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Isotope Separator On-Line: In-Flight Separator:. ISOL. IF. Experimental achievements and outlook (only a few examples to illustrate the achievements and to paint the “road map” for the future). Extreme proton-to-neutron ratios Isospin as a degree of freedom (along N=Z)

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Experimental achievements and outlook (only a few examples to illustrate the achievements

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Experimental achievements and outlook only a few examples to illustrate the achievements

  • Isotope Separator On-Line:

  • In-Flight Separator:

ISOL

IF

Experimental achievements and outlook

(only a few examples to illustrate the achievements

and to paint the “road map” for the future)

  • Extreme proton-to-neutron ratios

  • Isospin as a degree of freedom (along N=Z)

  • The heaviest nuclei

  • High-spins and exotic excitations

  • Giant resonances in cold- and hot nuclei

  • Developments in instrumentation and facilities


Experimental achievements and outlook only a few examples to illustrate the achievements

dC uncertainty budget

dR = 0.5%

ISOL

Q

T1/2

R

dR

<Ft>

Extreme proton-to-neutron ratios: masses

rp-process

F. Hertfurth, ISOLTRAP,

Hirschegg 2002

Super-allowed Fermi b-decay

74Rb (T1/2=65 ms)

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

ISOLDE


Experimental achievements and outlook only a few examples to illustrate the achievements

IF

Ch. Scheidenberger, GSI, Hirschegg 2002

238U fission

  • also at Mistral, SPEG (GANIL),...

  • mapping the mass surface

  • high-precision mass measurements on short-lived isotopes

  • nuclear structure, astrophysical scenarios, fundamental interactions

  • g.s. and i.s. properties (cfr. laser spectroscopy, e--RIB intersecting storage rings)


Experimental achievements and outlook only a few examples to illustrate the achievements

3.0

2.0

E (MeV)

1.0

?

oblate

prolate

0.0

186Pb

ISOL

IF

Extreme proton-to-neutron ratios: shapes, symmetries and low-lying excitations

N = 126

N = 104 (midshell)

188Po

189Po

191Po

Z = 82

decay and in-beam studies

spherical

Triple shape coexistence

at low excitation energy

Hartree-Fock + BCS (Skyrme SLy6 interaction + density dependent zero-range pairing force) (M. Bender, P.H. Heenen)


Experimental achievements and outlook only a few examples to illustrate the achievements

190Po

190Bi

191gBi

104

a

g - RP - a

103

191Bi

188Bi

Ea190Po decay

DT(RP - a) < 10ms

190Po

191Po

188Bi

102

192Po

Counts

10

6200 6400 6600 6800 7000 7200 7400 7600

IF

Energy / keV

Extreme proton-to-neutron ratios: shapes, symmetries and low-lying excitations

Recoil Decay Tagging (RDT)

RITU - JYFL

Recoil

Q

D

Q

beam

Decay

Q

target

g-detectors

PSSD

Tagging

52Cr (255 MeV) + 142Nd 190Po + 4n

s 160 nbarn !!

190Po


Experimental achievements and outlook only a few examples to illustrate the achievements

REX-ISOLDE - CERN + MINIBALL array

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

30Mg + 2H 31Mg + 1H

10.000 atoms/sec

2.23 MeV/u

31Mg

16N (from beam contamination)

ISOL

E (keV)

Extreme proton-to-neutron ratios: shapes, symmetries and low-lying excitations

First results from SPIRAL and REX-ISOLDE

SPIRAL - GANIL + EXOGAM array

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

76Kr + 48Ti

500.000 atoms/sec

2.6 - 4.4 MeV/u

  • decay- and RTD studies of exotic nuclei

  • Coulomb excitation and one- or two particle transfer reactions with energetic radioactive beams (e.g. around 132Sn and 100Sn - 78Ni, light Pb nuclei)


Experimental achievements and outlook only a few examples to illustrate the achievements

ISOL

IF

Extreme proton-to-neutron ratios: unbound systems and the lightest nuclei

Position of the neutron drip line:

one extra proton added to the closed Z=8 shell binds 6 extra neutrons!

one-proton halo

8

  • complete kinematics: 6He, 11Li

  • p-elastic scattering @ relativistic energies

  • ...

  • in-beam gamma spectroscopy

20

31F

24O

Z

2

one-neutron halo

8

2

N

two-neutron halo

four-neutron halo

N=8

N=2

Z=2

3He

4He

5He

6He

7He

8He

9He

10He

3H

2H

1H

1n


Experimental achievements and outlook only a few examples to illustrate the achievements

IF

Extreme proton-to-neutron ratios: unbound systems and the lightest nuclei

In-beam gamma-ray spectroscopy

Sn=3.34(23) MeV

wedge

24F, 25,26Ne, 27,28Na, 29,30Mg

2+-0+

Counts

thick target

20C

SISSI target

36S

SPEG spectrometer

Gamma-ray detectors

E(keV)

  • high intensity beam (36S at 77.5 MeV/A, I  500pnA)

  • thick target 216 mg/cm2 of C and H

  • low counting rate in gamma-ray detectors

7000

C

6000

O

5000

Energy 2+ (keV)

4000

24O

3000

2000

20C

M. Lewitowicz Hirschegg 2002

1000

4

6

8

10

12

14

16

18

closed shell

N


Experimental achievements and outlook only a few examples to illustrate the achievements

