- Email: [email protected]
Proposal for a prototype of portable μXRF spectrometer
Nuclear Instruments and Methods in Physics Research B xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb
Proposal for a prototype of portable lXRF spectrometer C. Polese a,b,⇑, S.B. Dabagov a,c,f, A. Esposito a, A. Liedl a,d, D. Hampai a, C. Bartùli b, M. Ferretti e a
INFN – LNF, XLab Frascati – Via E. Fermi, 40, I-00044 Frascati, Italy Dip. DICMA, Univ. Roma ‘‘Sapienza’’, Via Eudossiana 18, Roma, Italy c RAS P.N. Lebedev Physical Institute, Leninsky pr. 53, 119991 Moscow, Russia d Dip. Scienze, Univ. Roma3, Largo San Leonardo Murialdo 1, Roma, Italy e ITABC, CNR, Montelibretti, Roma, Italy f National Research Nuclear University MEPhI, Kashirskoe shosse 31, 115409 Moscow, Russia b
a r t i c l e
i n f o
Article history: Received 23 December 2014 Received in revised form 10 February 2015 Accepted 12 February 2015 Available online xxxx Keywords: Micro-XRF Polycapillary optics Cultural heritage
a b s t r a c t lXRF is a powerful instrument for non-destructive characterization of materials of cultural interest. At the XLab Frascati Laboratory this technique is already well performed thanks to the polyCO set equipment allowing simultaneous lXRF 2D mapping. However, due to the strict demand for in situ analysis in this particular field, a new portable lXRF spectrometer equipped with a full polycapillary lens conjugated with a transmission anode X-ray tube is proposed. Many cultural objects are characterized by elements (Ag, Sn, etc.) with high energy fluorescence K-lines. Thus, the capability of a full lens to deliver a high energy fraction of X-ray spectrum, in order to excite the fluorescence K-lines of such elements, is tested. Ó 2015 Elsevier B.V. All rights reserved.
1. Introduction X-ray fluorescence (XRF) spectrometry is widely used in in situ campaign for non-destructive characterization of materials of cultural interest [1]. Medium-Z elements (Ag, Sn, Sb, Ba etc.) are abundant in many different types of these materials such as paintings [2], glasses, and metals [3]. Their optimum detection involves the capability of exciting their fluorescence K-lines [4] by means of a high energy primary beam. Dealing with this kind of materials, the spatial resolution is also important because the details to be investigated can be very small [5] (Fig. 1). Advances in X-ray optics have made micro-beams available. Among them, polycapillary lenses [6–11] are very efficient in delivering high flux beams thanks to their peculiar geometry and large acceptance solid angle. They consists of many hollow glass channels that work by total external reflection (TER), as a guide for X-ray photons, and are arranged in barrel (focusing full-lenses) or half-barrel shapes (collimating semi-lenses). Commercial polyCO (XOS, IFG, XCT, etc.) act as a sort of low pass filter, suppressing the high energy fraction (>20 keV) of the beam [12,13], due to the severe energy dependence for TER critical angle (hc )
hc ðhxp Þ=E;
ð1Þ
⇑ Corresponding author at: INFN – LNF, XLab Frascati – Via E. Fermi, 40, I-00044 Frascati, Italy.
namely inverse proportional to the photon energy (hc < 1 for E > 2 keV). By theoretical calculation we can estimate a gain in the radiation density with respect to a pinhole focusing in the same size spot at the same distance according to the equation [6]:
G¼
X2l kT ; X2p
ð2Þ
where Xl is the solid angle captured by the lens at the input focal distance (IFD), Xp is the solid angle viewed in the spot obtained with the pinhole at distance L from the source, and kT is the polyCO transmission efficiency. In this paper we present the preliminary results in achieving relatively high energy micro-beams for portable systems. The rationale is to harden the input spectrum by means of filters and to use the central section of the lens, more efficient at high energies. 2. Experimental setup and preliminary results The measurements were carried out at XLab Frascati [14], a LNF INFN facility [15] dedicated to the study and characterization of Xray optics, with particular attention for polyCO lenses, and various X-ray analytical techniques [16,17], such as lXRF, lXRF 2D/3D imaging, X-ray micro-tomography (l-CT) [18,19], total reflection X-ray fluorescence (TXRF) [20], and X-ray diffraction (XRD).
http://dx.doi.org/10.1016/j.nimb.2015.02.043 0168-583X/Ó 2015 Elsevier B.V. All rights reserved.
Please cite this article in press as: C. Polese et al., Proposal for a prototype of portable lXRF spectrometer, Nucl. Instr. Meth. B (2015), http://dx.doi.org/ 10.1016/j.nimb.2015.02.043
2
C. Polese et al. / Nuclear Instruments and Methods in Physics Research B xxx (2015) xxx–xxx
Fig. 1. Picture of a medieval enameled silver plate.
Fig. 3. Transmission of the polyCO.
Fig. 2. Spectra of the primary beam and the focused one, normalized with respect to the total count rate.
