In response to the recent measurements of the 54.4 eV e–H(2p) reduced Stokes parameters by Gradziel and O'Neill (2004 J. Phys. B: At. Mol. Opt. Phys. 37 1893) we perform corresponding calculations using two recently developed techniques. These are the propagating exterior complex scaling direct approach to the solution of the underlying Schrödinger equation, and the box-based convergent close-coupling method. We find the results to be almost identical to the Laguerre-based convergent close-coupling method of Bray and Stelbovics (1992 Phys. Rev. A 49 1066). Hence we are unable to explain the substantial discrepancy with experiment for the parameter in the vicinity of 30°.

One sector or approximately one-quarter betatron osciUat ion away from Am-1, the beam has reached its maximum deviation of 1 em, and gasses by the septum of MX-2. RIX-I L an &-cored puked magnct whose field Btrength is 4 kilogause, PWT-2 provides an additional bending of approximately 17' to the beam. It is this rather Bevsre bending, necessary to extract the beam, which pose8 the greatest danger of aberration~i. Upon leavina M X-2 the beam proceeds across the pole of the next negative magnet which further deflects the beam outward. At this point it passes out of the main accelerator vacuum tank. In order to nxiss the next magnet back leg, further bending is required. Because of the small amount of space available, another pulsed magnet, MX-3,' is employed. MX-3 is a 5 tilogauss picture frame ironcored magnet which bends the beam 24'. MX-4 and PAX-6 a r e dc 5 kilogauss magnets with'adjustable &* entrance edge angles, With appropriate choice of edge angles, spacings and bendhg angles of NIX-4 and fMX-5, particles initially on dfffereat equilibrium orbits of the accelerator will all Ue on a single line when / leaving MX-5. MX-4 is placed 80 cm f m m MX-3 and bends the beam 30°, Its entrance edge angle is lo (radially focusing). M X-5 is placed 1 meter from 1W[-4 and bends the beam 45'. Its entrance edge angle is 0.3O (radially focusing), The small entrance edge angles help to minimbe \ the aberrations in the system. At several placoe in, the oystem electrostatic induction electrodes are provided to detect tho, position of the center of mass of the beam.