- Email: [email protected]
Target K-shell ionization accompanied by single and double capture in F9++Ar collisions
Nuclear Instruments and Methods in Physics Research B xxx (2017) xxx–xxx
Contents lists available at ScienceDirect
Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb
Target K-shell ionization accompanied by single and double capture in F9þ þ Ar collisions D.S. La Mantia a,⇑, P.N.S. Kumara a, A. Kayani a, A. Simon b, J.A. Tanis a a b
Department of Physics, Western Michigan University, Kalamazoo, MI 49008-5252, USA Department of Physics, University of Notre Dame, Notre Dame, IN 46556-5670, USA
a r t i c l e
i n f o
Article history: Received 14 November 2016 Received in revised form 5 March 2017 Accepted 1 April 2017 Available online xxxx Keywords: K-shell ionization Capture cross section
a b s t r a c t Cross sections for target Ar K-shell X-ray emission accompanied by single and double electron capture, as well as the total cross sections for single and double electron capture, have been measured for incident 1.8–2.4 MeV/u F9+ ions colliding with Ar. Coincidences between the detected X-rays and the chargechanged projectile ions were recorded. Preliminary analysis indicates total cross sections for single electron capture on the order 1017 cm2 , with those for double capture being about an order of magnitude smaller. The corresponding cross sections for target K-shell X-ray emission accompanied by single and double electron capture, despite being about 103 times smaller, are nearly flat and approximately equal, a result that was not expected. Ó 2017 Elsevier B.V. All rights reserved.
1. Introduction Ion-atom collisions are of fundamental importance in atomic physics, with the charge exchange and ionization processes being of particular interest. Cross sections for these processes are needed extensively in studies of astrophysics, plasma physics, and radiation detection to name a few. Specifically, there have been extensive studies of K-shell ionization. Theoretical studies generally deal with the calculation of electron capture cross sections [1–3], while experimental studies deal with the measurement of these cross sections [4–6]. Motivation for the present investigation is based on previous work for fully-stripped fluorine [7,8] and oxygen [9] projectiles on Ar targets. The use of coincidence techniques in the present work to assign the Ar K-shell X-rays emitted to charge-captured projectiles allows for the determination of cross sections for more select events than recorded in the previous works. Fully-stripped fluorine ions colliding with Ar target atoms can result in the loss of one or two Ar K-shell electrons as shown in Fig. 1, following which an electron from an outer shell of the Ar atom can then fall to the K-shell with the emission of an x ray. The projectile may capture no electrons, or capture one, two or more electrons in the collision process. The captured electron can come from any of the target shells, and not necessarily from the Ar K-shell. In this work the cross sections for one and two electron ⇑ Corresponding author. E-mail address: [email protected] (D.S. La Mantia).
capture from the target were measured. Cross sections for target Ar K-shell X-ray production accompanied by single and double electron capture to the incident projectile and the total cross sections for single and double electron capture were determined for ion beam energies of 1.8–2.4 MeV/u.
2. Experimental procedure This work was performed using the tandem Van de Graaff accelerator at Western Michigan University. An analyzing magnet was used to select F7þ ions with the desired energy. These ions were then post-stripped to F9þ by a thin carbon foil following acceleration. This final ion beam was then deflected into the beamline and collimated by adjustable apertures before entering the experimental apparatus as shown in Fig. 2. The collision chamber is a differentially pumped gas cell 3.65 cm long with entrance and exit aperture diameters of about 3 mm. The target gas pressure is measured with a capacitance manometer and the pressures were set to have values in the single collision regime (less than 5 mTorr). A Si(Li) X-ray detector was positioned at 90° to the beamline to view the interaction region. After passing through the collision chamber, the ion beam was charge state analyzed using a dipole magnet. The beam components of single and double capture were detected using silicon surface-barrier particle detectors. The primary ion beam was collected in a Faraday cup biased to 200 V to suppress electrons and measured with a Keithley electrometer and then digitized to
http://dx.doi.org/10.1016/j.nimb.2017.04.008 0168-583X/Ó 2017 Elsevier B.V. All rights reserved.
