Results of beam tests on a high current EBIS test stand
At Brookhaven National Laboratory there is an R&D program to design an Electron Beam Ion Source (EBIS) for use in a compact ion injector to be developed for the Relativistic Heavy Ion Collider (RHIC). The BNL effort is directed at developing an EBIS with intensities of 3/spl times/10/sup 9/ particles/pulse of ions such as Au/sup 35+/ and U/sup 45+/, and requires an electron beam on the order of 10 A. The construction of a test stand (EBTS) with the full electron beam power and 1/3 the length of the EBIS for RHIC is nearing completion. Initial commissioning of the EBTS was made with pulsed electron beams of duration <1 ms and current up to 13 A. Details of the EBTS construction, results of the pulse tests, and preparations for DC electron beam tests are presented.
Status of the Brookhaven National Laboratory high current electron beam ion source test stand
As part of a new, compact heavy ion injector for the AGS/RHIC complex at Brookhaven National Laboratory we are developing an electron beam ion source (EBIS) that would satisfy present and future requirements. Such a source should be capable of producing intensities of, e.g., Au35+ ions of about 3×109 particles/pulse or U45+ of about 2×109 particles/pulse. To achieve this, the required e-beam intensity is 10 A, at a pulse length of 100 ms. An EBIS test stand has been constructed, designed for the full electron beam power and having close to 1/2 of the trap length of an EBIS for RHIC. Initial electron beam tests have resulted in a 50 μs, 13 A electron beam. Ion production and extraction has been shown with a 3.1 A, 50 ms electron beam, achieving an ion yield of 19 nC/pulse (neutralization degree of 61%); fast extraction trials have yielded extracted ion pulses of 1 mA peak current and 18 μs at FWHM. Details of the test stand construction, results of the electron beam studies, and properties of the extracted...
Resonant Auger decay study of C1s -> pi* core-excited OCS
The present work aims at characterizing short-lived C1s((-1)) pi*((1)) core-excited states of the OCS molecule based on the analysis of the vibrational fine structure and lineshape profiles of the high-resolution resonant Auger decay spectra recorded at the excitation energies along the C1s -> pi* resonance in the binding energy region 15-19eV. Very different behavior in terms of lineshape and resonant enhancement is observed for the (A) over tilde, (B) over tilde and (C) over tilde final states. This is explained by (1) the variation in the C-O bond lengths for the states involved in the electronic relaxation and (2) different contributions in terms of Mulliken population to the molecular orbitals determining the electronic character of the corresponding states. Since the final-state geometries are known from a number of previous experiments and ab initio calculations, the geometry of the C1s((-1)) pi*((1)) intermediate states can be predicted in analogy with e.g. the N-2, CO2 and N2O molecules. (C) 2009 Elsevier B.V. All rights reserved. (Less)