Multiple Monoenergetic Gamma Radiography (MMGR) with a compact superconducting cyclotron

Smuggling of special nuclear materials (SNM) and nuclear devices through borders and ports of entry constitutes a major risk to global security. Technologies are needed to reliably screen the flow of commerce for the presence of high-$Z$ materials such as uranium and plutonium. Here we present an experimental proof-of-concept of a technique which uses inelastic ($p,p'$) nuclear reactions to generate monoenergetic photons, which provide means to measure the areal density and the effective-$Z$ ($Z_{\text{eff}}$) of an object with an accuracy which surpasses that achieved by current methods. We use an ION-12$^{ \text{SC}}$ superconducting 12~MeV proton cyclotron to produce 4.4, 6.1, 6.9, and 7.1~MeV photons from a variety of nuclear reactions. Using these photons in a transmission mode we show that we are able to accurately reconstruct the areal densities and $Z_{\text{eff}}$ of a test object. This methodology could enable mobile applications to screen commercial cargoes with high material specificity, providing a means of distinguishing common cargo materials from high-Z materials that include uranium and plutonium

Recoil Studies in the Reaction of 12-C Ions with the Enriched Isotope 118-Sn

The recoil properties of the product nuclei from the interaction of 2.2 GeV/nucleon 12-C ions from Nuclotron of the Laboratory of High Energies (LHE), Joint Institute for Nuclear Research (JINR) at Dubna with a 118-Sn target have been studied using catcher foils. The experimental data were analyzed using the mathematical formalism of the standard two-step vector model. The results for 12-C ions are compared with those for deuterons and protons. Three different Los Alamos versions of the Quark-Gluon String Model (LAQGSM) were used for comparison with our experimental data.Comment: 10 pages, 6 figures, submitted to Nucl. Phys.

Chemical–Genetic Profiling of Imidazo[1,2-a]pyridines and -Pyrimidines Reveals Target Pathways Conserved between Yeast and Human Cells

Small molecules have been shown to be potent and selective probes to understand cell physiology. Here, we show that imidazo[1,2-a]pyridines and imidazo[1,2-a]pyrimidines compose a class of compounds that target essential, conserved cellular processes. Using validated chemogenomic assays in Saccharomyces cerevisiae, we discovered that two closely related compounds, an imidazo[1,2-a]pyridine and -pyrimidine that differ by a single atom, have distinctly different mechanisms of action in vivo. 2-phenyl-3-nitroso-imidazo[1,2-a]pyridine was toxic to yeast strains with defects in electron transport and mitochondrial functions and caused mitochondrial fragmentation, suggesting that compound 13 acts by disrupting mitochondria. By contrast, 2-phenyl-3-nitroso-imidazo[1,2-a]pyrimidine acted as a DNA poison, causing damage to the nuclear DNA and inducing mutagenesis. We compared compound 15 to known chemotherapeutics and found resistance required intact DNA repair pathways. Thus, subtle changes in the structure of imidazo-pyridines and -pyrimidines dramatically alter both the intracellular targeting of these compounds and their effects in vivo. Of particular interest, these different modes of action were evident in experiments on human cells, suggesting that chemical–genetic profiles obtained in yeast are recapitulated in cultured cells, indicating that our observations in yeast can: (1) be leveraged to determine mechanism of action in mammalian cells and (2) suggest novel structure–activity relationships