Multinucleon Transfer Reactions –

a New Way to Exotic Nuclei?

Sophie Heinz

GSI Helmholtzzentrum and

Justus-Liebig Universität Gießen

Trento, May 26 - 30, 2014

Synthesis of Exotic Nuclei

Figure: courtesy R. Knöbel

Multinucleon Transfer ?

Fusion, Fragmentation and Fission

Deep Inelastic Transfer Reactions

FUSION

DEEP INELASTIC TRANSFER

Nuclear Molecule

Compound Nucleus

EvaporationResidue (ER)

FUSION-FISSION

FissionFragments

σER = σcapture ∙ Pprim ∙ Psurvival

EvaporationResidue (ER)

FissionFragments

Primary Transfer Products

E* = Ecm – TKE + Q

Population of nuclei along the N = 126 shell in transfer reactions

1 μb

The small cross-sections of <1 μb require separation + single event detection

136Xe + 208Pb

Theoretical Model Predictions

→ Application of neutron-rich projectiles and targets in the Pb region→ Application of beam energies at the Coulomb barrier

Myeong-Hwan Mun, G.G. Adamian et al.,PRC 89, 034622 (2014).

V. Zagrebaev, W. Greiner, PRL 101, 122701 (2008).

ANi + 198Pt

1 μb

DNS modeladiabatic potentials

The Velocity Filter SHIP

Nbeam ≈ 5·1012 / s

Ndetector ≈ 100 / s

v ~ E/B1

2

sf

3

E, T1/2

E, T1/2

E, T1/2

Isotope identification via radioactive decays

Separation and identification of heavy reaction products at SHIP

5 ms

15 ms

ΔΘ = (0 ± 2)°; ΔΩ = 10 msr

pulsed beam structure

β−

γ

ZX

Z+1Y

Population of Transfer Products along N=126

identified isotopes

target nucleus, 207Pb

The reaction 64Ni + 207Pb at 5.0 MeV/u studied at SHIP

→ Isotope identification via gamma spectroscopy in the focal plane of SHIP→ identificaiton of isotopes with Z = 73 – 89 with cross-sections >10 μb

for neutron-rich nuclei: σTransfer ≥ σFragmentation

− SHIP exp.: S. Heinz, O. Beliuskina, proceedings of the ECHIC2013, Jour. Conf. Ser. 515, (2014) 012007.− [1] W. Krolas et al., Nucl. Phys. A 724 (2003) 289.

Population of Transfer Products along N=126

Transfer and fragmentation cross-sections

Transfer and Fragmentation

Transfer Fragmentation

Nbeam 5 · 1012 / s 5 · 109 / s

dTarget 500 μg / cm2 5 g / cm2

angular efficiency <5% (SHIP) <50% (FRS)

angular distribution up to ~50º(Coulomb barrier)

few degree(relativistic energies)

A, Z identification α, β decays E, ΔE, TOF, Bρ

→ Consideration on experimental conditions

only applicable for nucleiwith appropriate decayproperties

applicable forall nuclei

experimental conditions are much more favourable in fragmentation reactions

Population of Transfer Products along N=126

Transfer and Fragmentation yields (at the target)

Nbeam dTarget efficiency

Transfer

Fragmentation

5 · 1012 / s

5 · 109 / s

500 μg / cm2

5 g / cm2

< 5% (SHIP)

< 50% (FRS)

yield (Fragmentation) > 10 x yield (Transfer)

Population of N-rich Transuranium Isotopes

Transfer reactions in 48Ca + 248Cm studied at SHIP

→ Transuranium nuclei are not reachable in fragmentation reactions

identified at SHIP

48Ca + 248Cm (transfer), H. Gäggeler et al., PRC 33, 1983 (1986) 238U + 248Cm (transfer), M. Schädel et al., PRL 48, 852 (1982)

Detection of new isotopes is restricted by missing identification techniques

Isotope ID via Precision Mass Measurements?

Penningtrap• mass selective• T1/2 > 100 ms

• m/Δm > 106 - 107

Time-of-Flight spectrometer• broad-band• T1/2 > 10 ms

• m/Δm > 105

stopping cell

(T. Dickel, W. Plaß et al., JLU Gießen)

Isobar identification

► Model calculations suggest the production of new neutron-rich nuclei in the region of Z > 92 and along N = 126 in transfer reactions → lack of experimental data

► Small cross-sections (< 1 μb) require effective separation + single event ID → lack of dedicated experimental setups → but: separators used in SHE research can be used for transfer studies

► Investigation of transfer reactions at SHIP: ▪ N = 126: 64Ni + 207Pb reactions → observation of n-rich isotopes with Z = 73 - 89

→ σTransfer ≥ σFragmentation but: fragmentation leads to much higher yields

Summary

▪ Z > 92: 48Ca + 248Cm reactions → observation of n-rich isotopes with Z = 84 – 102 → region cannot be accessed in fragmentation or fusion reactions with stable beams

► main restriction is presently missing identification techniques for heavy transfer products