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Hendrik Schatz JINA Department Head Experimental Nuclear Astrophysics   PhD, Physics, University of Heidelberg 1997 Joined NSCL in December 1999 Phone (517) 908-7397 Fax (517) 353-5967 Office W211   schatz at nsclmsuedu Professional homepage

The goal of our experimental research program is to understand the nuclear processes that occur naturally in the cosmos. To that end, we take advantage of the capabilities of NSCL and other laboratories to produce the same exotic isotopes that are created in extreme astrophysical environments such as supernovae—hydrogen explosions on neutron stars and white dwarfs—and the crusts of neutron stars. Some of the questions we are addressing currently by measuring the properties of these very short lived isotopes are: What is the origin of the heavy elements in nature made in the rapid neutron capture process (r-process)? What powers the frequently observed x-ray bursts and what can the observations tell us about the astrophysical site? What are the processes in the crusts of neutron stars that convert ordinary nuclei into exotic isotopes beyond the limits of neutron stability?

These questions are addressed by carrying out different types of experiments. We perform beta decay studies to obtain information on the most extreme rare isotopes one can produce in the laboratory. To that end, we have developed the neutron detector NERO that allows us to measure the probability for neutron-rich nuclei to emit neutrons when they decay. Decay studies of the proton-rich nuclei that briefly exist in x-ray bursts recently have become possible with the new RF Fragment Separator. We already have carried out a number of experiments observing beta-delayed proton emission. We also are developing a technique to measure the masses of extremely unstable nuclei by measuring precisely how long they take to fly from the production target to the S800 spectrometer. Most of our experiments are done in collaboration with other NSCL groups providing broad experimental training opportunities with many different devices.

While we will continue to take advantage of these techniques, technical developments in the coming years will focus on the new ReA3 facility at NSCL. This facility will be especially important for nuclear astrophysics, as it produces beams of rare isotopes at low energies that match the temperatures encountered in astrophysical environments. Our main project will be the construction of a windowless gas jet target. The challenge is to generate a higher density than previously achieved, while maintaining good vacuum before and after the target by rapid pumping. We also are involved in a number of other technical projects at ReA3, such as ANASEN or the AT-TPC.

Research in nuclear astrophysics requires a close connection to theoretical astrophysics and astronomy. Observations define the open questions and astrophysical models tell us which experiments are the most important ones. Several astrophysical models describing the r-process, x-ray bursts, and neutron star crusts have been developed by our group and are available to guide experiments and to investigate the impact of results on astrophysical questions. In addition, our research program is tied into the Joint Institute for Nuclear Astrophysics (JINA), an international network of institutions and researchers that brings together nuclear physicists and astrophysicists. Through the JINA network, larger scale models for supernovae or stellar evolution are available, which students can take advantage of through research stays in the US and abroad. JINA also facilitates connections to astronomers and experimental facilities at other institutions.