laser ion pulse profile

– Source material and atomic beam evaporation investigations

• RF quadrupole ion cooler for negative ions

• Isobar suppression by laser photodetachment

���� contact yliu@ornl.gov

Outline

Recoil Mass Spectrometer

(RMS)

Injector for Radioactive Ion

Species 1 (IRIS1)

25MV Tandem

Electrostatic Accelerator

Daresbury Recoil Separator (DRS)

Oak Ridge Isochronous Cyclotron (ORIC)

On-Line Test

Facility (OLTF)

High Power Target

Laboratory (HPTL)

Stable Ion Injector (ISIS)

EngeSpectrograph

Holyfield Radioactive Ion Beam Facility

� High Power Target Laboratory (HPTL) installed

� Beam development R&D facility for RIA

� High power ORIC beams utilized for development of advanced targets, target/ion

sources, beam preparation components, and purification techniques.

� Injector 2 for Radioactive Ion Species 2 (IRIS2) initiated

� Second fully operational production station with substantially improved functions

� Enlarged space to accommodate new production techniques such as RILIS

� Laser lab. allocated to provide an operating venue for on-line resonance laser ion

sources and other in-beam purification schemes employing lasers.

� Schedule of implementation: January 2006 - February 2009

HRIBF Major Updates 2005 ���� today

HRIBF with HPTL / IRIS2 Status 2007 - 2009

IRIS1

HPTL / IRIS2

Laser Room

Off-line Ion Source Test Facilities 1 & 2

Off-line Ion Source Test Facility 1

ISTF-1 � negative ion beams,

quadrupole cooler and

laser photodetachment

Ion Cooler

Energy Analyzer

X-Y Emittance Device

Off-line Ion Source Test Facility - 2 (ISTF-2)

ISTF-2 � positive ion beams,

source developments -ECR source, laser ion source

HV @ 30 kV

• Collaboration between Atomic Physics Group, ORNL Physics Division

Yuan Liu, Charly C. Havener, Herb F. Krause, Dave R. Schultz, C. Randy Vane

+ support by Cyrus Baktash, Jim R. Beene, J.F. Liang, Dan W. Stracener

and the Larissa Coll., Physics Department, UMz

Christopher Geppert, Thomas Kessler, Katja Wies, Tina Gottwald, Ben Tordoff, K. W.

• Project started at ISTF2 in 2004 using RIA R&D funding

• One joint experimental campaign of ~3 weeks per year conducted

(09/2004, 09/2005, 10/2006, 10/2007,…)

• Primarily : complete Ti:Sapphire laser system provided by Mainz

since 2006 : sequential purchase of ORNL Ti:Sa laser system

• Elements successfully investigated at ORNL so far:

� (2004) Sn, Ni, Ge; (2005) Cu, Mn; (2006) Fe, Al;

ORNL Laser Ion Source Project

Photonics Ti:Sapphire Laser 3 fundamental- full range tunable -

Photonics 100 W Pump Laser

UMz Ti:Sapphire Lasers SS 1 DS 2

Mixed Ti:Sapphire Laser Setup at HRIBF - 2006

UMz Tripler & Quadrupler

Activities at the ISTF 2 Laser Ion Source

• Identification of Ti:Sa laser excitation schemes for various elements

• Optimization of source geometry – transfer tube / atomizer funnel

• Study of source material – Ta, TaC, …

• Optical Spectroscopy on Rydberg and auto-ionizing states

• Investigation of spatial and temporal behaviour of laser ion beam

���� Optimization of laser ionization conditions and efficiency

IP62317.44 cm-1

217.963 nm11469.828 cm-1

(4th Harmonic)

0 cm-1

45879.31 cm-1 3d94s4p 2P0 J=3/2

3d106d 2D J=3/2

761.23 nm13136.71 cm-1

3d94s5p4D0J=3/2

832.380 nm12013.739 cm-1

57895.10 cm-1

832.238 nm12015.789 cm-1

70414.50 cm-13d94s5p4F0J=5/2

798.76 nm12519.40 cm-1

3d106d 2D J=5/2

3d10 2S J=1/2

Typical Excitation Scheme: Copper

Scheme 1Scheme 2

99.7% @2300K

0 5000 10000 15000 20000 25000

0

5

10

15

20

surface ions not corrected

surface ions corrected

ion c

urr

ent

/ nA

time / s

~2.4%

Cu

>3.3%

Ge

2.7%22%

NiSn

0

10

20

30

40

50

60

70

0 1 2 3 4 5 6 7 8 9 10

Time (hour)

Ion

Curr

en

t (n

A)

21%

23%

0

5

10

15

20

25

0 2 4 6 8 10 12

Time (hour)

I (nA)

