Plans to measure neutron capture cross-sections and half-lives of cosmogenic radio-nuclides

1. Plans to measure neutron capture cross-sections and half-lives of cosmogenic radio-nuclides Rugard Dressler, Dorothea Schumann

2. Summary Mn-53 MeaNCoRN Introduction Cosmogenic Radio-Nuclides(CoRN) • Produced • via neutron capture reaction • during explosive phases of star evolution • in spallation reactions with high energetic cosmic rays • Present in the Solar System and on Earth • as constitute of molecular cloud formed our Sune.g. 53Mn found in meteorites • injected continuously to „present days“ from super novae e.g. 60Fe • continuously produced at Earth from cosmic rayse.g. 7Be, 14C, 32Si, 53Mn

3. Summary Mn-53 MeaNCoRN Introduction Short Lived Cosmogenic Radio-Nuclidest1/2 < 100 Ma adapted from N. Dauphas, M.Chaussidon: Annu. Rev. Earth Planet. Sci. 39 (2011) 351

4. Summary Mn-53 MeaNCoRN Introduction

5. Summary Mn-53 Introduction MeaNCoRN MeaNCoRN Measurement of neutron capture cross-sections and determination of half-live of short-lived cosmogenic radio-nuclides Rugard Dressler, Dorothea Schumann Laboratory of Radiochemistry and Environmental Chemistry BIO @ PSI Jost Eikenberg Division of Radioprotection and Safety LOG @ PSI Ines Günther-Leopold Hot Laboratory Division NES @ PSI Klaus Kirch Laboratory of Particle Physics NUM @ PSI Friedrich-Karl Thielemann, Marco Pignatari Theoretical Astro-, Nuclear-, and Particle Physics, University Basel, Switzerland Gunther Korschinek Physics Department, Technical University Munich, Germany René Reifarth Institute for Applied Physics, Goethe University Frankfurt, Germany

6. Summary Mn-53 Introduction MeaNCoRN Subjects of MeaNCoRN • Neutron Capture Cross Section • thermal neutron: NAA, PNA at PSI • cold neutrons: BOA, ICON at PSI; FRM II in Munich • ultra cold neutrons: UCN at PSI • neutrons at cosmic energies: FRANZ at SGC Frankfurt • Half-Life • 60Fe, 63Ni • 10Be, 53Mn • 26Al, 32Si, 59Ni • 41Ca, 79Se, 126Sn, …

7. Summary Mn-53 Introduction MeaNCoRN Half-Life Measurement Determination of sample activity A • a- / b- / g-Spectroscopy or Liquid Scintillation Counting Determination of number of atoms N • AMS / ICP-MS / HI-ERD • 10Be t1/2 = 1.388 ± 0.018 Ma G. Korschinek, et al.: Nucl. Instr. and Methods B 268 (2010) 187 • 79Se t1/2 = 0.327 ± 0.008 Ma G.Jörg, et al.: Applied Radiation and Isotopes 68 (2010) 2339 • 60Fe t1/2 = 2.62 ± 0.04 Ma G. Rugel, et al.: Phys. Rev. Lett. 103 (2009) 072502

8. Summary Introduction MeaNCoRN Mn-53 53Mn • produced in core collapsed SN (type II) via Si/O burning • Neutron capture • destruction via n, p, and α induce reaction • 53Mn(nth; g)54Mn • measurable with high sensitivity • Half-Life t1/2= 3.7±0.37 Ma • 53Mn – 53Cr chronometer • used to date events in solar system (20 Ma) • 53Mn / 55Mn isotopic ratio • used to determine the terrestrial exposure timeDry Valleys, Southern Victoria Land, and Antarctica

9. Summary Introduction MeaNCoRN Mn-53 Dating Problem 53Mn/55Mn vs. 207Pb/206Pb L.E. Nyquist, et al.: Geochim. Cosmochim. Acta 73 (2009) 5115

10. Summary Introduction MeaNCoRN Mn-53 Neutron Capture Cross-Section 53Mn

11. Summary Introduction MeaNCoRN Mn-53 Neutron Capture Cross-Section 53Mn

12. Summary Introduction MeaNCoRN Mn-53 CoRNStorehouses Fe samples of STIP total material ~ 60 g steel radio nuclides available 26Al 300 Bq ~ 1016 atoms 44Ti 300 MBq ≈ 8.4·1017 atoms 54Mn 70 MBq ( 53Mn ~1019 atoms) 60Co 70 MBq Cu beam dump total material ~ 500 g copper radio nuclides inventory 26Al 7 kBq ≈ 2.3·1017 atoms 32Si 10 MBq ≈ 7.8·1016 atoms 44Ti 100 MBq ≈ 2.8·1017 atoms 53Mn 500 kBq ≈ 8.4·1019 atoms 59Ni 8 MBq ≈ 2.7·1019 atoms 60Fe 5 kBq ≈ 5.9·1017 atoms 60Co 5 GBq

13. STIP samples pro low 60Co content separated from matrix purified final product cons high amount of stable isotopes storage time ~12 aEoB Dec 1999 high 54Mn activity Summary Introduction MeaNCoRN Mn-53 CoRN Storehouses Cu beam dump pro • storage time ~20 aEoB Dec 1992 • low 54Mn activity • non carrier added cons • high activity of 60Co • not separated from Cu • not purified

14. Introduction MeaNCoRN Mn-53 Summary Summary • 26Al, 32Si, 44Ti, 53Mn, 60Feavailable at PSI (1016 – 1020 atoms) • MeaNCoRN • neutron activation experiments at PSI • measurements of excitation function at n_TOF • 53Mn • up to 1020 atoms available • re-measurement of half-life

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