laser, joint eurons-eurisol town meeting, helsinki, sept. 17, 2007 laser techniques for exotic...

LASER, Joint EURONS-EURISOL Town Meeting, Helsinki, Sept. 17, 2007

LASer techniques for Exotic nuclei Research (LASER)

LASer techniques for Exotic nuclei Research (LASER)

Iain Moore (JYFL)on behalf of the LASER collaboration

Iain Moore (JYFL)on behalf of the LASER collaborationParticipating institutes:

IKS – K.U. Leuven, Belgium IPN – Orsay, IN2P3, France IP-Quantum, Mainz, Germany JYFL, Finland ISOLDE, CERN, Switzerland IKP, Mainz, Germany GSI – Darmstadt, Germany University of Manchester, UK


• To develop tools and perform R&D for the resonance ionization laserion sources for the production of extremely pure ground state and isomericbeams of exotic nuclei.• In-source laser spectroscopy• Accumulation, cooling, bunching and polarization of radioactive ion beams

Increase of ionization efficiency

Increase of ionization efficiency

Energy (eV)

0

4

Resonant Laser Ionization

• More efficient use of ISOL beams• New exotic (polarized, isomeric) RIB• Optimization of RIB time structure• Easy injection into ion traps• Determination of radii, spins and moments using in-source spectroscopy• Reduction of backgroundin collinear spectroscopy

• More efficient use of ISOL beams• New exotic (polarized, isomeric) RIB• Optimization of RIB time structure• Easy injection into ion traps• Determination of radii, spins and moments using in-source spectroscopy• Reduction of backgroundin collinear spectroscopy

- purity- emittance- time structure

Increase of ion beam quality

Objectives


Description of work: Task T-J08-1: Development of a new laser system for RILIS (K. Wendt, Mainz)

Task T-J08-2: New laser ionisation schemes and new beams (I. Moore, JYFL) Task T-J08-3: Prototype LIST system (W. Nörtershäuser, GSI) Task T-J08-4: Improve selectivity of RILIS: reduction of surface ionisation

(V. Fedosseev, ISOLDE) Task T-J08-5: Implementation of electrical fields in the gas cell concept (S. Franchoo, IPNO) Task T-J08-6: Feasibility study to polarize exotic nuclei with lasers (G. Neyens, K.U.Leuven)

Research program


Task 1 – Development of new laser system for RILIS

Participants: U-Mainz, JYFL, U-Manchester, K.U. Leuven, ISOLDE,IN2P3 IPO Orsay

Development of prototype solid state laser system + doubling/tripling/quadrupling Installed at U- Mainz, JYFL, TRIUMF, ORNL (tested) Recent successful demonstration of injection-locked Ti:Sapphire laser with spectroscopy on 27Al Intercomparison of dye ↔ Ti:Sa and high rep rate ↔ low rep rate suitable at JYFL

T. Kessler et al., Hyp. Int. 171 (2006) 121


-1500 -1000 -500 0 500 1000 15000

60

120

180

coun

t rat

e

/ MHz

3s 3p2 2P 1/2

3s 3d 2 2D 3/2

27A l I=5 /2

308.3048 nm

462 nm

4321

3

2

I.P. 48278.37 cm -1

32435.44 cm -1

0 cm -1

Laser development highlights

T. Kessler et al., to be submitted

U-Mainz and JYFL

0 200 400 600 8000.0

0.2

0.4

0.6

0.8

1.0 Dye laser Ti:Sapphire laser CVL Nd:YAG

No

rma

lized

am

pli

tud

e

Time (ns)

JYFL

~5 GHz Ti:Sa seeded to 20 MHz!


Ti:Sapphire lasers pumpedby Nd:YAG (12 kHz)

CW dye lasers

Pulsed dye lasers,pumped by CVL (12 kHz)or by 50 Hz Nd:YAG

Full spectral coverage at a range of repetition rates,linewidths and powers….

FURIOS at JYFL – a twin laser facility

I.D. Moore, J. Phys. G 31 (2005) S1499

2007 – LARIS lab settingup at ISOLDE, CERN2008 – off-line RILIS ionsource to be built


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 97

..with fundamental & frequency doubling.

..with frequency tripling.

..with frequency quadrupling.

..successfully tested.

titanium:sapphire laser excitation scheme accessible …..

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

1H 2He


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




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


90Th 91Pa 92U 93Np 94Pu 95Am 96Cm 97

1H 2He


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




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


90Th 91Pa 92U 93Np 94Pu 95Am 96Cm 97

..with fundamental & frequency doubling.

..with frequency tripling.

..with frequency quadrupling.

..successfully tested.

titanium:sapphire laser excitation scheme accessible …..

