1. Observation of new neutron-deficient multinucleon transfer reactions
isotopes with Z ≥ 92 in
multinucleon transfer reactions
Sophie Heinz
GSI Helmholtzzentrum and Justus-Liebig-Universität Gießen
ECT* Trento, September 1 – 4, 2015

2. Fusion, Fragmentation and Fission
Deep inelastic Transfer ?
Figure: courtesy R. Knöbel

3. The small cross-sections require separation + single event detection
Deep Inelastic Reactions of Heavy Ions
E* = Ecm – TKE + Q
FUSION
Compound
Nucleus
QUASIFISSION
Primary Products (PP)
Evaporation
Residue (ER)
Fission
Fragments
σER = σcap ∙ PPP ∙ Psurvival
→ σ << 1 μb for new exotic heavy nuclei
The small cross-sections require separation + single event detection

4. Isotope identification
The Velocity Filter SHIP at GSI
Separation and identification of heavy reaction products at SHIP
Nbeam ≈ 5·1012 / s
Ndetector ≈ 100 / s
v ~ E/B 1 2 sf 3
E, T1/2
Isotope identification
via α decay chains
5 ms
15 ms
ΔΘ = (0 ± 2)°; ΔΩ = 10 msr
pulsed beam structure

5. Isotope identification via radioactive decays
The Velocity Filter SHIP at GSI
Separation and identification of heavy reaction products at SHIP
Very sensitive method
Nbeam ≈ 5·1012 / s
Ndetector ≈ 100 / s
v ~ E/B 1 2 sf 3
E, T1/2
Isotope identification
via radioactive decays
5 ms
15 ms
ΔΘ = (0 ± 2)°; ΔΩ = 10 msr
pulsed beam structure
σ1 event ≈ 50 pb
low limit cross-sections:
T1/2 ≥ 20 μs
access to short-living nuclei:

6. elastically scattered
Velocity Spectra of DIT products at θ = 0º
compound
nucleus
elastically scattered
target ions
yield
transfer products
v / vcm
Compound nucleus velocity:
Elastically scattered target ions:

7. elastically scattered
Velocity and Bρ Spectra
Example: Ca + Cm
compound
nucleus
elastically scattered
target ions

8. Transfer Products from 48Ca + 248Cm
Theoretical model calculations for 48Ca + 248Cm
→ V. Zagrebaev and W. Greiner
Ecm = 210 MeV (= 1.05 VCoulomb)
cross-section (mb)
primary TP
excitation energy (MeV)

9. 48Ca + 248Cm Reactions at SHIP
E = 225 MeV ( = 1.12 Vcoulomb)
alpha spectrum measured at a setting for target-like quasi-fission products
→ beam-off condition

10. → First synthesis of new heavy isotopes in DIT reactions
Identified Isotopes
→ First synthesis of new heavy isotopes in DIT reactions
H.M. Devaraja et al., „Observation of new neutron-deficient isotopes with Z ≥ 92 in multinucleon
transfer reactions“, accepted for publication in Phys. Lett. B

11. Example: New Isotopes of 95Am and 97Bk
Observed decay chains

12. Isotopic distributions
► measured isotopic distributions are located ~5 neutrons left from the expected
primary distributions → ~5 neutrons are evaporated from the PTP
→ E* (PTP) ≈ 50 MeV → for target-like TP with Z = 86 – 92

13. Energy dissipation
Total kinetic energy: TKE = Ecm – E* + Q = Ecm – TKEL
TKE goes below the Viola energy of a fissioning compound nucleus
→ this reflects the quasi-fission process

14. Comparison of DIT and Fusion Reactions
Cross-sections of uranium isotopes from transfer and fusion
92U
► Systematic uncertainties: estimated up to factor 10 for fusion and DIT

15. Summary
► DIT reactions are heavily discussed as a means to produce new isotopes
in the region of superheavy nuclei and N ≈ 126 nuclei
► Recently we observed for the first time new neutron-deficient Z ≥ 92 nuclei
using the velocity filter SHIP at GSI
→ σ1 event ~50 pb
→ selection of DIT products from central collisions with low angular momenta
► Cross-sections of the new isotopes:
σ ~ (1 – 10) nb → comparable to fusion cross-sections in this region
but: DIT reactions populate vast region of nuclei in the same experiment
► Are DIT reactions favourable for production of (super)heavy nuclei?
● Z > 92, N ≈ 126 → DIT appears favourable
● Z < 82, N ≈ 126 → Fragmentation appears favourable
(O. Beliuskina et al., Eur. Phys. J. A 50, 161 (2014))
● N-rich SHN → DIT very difficult: tiny σ and missing ID methods

16. DIT for the N ≈ 126, Z < 82 region?
DIT reactions in 64Ni + 207Pb
Transfer and fragmentation cross-sections
for neutron-rich nuclei: σTransfer ≥ σFragmentation
− O. Beliuskina et al., Eur. Phys. J. A 50, 161 (2014).
− [1] W. Krolas et al., Nucl. Phys. A 724 (2003) 289.

17. DIT for the N ≈ 126, Z < 82 region?
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)

18. How to reach „heavy“ SHN?
Pb, Bi targets
actinide targets
radioactive beams
► The N = 184 shell can be reached with exotic ion beams
► but: only small RIB intensities available: << 109 / s

19. Synthesis of Neutron-rich Isotopes with RIBs
Predicted cross-sections in the region of expected shell closures
example: AGe + 208Pb → A114*
(G. Adamian, N. Antonenko, W. Scheid, DNS model)
stable
282114
294114
expected yields for σ = 1 pb and ≤109 projectiles/s: 1 event in ≥30 years

20. The Fusion Process in Heavy Systemsmb
Nuclear Molecule
FUSION
Compound
Nucleus (CN)
QUASI-FISSION (QF)
FUSION-FISSION (FF)
Fission
Fragments
Evaporation
Residue (ER)
σER = σcapture ∙ PCN ∙ Psurvival
Superheavy systems: σER << σcapture → σcapture ≈ σQF + σFF = 10 – 100 mb

21. The Fusion Process in Heavy Systems
Movement of the system on the potential energy surface
V. Zagrebaev and W. Greiner
► Study of QF and FF as a function of beam energy and isospin allows the
„mapping“ of the potential energy surface

22. Probing of the Z=120, N=184 Region
The reaction ARb + 209Bi → A120*
→ N = 184 shell is reached with 95Rb beams
Ecm / Bfu ~ ZCN2 (exp. data)
Ecm = Bfu
but:
Ecm / Bfu (1n channel)
Z (compound nucleus)
E*CN < Sn ≈ 10 MeV → no neutron evaporation
E*CN < Bf ≈ 5 MeV → no CN fission
E*CN < → no CN formation
hindrance to fusion increases with Z → requires increasing beam energy

23. Future Experiments with Radioactive Ion Beams
at HIE-ISOLDE (CERN)
Decision of the CERN INTC, December 2012:
„ ...
... “

24. The New Isotope 216U
Observed decay chain and decay properties

25. The New Isotopes 223Am and 219Np
Observed decay chain and decay properties