Opening page

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Opening page
Radioactive Ion Beams where are we now
experimentally? M. Huyse K.U. Leuven Moriond,
March 2003
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The exploration of the chart of nuclei
284 isotopes with T1/2 gt 109 year Our beams till
1989 !
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The exploration of the chart of nuclei
lt1940 495
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The exploration of the chart of nuclei
Reactors n on U
lt1940 1940 495 822
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The exploration of the chart of nuclei
First Isotope Separator On-Line (ISOL)
experiment Niels Bohr Institute 1951 fast n on U
Kr and Rb isotopes
lt1940 1940 1950 495 822 1244
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The exploration of the chart of nuclei
Selective detection method ? decay
lt1940 1940 1950 1960 495 822 1244
1515
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The exploration of the chart of nuclei
Light-ion induced spallation Heavy-ion induced
fusion
lt1940 1940 1950 1960 1970 495
822 1244 1515 2010
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The exploration of the chart of nuclei
Projectile and target fragmentation In-flight
separation
lt1940 1940 1950 1960 1970 1980 495
822 1244 1515 2010 2270
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The present chart of nuclei

• -Explaining complex nuclei from basic
  constituents
• -The size of the nucleus halos and skins
• -Isospin dependence of the nuclear force
• Measuring and predicting the limits of nuclear
  existence
• Doubly-magic nuclei and shell structure far from
  stability
• The end of Mendeleevs table superheavies
• Understanding the origin of elements
• Testing the Standard Model
• Applications in materials and life sciences

Around 3000 of the expected 6000 nuclei have been
observed
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IF versus ISOL
In Flight (IF)
Isotope Separator On Line (ISOL)
driver accelerator or reactor

• heavy ions
• fusion
• fragmentation

• light and heavy ions, n, e
• -spallation
• -fission
• fusion
• fragmentation

thin target
high-temperature thick target
ion source
fragment separator
mass separator
GeV eventually slowed down ms

• experiment
• detectors
• spectrometers
• ...

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First generation Radioactive Beam Projects in
Europe
CRC, Louvain-la-Neuve, Belgium delivering ISOL
beams since 1989
GSI, Darmstadt, Germany delivering IF beams since
1990
SPIRAL, Caen, France delivering IF beams since
1984 delivering ISOL beams since 2001
MAFF, Munich, Germany under construction
REX-ISOLDE, Geneva, Switzerland delivering ISOL
beams since 2001
SPES, Legnaro, Italy project
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First generation Radioactive Beam Projects
 
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Louvain-la-Neuve focus on nuclear astrophysics
CYCLONE 110
30 MeV p 13C gt 13N n 13N p gt 14O
? Hot CNO cycle
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Louvain-la-Neuve nuclear physics
6He 238U fusion-fission
6He 4He elastic scattering
J. L. Sida et al. PRL84 (2000) 2342
R. Raabe et al. PLB458 (1999) 1
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First results from SPIRAL and REX-ISOLDE
REX-ISOLDE - CERN MINIBALL array
SPIRAL - GANIL EXOGAM array
Coulomb excitation of 76Kr (T1/214.6 h)
Neutron pick-up of 30Mg (T1/20.3 s)
76Kr 208Pb 500.000 atoms/sec 2.6 - 4.4 MeV/u
30Mg 2H ? 31Mg 1H 10.000 atoms/sec 2.23
MeV/u
31Mg
16N (from beam contamination)
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Mass measurements
rp-process
Super-allowed Fermi b-decay 74Rb (T1/265 ms)
dm 4.5 keV (dm/m 6 10-8)
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The new generation of Radioactive Beam Facilities

• Experimental aim of the second generation
  facilities
• ? figure of merit for the study of exotic nuclei
  x gt 1000
• Technological challenge
• increase the global selectivity and sensitivity
• increase the secondary beam intensity

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Intensity and Selectivity
Intensity
100Sn 8 at/s
78Ni 70 at/s
Selectivity
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Figures of Merit (in first approximation)
Isecondary sproduction Ntarget Ibeam x
erelease transport x eionization x etransport
- storage - post-acceleration
Intensity
Intensity
Icounts(reaction) Isecondary hbranching
sreaction Nsecondary target x espectrometer x
edetector Icounts(decay) Isecondary
hbranching x edetector
Event rate
Sensitivity
Selectivity
Isecondary/Itotal
Purity
Rresolving power (suppression of background,
identification of events)
Peak to background
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An example Coulomb excitation of 78Ni at an ISOL
system
78Ni _at_ 3-5 MeV/u Ex(2-0) 4 MeV B(E2)500
e2fm4 s(Coulex) ? 100 mb Nsecondatytarget (58Ni)
3mg/cm2 Ntarget (238U, s 100 pbarn) 100 g/cm2
needs pure conditions
modest intensity!
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78Ni produced at an ISOL system rates
beam purity?
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78Ni produced at an IF system rates

• (1) based on the first identification of 78Ni
• C. Engelmann et al., Z. Phys. A352 (1995) 351
• I(238U) 2 107 at/s
• ein-flight separator 1.6
• I(78Ni) 0.5 at/day
• (2) GSI Conceptual Design Report
• (3) RIA I(238U) 2 1013 at/s _at_ 400 MeV/u
  I(78Ni) 70 at/s

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Stopping of fragments in a gas cell (I)
Heavy-Ion Beam

• range bunching
• stopping of reaction products in buffer gas
• electrical fields (AC and DC)
• remove electrons (neutralization)
• drag ions towards exit hole

High-power target
Range bunching
Gas catcher
Low energy beam
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Stopping of fragments in a gas cell (II)

• what is the intensity limit?

heavy-ion ion guide
M. Huyse,- Nucl. Instr. Meth. B
Fragmentation G. Savard ,- _at_ ANL and GSI G.
Bollen ,- _at_ MSU M. Wada ,- _at_ RIKEN
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RIA
fission ion guide
2
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Shiptrap
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He (1 atm)
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RADRIS

• laser ionization after the plasma has decayed
• increased selectivity!

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Laser Ion Source
Laser ion source at ISOLDE

• efficiency up to 10
• selectivity depending on the implementation
• applicable for many elements (universal)

surface ions
photo ions


laser



high-temperature cavity
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The problem of selectivity an example from ISOL

• b-decay of 78Cu at ISOLDE

• p(1 GeV) Ta-rod ? neutron
• neutron 238U ? 78Cu
• ? no deep spallation

?104
srelative
?102
N50
laser ionization of Cu
Z28
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The decay of 78Cu

• laser ionization of Cu isotopes
• b-gated gamma decay spectrum

Production rates
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Production of isomeric beams 70Cum1,m2,g

• laser ionization in a hot cavity
• different hyperfine splitting for the different
  isomers
• enhancement of specific isomers

V. Fedoseev, U. Koster, J. Van Roosbroeck et al.,
ISOLDE

• increase selectivity of laser ion sources
• reduce power, pressure and Doppler broadening

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Outlook

• high-power accelerators

• high-power targets
• geometrical optimization
• radiation safety

production

• laser ionization (selectivity, isomeric beams)
• release optimization, chemistry
• gas cell (space-charge limit, laser
  re-ionization)
• charge-state breeding vs. 1 acceleration

ionization

• RF-coolers, traps
• (intensity limit, high-resolution mass separator)

purification
acceleration / deceleration / storage

• g-identification
• fast tracking of particles

• measurement
• identification
• reaction / decay / g.s. properties
• ...