1. SMI-06 Workshop, Groningen, 27-28.03.2006
Systematic comparison of ISOLDE-SC yields with calculated in-target production rates
SMI-06 Workshop, Groningen,
S. Lukić GSI - Darmstadt

2. SMI-06, March 27-28, Groningen S. Lukić
Outline
Motivation
ISOLDE SC yield database
In-target production
Results of the comparison
Conclusions
SMI-06, March 27-28, Groningen S. Lukić

3. SMI-06, March 27-28, Groningen S. Lukić
Motivation
Future ISOL facility projects (EURISOL, SPIRAL2, RIA)
Nuclide production optimization
Optimal nuclear reaction
Target and ion-source development
Need for beam intensity predictions in various scenarios
Nuclear reaction data and models
Extraction-efficiency prediction
SMI-06, March 27-28, Groningen S. Lukić

4. SMI-06, March 27-28, Groningen S. Lukić
Motivation
Isotope Separation OnLine – nuclide production in a thick target + extraction and mass separation
Part of the produced nuclei is lost to:
Sticking to walls
Escaping ionization
Chemical reactions
Radioactive decay
All these losses are difficult to directly estimate.
Their overall effect can be deduced from a comparison of the final yields with the in-target production rates
SMI-06, March 27-28, Groningen S. Lukić

5. ISOLDE SC yield database
At ISOLDE, isotopic yields for 64 different elements were documented during its operation with the SC proton beam in CERN (196? – 1992)
H.-J. Kluge, ISOLDE User's Guide, CERN 86-05,
SMI-06, March 27-28, Groningen S. Lukić

6. ISOLDE SC yield database
Yield uncertainties because of isobaric and molecular contaminations
In general, the accuracy is estimated to be within a factor of 2-3 close to stability, and up to one order of magnitude far-off stability
H.-J. Kluge, ISOLDE User's Guide, CERN 86-05,
SMI-06, March 27-28, Groningen S. Lukić

7. In-target production

8. In-target production Experimental data
Cross-section data in inverse kinematics in GSI
Wide range of colliding systems (Fe – U / p – Pb)
Wide range of energies (300 – 1000 A MeV)
SMI-06, March 27-28, Groningen S. Lukić

9. In-target production - ABRABLA
238U + 1 A GeV
Reaction simulation code
Benchmarked against GSI data
Complex physics, high predictive power
SMI-06, March 27-28, Groningen S. Lukić

10. In-target production – thick target
Energy loss – mean value of xs used
Beam attenuation
Secondary reactions – low-energy fission – comparison with exp. data
SMI-06, March 27-28, Groningen S. Lukić

11. Results

12. SMI-06, March 27-28, Groningen S. Lukić
Results – francium
Non-uniform dependence of half-lives with the mass number
Clear correlation of the extraction efficiency with the half-life
SMI-06, March 27-28, Groningen S. Lukić

13. SMI-06, March 27-28, Groningen S. Lukić
Results – francium
Same general behavior in many different cases:
Constant efficiency for long half-lives
Power-function behavior for short half-lives
Parameterization:
SMI-06, March 27-28, Groningen S. Lukić

14. Results – more examples
SMI-06, March 27-28, Groningen S. Lukić

15. Results – saturation efficiency for different groups
SMI-06, March 27-28, Groningen S. Lukić

16. Results – α parameter across the solid targets
Theoretical value: 1.5 U. Köster, PhD Thesis, Munich Technical University (2000)
SMI-06, March 27-28, Groningen S. Lukić

17. Results – uncertainties
Uncertainties come from:
difficulties to precisely calculate cross sections at the steep outer slopes of isotopic distributions far off stability
isobaric and molecular contaminations of ISOLDE beams
side feeding
unknown fraction of nuclides of a certain type that are produced in isomeric states
Sometimes, these effects are so large that...
SMI-06, March 27-28, Groningen S. Lukić

18. Results – cases that "don't work"
In ~30% of cases, no apparent correlation of efficiencies with half-lives
SMI-06, March 27-28, Groningen S. Lukić

19. SMI-06, March 27-28, Groningen S. Lukić
Conclusions
Measured ISOLDE yields have been compared with new and high-quality information on the nuclide-production cross sections in proton-induced reactions.
Essential properties of the overall ISOL efficiencies have been quantified for a wide variety of isotopic chains from different target and ion-source systems. :
The parameter εs – extraction efficiency in the limit of long half-lives – directly indicates the overall losses that occur apart from the decay losses.
The parameters t0 and α describe the effect of the decay losses with short half-lives
This information helps in completing our understanding of the efficiencies of the ISOL method, as well as in identifying the issues that need most attention in the process of ISOL target and ion-source development
This kind of study is, in principle, applicable across the entire table of elements and for all target and ion-source systems.
SMI-06, March 27-28, Groningen S. Lukić

20. SMI-06, March 27-28, Groningen S. Lukić
Acknowledgment
Co-authors: F. Gevaert, A. Kelić, M.V. Ricciardi, K.-H. Schmidt, O. Yordanov
We are grateful to Ulli Köster for very helpful remarks and discussion about specific ISOLDE data points
We acknowledge the financial support of the European Community under the FP6 “Research Infrastructure Action – Structuring the European Research Area”, EURISOL DS Project, contract no RIDS. The EC is not liable for any use that may be made of the information contained herein.
SMI-06, March 27-28, Groningen S. Lukić

21. Thank you!