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

Ti:Sapphire laser ion source

• New ionization schemes: Al, Ca, Fe, Ni, Cu, Fe, Ni, Cu, Ga, Zn, Zn, Ge, Y, Tc, Pd, Sn, Sn, Gd, Yb, Th, Pu

(on-line experiments)(on-line experiments)


Task 2 – New laser ionization schemes and new beams

Participants: GSI

A Selective and Efficient Ionization Scheme for Lithium


6360 6370 6380 6710 6720 67300

50

100

150

200

250

300

Cts

/ 22

0 s

Beat Frequency (MHz)

11Li

15-10-04-012 to 15-10-04-033

R. Sánchez et al., PRL 96, 033002 (2006)Nature Physics 2, 145 (2006)M. Puchalski et al., PRL 97, 133001 (2006)

R. Sánchez et al., PRL 96, 033002 (2006)Nature Physics 2, 145 (2006)M. Puchalski et al., PRL 97, 133001 (2006)

Measurement of the charge radius of the halo nucleus 11Li

F=2 → F=2

F=1 → F=1


Laser ionization of polonium at the ISOLDE-RILIS

Participants: K.U. Leuven, ISOLDE, IN2P3 IPO Orsay, U-Mainz

Development of 2new laser ionizationschemes for Po – first time forlaser ionization ofpolonium

First test to study thesaturation capability ofthe chosen schemes


Based on the extractedyields experiments havebeen proposed andperformed: IS452, in-source spectroscopyof Po.

The RILIS yields of n-deficient polonium isotopes are compared to the 20 year old yieldsobtained from the hot plasma source MK5. Note the U density in the target was 5 timesless in the earlier work.

Test in November 2006


Study of ground-state properties of n-def Po

Spectroscopy performedon the second transition

new down to 182Pb (T1/2 = 55 ms)

Odd-even staggering in Hg

H. De Witte et al., Phys. Rev. Lett. 98 (2007) 112502

• in-source laser spectroscopy: <r2>, Q, (down to 193)• decay spectroscopy• post-accelerated (isomeric beams) with REX-ISOLDE: Coulomb excitation, transfer reaction studies

K.U. Leuven, Mainz, ISOLDE,IPNO-Orsay


82 84 86 88 90 92 94 96 98 100 1020

4000

8000

12000

16000

160000

200000 Rubidium surface ions and 99Tc laser ions

Lasers "on"

Lasers "off"

Co

un

t ra

te (

ion

s/se

con

d)

Mass / amu

Selectivity ~56

430 nm

395 nm

842 nm

0 cm-1

23265 cm-1

48572 cm-1

7.28 eV60453 cm-1

1014 atoms of 99Tc (t½ = 2.1×105 years)on Re filament (Mainz)

3-step laser ionization schemeusing Nd:YAG pumpedTi:Sapphire lasers (JYFL)

Off-line laser ionization of Tc – towards N = Z studies

Participants: JYFL, Mainz, KU-Leuven

T. Kessler et al., Hyp. Int. 171 (2006) 121


Off-line laser ionization of Tc – 2 step at LISOL


Task 3 – Prototype LIST system

1. Atomic Beam Source with Surface Ion Repeller – Gas cell

3. Mass Separator 4. Laser System

Proton Beam

Ion Repeller

to Experiments

Laser- Beams

HV Platform

typicalISOL

Source

IonBeam

Ti:Sa 1

Ti:Sa 2

Ti:Sa 3

Nd:YAG

Laser System

Mass Separator

Gas filledRFQ Trap

2. Gas filled RFQ Trap Section for Bunching and Cooling

Production of isobarically pure ion beams with optimum spatial and temporal ion pulse control using a gas-filled RFQ structure

Participants: GSI, Mainz, JYFL, Manchester


Electron Repeller

Ion Repeller

Z

Release

10 mmEnd Plate

SIMION 7.0: simulation of the potential distribution

Laser Ions

Surface Ions

UDC

Atomizer

Electrons

Laser Beams Atoms Ions

SwitchableElectrodes

RFQ Segments

Accumulate

Buffer Gas

Laser Ionization inside the Trap Structure

Laser Ionization

The gas-filled linear RFQ trap


Integrated 65514 Ion-pulses

FWHM < 7 µs

0 25 50 75 100 125 150 175 200

0

2500

5000

7500

10000

12500

15000

17500

20000

Ion

s

Time / µs

Pulsing: 10 ms accumulation of 100 laser shots

in the trap, no gas, no cooling

Cooling:100 laser shots,

cooled and bunched,efficiency ~ 12 %

Ions from individual laser shots per 100 s

Stable Ga isotopes@ RISIKO, UMz

Pulsed and cooled beams from LIST

Maximum loading capacity 4×106 ions/cooling cycle


JYFL sextupole ion guide

0 5 10 15 20 25 30 350

1000

2000

3000

4000

5000

1134 /A s

141 /A s

SPIG (MRP~620) Skimmer (MRP ~250)