Please cite this article in press as: D.S. La Mantia et al., Target K-shell ionization accompanied by single and double capture in F9þ þ Ar collisions, Nucl. Instr. Meth. B (2017), http://dx.doi.org/10.1016/j.nimb.2017.04.008
2
D.S. La Mantia et al. / Nuclear Instruments and Methods in Physics Research B xxx (2017) xxx–xxx
Fig. 1. Schematic showing the loss of one (or two) electrons from the target Ar Kshell by an incident F9þ projectile. In addition to no capture, the projectile may capture one, two or more electrons. The captured electron(s) can come from any of the shells and not necessarily the K-shell. The brackets indicate the final projectile charge states measured in this work. Fig. 3. Total single and double capture cross sections for Ar targets. The solid points for F9þ are the present data and the open symbols for O8þ are data from Ref. [9]. The lines are drawn to guide the eye. The absolute errors of the cross sections for the present data are estimated to be about 25%.
Fig. 2. Schematic of the experimental setup showing the detection of coincidences between X-rays emitted and the charge-changed ions. Silicon surface-barrier (SB) detectors were used to observe the individual charge states. The X-ray detector is a lithium-drifted silicon detector, i.e., a Si(Li).
give the number of incident particles. The X-ray and particle detector data were collected using an event-mode data acquisition system to assign the measured X-rays to the charge-changed particles.
3. Results and discussion Total capture cross sections were determined by measuring the number of single and double charge-exchanged particles relative to the total number of particles in the beam collected. These cross sections are shown in Fig. 3. For single electron capture, the total capture cross sections are on the order of tens of megabarns, starting with a value of about 85 at the beginning of the energy range measured and then decreasing from this value. The values are consistent with similar measurements for fully-stripped oxygen projectiles on Ar [9] over a similar energy range, also shown in Fig. 3. The total cross sections for double electron capture are about an order of magnitude lower than for single electron capture. The cross sections for F9þ are somewhat larger than the corresponding ones for O8þ due to the higher charge state. Both cross sections are seen to decrease with the projectile beam energy, with the fluorine cross sections decreasing more strongly presumably due to the higher charge state. Singly and doubly charge-changed particles detected in coincidence with target X-rays were also recorded. Typical spectra for
these data, corrected for random background coincidences, are shown in (Fig. 4), where the Ar Ka and Kb X-ray peaks can be seen for single and double electron capture. The Ar Ka peak is seen to be about 4 times larger than the Kb peak. The K-shell emission peaks are seen to occur in the same position for single and double capture. However, the yield of both peaks is seen to be on the same order of magnitude, a result that was not expected. The ratios of the cross sections for the emission of Ar K-shell Xrays accompanied by double to single electron capture range from about 1.25–0.55, as shown in Fig. 5. These ratios decrease with increasing projectile beam energy, showing that double electron capture emits target Ar K-shell X-rays at lower energies with higher probability. This is most likely due to the fact that at higher projectile energies the electron capture probability falls off rapidly [9], with double capture decreasing more strongly than single capture when a K-shell electron is ejected. Unexpectedly, these ratios do not show a factor of ten variation between the values for the total single and double capture cross sections displayed in Fig. 3. The cross section values for these data are approximately equal and are on the order of tens of kilobarns. These cross sections, as well as the total capture cross sections again, are shown in Fig. 6. To obtain the absolute cross sections corresponding to the data of Fig. 4, the yields of single and double capture were normalized to the total K X-ray cross section values given in Ref. [7]. Total Ar K Xray cross sections from Ref. [7] and Ref. [10] are also plotted in Fig. 6. These cross sections are about a factor of 5 larger than the determined cross sections for Ar K X-ray emission accompanied by single and double electron capture. With the cross sections for Ar K X-ray emission associated with single and double capture both being about 20% of the total K-shell production, it is reasonable given that the major contributing factor to the total cross section is impact-induced ionization [3]. Unfortunately, more data on similar cross sections could not be found in the literature. The total capture cross sections are 103 —102 times larger than the Ar K X-ray cross sections over the energy range. The fluorescence yield of Ar (0.10) indicates that mainly target L- and Mshell electrons are captured by the projectile and not K-shell electrons. In fact, for fast ion projectiles incident on Ar in the energy range studied here, capture primarily occurs for electrons from the L shell, while target electron ionization is primarily from the M shell [11]. Moreover, at these energies impact-induced ioniza-
