Seminar: Research Activities in the Detection, Characterization, and Imaging Group at Penn State - Department of Nuclear Engineering Seminar: Research Activities in the Detection, Characterization, and Imaging Group at Penn State - Department of Nuclear Engineering

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Seminar: Research Activities in the Detection, Characterization, and Imaging Group at Penn State

September 6, 2018 @ 4:00 pm - 5:00 pm

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Dr. Marek Flaska
Assistant Professor
Mechanical and Nuclear Engineering Department
Penn State University

Abstract:

Two projects will be discussed during the talk. The first project is focused on measuring independent and cumulative fission yields of ~70 short-lived fission products for post-detonation nuclear-forensics non-destructive analyses. A wide range of short-lived fission fragments are being characterized with half-lives between approximately one second and several hours by using cyclic neutron activation analysis (CNAA) to support DTRA’s research and development efforts for pre- and post-detonation nuclear forensics. We also use traditional neutron activation analysis (NAA) in conjunction with tailored radiochemistry procedures for fission fragments with half-lives up to several days. Specifically, we use monoenergetic 14-MeV and fast-neutron spectrum (~MeV) to measure independent and cumulative fission yields of short-lived fission products (FPs) from fissile and fissionable actinides to enhance precision and expediency of pre- and post-detonation nuclear-forensics non-destructive analyses. These fundamental parameters are poorly known for many FPs, especially for short-lived FPs. As a result, the measurement precision of pre- and post-detonation analyses based on detection of neutrons and gammas emitted from a sample is substantially limited. The Pennsylvania State Breazeale Reactor (PSBR) and PNNL’s Thermo-Scientific D711 deuterium-tritium (D-T) 14-MeV neutron generator are also used to induce fissions in various actinides of interest, namely Th-232, U-233, U-235, U-238, and Am-241. The PSBR’s fast-neutron irradiator (FNI) provides a neutron spectrum similar to that expected from a nuclear weapon, thus providing a unique capability for these measurements. Tailored radiochemical separation is used to isolate problematic isotopes such as Ba-139, Ce-143, Rh-105, Pr-145, and Pm-151 with weak or low-energy gamma signatures for accurate quantification.

The primary objective of the second project is to assess and optimize performance of large-area imaging arrays of scintillators coupled to silicon photomultipliers (SiPMs) for nuclear fuel monitoring, while minimizing the number of readout channels. Traditionally, photomultiplier tubes (PMTs) have been used for radiation-detection applications based on scintillators. However, silicon photomultipliers (SiPMs) have matured over the last several years such that they now offer performance competitive with or superior to that of photomultiplier tubes (PMTs) in many characteristics. Such characteristics include both fundamental ones such as photon detection efficiency, gain, and intrinsic time resolution, and contrived ones such as pulse shape discrimination (PSD) for organic scintillators. We have been developing a method based on mixing SiPM pulses with a sinusoid of specific frequency as a SiPM flag. Our method uses a relatively straightforward scheme and aims to minimize performance degradation and maximize position reconstruction. During the talk, the impact of channel multiplexing on the imaging performance with various organic and inorganic scintillators will be discussed.

About Marek Flaska:

Marek Flaska is an assistant professor of the Mechanical and Nuclear Engineering Department (MNE) at the Pennsylvania State University (PSU). He joined MNE in 2015 and his research interests are radiation detection, characterization, and imaging with a focus on nuclear nonproliferation, nuclear safeguards, nuclear forensics, health physics, and fundamental nuclear physics. Prof. Flaska currently teaches MNE’s undergraduate-level courses “Radiation Detection and Measurement” and “Radiological Safety,” as well as the graduate-level courses “Detector and Source Technologies for Nuclear Security” and “Nuclear and Particle Physics for Nuclear Science.” During his professional career, he has advised a large number of graduate and undergraduate students and published approximately 190 papers in peer reviewed scientific journals and international conference proceedings.

Details

Date:
September 6, 2018
Time:
4:00 pm - 5:00 pm
Event Categories:
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Venue

1202 Burlington Labs
2500 Stinson Dr
Raleigh, NC 27607 United States
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