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International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
Latest developments at the IGISOL laser ion source
Latest developments at the IGISOL laser ion source
Iain MooreUniversity of Jyväskylä
Iain MooreUniversity of Jyväskylä
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
Mass & decay spectroscopy
Collinear laser spectroscopy
Ion guide & SPIG (see T. Sonoda talk)
RFQ cooler & buncher – optical manipulation (see B. Cheal talk)
FURIOS laser cabin
The IGISOL Beamline at JYFLThe IGISOL Beamline at JYFL
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
Why do we need to develop a laser ion source?Why do we need to develop a laser ion source?
The IGISOL is both FAST and UNIVERSAL. However there aredeficiencies in this technique that arise when working far from stability:
UNSELECTIVE
Combining the laser ion sourcewith the light ion bombardment ofheavy actinide targets (fission)will help to reduce the overwhelmingisobaric background.
The laser ion source (trap) LISTtechnique will be used for thispurpose (T. Sonoda talk).
INEFFICIENT
In some cases the IGISOL isnot so efficient. In fission, acombination of ~1% stoppingand severe recombination ofions due to the intense plasmareduces the efficiency (few ×10-4).
In addition, the laser ion sourcewill be combined with the heavy-ion induced fusion evaporation(HIGISOL) work to improve theefficiency (~0.5%).
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006100 ms lifetime line
JYFLTRAP +Fission ion guide
JYFLTRAP +HIGISOL (new ion guide)
80Y t½ = 33.8 sc precision trap 900ms exc. time
101Y t½ = 448 ms
Switchyard pulsing100 ms, 1-2 ions/bunch
c precision trap 400ms exc. time
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
Principles of resonance laser ionization for exotic nucleiPrinciples of resonance laser ionization for exotic nuclei
target
cyclotron beam
laser
gas cell
RF-ion guide
to mass separator
Ar - He
• gas cellLISOL- Louvain-la-NeuveMainz (trans-U spectroscopy)
Y. Kudryavtsev,- NIM B179 (2001) 412M. Facina,- NIM B226 (2004) 401 M. Sewtz,- PRL 90 (2003) 163002
• Efficient (> 10 %)• Fast (element dependent)• Selective: 100-1000 (laser >> 106)• Universal
λ2
λ1
λ2
λa.i.
λ1
~
P.V. Duppen, ENAM 2004 talk
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
Ti:Sapphire lasers
Nd:YAG100W, 11 kHz
Pulsed dye lasers
Copper vapour laser 45W, 10kHz
cw dye laser
cw pump laser
Isotope separatorIon guide
Fast Universal Resonant laser IOn Source, FURIOSFast Universal Resonant laser IOn Source, FURIOS
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
First laser ionization study - yttriumFirst laser ionization study - yttrium
Off-line studies in an atomic beam unit.
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
Typical AI state resonance
Typical bound state resonance
Three sharp resonances found from 2 different atomiclevels but at exactly the same wavelength! Thesecorrespond to the dye laser driving second steptransitions.
The chosen scheme for the ion guide worktherefore involves both Ti:Sapphire and dye lasersecond step transitions – more efficient than using thediscovered AI states.
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
A laser ion guide for heavy-ion fusion evaporation reactionsA laser ion guide for heavy-ion fusion evaporation reactions
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
First on-line HIGISOL run November 2005First on-line HIGISOL run November 2005
natNi target - 3.7mg/cm2, Y target – 3.5mg/cm2, 165 MeV 32S7+ beam (35 enA)
He pressure 40 mbar. Ions detected on MCP plates.
Y filament, 6.4mg/cm2, 2.8 mm at thinnest point
Cyclotron 3s on 3s off, 10 cycles Y
Laser on Laser off
Co
un
ts p
er
bin
an
d c
yc
le
Time (ms)
0.54
0.25
0.12
Beam ionization
Yttrium filament
Y+
Laser
Exit hole
Y+ + e- Y
Laser
Y + O2 YO +O
Y+ + O2 YO+ + O
Beam
Y+ + O
Beam
Y+ + e- Y
LaserYO+ + e- YO
UNWANTED CONTAMINANTS!