Please cite this article in press as: D.S. La Mantia et al., Target K-shell ionization accompanied by single and double capture in F9þ þ Ar collisions, Nucl. Instr. Meth. B (2017), http://dx.doi.org/10.1016/j.nimb.2017.04.008
D.S. La Mantia et al. / Nuclear Instruments and Methods in Physics Research B xxx (2017) xxx–xxx
3
Fig. 4. Coincidence X-ray spectra accompanied by (a) single electron capture and (b) double electron capture for 2.4 MeV/u F9þ + Ar at a pressure of 4 mTorr. These spectra have been corrected for random coincidences which have been subtracted.
tion dominates the electron removal processes over electron capture [12]. There is therefore a lower probability that a K-shell electron will be captured or even ionized. When an Ar K x ray is emitted, it is plausible that the probability of capture of one, two, or more (not measured) electrons will be comparable. The Ar K X-ray cross sections do not show the strong decrease over the projectile energy range that the total cross sections exhibit, and instead increase somewhat. This result was not expected and may be due to the fact that the higher K-shell ionization energy results in the electrons being more likely captured in this projectile energy range. The cross sections for single and double capture from the Ar K-shell being approximately equal likely confirms this, given that the ionization energy of both electrons versus that for a single electron in comparison to the projectile energy is approximately equal. The reason for this behaviour will be further investigated in future work. 4. Summary Fig. 5. Ratios of the present data for Ar K X-ray emission accompanied by double to single electron capture. The line is drawn to guide the eye. The absolute errors for these ratios are estimated to be 10%.
Cross sections for total single and double electron capture for F9þ + Ar were measured over the projectile energy range 1.8– 2.4 MeV/u, as well as the cross sections for single and double electron capture associated with the emission of target Ar K-shell x rays. This was done using coincidence techniques employing a Si (Li) X-ray detector and silicon surface-barrier particle detectors. The cross sections for total single electron capture were found to be on the order of tens of megabarns, while the total cross sections for double electron capture were about an order of magnitude lower. Both cross sections decrease strongly with increasing ion projectile energy. The cross sections for the emission of Ar Kshell X-rays accompanied by single and double electron capture were found to be on the order of tens of kilobarns with the ratios of the double to single cross sections accompanied by K-shell Xray emission being close to unity. This latter finding was not expected and the reason for these single and double capture cross sections being on the same order of magnitude will be investigated further. Acknowledgements This work was supported in part by NSF under Grant No. PHY1401429.
Fig. 6. Total single and double capture cross sections and cross sections for the emission of Ar K-shell X-rays accompanied by single and double electron capture for F9þ + Ar. The measured single and double capture Ar K X-ray yields Fig. 4 were normalized to the total Ar K X-ray cross section data of Ref. [7] to obtain the cross sections shown. The curves are drawn to guide the eye. The unfilled diamond [7] and stars [10] are the cross sections for total K X-ray production. The Ar K X-ray cross sections for single and double capture for the present data have absolute errors estimated to be about 40%.
References [1] [2] [3] [4]
R.E. Olson, Phys. Rev. A 18 (1978) 2464–2469. J. Eichler, F.T. Chan, Phys. Rev. A 20 (1979) 104–112. M.L. McKenzie, R.E. Olson, Phys. Rev. A 35 (1987) 2863, 541. J.R. Macdonald, L. Winters, M.D. Brown, T. Chiao, L.D. Ellsworth, Phys. Rev. Lett. 29 (1972) 1291–1295. [5] T.R. Dillingham, J.R. Macdonald, P. Richard, Phys. Rev. A 24 (1981) 1237–1248.
