Research

What makes a star explode and eject its material into space to create planets like earth? What is the mass of the neutrino? And what forces govern the properties of nuclei? Although these questions are very diverse, the research group that I lead uses a common tool to investigate all: charge-exchange reactions. In a nuclear reaction, a projectile nucleus collides with a target nucleus. In a charge-exchange reaction, they exchange a proton for a neutron. These reactions can inform us about electron capture and beta decays that take play important roles in astrophysical phenomena. We are especially interested in supernovae, neutron stars, and processes that create elements in the universe. Another category of processes that we study are those that involve reactions with neutrinos. Such processes also have astrophysical applications. In addition, they help us better understand how these strange particles interact with matter. Finally, we study giant resonances, which are collective oscillations of nuclei that can inform us about bulk properties and equation of state of nuclear matter, which are also important in studying dense stellar phenomena, such as supernovae and neutron stars. To pursue these objectives, we perform experiment with fast beam of rare isotope and use the spectrometer at FRIB, in combination with neutron, gamma, and charged-particle detectors. An important aspect of the research performed is to directly couple the experimental results to astrophysical simulations in order to effectively increase our understanding and interpretation of astronomical observations.  

Biography

I was born and stayed in the Netherlands until I finished my PhD in 1999 at the University of Groningen. My master’s degree was in Technical Physics, with a focus on materials science. I switched to experimental nuclear science and performed my thesis work on charge-exchange reactions and giant resonances at the Kernfysisch Versneller Instituut, which also included analysis of data from an experiment at the Indiana University Cyclotron Facility. After graduation, I worked as a postdoc at the SPring-8 facility (focusing on the photoproduction of kaons) and the Research Center for Nuclear Physics (focusing on nuclear charge-exchange reactions) in Japan. In 2003, I joined the Lab and founded the charge-exchange research group. We do a wide variety of experiments and play a leading role in the development of charge-exchange reactions with rare isotope beams. Because my research involves magnetic spectrometers, I led the planning for a new High Rigidity Spectrometer at FRIB that will greatly advance the opportunities for research with very neutron-rich nuclei and presently serve as the scientific spokesperson for this project. Finally, I am passionate about the education and training of junior researchers, and my career has included several roles in support of these activities.

How students can contribute as part of my research team

Students in my research group are active in the preparation, running, and interpretation of experiments performed at FRIB or the Research Center for Nuclear Physics (RCNP) in Japan. In addition, we build detector systems for these experiments, such as the low-energy neutron detector array. Although we work closely with theorists and astrophysicists, we do a lot of the calculations ourselves, and students can be strongly engaged with these aspects as well. Therefore, research projects can be adapted to meet the interests of students in the group, and students can gain expertise in a broad range of topics, especially since we also work closely with other groups at FRIB, and beyond, who have developed detector systems that we use in experiments. With the development of tools to study charge-exchange reactions with rare-isotope beams, we are very excited to study these reactions far from stability at FRIB. Students who have graduated in my group have pursued careers in academia, national laboratories, industry, and governmental agencies and contractors, and the multidisciplinary aspects of the research conducted in my group benefits the skill development for such careers.

Scientific publications

• β⁺ Gamow-Teller Strengths from Unstable ¹⁴O via the (d,²He) Reaction in Inverse Kinematics, S. Giraud et al., Phys. Rev. Lett. 130, 232301
• The Sensitivity of Core-Collapse Supernovae to nuclear Electron Capture – C. Sullivan et al., The Astrophysical Journal, 816, 44 (2015).