The reaction ' B(p, y}"C has been investigated in the energy range E~=0.07 -2.20 MeV. The broad resonant structure previously observed in the ground state transition near E"=1. 2 MeV has been seen also in y-ray transitions to excited states. The observed excitation functions as well as the y-ray angular distributions can be explained by assuming several broad overlapping resonances.The low-energy data (Ep & 0.6 MeV) reveal the existence of two s-wave resonances at Ep =0.010 and 0.56 MeV. Spectroscopic factors for several final states have been obtained from observation of direct capture processes to them; they are in fair agreement with results from stripping reaction studies. The present data also provide information on partial and total widths of the states at E"=8 -9 MeV. The energy range investigated corresponds to the temperature range of T=(0.01 -5) &&10 K. The thermonuclear reaction rates deduced from the present results are compared with previously reported values.' NUCLEAR REACTIONS ' B(p,y), Ep =0.07 -2.20 MeV; measured y yield for ' "C states up to E"=10. 7 MeV. Deduced resonance parameters, branching ratios, and direct capture contributions for proton-unbound states; deduced spectroscopic factors, I y/I t t and I ", for several a-unbound states. Calculated thermonuclear reaction rate for T=(0.01 -5) & 10 K.
Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR) have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the ''prompt'' electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the ''swept'' electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100 s. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the quadrupole.
Initial commissioning of a 6.7-MeV 100-mA RFQ is underway. The RFQ is part of LEDA, the H + injector for the Accelerator Production of Tritium (APT) project. To benchmark the RFQ performance, beam physics experiments will be done with low and high current beams for both pulsed and cw beam operation. Commissioning efforts thus far have been limited to low-current pulsedbeam LEDA operation.Measurements to fully characterize the RFQ will ultimately include the dependence of RFQ beam transmission on RFQ vane voltage, input beam energy, input match, and input transverse centroids. Other commissioning measurements for the RFQ will include output beam energy, phase, noise, transverse profiles, and transverse rms emittances. This paper contains initial LEDA RFQ commissioning results, including RFQ pulsed output beam currents up to 40 mA.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.