Level structure of Mg21: Nuclear and astrophysical implications
Resonant elastic scattering of a radioactive $^{20}\mathrm{Na}$ beam incident upon protons in a polyethylene target has been used to probe the level structure of $^{21}\mathrm{Mg}$ above the proton decay threshold. Three states have been observed, and their properties deduced through analysis based on the R-matrix formalism. The results improve and extend previous studies of this nucleus. An estimate of the $^{20}\mathrm{Na}$(p,\ensuremath{\gamma})$^{21}\mathrm{Mg}$ reaction rate, including these new data, suggests this reaction will not play a significant role in explosive hydrogen burning in astrophysical sites such as novae and x-ray bursts.
The DRAGON facility for nuclear astrophysics at TRIUMF-ISAC
A facility for measuring cross-sections (resonance strengths) for reactions of astrophysical importance involving short-lived, radioactive reactants has been designed, built and installed at the new TRIUMF-ISAC Radioactive Beams Laboratory in Canada. Named DRAGON (Detector of Recoils And Gamma-rays of Nuclear reactions), it has been successfully commissioned with stable and radioactive heavy ion beams from ISAC. This report presents the main components of the facility, namely, the windowless gas target, the surrounding g detector array, the subsequent electromagnetic recoil mass separator, the focal plane detectors for recoils, the detection system for elastics, and the modular electronics and computer software used for the data acquisition. Examples of the operation of the facility for both stable beam reactions and the first radioactive beam reaction study, Naðp; gÞMg are also presented, along with future plans for the program. r 2003 Elsevier Science B.V. All rights reserved.
12.2: Enhanced Electron Emission of the Cone‐Shaped Emitters with Carbon Nanostructures
We developed novel cone‐shaped emitters with individual carbon nanotips using the resist‐assisted patterning process. The novel cone‐shaped nanotip emitters were arranged in an array with many nano emitters in pre‐patterned diameters of 3 μm. The cone‐shaped nanotip emitters consist of a number of carbon‐based nanostructures such as nanotubes and/or nanofibers with silicon and nitrogen elements at the periphery of each element. The cone‐shaped nano‐emitters strongly adhered to the substrate due to the large area bottom contact which is covered with diffused silicon elements. The growth mechanism and enhanced electron emission of cone‐shaped nanotip emitters was discussed.