Y+
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
Impurities – yttrium reacting with oxygenImpurities – yttrium reacting with oxygen
exit = 1.0mm, tevac of whole chamber ~600ms, tevac of neutralization channel ~250s
dn/dt = -kn[M] where [M] is impurity concentration, k = 4.1×10-10 cm3/s for this reaction
= 1/k[M], for 40 mbar He τ ~2.2ms, for 200 mbar He τ ~460s.
250s
2.2ms
250s
460s
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
0 2000 4000
0.0
1.5
3.0
4.5
Cyclotron 1s on 5s off 20 cycles, laser on 2-3 sC
ou
nts
pe
r b
in a
nd
cy
cle
Time (ms)
YO+4.5
0.06
0 1000 2000 3000 40000.0
0.2
0.4
0.6
0.8
Cyclotron 1s on 5s off 20 cycles Y
Laser on 2-3 s Laser on 0.25-1 s
Co
un
ts p
er
bin
an
d c
yc
le
Time (ms)
0.63
0.3
0.07
Without the plasma the ratio of Y+ to Y0+ is equal.
Evacuation times of small channel simulated to be ~10µs,hence yttrium can survive without reacting with impurities.
Y+
With plasma, no laser effectseen on YO+
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
0 500 1000 1500 2000 2500 3000 3500 4000 45000,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
1,6
Co
un
ts p
er b
in
Time (ms)
Elastic scattering/sputtering from target with 32S7+ beamElastic scattering/sputtering from target with 32S7+ beam
Fitted decay time ~450 ms
Simulation of flow of created sputtered ions
0 1 2 3 4 50
5
10
15
20
25
30
Co
un
ts /
0.0
5s
Time (s)
Simulated decay time ~650 ms
From elastic scattering ~0.5% recoils stopped in 40mbar He.Sputtering process yields ~0.1%, yet these recoils are stoppedonly 1mm from the target, therefore the extraction time is longand most are lost to the walls through diffusion.
NO LASER EFFECT SEEN
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
Immediate future (on-line and off-line)Immediate future (on-line and off-line)
1. Later this week we have an on-line run to compare the Leuven laser ion guide withthe HIGISOL laser ion guide. Yttrium filament, combined with yttrium froman α beam impinging on an yttrium target.(Collaboration with Leuven/Mainz – Yuri/Klaus to attend)
2. Later in the summer we will combine the new MIVOC technique used by the cyclotron to produce an yttrium beam which will be used to make a direct efficiency measurement. The immediate goal is to improve the present HIGISOL efficiency of ~0.5% - then we can reach exotic nuclei such as the N=Z nucleus 78Y.
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
3. A new off-line rig enables continuous development work to be done. This rig allows us to simulate the IGISOL conditions yet is far cleaner. At present a new cold baffle is being installed between the roots pump and the gas cell. In addition a QMA system will allow us to study impurities AFTER the gas has flowed through the ion guide – and how the filament produced yttrium laser ion current is affected.
4. A comparison is to be made between a 50 Hz repetition rate Nd:YAG pumped dye laser system and that of a 11 kHz CVL pumped system. Bismuth is the element of choice, with a two step dye laser scheme to a known autoionizing state. The laser ion current will be measured under identical conditions to see if there is anything more fundamental happening than the expected yield increase with a higher repetition rate laser system.
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
Thanks to the following people involved in the laserion source project:
T. Kessler, K. Peräjärvi, T. Sonoda, B. Tordoff,P. Karvonen, S. Rinta-Antila, P. Ronkanen and J. Äystö
and to: The IGISOL group, Manchester Universityand the University of Mainz
Financial support:
Centre of Excellence Programme / Academy of Finland,Marie Curie Foundation (EC), NIPNET RTD project.
THANKS FOR YOUR ATTENTION!
International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006International Workshop on Stopping and Manipulation of Ions, Groningen, 28 March 2006
Second on-line HIGISOL run December 2006Second on-line HIGISOL run December 2006
Beta gated gamma spectrum natNi(32S7+, 5p3n )82Y32S7+ 165 MeV40 enA on target
With 300 mbar He, 82Y yield = 1.8 ions/s/pnA
M. Oinonen et al.,NIMA 416 (1998) 48582Y yield ~2 ions/s/pnA
3rd HIGISOL run (December)Mass measurements made on:85-88Nb, 79-83Y and 83-88Zrusing the new ion guide withan efficiency ~0.5%.
Beta efficiency ~57%Gamma eff. ~1.9%
NO LASER EFFECT SEEN