Accelerator Mass Spectrometry and Radioisotope Detection at the Argonne FN Tandem Facility Page: 8 of 63
63 pagesView a full description of this article.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
7
2.2.2. Low-energy beam transport.
The low-energy injection system into the tandem (see fig. 1) serves
two major functions: to match the beam acceptance phase ellipse of the
accelerator and to provide some mass selection. The mass selection is
provided by the 40 injection magnet approximately halfway between the ion-
source and the first acceleration electrode. The magnet is double focussing
and provides a mass resolution of approximately 1 in 80. This is sufficient
for the mass range presently of interest, i.e. A 60, to reduce neighboring
background beams, which otherwise lead to unnecessary loading of the
accelerator.
Except for the 40* injection magnet, all ion-optical components
at the low-energy end of the tandem are electrostatic. As a consequence,for the fi>
injection voltage of at present 132 kV achieved through pre-acceleration with
two of the three NEC general-purpose accelerator tubes right after the ion source,
all jingly-charged negative ions will follow identical beam optics because they
have identical energy versus charge ratio, E/q. This is important for the
radioisotope measurements, where ratios are determined for beam currents,
respectively ion rates from different isotopes. Mass-dependence in beam
transmission due to the 40 injection magnet is minimized by the fact that
the beam injected into the tandem has an emittance of 4 mm-mrad-MeV2, which is
at least a factor of two smaller than the acceptance of the accelerator.
The low-energy beam optics is as follows: The beam from the source
will normally produce a waist following pre-acceleration. The waist
location is chosen halfway to the 40* magnet. A 30-KV 2-" einzel lens close
to the entrance of the 40 magnet provides a virtual object for the lens formed
by the magnet and the electrostatic quadrupole triplet. The use of
the electrostatic quadrupole triplet allows the production of the vertical
Upcoming Pages
Here’s what’s next.
Search Inside
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
Henning, W.; Kutschera, W.; Paul, M.; Smither, R. K.; Stephenson, E. J. & Yntema, J. L. Accelerator Mass Spectrometry and Radioisotope Detection at the Argonne FN Tandem Facility, article, 1980; Illinois. (https://digital.library.unt.edu/ark:/67531/metadc1212472/m1/8/: accessed July 16, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.