Q2p =1.14 MeV

T1/2 =3.8 ms

IF

Extreme proton-to-neutron ratios: unbound systems and the lightest nuclei

Two-proton decay of 45Fe

22 events

  • study of neutron skin nuclei, halo nuclei

  • confirmation of two-proton decay, correlations, map the proton drip line

  • clustering phenomena in unstable nuclei

  • increased intensity and beam purity of the second generation facilities is needed

GANIL

GSI


Experimental achievements and outlook only a few examples to illustrate the achievements

Isospin as a degree of freedom

  • isospin symmetry and mirror pairs (extended to heavier masses along the N=Z line):

  • changes in collectivity: strong overlap between p- and n-wave function along the N=Z line

  • proton-neutron pairing: T=1 versus T=0

LNL - Legnaro

Gammashpere

  • direct reactions with RIB

  • high-intensity stable beams and instrumentation (cfr. AGATA)

quenching of p-n pairing field in neighboring NZ nuclei?


Experimental achievements and outlook only a few examples to illustrate the achievements

IF

The heaviest elements

1996

  • confirmation element Z=112 (GSI)

  • chemistry Hs (Z=108) (GSI)

  • new results from Dubna tentatively assigned to Z=114, 116, 118

  • gamma- and electron spectroscopy around 245No (e.g. RITU-JYFL)

2000

2001

  • n-rich RIB on n-rich targets: reach region where decay chain from Z=114, 116,... ends

  • exploration of the structure of the trans-uranium nuclei

  • high intensity stable beams, new spectrometers and detectors

electron spectrum from 245No (Z=102)


Experimental achievements and outlook only a few examples to illustrate the achievements

143Eu

143Eu

SD

ND

SD

ND

The highest spin and exotic excitations

  • Euroball (Legnaro and Strasbourg) Gammasphere

    • giant dipole resonances on super deformed states

    • “wobbling mode”: breaking of axial symmetry

    • magnetic rotation

    • spontaneous chiral symmetry breaking

  • Rising at GSI

  • search for hyperdeformed states

  • need for intense stable beams

  • gamma-ray tracking (cfr. AGATA)


Experimental achievements and outlook only a few examples to illustrate the achievements

IF

Giant resonances in cold- and hot nuclei

  • Strength, centroid energy and width: governed by macroscopic nuclear properties (isoscalar - isovector modes)

  • Microscopically: coherent 1p-1h excitations / properties depend on the isoscalar and isospin dependence of the effective n-n interaction

16O

real photons

  • Neutron-skin thickness can be deduced from Giant resonances (so far stable isotopes only)

  • Large proton-neutron asymmetry (exotic nuclei) can lead to “soft” collective resonances

20O

virtual photons from 500-600 MeV/u 20,22O on Pb

22O

  • Photo-neutron cross sections for 16, 20, 22O

    • s(g,xn) strongly fragmented/extended to low energy

    • impact on astrophysical scenarios

GSI

  • study the bulk properties of p-n asymmetry in nuclear matter (exotic nuclei): e.g. n-skin thickness

  • high-quality data with (d, 2He), (3He,t),... combined with large scale shell model calculations

  • elastic- and inelastic electron scattering, scattering on light nuclei and transfer reactions using RIB (intersecting storage rings)


Experimental achievements and outlook only a few examples to illustrate the achievements

ISOL

IF

Instrumentation and facilities

  • ISOL and IF are complementary

  • 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

  • target-ion source developments

  • (e.g. laser ionisation,...)

  • spectrometer developments

  • detector developments

  • (e.g. AGATA, ...)

  • accelerator developments

  • target and ion source developments


Experimental achievements and outlook only a few examples to illustrate the achievements

EURISOL

European Separator On-Line

Radioactive Nuclear Beam Facility

GSI

ISOL

IF

Instrumentation and facilities

TSL-Uppsala

KVI-Groningen

JYFL-Jyväskylä

CRC-Louvain-la-Neuve

FZJ-Jülich

GANIL-Caen

GSI-Darmstadt

ISOLDE - CERN

LNL-Legnaro

Oak-Ridge, MSU, Triumf and RIA

(North-America)

RIKEN (Japan)

Radioactive Beam Factory

ECT*-Trento


Experimental achievements and outlook only a few examples to illustrate the achievements

Conclusion and recommendations

  • The last 5 years have witnessed important advances in technical developments and in the understanding of the atomic nucleus. Key issues, that should be addressed, have been identified.

  • Stable-beam experiments have been the driving force for many decades of nuclear-structure research. This limit of some 300 different beams will be overcome by the second generation radioactive beam facilities and a major part of the chart of nuclei will be available for tailored experiments.

  • Exotic nuclei are indeed a very selective probe (N/Z variation, neutron skins, coupling to the continuum,...) and the planned developments will bring new, accurate and unique information.

  • Vigorous exploitation of the existing accelerators and instrumentation (including upgrades)

    • physics results

    • R&D for beam production and detector systems

    • experimental capabilities for the coming 5 to 10 years

  • Full support for the new GSI accelerator complex and for the EURISOL project

    • ISOL and IF facilities are both needed (complementary aspects)

    • the new GSI accelerator complex: full support and start construction

    • EURISOL: next 5 years full conceptual design should be made and site determined, start construction at the end of this period

    • multi-users aspect should be incorporated

  • Very strong support for rebuilding nuclear-structure and nuclear-reaction theory efforts

    • provisions for new theoretical groups and expansion of existing groups

    • support for ECT* maintained and expanded

  • Communicate the highlights to society


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