Please cite this article in press as: D.S. La Mantia et al., Target K-shell ionization accompanied by single and double capture in F9þ þ Ar collisions, Nucl. Instr. Meth. B (2017), http://dx.doi.org/10.1016/j.nimb.2017.04.008
4
D.S. La Mantia et al. / Nuclear Instruments and Methods in Physics Research B xxx (2017) xxx–xxx
[6] A.S. Schlachter, J.W. Stearns, W.G. Graham, K.H. Berkner, P.V. Pyle, J.A. Tanis, Phys. Rev. A 27 (1983) 3372–3374. [7] L.M. Winters, J.R. Macdonald, M.D. Brown, T. Chiao, L.D. Ellsworth, E.W. Pettua, Phys. Rev. A 8 (1973) 1835–1843. [8] F. Hopkins, R.L. Kauffman, C.W. Woods, P. Richard, Phys. Rev. A 9 (1974) 2413– 2420.
[9] J.H. Houck, P.A. Zavodszky, J.A. Tanis, Phys. Rev. A 56 (1997) 1954–1957. [10] S.J. Czuchlewski, J.R. Macdonald, L.D. Ellsworth, Phys. Rev. A 11 (1975) 1108– 1113. [11] A. Muller, B. Schuch, W. Grob, E. Salzborn, H.F. Beyer, P.H. Mokler, R.E. Olson, Phys. Rev. A 33 (1986) 3010–3017. [12] R.E. Olson, A. Salop, Phys. Rev. A 16 (1977) 531–541.
Please cite this article in press as: D.S. La Mantia et al., Target K-shell ionization accompanied by single and double capture in F9þ þ Ar collisions, Nucl. Instr. Meth. B (2017), http://dx.doi.org/10.1016/j.nimb.2017.04.008
Contents lists available at ScienceDirect
Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb
Target K-shell ionization accompanied by single and double capture in F9þ þ Ar collisions D.S. La Mantia a,⇑, P.N.S. Kumara a, A. Kayani a, A. Simon b, J.A. Tanis a a b
Department of Physics, Western Michigan University, Kalamazoo, MI 49008-5252, USA Department of Physics, University of Notre Dame, Notre Dame, IN 46556-5670, USA
a r t i c l e
i n f o
Article history: Received 14 November 2016 Received in revised form 5 March 2017 Accepted 1 April 2017 Available online xxxx Keywords: K-shell ionization Capture cross section
a b s t r a c t Cross sections for target Ar K-shell X-ray emission accompanied by single and double electron capture, as well as the total cross sections for single and double electron capture, have been measured for incident 1.8–2.4 MeV/u F9+ ions colliding with Ar. Coincidences between the detected X-rays and the chargechanged projectile ions were recorded. Preliminary analysis indicates total cross sections for single electron capture on the order 1017 cm2 , with those for double capture being about an order of magnitude smaller. The corresponding cross sections for target K-shell X-ray emission accompanied by single and double electron capture, despite being about 103 times smaller, are nearly flat and approximately equal, a result that was not expected. Ó 2017 Elsevier B.V. All rights reserved.
