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Radioactive Ion Beams: where are we now experimentally? M. Huyse K.U. Leuven Moriond, March 2003. Opening page. The exploration of the chart of nuclei. 284 isotopes with T 1/2 > 10 9 year Our beams till 1989 !. The exploration of the chart of nuclei. <1940 495.

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the exploration of the chart of nuclei
The exploration of the chart of nuclei

284 isotopes with T1/2 > 109 year

Our beams till 1989 !

the exploration of the chart of nuclei2
The exploration of the chart of nuclei

Reactors: n on U

<1940 1940

495 822

the exploration of the chart of nuclei3
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

<1940 1940 1950

495 822 1244

the exploration of the chart of nuclei4
The exploration of the chart of nuclei

Selective detection method:  decay

<1940 1940 1950 1960

495 822 1244 1515

the exploration of the chart of nuclei5
The exploration of the chart of nuclei

Light-ion induced spallation

Heavy-ion induced fusion

<1940 1940 1950 1960 1970

495 822 1244 1515 2010

the exploration of the chart of nuclei6
The exploration of the chart of nuclei

Projectile and target fragmentation

+

In-flight separation

<1940 1940 1950 1960 1970 1980

495 822 1244 1515 2010 2270

the present chart of nuclei
The present chart of nuclei
  • stable

+ decay

  • - decay

 decay

p decay

spontaneous fission

  • -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 Mendeleev’s 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

if versus isol

In Flight (IF)

Isotope Separator On Line (ISOL)

gas cell

~ ms

storage ring

post accelerator

meV to 100 MeV/u

ms to several s

good beam quality

driver accelerator

or

reactor

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

thin target

high-temperature thick target

ion source

fragment separator

mass separator

GeV

eventually slowed down

ms

  • experiment
  • detectors
  • spectrometers
  • ...
first generation radioactive beam projects in europe
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

first generation radioactive beam projects

Location

Start

Driver

Post-accelerator

Upgrade

planned

CRC, Louvain-la-Neuve, Belgium

1989

cyclotron

p, 30 MeV, 200A

cyclotrons

K = 44 and 110

SPIRAL, GANIL, Caen, France

2001

2 cyclotrons

heavy ions up to 95 MeV/u

6 kW

cyclotron

K = 265

2 - 25 MeV/u

new driver

REX-ISOLDE, CERN, Geneva, Switzerland

2001

PS booster

p, 1.4 GeV, 2 A

linac

0.8 - 2.2 MeV/u

energy upgrade

4.3 MeV/u

HRIBF, Oak Ridge, USA

1998

cyclotron

p, d, , 50 -100 MeV

10 - 20 A

25 MV tandem

ISAC, TRIUMF, Vancoucer, Canada

2000

synchrotron

p, 500 MeV, 100 A

linac

1.5 MeV/u

energy upgrade

6.5 MeV/u

First generation Radioactive Beam Projects
louvain la neuve focus on nuclear astrophysics
Louvain-la-Neuve: focus on nuclear astrophysics

CYCLONE 110

30 MeV p + 13C => 13N + n

13N + p => 14O + 

Hot CNO cycle

louvain la neuve nuclear physics
Louvain-la-Neuve: nuclear physics
  • ds/dW (mb/sr)
  • 4He(6He,6He)4He
  • Ec.m. = 11.6 MeV

6He + 238U

4He + 238U

6Li + 238U

4He + 238U

  • qc.m.

