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Radioactive beam research notches up 50 years
Author Karsten Riisager
2001
Otto Kofoed-Hansen and Karl Ove Nielsen were the
authors of NBI's first experiment (using ISOL
technique). Their basic intent was to measure the
recoil momentum resulting from the emission of a
neutrino in beta decay. The best way to do this
is with noble gas atoms, so Kofoed-Hansen and
Nielsen set out to collect neutron-rich krypton
isotopes produced in the fission of uranium.
The annual group photo for the Copenhagen
theoretical physics institute
www.cerncourier.com/main/article/42/4/18/1
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RNB with medium energy beams
Antonio C.C. Villari GANIL
ISOL introduction and two examples 18Ne and 6He
This exercise is done for the selected cases and
for low-intermediate energies
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ISOL Production technique
N ?.Ni.Nt.?
C . ? . I . R . ?
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Production issues in ISOL
N ?.Ni.Nt.? C . ? . I . R . ?
Disadvantage of lower energies R Advantages of
lower energies ? and (?)
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Projectile fragmentation
? . I . R . ?
Cross sections Production of 18Ne via 20Ne C
at 100A MeV 2.3 mb Production of 18Ne via
p24Mg at 1 GeV 0.7 mb
You can increase the production by 60 in using
MgO target
Ntarget 1.2 109 for 1pµA beam
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Primary beam
? . I . R . ?
Imax today (20Ne) 100 pµA
Ntarget 1.2 1011 (18Ne)
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Size of the target
? . I . R . ?
Total beam power 200kW
20Ne
18Ne
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Primary beam
? . I . R . ?
Yield as a function of energy In 1st
approach equal for any case.
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SPIRAL example
? . I . R . ?
Diffusion target for 6kW of primary beam power
J. Obert
The total size is not optimised, in this
case, for 20Ne beam For 24kW, the total
radiating surface should be multiplied by 4 f
12 cm
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Projectile fragmentation
? . I . R . ?
Cross section Production of 6He via 7Li C at
100A MeV 8.0 mb Yield for 1pµA of 7Li 1.7
1010
Present intensity for 7Li 300pµA Therefore,
possible yield 5 1012 pps with 7Li 100A MeV
and 8 1012 pps with 7Li target
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Size of the target
? . I . R . ?
Total beam power 210kW
7Li
100
Total decoupling of production and diffusion
6He
( 10000)
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(No Transcript)
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Diffusion properties
? . I . R . ?
Measured at SIRa
6He on POCO graphite (1µ)
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Diffusion properties
? . I . R . ?
For 18Ne 80
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Effusion efficiency
? . I . R . ?
Extremely dependent on the geometry. The smaller
target the better efficiency. For 1s lifetime
(1.7s and 0.8s) 100 should be achievable.
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Ionisation efficiency
? . I . R . ?
Permanent magnets, 10 GHz
Running Online He(1)60 Ne(1)60 Ne(5)14
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Overall efficiency...
? . I . R . ?
Diff. Eff. Ion C.B.
6He 100 100 60 P.S.
18Ne 80 100 60 P.S.
The efficiency up to the C.B. can be of the order
of 50
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Final yields
? . I . R . ?
Conservative version
On target
In C.B.
20Ne 100A MeV 18Ne 1 1011 5 1010
7Li 100A MeV 6He 5 1012 2.5 1012
This is supposing a 300MV HI driver
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Lower energies - I
The reaction 9Be(n,a)6He is being discussed in
this session.
M.G. Saint-Laurent
Production of neutrons using SPIRAL2
approach 5mA Deuterons 40MeV on C X 3 1016
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Lower energies - I
In order to produce 1 1013 in target, the
thickness of Be corresponds to 100g/cm2 (55 cm).
NO ATTENUATION Conclusion 2 D 40MeV 5mA on C
Be (55cm) 1 1013 pps of 6He
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Conclusions
Very high efficiencies of light ions
(particularly noble gases) can be achieved in
ISOL. The requested yields of 6He and 18Ne
requested for ß-beams seem feasible using
standard solutions with projectile
fragmentation. Solutions using very low beam
energies (with high beam currents) look
promising and should be better investigated.