Application of compact laser-driven accelerator X-ray sources for industrial imaging

X-rays generated by betatron oscillations of electrons in a laser-driven plasma accelerator were characterised and applied to imaging industrial samples. With a 125TW laser, a low divergence beam with 5.2±1.7 × 107photonsmrad−2 per pulse was produced with a synchrotron spectrum with a critical energy of 14.6±1.3keV. Radiographs were obtained of a metrology test sample, battery electrodes, and a damage site in a composite material. These results demonstrate the suitability of the source for non-destructive evaluation applications. The potential for industrial implementation of plasma accelerators is discussed

Tracking the Hirnantian glaciation using Os isotopes

Here we present initial 187Os/188Os (Osi) values integrated with δ13Corg for the first Paleozoic section — the Ordovician/Silurian boundary GSSP at Dob's Linn, Scotland. Our 187Os/188Os data tracks major changes in climate that occurred during the Late Ordovician (Hirnantian glaciation), which coincides with the second largest known mass extinction. During the complanatus and early anceps Biozones Osi values increase from 0.28–1.08. This provides evidence for a period of increased silicate weathering of radiogenic continental crust, likely from the Caledonian Orogen. This increase in weathering was likely the driving mechanism for the drawdown in atmospheric CO2 and global cooling that resulted in the onset of the Hirnantian Glaciation. A decrease to less radiogenic Osi occurs at the base Hirnantian extraordinarius Biozone and coincides with the trend to more positive δ13Corg values that mark the onset of the Hirnantian Glaciation. The trend in Osi during this interval is ascribed to Hirnantian ice cover and reduced chemical weathering rates cutting the supply of radiogenic material to the Iapetus Ocean. The reduction in silicate weathering enabled atmospheric CO2 to return back to greenhouse levels, causing rapid deglaciation during the mid persculptus Biozone. This period is marked by an abrupt increase in Osi values from 0.6 to 1.08 over 19 cm of stratigraphy and coincides with the deglacial limb of the δ13Corg profile. We interpret the Osi data to reflect the leaching of exposed radiogenic 187Os/188Os bearing glacial deposits and increased weathering of radiogenic 187Os/188Os silicate terrane during the deglaciation. Previous workers have identified the Hirnantian glaciation primarily through δ13C stratigraphy. However, our Os isotope data indicate that an initial mechanism (i.e. increased silicate weathering) was the driving mechanism behind the Hirnantian Glaciation and subsequent mass extinction. Thus, by coupling Osi and δ13Corg proxies we provide the most direct evidence for the initiation and cessation of the Hirnantian glaciation. Furthermore, this study demonstrates the first use of 187Os/188Os chemostratigraphy for the Paleozoic as a proxy for reconstructing the Earth's climate system, particularly palaeoceanography

Effects of maize height difference on the growth and yield of intercropping soybeans

Meeting: Symposium on Intercropping for Semi-Arid Areas, 10-12 May 1976, Morogoro, TZIn IDL-196

The 3

The 3H(d, γ)5He reaction has been measured using a 500-keV pulsed deuteron beam incident on a stopping titanium tritide target at Ohio University’s Edwards Accelerator Laboratory. The time-of-flight (TOF) technique has been used to distinguish the γ-rays from neutrons detected in the bismuth germinate (BGO) γ-ray detector. A stilbene scintillator and an NE-213 scintillator have been used to detect the neutrons from the 3H(d, n)4He reaction using both the pulse-shape discrimination and TOF techniques. A newly-designed target holder with a silicon surface barrier detector to simultaneously measure α-particles to normalize the neutron count was incorporated for subsequent measurements. The γ-rays have been measured at laboratory angles of 0°, 45°, 90°, and 135°. Information about the γ-ray energy distribution for the unbound ground state and first excited state of 5He can be obtained experimentally by comparing the BGO data to Monte Carlo simulations. The 3H(d, γ)/3H(d, n) branching ratio has also been determined