Experiments with a synchrotron x-ray source and conventional, ECR, and storage-ring ion sources Page: 7 of 13
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Table V Typical Photon Beaus from the
CHISR RingSuperconducting Wiggler at the
Beam Horizontal Vertical Flux
Energy AE and AE/E Size (2a) Size (2a) photons/(s-mr)
keV - as
A. Unfocussed White Beam
5 60 25 1 x 1017
20 60 14 5 x 1016
100 60 7
B. Focussed White Beam
5 10 25 1 x 1017
20 10 14
(High Energy Cut-Off at 20 keV.
C. Silicon Monochrom for
5 1.0 x 20- 1.2 x 1013
10 1.7 x 10-3 1.1 x 1013
20 2.7 x 10-3 7.9 x 1012
50 5.2 x 10-3 2.2 x 1012
100 9.0 x 10-3 2.5 x 1011
It must be remembered that the SRS is a pulsed machine. The
NSLS produces bursts of photons with a width of 0.6-1. ns (4a) that
occur at intervals of 18.9 ns. The microstructure of the beam makes
measurements of the background in the beam-beam experiments fairly
easy.
PHOTOIONIZATION WITH A CONVENTIONAL ION SOURCE
The only experiments on tha photoionization of an ion beam to
date6 used a surface ionization type source to produce beams such as
Ba+ and K+. Currents of about 10 nA were obtained at an energy of 2
keV and a beam size of 2 m x 3 ms. !e photon fluxes incident on
the ion beam varied from 10 to 6 x 10 photons/s depending on the
energy resolution of the monochromator employed. A merging length of
12.5 cm was used to achieve a signal rate of 100 events/s with the
high resolution beam and a cross section of abou 10'I cm2. By
definition the luminosity is of the order of 101 cm-2 s-1 for the
long path length of 12.5 cm. This can be verified by direct
calculation of the expected rate for the conditions mentioned above.
The background rate was about 1/2 to 1/5 the signal at the point of
highes cross section. The background luminosity is then around 2-5
x 101 cm- s- . Extracting the signal from this background
ultimately limits the size of cross section which can be investigated.
Lyon et al.6 cite a value of about 1020 cm2 for that number.
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Jones, K. W.; Johnson, B. M. & Meron, M. Experiments with a synchrotron x-ray source and conventional, ECR, and storage-ring ion sources, article, January 1, 1988; Upton, New York. (https://digital.library.unt.edu/ark:/67531/metadc1107459/m1/7/: accessed April 26, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.