Sn Ni

Sn: controllable

and reproducible release

Ni: reaction with Ta source

material above Tcritical

Cu

Cu: explosive evaporation

Efficiency and Detection Limit

Importance of geometry and material of atomizer and transfer tube

Pureness of buffer gas in gas-cell or gas-filled RFQ trap

1 2 0 0 0 1 2 0 5 0 1 2 1 0 0 1 2 1 5 0 1 2 2 0 0 1 2 2 5 00

4

8

1 2

1 66 1 3 0 0 6 1 3 5 0 6 1 4 0 0 6 1 4 5 0 6 1 5 0 0 6 1 5 5 0 6 1 6 0 0

ion

cu

rre

nt

/ nA

ν3 / c m

-1

νto ta l

/ c m-1

Atomic Level Spectroscopy

12260 12265 12270 12275 12280 122850

1

2

3

4

5

61575 61580 61585 61590 61595 61600

ion c

urr

ent /

nA

ν3 / cm

-1

νtotal

/ cm-1

Atomic Rydberg levels

17 < n < 72

Nickel

Small δ with increasing trend � assignment of configuration 3d9(2D5/2) nf 2[7/2]o3,4,5 or nf 2[9/2]o3,4,5

Ionization potential: EIP (Ni) = 61 619.8 (1) cm-1,

(EIP(Lit.) = 61 619.1(10) cm-1)

R.H. Page and C.S. Gudeman,

J. Opt. Soc. Am. B 7 (1990) 1761

20 30 40 50 60 70

-0,10,00,1

12000

12050

12100

12150

12200

12250

61300

61350

61400

61450

61500

61550

61600

Resid

uals

Waven

um

ber

thir

d s

tep /

cm

-1

Principal quantum number n

Tota

l e

nerg

y /

cm

-1

20 30 40 50 60 70

-0,15

-0,10

-0,05

0,00

0,05

0,10

0,15

Quantu

m d

efe

ct

δ

Principal quantum number n

Quantum Defect δδδδ and Ionization Potential

Precision:

~ 1 GHz

≅ 0.05 cm-1

Nickel

0

400

800

1200

1600

2000

0 100 200 300 400 500

Heating Current (A)

Te

mp

era

ture

(C

)

Ionizer cavity

Vapor transport tube

Finite element thermal analysis

� temperature distribution

� drift field profile

Measured Temperatures

Ion Source Geometry and Material Optimization

1

400

554.913

709.826

864.739

1020

1175

1329

1484

1639

1794

NODAL SOLUTION

STEP=4

SUB =15

TIME=4

TEMP (AVG)

RSYS=0

SMN =400

SMX =1794

Calculated temp. profile agrees …

Heating current = 400A

0 40 80 120 160 200 240 280

0.0

0.2

0.4

0.6

0.8

1.0

Sn, Ionizer 300 A / Target 300A

Cu, Ionizer 355A / Target 50A

Ni, Ionizer 400A w/o Target

norm

aliz

ed c

ounts

time / µs

Time Profiles of Different Elements

repeller = 0V

0

0.2

0.4

0.6

0.8

1

-50 0 50 100 150 200 250 300

Time (us)

Co

un

ts (

a.u

.)

Cu data

Sn data

Cu-MC

Sn-MC

Universality of the RIMS approach

Presently laser ion beams of 19 elements available from hot cavity Ti:Sa RILIS or LIST

under preparation: --- Co, Cd, In, Sb, Te, V ---

1H 2He

3Li 4Be 5B 6C 7N 8O 9F 10Ne

11Na 12Mg 13Al 14Si 15P 16S 17Cl 18Ar

19K 20Ca 21Sc 22Ti 23V 24Cr 25Mn 26Fe 27Co 28Ni 29Cu 30Zn 31Ga 32Ge 33As 34Se 35Br 36Kr

37Rb 38Sr 39Y 40Zr 41Nb 42Mo 43Tc 44Ru 45Rh 46Pd 47Ag 48Cd 49In 50Sn 51Sb 52Te 53I 54Xe

55Cs 56Ba 57La 72Hf 73Ta 74W 75Re 76Os 77Ir 78Pt 79Au 80Hg 81Tl 82Pb 83Bi 84Po 85At 86Rn

87Fr 88Ra 89Ac 104Rf 105Ha 106 107 108 109 110 111 112 113

58Ce 59Pr 60Nd 61Pm 62Sm 63Eu 64Gd 65Tb 66Dy 67Ho 68Er 69Tm 70Yb 71Lu

90Th 91Pa 92U 93Np 94Pu 95Am 96Cm 97Bk 98Fc 99Es 100Fm 101Md 102No 103Lr

..with fundamental & frequency doubling.

..with frequency tripling.

..with frequency quadrupling.

..successfully tested.

Bk 98Fc 99Es 100Fm 101Md 102No 103Lr

HR-RIMS excitation schemes accessible …..using Ti:Sa lasers

Conclusion & Outlook

• HRIBF laser ion source development

– Ti:Sapphire laser system with 100 W pump laser on its way

– Strong off-line activities at ISTF 2

• source and material optimization

• identification of excitation schemes

– Preparation of on-line activities at HRIBF – IRIS 2

• Positive ion production & charge exchange

& laser photodetachment in cooler/buncher