1. Introduction Ion-atom collisions are of fundamental importance in atomic physics, with the charge exchange and ionization processes being of particular interest. Cross sections for these processes are needed extensively in studies of astrophysics, plasma physics, and radiation detection to name a few. Specifically, there have been extensive studies of K-shell ionization. Theoretical studies generally deal with the calculation of electron capture cross sections [1–3], while experimental studies deal with the measurement of these cross sections [4–6]. Motivation for the present investigation is based on previous work for fully-stripped fluorine [7,8] and oxygen [9] projectiles on Ar targets. The use of coincidence techniques in the present work to assign the Ar K-shell X-rays emitted to charge-captured projectiles allows for the determination of cross sections for more select events than recorded in the previous works. Fully-stripped fluorine ions colliding with Ar target atoms can result in the loss of one or two Ar K-shell electrons as shown in Fig. 1, following which an electron from an outer shell of the Ar atom can then fall to the K-shell with the emission of an x ray. The projectile may capture no electrons, or capture one, two or more electrons in the collision process. The captured electron can come from any of the target shells, and not necessarily from the Ar K-shell. In this work the cross sections for one and two electron ⇑ Corresponding author. E-mail address: [email protected] (D.S. La Mantia).
capture from the target were measured. Cross sections for target Ar K-shell X-ray production accompanied by single and double electron capture to the incident projectile and the total cross sections for single and double electron capture were determined for ion beam energies of 1.8–2.4 MeV/u.
2. Experimental procedure This work was performed using the tandem Van de Graaff accelerator at Western Michigan University. An analyzing magnet was used to select F7þ ions with the desired energy. These ions were then post-stripped to F9þ by a thin carbon foil following acceleration. This final ion beam was then deflected into the beamline and collimated by adjustable apertures before entering the experimental apparatus as shown in Fig. 2. The collision chamber is a differentially pumped gas cell 3.65 cm long with entrance and exit aperture diameters of about 3 mm. The target gas pressure is measured with a capacitance manometer and the pressures were set to have values in the single collision regime (less than 5 mTorr). A Si(Li) X-ray detector was positioned at 90° to the beamline to view the interaction region. After passing through the collision chamber, the ion beam was charge state analyzed using a dipole magnet. The beam components of single and double capture were detected using silicon surface-barrier particle detectors. The primary ion beam was collected in a Faraday cup biased to 200 V to suppress electrons and measured with a Keithley electrometer and then digitized to
http://dx.doi.org/10.1016/j.nimb.2017.04.008 0168-583X/Ó 2017 Elsevier B.V. All rights reserved.
Please cite this article in press as: D.S. La Mantia et al., Target K-shell ionization accompanied by single and double capture in F9þ þ Ar collisions, Nucl. Instr. Meth. B (2017), http://dx.doi.org/10.1016/j.nimb.2017.04.008
2
D.S. La Mantia et al. / Nuclear Instruments and Methods in Physics Research B xxx (2017) xxx–xxx
Fig. 1. Schematic showing the loss of one (or two) electrons from the target Ar Kshell by an incident F9þ projectile. In addition to no capture, the projectile may capture one, two or more electrons. The captured electron(s) can come from any of the shells and not necessarily the K-shell. The brackets indicate the final projectile charge states measured in this work. Fig. 3. Total single and double capture cross sections for Ar targets. The solid points for F9þ are the present data and the open symbols for O8þ are data from Ref. [9]. The lines are drawn to guide the eye. The absolute errors of the cross sections for the present data are estimated to be about 25%.
Fig. 2. Schematic of the experimental setup showing the detection of coincidences between X-rays emitted and the charge-changed ions. Silicon surface-barrier (SB) detectors were used to observe the individual charge states. The X-ray detector is a lithium-drifted silicon detector, i.e., a Si(Li).
give the number of incident particles. The X-ray and particle detector data were collected using an event-mode data acquisition system to assign the measured X-rays to the charge-changed particles.
