Experimental Nuclear Physics
Nuclear Physics and the structure of Matter
Dr. Miguel Madurga is an Assistant Professor in the Department of Physics, University of Tennessee. Native of Madrid, Spain, son of a physicists and surrounded by physicists from a young age, there was little doubt he would join the academic profession. Currently a proud Tennessean (go Vols!), researching the origin of nuclear matter, and teaching the next generation of physicists.
Articles and Books
NEW HALF-LIVES OF R-PROCESS ZN AND GA ISOTOPES MEASURED WITH ELECTROMAGNETIC SEPARATION
September 13, 2012
The β decays of neutron-rich nuclei near the doubly magic 78Ni were studied at the Holifield Radioactive Ion Beam Facility using an electromagnetic isobar separator. The half-lives of 82Zn (228±10 ms), 83Zn (117±20 ms), and 85Ga (93±7 ms) were determined for the first time. These half-lives were found to be very different from the predictions of the global model used in astrophysical simulations. A new calculation was developed using the density functional model, which properly reproduced the new experimental values. The robustness of the new model in the 78Ni region allowed us to extrapolate data for more neutron-rich isotopes. The revised analysis of the rapid neutron capture process in low entropy environments with our new set of measured and calculated half-lives shows a significant redistribution of predicted isobaric abundances strengthening the yield of A>140nuclei.
EVIDENCE FOR GAMOW-TELLER DECAY OF 78NI CORE FROM BETA-DELAYED NEUTRON EMISSION STUDIES
August 23, 2016
The β-delayed neutron emission of 83,84Ga isotopes was studied using the neutron time-of-flight technique. The measured neutron energy spectra showed emission from states at excitation energies high above the neutron separation energy and previously not observed in the β decay of midmass nuclei. The large decay strength deduced from the observed intense neutron emission is a signature of Gamow-Teller transformation. This observation was interpreted as evidence for allowed β decay to 78Ni core-excited states in 83,84Ge favored by shell effects. We developed shell model calculations in the proton fpg9/2 and neutron extended fpg9/2+d5/2 valence space using realistic interactions that were used to understand measured β-decay lifetimes. We conclude that enhanced, concentrated β-decay strength for neutron-unbound states may be common for very neutron-rich nuclei. This leads to intense β-delayed high-energy neutron and strong multineutron emission probabilities that in turn affect astrophysical nucleosynthesis models.
SEARCH FOR BETA-DELAYED PROTON EMISSION FROM 11BE
March 20, 2020
We report on an attempt to reproduce the observation of 𝛽−β−-delayed proton emission from 1111Be through detection of the final state nucleus 1010Be with accelerator mass spectrometry. Twelve samples were collected at the ISOLDE facility at CERN at different separator settings, allowing tests of different sources of contamination to be carried out. The observed amounts of 1010Be per collected 1111Be rule out several contamination sources, but do not agree internally. Formation of BeH molecular ions in the ion source may explain our data, in which case an upper limit of the 𝛽βp branching ratio of 2.2×10−62.2×10−6 can be derived.