Measurements of the Total Charge-Changing Cross Sections for Collisions of Fast Ions with Target Gas Using High Current Experiment Page: 6 of 10
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Table I: Total cross sections measured using the whole magnetic transport section as a
gas cell.Gas Total cross
section (m2)
H2 1.35 x 10-
N2 2.98 x 10-19
He 5.62 x 10-20
Ne 1.19 x 10-19
Kr 5.20 x 10-19
Xe 7.11 x 10-19
Ar 3.71 x 10-19
H20 3.17 x 10-19Standard
deviation (m2)
1.55 x 10-z0
2.98 x 10-20
5.70 x 10-21
1.01 x 10-20
6.83 x 10-20
7.68 x 10-20
4.38 x 10-20
4.81 x 10-20The background pressure is obtained by adjusting the Stabil-Ion gauge
measurement with the calibration factor for the different gas species provided by the
manufacturer. The data are not adjusted to remove a small error caused by the
background gas contribution, which is minimized by the fact that the leaked gas is
flowing in the direction of the magnetic section exits, where most of the vacuum pumps
are located. The last line of Table I estimates the water vapor contribution into the cross
section. The errors for the experimental data are in the order of 10-15%, which includes
the beam reproducibility of -5%. Conservatively assuming that the Stabil-Ion gauge used
in the measurements is uncalibrated with expected accuracy of ~6% and the errors add in
quadrature, thus, the total error is approximately 16%.
Results of simulations using the CTMC method for the ionization and charge
exchange cross sections for the interaction of 1 MeV K+ with H2, He, and Ne are
summarized in Table II. For a 1 MeV K+ beam, the values of charge exchange cross
sections are 2-4 times higher than the ionization cross sections.
Table II: Ionization and charge exchange cross sections for the interaction of 1 MeV K+
with H2, He, and Ne. Atomic and ion potentials are taken from Ref. [24].Charge Exchange
cross section
5.92 x 10-20
4.10 x 10-20
9.46 x 10-20Ionization
cross section (m2)
3.00 x 10
1.10 x 10-20
3.91 x 10-20Table III: Comparison of calculated values of the total cross sections with experimental
data for interaction of 1 MeV K+ with H2, He, and Ne. The total error in experimental
data is about 16%.6
Gas
H2
He
NeCross Experiment Slater model
Section (m ) (m2)
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Covo, Michel Kireeff; Molvik, Arthur W.; Kaganovich, Igor D.; Shnidman, Ariel & Vujic, Jasmina L. Measurements of the Total Charge-Changing Cross Sections for Collisions of Fast Ions with Target Gas Using High Current Experiment, article, April 13, 2009; Berkeley, California. (https://digital.library.unt.edu/ark:/67531/metadc930444/m1/6/: accessed July 16, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.