3. Results and discussion Total capture cross sections were determined by measuring the number of single and double charge-exchanged particles relative to the total number of particles in the beam collected. These cross sections are shown in Fig. 3. For single electron capture, the total capture cross sections are on the order of tens of megabarns, starting with a value of about 85 at the beginning of the energy range measured and then decreasing from this value. The values are consistent with similar measurements for fully-stripped oxygen projectiles on Ar [9] over a similar energy range, also shown in Fig. 3. The total cross sections for double electron capture are about an order of magnitude lower than for single electron capture. The cross sections for F9þ are somewhat larger than the corresponding ones for O8þ due to the higher charge state. Both cross sections are seen to decrease with the projectile beam energy, with the fluorine cross sections decreasing more strongly presumably due to the higher charge state. Singly and doubly charge-changed particles detected in coincidence with target X-rays were also recorded. Typical spectra for
these data, corrected for random background coincidences, are shown in (Fig. 4), where the Ar Ka and Kb X-ray peaks can be seen for single and double electron capture. The Ar Ka peak is seen to be about 4 times larger than the Kb peak. The K-shell emission peaks are seen to occur in the same position for single and double capture. However, the yield of both peaks is seen to be on the same order of magnitude, a result that was not expected. The ratios of the cross sections for the emission of Ar K-shell Xrays accompanied by double to single electron capture range from about 1.25–0.55, as shown in Fig. 5. These ratios decrease with increasing projectile beam energy, showing that double electron capture emits target Ar K-shell X-rays at lower energies with higher probability. This is most likely due to the fact that at higher projectile energies the electron capture probability falls off rapidly [9], with double capture decreasing more strongly than single capture when a K-shell electron is ejected. Unexpectedly, these ratios do not show a factor of ten variation between the values for the total single and double capture cross sections displayed in Fig. 3. The cross section values for these data are approximately equal and are on the order of tens of kilobarns. These cross sections, as well as the total capture cross sections again, are shown in Fig. 6. To obtain the absolute cross sections corresponding to the data of Fig. 4, the yields of single and double capture were normalized to the total K X-ray cross section values given in Ref. [7]. Total Ar K Xray cross sections from Ref. [7] and Ref. [10] are also plotted in Fig. 6. These cross sections are about a factor of 5 larger than the determined cross sections for Ar K X-ray emission accompanied by single and double electron capture. With the cross sections for Ar K X-ray emission associated with single and double capture both being about 20% of the total K-shell production, it is reasonable given that the major contributing factor to the total cross section is impact-induced ionization [3]. Unfortunately, more data on similar cross sections could not be found in the literature. The total capture cross sections are 103 —102 times larger than the Ar K X-ray cross sections over the energy range. The fluorescence yield of Ar (0.10) indicates that mainly target L- and Mshell electrons are captured by the projectile and not K-shell electrons. In fact, for fast ion projectiles incident on Ar in the energy range studied here, capture primarily occurs for electrons from the L shell, while target electron ionization is primarily from the M shell [11]. Moreover, at these energies impact-induced ioniza-
Please cite this article in press as: D.S. La Mantia et al., Target K-shell ionization accompanied by single and double capture in F9þ þ Ar collisions, Nucl. Instr. Meth. B (2017), http://dx.doi.org/10.1016/j.nimb.2017.04.008
D.S. La Mantia et al. / Nuclear Instruments and Methods in Physics Research B xxx (2017) xxx–xxx
3
Fig. 4. Coincidence X-ray spectra accompanied by (a) single electron capture and (b) double electron capture for 2.4 MeV/u F9þ + Ar at a pressure of 4 mTorr. These spectra have been corrected for random coincidences which have been subtracted.
tion dominates the electron removal processes over electron capture [12]. There is therefore a lower probability that a K-shell electron will be captured or even ionized. When an Ar K x ray is emitted, it is plausible that the probability of capture of one, two, or more (not measured) electrons will be comparable. The Ar K X-ray cross sections do not show the strong decrease over the projectile energy range that the total cross sections exhibit, and instead increase somewhat. This result was not expected and may be due to the fact that the higher K-shell ionization energy results in the electrons being more likely captured in this projectile energy range. The cross sections for single and double capture from the Ar K-shell being approximately equal likely confirms this, given that the ionization energy of both electrons versus that for a single electron in comparison to the projectile energy is approximately equal. The reason for this behaviour will be further investigated in future work. 4. Summary Fig. 5. Ratios of the present data for Ar K X-ray emission accompanied by double to single electron capture. The line is drawn to guide the eye. The absolute errors for these ratios are estimated to be 10%.
