Köln 2004 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 34: Nuclear and Particle Astrophysics II

HK 34.4: Vortrag

Mittwoch, 10. März 2004, 15:00–15:15, F

Measurement of the (γ,n) cross section of the nucleus ¹⁸⁷Re close above the reaction threshold^* — •S. Müller, D. Galaviz, A. Kretschmer, K. Sonnabend, K. Vogt, and A. Zilges — Institut für Kernphysik, Technische Universität Darmstadt, Germany

Motivated by the Re/Os chronometer problem [1,2,3] the (γ,n) cross section of the nucleus ¹⁸⁷Re has been measured close above the reaction threshold E_thr=7.363 MeV at the Darmstadt electron accelerator S-DALINAC using the method of photoactivation. Our experimental method, the implications on the s-process branching point ¹⁸⁶Re and consequently the relevance for the Re/Os chronometer problem are discussed. In addition our results will allow to use ¹⁸⁷Re as a new standard for photoactivation experiments [4]. ^*supported by the DFG (SFB 634 and Zi 510/2-2)

[1] D.D. Clayton, Astrophys. J. 139, 637 (1964).

[2] S.E. Woosley and W.A. Fowler, Astrophys. J. 233, 411 (1979).

[3] K. Yokoi et al., Astron. Astrophys. 117, 65 (1983).

[4] K. Vogt et al., Nucl. Phys. A 707, 241 (2002).