40S

c io

ns/

s

Primary beam current (A)

Light-ion induced fusion-evaporation

0 2 4 6 8 10 12 14 16 18 20 220

50000

100000

150000

200000

36561175 /As

182501944 /A s

SPIG (MRP 480)

Skimmer (MRP 300)

112 R

h y

ield

(io

ns/

s)

Primary beam intensity (A)

Proton-induced fission of uranium

First LIST ions seen in using bismuth and technetium, optimizing of gas jet (Laval nozzle)

I.D. Moore et al., Hyp. Int. 171 (2006) 135 P. Karvonen, I.D. Moore et al., to be submitted


Task 4 – Improve selectivity of RILIS: reduce surface ions

Participants: ISOLDE, U-Mainz

+

NeutralsSurface ionization

Laser ionization

Traditional tube materials: tungsten Ø = 4.5 eV tantalum Ø = 4.2 eV molybdenum Ø = 4.6 eVat T > 2000 °C

210 230 250 270 290 310 330 3501.0E-12

1.0E-11

1.0E-10

1.0E-9

1.0E-8

1.0E-7

1

10

100

1000

10000

RILIS W: 69Ga Laser & Surface Ions vs Line Current

ILaser Ga [A]

ISurf Ga [A]

ILaser / ISurf

Line Current [A]

Beam

[A] Selectivity10-

20x

Efficiency 10 %


600 700 800 900 1000 1100 1200 13001E-15

1E-14

1E-13

1E-12

1E-11

1E-10

0.000000001

0.00000001

0.0000001

0.000001

1

10

100

1000

10000

100000

1000000

10000000

BrOSrO - Selectivity Ilaser

Isurf

ILaser / ISurf

T [C]

Beam

Curr

ent

[A]

Sele

ctiv

ity!

Other materials

T 1200 °C, Eff = 10%, Selectivity > 1000, Emittance 1 π mm mrad

GdB6 Ø = 1.5 eV, BaOSrO Ø < 1.4 eV


Task 5 – Implementation of electrical fields in gas cells

Participants: JYFL, Manchester, K.U. Leuven, U-Mainz, IPN Orsay

A new ion guide has been modelled and tested for the production of alow energy ion beam of daughter products from alpha-emitting isotopes.

Work is about to start on a design with an rf carpet, combined with DC fields at JYFL.

K.U. Leuven have tested a new gas cell where the laser ionization zone isshielded from the primary beam and stopping region.

B. Tordoff et al., NIM B 252 (2006) 347


363.3nm pumping

40% transfer

1 pA of 89Y continuous beam

Task 6 – Feasibility study to polarize nuclei with lasers

Optical manipulation in the RFQ cooler (JYFL, Manchester)

P. Campbell, Hyp. Int. 171 (2006) 143


98Y

97Y 89Y

96Y16.7 mins

98Y

5.17 hrs

Natural metastable population Effect of optical pumping from the ground state

Several cases of interest:

NiobiumPlatinumOsmiumRheniumIridiumTungsten etc

On-line success with neutron-rich yttrium


LASER summary

Almost all milestones are on track to be completed, some (task 6)have evolved far beyond what was originally expected.

Associate partners have been participating in workshops and in sharinginformation throughout the laser community (ORNL Oak Ridge, TRIUMFCanada, Gatchina Russia).

Workshops organised: 2005 (Leuven), 2006 (Poznan – as part ofApplication of Lasers in Atomic Nuclei Research conference), 2007(Saariselka, joint workshop with LASER-TRAPSPEC)

In most of the tasks, several facilities participated in developments andexperiments, sending students to gain experience.

Radioactive Ion Beam facility

• selectivity, efficiency, time structure• isomeric beams • management of the radioactive inventory


68Cu 6- (+1+)

6-

1+

68m,gCu (2.86 MeV/u, 3 105 pps, 74% pure) @ 120Sn (2.3 mg/cm2)

120Sn2+-0+

Energy (keV)

68Cu 1+

85 T1/2=7.84 ns1+

(2+)

(3+) 6-

4-

(3-)

610722

(5-)

0

956

778 0.7 <T1/2< 4 ns

178

693

85

3.7 min

30 s

6-

1+

3.7 min

30 s

722

0

Post-accelerated isomeric Cu beams @ ISOLDE

ISOLDEIPN-OrsayK.U. Leuven

laser, joint eurons-eurisol town meeting, helsinki, sept. 17, 2007 laser techniques for exotic...

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