1. Welcome to the CHARMS See – Tea Saturday, March 05, 2016 Comparison of ISOLDE yields with calculated in- target production rates Strahinja Lukić, 13.12.2005

2. 18-10-2005 Release of the Light Alkalis From ISOLDE Targets 2 Outline Release of nuclides from ISOLDE targets In-target production rates Dependence of the overall efficiency on the isotopic half-life

3. 18-10-2005 Release of the Light Alkalis From ISOLDE Targets 3 Release of Nuclides from ISOLDE Targets Nuclide production Thermal diffusion Effusion Ionization Extraction by 60 kV field Losses to chemical reactions, leaks, radioactive decay... Proton beam

4. 18-10-2005 Release of the Light Alkalis From ISOLDE Targets 4 Typical ISOLDE Target 20 cm

5. 18-10-2005 Release of the Light Alkalis From ISOLDE Targets 5 In-target production In-target production rates estimated taking into account:  Attenuation of the beam along the target due to nuclear reactions  Energy loss due to electromagnetic interactions and the resulting change in the production cross-sections along the target  Low-energy fission induced by secondary neutrons in fissile targets

6. 18-10-2005 Release of the Light Alkalis From ISOLDE Targets 6 Importance of the secondary reactions in the thick target Comparison of the total in-target production (ISOLDE, EURISOL report) with calculated in-target primary production rates in UC x target (50 g/cm 2, 20 cm depth, 1.4 cm diameter) Difference almost entirely due to low-energy fission induced by neutrons 40% of incident protons undergo a nuclear reaction Roughly 6 secondary neutrons per primary proton (in primary reactions) About 0.7% of the produced neutrons get captured by uranium

7. 18-10-2005 Release of the Light Alkalis From ISOLDE Targets 7 Correlation of ISOL yields with isotope half-life Comparison of ISOLDE-SC yields † to in-target production rates Ratio yield/produced → overall extraction efficiency for the nuclide. For a given element – target – ion source, the efficiency is correlated with the isotope half-life † H.-J. Kluge, Isolde users guide, CERN, Geneva, 1986, web: http://isolde.cern.chhttp://isolde.cern.ch Same general behavior found in many cases.

8. 18-10-2005 Release of the Light Alkalis From ISOLDE Targets 8 Examples

9. 18-10-2005 Release of the Light Alkalis From ISOLDE Targets 9 Alkalis Very easy to ionize by surface ionization, simple chemistry, volatile When ionized, electronic configuration of a noble gas High efficiencies – ε s often 100% Fast release – t 0 of the order of seconds

10. 18-10-2005 Release of the Light Alkalis From ISOLDE Targets 10 Alkaline earths Surface ionization Chemical separation from alkalis using fluoride gas leak, to form XF + molecular ions ε s several % t 0 of the order of tens of seconds

11. 18-10-2005 Release of the Light Alkalis From ISOLDE Targets 11 Halogens Negative ionization – difficult ε s several % t 0 of the order of tens to hundreds of seconds

12. 18-10-2005 Release of the Light Alkalis From ISOLDE Targets 12 Noble gases Plasma ionization Chemical separation by condensation of the impurities in the transfer line Fast release

13. 18-10-2005 Release of the Light Alkalis From ISOLDE Targets 13 Cases that "didn't work"

14. 18-10-2005 Release of the Light Alkalis From ISOLDE Targets 14 Conclusions Quantification of the essential properties of the overall ISOL efficiencies Practical  ε s is the important information  behavior with short half-lives indicates where to put the development efforts General in scope - applicable across the entire table of elements and for all target and ion- source systems