Cross sections for total single and double electron capture for F9þ + Ar were measured over the projectile energy range 1.8– 2.4 MeV/u, as well as the cross sections for single and double electron capture associated with the emission of target Ar K-shell x rays. This was done using coincidence techniques employing a Si (Li) X-ray detector and silicon surface-barrier particle detectors. The cross sections for total single electron capture were found to be on the order of tens of megabarns, while the total cross sections for double electron capture were about an order of magnitude lower. Both cross sections decrease strongly with increasing ion projectile energy. The cross sections for the emission of Ar Kshell X-rays accompanied by single and double electron capture were found to be on the order of tens of kilobarns with the ratios of the double to single cross sections accompanied by K-shell Xray emission being close to unity. This latter finding was not expected and the reason for these single and double capture cross sections being on the same order of magnitude will be investigated further. Acknowledgements This work was supported in part by NSF under Grant No. PHY1401429.
Fig. 6. Total single and double capture cross sections and cross sections for the emission of Ar K-shell X-rays accompanied by single and double electron capture for F9þ + Ar. The measured single and double capture Ar K X-ray yields Fig. 4 were normalized to the total Ar K X-ray cross section data of Ref. [7] to obtain the cross sections shown. The curves are drawn to guide the eye. The unfilled diamond [7] and stars [10] are the cross sections for total K X-ray production. The Ar K X-ray cross sections for single and double capture for the present data have absolute errors estimated to be about 40%.
References [1] [2] [3] [4]
R.E. Olson, Phys. Rev. A 18 (1978) 2464–2469. J. Eichler, F.T. Chan, Phys. Rev. A 20 (1979) 104–112. M.L. McKenzie, R.E. Olson, Phys. Rev. A 35 (1987) 2863, 541. J.R. Macdonald, L. Winters, M.D. Brown, T. Chiao, L.D. Ellsworth, Phys. Rev. Lett. 29 (1972) 1291–1295. [5] T.R. Dillingham, J.R. Macdonald, P. Richard, Phys. Rev. A 24 (1981) 1237–1248.
Please cite this article in press as: D.S. La Mantia et al., Target K-shell ionization accompanied by single and double capture in F9þ þ Ar collisions, Nucl. Instr. Meth. B (2017), http://dx.doi.org/10.1016/j.nimb.2017.04.008
4
D.S. La Mantia et al. / Nuclear Instruments and Methods in Physics Research B xxx (2017) xxx–xxx
[6] A.S. Schlachter, J.W. Stearns, W.G. Graham, K.H. Berkner, P.V. Pyle, J.A. Tanis, Phys. Rev. A 27 (1983) 3372–3374. [7] L.M. Winters, J.R. Macdonald, M.D. Brown, T. Chiao, L.D. Ellsworth, E.W. Pettua, Phys. Rev. A 8 (1973) 1835–1843. [8] F. Hopkins, R.L. Kauffman, C.W. Woods, P. Richard, Phys. Rev. A 9 (1974) 2413– 2420.
[9] J.H. Houck, P.A. Zavodszky, J.A. Tanis, Phys. Rev. A 56 (1997) 1954–1957. [10] S.J. Czuchlewski, J.R. Macdonald, L.D. Ellsworth, Phys. Rev. A 11 (1975) 1108– 1113. [11] A. Muller, B. Schuch, W. Grob, E. Salzborn, H.F. Beyer, P.H. Mokler, R.E. Olson, Phys. Rev. A 33 (1986) 3010–3017. [12] R.E. Olson, A. Salop, Phys. Rev. A 16 (1977) 531–541.
Please cite this article in press as: D.S. La Mantia et al., Target K-shell ionization accompanied by single and double capture in F9þ þ Ar collisions, Nucl. Instr. Meth. B (2017), http://dx.doi.org/10.1016/j.nimb.2017.04.008