• Wide spectrum of pure radioactive ion beams• Energy: from ~ rest up to 3 MeV/u

Post accelerated beams:

8,9,11Li, 10-12Be, 10C, 17F, 24-29Na, 28-32Mg, 61,62Mn, 61Fe, 68Ni, 67-71,73Cu, 74,76,78,80Zn, 70Se, 88,92Kr,96Sr, 108In,106,108,110Sn,122,124,126Cd,138,140,142,144Xe, 140,142,148Ba,148Pm, 153Sm, 156Eu, 182,184,186,188Hg, 202,204Rn

• The energies available at REX-ISOLDE are optimal to exploit Coulomb Excitation and Transfer reactions

The techniques: Coulomb ExcitationNuclear excitation by the electromagnetic interaction acting between two colliding nuclei.

Target and projectile excitation possible

Spectroscopic tool to study single-particle versus collective properties of nuclei High selectivity to (1) transition with E2 transitions most probable, (2) collectivityTypical reactions: heavy, closed-shell targetObservables• energies of -g rays• Momentum of projectile and recoil target (Doppler shift correction) • Absolute Excitation cross-section normalized to the known target excitation

Coulomb trajectories only if the colliding nuclei do not reach the “Coulomb barrier”

“SAFE” Coulomb Excitation: purely electromagnetic process, NO nuclear interaction,

calculable with high precision

“ Safe” Energy Requirements

The Coulomb Excitation cross-sections are a direct measurement of the matrix elements involved in the excitation

Spectroscopic tool to study single-particle properties of nuclei selectivity to (1) kinematical matching (e.g. Qopt = 0 for n-transfer) (2) nuclear structure

Typical reactions: (d,p), (t,p) …RIBs: inverse kinematics

Observables• energies of protons (+ Eg) è (single-particle) level energies• angular distributions of protons (+ g-rays) è spin/parity assignments• (relative) spectroscopic factors è particle configurations

The techniques: Transfer Reaction g-decay

dp

… both, successful tool in nuclear spectroscopy for more than 50 years!!!

München, Köln, Heidelberg, Darmstadt, Leuven, York, Liverpool,

Daresbury, Strasbourg,...

The MINIBALL detector array

MAIN CHARACTERISTIC• 8 Miniball clusters• Each cluster: 3 HPGe crystals• Each crystal: 6-fold segmented• 8% efficiency @ 1.3 MeV

Miniball

Target ( 1-2

mg/cm2)

REX-ISOLDE

PPAC

CD – detector

Double sided Si strip detector

“Safe” Coulomb Excitation experiments Particle (CD) – γ correlations

• Particle ID in a Double-Sided Si Strip Detector

• Event by event Doppler correction

• 17° < lab < 54°

Data Analysis

Doppler Corrected for target

• Event by event Doppler correction

• Absolute Cross Sections are determined by normalizing to the known target excitation

• CLX code or GOSIA code to extract the transitional matrix elements

Projectile

Target

120Sn1171 keV

Doppler Corrected for Projectile

70Cu127 keV

70Cu511 keV

beam

beam

• large solid angle (58% of 4p)• position sensitive• PID (DE-E): p, d, t, a, … and e- from b-decay (!)

Technical details:Barrel: 140 mm DE / 16 resistive strips 1000 mm E / padBackward CD: 500 mm DE / DSSSD 500 mm E / pad

(funded by TU München, KU Leuven, U Edinburgh, CSNSM Orsay, TU Darmstadt)

T-REX … Si detector array for Transfer experiments at REX-ISOLDE

Some data

Miniball

Identifying and characterizing the excited 0+ in 32Mg

Tritium-implanted Ti foil 3H 40 μg/cm2,Activity 10 GBq

30Mg at 1.8 MeV/nucleon, 4.6x104 pps

30Mg(t,p)32MgThe Island of Inversion

coexistence of spherical and deformed statesdeformed 2p−2h configuration becomes ground state in 32Mgwhere is the excited 0+ state?

Fusion reactions with neutron-rich nuclei (Köln) Neutron transfer reactions on 30Mg (Darmstadt)

Towards the doubly magic 78Ni (Leuven)

B(E2) measurements around 132Sn(Munich)

Towards the doubly magic 100Sn(Lund, CERN)

Mixed symmetry states in 88Kr(Warsaw)

Shape coexistence in 70Se(Liverpool)

“Island of inversion at N=20” (Heidelberg)

N=40: Coulex of 68Ni and 68,70,m,gCu (CERN, Leuven)

The REX-ISOLDE - MINIBALL physics program:Structure and Shapes

g-factors in Te isotopes(Bonn)

Stellar reaction14O(a,p)17F

(Edinburgh)

ENERGY:Energy upgrade (Coulex and transfer): 3.1 5 10 MeV/u

INTENSITY: ISOLDE proton driver beam intensity upgrade strongly linked to PS Booster improvements including linac4

QUALITY: ISOLDE radioactive ion beam quality: continuous developments for broader spectrum and higher quality (purity, emittance, time structure) and isomeric beams

NEW INSTRUMENTATION: • HELIOS, ACTAR • New set-up for transfer reactions• Recoil spectrometer (identification of the reaction products)

ISOLDE has a unique potential and combines unique capabilities: beams (pure, isomeric), techniques and instrumentation

Outlook and short and intermediate term

Helios

Solenoid for transfer reactionsImproves particle resolution with respect to T-REX but no gamma detectionNeeds buncher/chopper for TOF measurement with 2 ns resolutionCurrently operating at ANL; UK proposal to build a new version

ACTAR

Active target for resonant scattering and transfer reactionsAllows to measure with very low intensitiesMAYA operational at GANIL and in ISOLDE in 2012Would benefit from slow extractionNew electronics (GET) being developed

AX

• Energy• Spin and Parity• Decay Strength Distributions• E.M.-Transition Matrix Elements• Spectroscopic Factors• Shapes and Moments

Coulomb excitation

Fusion Evaporation, Fragmentation, Fission

AY

T1/2

Radioactive Decay

see M. Borge, A. Jokinen

A-1X (e.g. d,p)

Few nucleon transfer

Deep inelastic scattering

see Th. Nilsson

Capture reactions

Oak-Ridge - GANIL - GSI - MSU - RIKEN - TRIUMF -LLN

Z=28

Z=50

N=4

0Z=82

20

N=5

0

N=8

2

N

Z

Structure of light exotic nuclei

Towards 78Ni: shell structure along Z=28 and N=50

Shape coexistence along Z=82

Nuclear structure along the N=Z line

Fundamental interaction studies

n-induced and beta-delayed fission

The Belgian Research Initiative on eXotic nuclei (BriX) (2007-2011)

Feasibility study for ISOL@MYRRHA“Island of inversion around 32Mg”

• Physics