6He + 238U fusion-fission

6He + 4He elastic scattering

J. L. Sida et al. PRL84 (2000) 2342

R. Raabe et al. PLB458 (1999) 1

first results from spiral and rex isolde
First results from SPIRAL and REX-ISOLDE

E (keV)

SPIRAL - GANIL + EXOGAM array

REX-ISOLDE - CERN + MINIBALL array

Coulomb excitation of 76Kr (T1/2=14.6 h)

Neutron pick-up of 30Mg (T1/2=0.3 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)

mass measurements
Mass measurements

rp-process

Super-allowed Fermi b-decay

74Rb (T1/2=65 ms)

dm = 4.5 keV (dm/m = 6 10-8)

the new generation of radioactive beam facilities

EURISOL

European Separator On-Line

Radioactive Nuclear Beam Facility

Rare Isotope Accelerator: RIA

GSI

RI-Beam factory: RIKEN

The new generation of Radioactive Beam Facilities
  • Experimental aim of the second generation facilities
    •  figure of merit for the study of exotic nuclei x > 1000
  • Technological challenge
    • increase the global selectivity and sensitivity
    • increase the secondary beam intensity
intensity and selectivity
Intensity and Selectivity

RIA expected yields

77

76

79

80

78Ni

A=78

RIA expected yields

Intensity

100Sn: 8 at/s

78Ni: 70 at/s

Selectivity

figures of merit in first approximation
Figures of Merit (in first approximation)

Isecondary = sproductionNtarget Ibeam

x erelease – transport

x eionization

x etransport - storage - post-acceleration

Intensity

Intensity

Icounts(reaction) = Isecondary hbranchingsreaction Nsecondary target

x espectrometer

x edetector

Icounts(decay) = Isecondary hbranching

x edetector

Sensitivity

Event rate

Selectivity

Isecondary/Itotal

Purity

Rresolving power

(suppression of background, identification of events)

Peak to background

an example coulomb excitation of 78 ni at an isol system
An example: Coulomb excitation of 78Ni at an ISOL system

78Ni @ 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!

78 ni produced at an if system rates
78Ni produced at an IF system: rates

! ! !

Nsec. target

(IF) = 100 x (ISOL)

but

Low energy background

and

Doppler correction

  • (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 @ 400 MeV/u I(78Ni) = 70 at/s
stopping of fragments in a gas cell i

100 cm

Delay

(ms)

1000

100

10

1

0.1

30 cm

0.5 – 1 bar

Argon

Helium

G. Savard @ ANL

0.01 0.1 1 10 E/N

(10-17 V . cm2)

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

stopping of fragments in a gas cell ii

laser

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 ,- @ ANL and GSI

G. Bollen ,- @ MSU

M. Wada ,- @ RIKEN

1

RIA

fission ion guide

2

5

Shiptrap

4

He (1 atm)

3

RADRIS

  • laser ionization after the plasma has decayed
    • increased selectivity!
laser ion source
Laser Ion Source

Energy (eV)

4

0

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

the problem of selectivity an example from isol
The problem of selectivity: an example from ISOL

78Se

(8+)

(6+)

908 keV

(4+)

78Cu

0.34 s

78Ni

0.2 s

78Ge

88 m

78As

1.5 h

78Zn

1.5 s

78Ga

5.5 s

890 keV

(2+)

1

730 keV

0+

78Zn

J.M. Daugas et al.

Phys. Lett. B476 (2000) 213

  • b-decay of 78Cu at ISOLDE
  • p(1 GeV) + Ta-rod  neutron
  • neutron + 238U 78Cu
  •  no deep spallation

104

srelative

102

N=50

laser ionization of Cu

Z=28

the decay of 78 cu
The decay of 78Cu

730 keV

890 keV

(8+)

laser on

(6+)

105

104

103

78Ga

78Cu

908 keV

(4+)

890 keV

laser off

(2+)

700 800 900

730 keV

Energy (keV)

0+

78Zn

J.M. Daugas et al.

Phys. Lett. B476 (2000) 213

600 700 800 900 1000

Energy (keV)

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

Production rates:

production of isomeric beams 70 cu m1 m2 g
Production of isomeric beams: 70Cum1,m2,g

(keV)

(1+)

6.6(2) s

b

200

(3-)

33(2) s

100

44.5(2) s

(6-)

0

70Cu41

29

  • 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
outlook
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
  • ...