Measurement of the ⁸⁶Kr(α,n)⁸⁹Sr cross section at energies relevant for the weak r-process

¹ University of York, Heslington, York, YO10 5DD, United Kingdom
² Triumf, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3, Canada
³ CTU, 166 36 Prague 6, Czechia
⁴ University of Guelph, 50 Stone Rd E, Guelph, ON N1G 2W1, Canada
⁵ Simon Fraser University, 8888 University Dr, Burnaby, BC V5A 1S6, Canada
⁶ Instituto de Ciencia de Materiales de Sevilla, CSIC-Univ. Seville, Avda. Américo Vespucio 49, 41092 Seville, Spain
⁷ Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, South Korea
⁸ Colorado School of Mines, 1500 Illinois St, Golden, CO 80401, United States
⁹ Technische Universität Darmstadt, Schlossgartenstrasse 2, 64289 Darmstadt, Germany
¹⁰ Department of Physics, University of Basel, 4056 Basel, Switzerland
¹¹ Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB, United Kingdom
¹² CEMHTI, UPR3079 CNRS, 1D avenue de la Recherche Scientifique, 45071 Orléans, France
¹³ University of Notre Dame, Notre Dame, IN 46556, United States
¹⁴ University of British Columbia, Vancouver BC V6T 1Z4, Canada

^* Corresponding author: cja543@york.ac.uk

Published online: 22 March 2023

Abstract

The r-process has been shown to be robust in reproducing the abundance distributions of heavy elements, such as europium, seen in ultra-metal poor stars. In contrast, observations of elements 26 < Z < 47 display overabundances relative to r-process model predictions. A proposed additional source of early nucleosynthesis is the weak r-process in neutrino-driven winds of core-collapse supernovae. It has been shown that in this site (α,n) reactions are both crucial to nucleosynthesis and the main source of uncertainty in model-based abundance predictions. Aiming to improve the certainty of nucleosynthesis predictions, the cross section of the important reaction ⁸⁶Kr(α,n)⁸⁹Sr has been measured at an energy relevant to the weak r-process. This experiment was conducted in inverse kinematics at TRIUMF with the EMMA recoil mass spectrometer and the TIGRESS gamma-ray spectrometer. A novel type of solid helium target was used.