Werner Tornow

My research interests are in experimental nuclear physics studies performed with beams of neutrons, photons and neutrinos. While the early focus was on polarization phenomena in few-body systems studied mainly with polarized neutrons first at the University of Tuebingen and later at TUNL (Triangle Universities Nuclear Laboratory at Duke University), subsequent activities include experiments in the broad field of weak-interaction nuclear physics.

In 1998 TUNL joined the KamLAND collaboration in Japan to pursue reactor antineutrino oscillation measurements. Supported by the U.S. Department of Energy (DOE), I was the principle investigator (PI) of TUNL’s effort in building the veto detector of KamLAND. At about the same time I became one of the four originators of the Majorana zero-neutrino double-beta decay experiment on ⁷⁶Ge, which later received DOE funding and is now known as the MAJORANA DEMONSTRATOR. Simultaneously, my group performed two-neutrino double-beta decay experiments to excited states in the daughter nucleus at TUNL and at the Kimballton mine in Virginia. In 2011, the KamLAND detector was modified to search for the zero-neutrino double-beta decay of ¹³⁶Xe, resulting in the currently most stringent lower limit of larger than 3.8 x 10²⁶ years for the decay half-life time for any zero-neutrino double-beta decay candidate nucleus, corresponding to an effective neutrino mass in the range of 28 to 125 meV, depending on the adopted nuclear matrix element calculations.  

When I started my 10-year tenure as Director of TUNL in 1996, the Duke University Free-Electron Laser Laboratory (DFFLL), funded at the time by the U.S. Air Force Medical Free-Electron Laser Program, was already collaborating with nuclear physics faculty at TUNL In November 1996 I was fortunate enough to detect the first high-energy photons produced via Compton backscattering of free-electron laser low-energy photons from electrons circulating in the Duke 1.1 GeV electron storage ring. This was the beginning of HIGS, the High-Intensity Gamma-ray Source (strictly speaking the notation “Gamma-ray” is somewhat misleading; the “Gamma-Rays” produced at HIGS are actually high-energy photons and do not originate from nuclei, as gamma-rays do). After years of work sufficient funding was raised from DOE and Duke University to upgrade HIGS and convert it into a Nuclear Physics research facility operated by TUNL. As a result, I had to enlarge my nuclear physics portfolio to now include many-body physics as well, in order to manage the research opportunity provided by this worldwide unique facility. Here, nuclear structure experiments performed with mono-energetic incident photons in the 2 to 15 MeV energy range were of special interest for the many users from all around the world.  

After retiring from teaching at Duke University in 2011, my research focus at TUNL’s Tandem Accelerator Laboratory was on experiments with mono-energetic neutron beams in the 0.5 to 30 MeV energy range. Here, nuclear fission studies have played a major role for about 12 years. In addition, my research group performed measurements to help quantify the neutron-induced background in zero-neutrino double-beta decay searches on ⁷⁶Ge, ¹³⁰Te and ¹³⁶Xe as well as in associated shielding materials, including ⁴⁰Ar. Furthermore, we studied reactions of importance for the National Ignition Facility (NIF) to help better understand the complicated physics governing the plasma generated in inertial confinement fusion laser shots at Lawrence Livermore National Laboratory. All these activities were supported by the Stewardship Science Academic Alliances Program of DOE’s National Nuclear Security Administration (NNSA).