Principal goal of these preliminary measurements was to characterize the primary beam focused by the optics and to evaluate its efficiency in exciting high energies fluorescence K-lines. An Oxford Apogee W anode X-ray tube, set at 50 kV and 1 mA, was used. The outcoming spectrum was recorded by placing a SDD detector (to be used also in the prototype: 10 mm2 active area, 450 lm thickness, FWHM 175 eV @ 5.9 keV) at 39 cm from the tube focus. The spectrum was corrected for the detector energy efficiency, and the time acquisition was 120 s. A filter made of a 70 lm thick sheet of stainless steel (Fe 74%, Cr 18%, Ni 8%) and a 60 lm thick sheet of copper was placed at the entrance of the lens, in order to enhance the high energy fraction of the spectrum. The polycapillary full-lens parameters correspond to the input focal distance (IFD) of 56.5 mm, the output focal distance (OFD) of 44 mm, the length of 12 cm, the input diameter of 4 mm, and a 100 lm focal spot size. The nominal values of OFD and beam size have been verified by taking some CCD images at various distances from the lens. The polyCO lens reduces the bremsstrahlung component at high energies and shifts its maximum to lower values (from 19 to 14 keV) (Fig. 2). The polyCO results to have a good efficiency in the energy range of 6–20 keV (Fig. 3) [21].
The spectra of focused beam with and without filter are shown in Fig. 4. It is evident that the filtering allows enhancing the high energy fraction of the primary beam. To estimate the setup capability of exciting high energy fluorescence K-lines, some XRF spectra for a standard bronze alloy have been recorded. Fig. 5 shows a comparison between the XRF spectra recorded filtering the primary beam, using a pinhole, the above mentioned polyCO and another full-lens optimized for high energies (HE) and with similar geometrical parameters. The first lens results to be not efficient in the high energy region, but both the polyCO provide a better excitation in the low energy region with respect to the pinhole. Fig. 6 shows, for the HE lens, the improvement in the excitation given by the filter. In this case the intensities of the two XRF spectra have been normalized in order to be comparable, because the unfiltered spectrum has been recorded at 60 lA. According to the experimental results, the first polyCO provides a gain of 3 orders of magnitude for Cu Ka and 1 over 10 keV, while the HE polyCO 4 orders for copper and even 3 up to 25 keV. It is evident that a lens with such parameters as the HE one could be suitable for the realization of a portable lXRF spectrometer able in the detection of high energy K-lines.
3. Prototype proposal To further improve the high flux beam focused by a polyCO, a transmission anode X-ray tube [11] could be used. It is characterized by a strongly reduced focus-window distance, and this property combined with the use of a fifth generation micro-lens, optimized for the transmission of high energy photons and with low IFD (<25 mm), would lead to capture a larger acceptance angle. To realize such a prototype, we propose a Moxtek transmission W anode X-ray tube: 50 kV, 200 lA, focal spot size 400 lm, 0.25 mm thick Be window, 92° emission solid angle, and a total weight of 950 g (important for the portability). The target is recessed of 2.29 mm from the front end, but with the lens of an input diameter smaller than the external Al collimator diameter (4.5 mm) it is possible to get closer to the target. As an alternative, also a polyCO like the HE one could be used by placing it closer than its optimum IFD value and using only its central section, which consists of channels with a low curvature radius and therefore is more efficient for the total reflection of the higher energy photons.
Please cite this article in press as: C. Polese et al., Proposal for a prototype of portable lXRF spectrometer, Nucl. Instr. Meth. B (2015), http://dx.doi.org/ 10.1016/j.nimb.2015.02.043
C. Polese et al. / Nuclear Instruments and Methods in Physics Research B xxx (2015) xxx–xxx
3
Fig. 4. Spectra of the focused primary beam, with (red line) and without (black dashed line) filter, normalized with respect to the total count rate. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 5. XRF spectra of a standard bronze alloy, with a pinhole (black), the polyCO optimized for low energies (blue) and the one for higher energies (red). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 6. XRF spectra of a standard bronze alloy obtained with the HE polyCO, with (red) and without (black) filter. The intensities have been normalized with respect to the total count rate. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Please cite this article in press as: C. Polese et al., Proposal for a prototype of portable lXRF spectrometer, Nucl. Instr. Meth. B (2015), http://dx.doi.org/ 10.1016/j.nimb.2015.02.043
4
C. Polese et al. / Nuclear Instruments and Methods in Physics Research B xxx (2015) xxx–xxx
4. Conclusion A preliminary study on the possibility of obtaining high energy beams and a spatial resolution of 100 lm by means of a full polyCO, for their application in in situ XRF analysis of materials of cultural interest, has been carried out. Filtering the beam proved to efficiently harden the primary focused beam, and the entire setup has resulted to be capable in exciting the K-lines of medium-Z elements (<30 keV). Hence, to realize a portable lXRF system we propose the use of a transmission anode tube combined with a polyCO similar to the tested one, placed closer than its IFD to the target. Such a tube would also allow to entirely exploit the potentiality of microlenses (soon manufactured at XLab Frascati), optimized for high energies and with lower IFDs. Acknowledgments One of the authors (SD) would like to acknowledge the support by the Ministry of Education and Science of RF in the frames of Competitiveness Growth Program of NRNU MEPhI, Agreement 02.A03.21.0005. References [1] C. Seccaroni, P. Moioli, Fluorescenza X. Prontuario per l’analisi XRF portatile applicata a superfici policrome, Nardini Editore, Firenze, Italy, 2002.
[2] L. De Viguerie, P. Walter, E. Laval, B. Mottin, A. Sole, Angew. Chem. Int. Ed. 49 (2010) 1–5. [3] M. Ferretti, C. Polese, C. Roldan Garcia, Spectrochim. Acta B 83–84 (2013) 21– 27. [4] M. Ferretti, J. Anal. At. Spectrom. 29 (2014) 1753. [5] A. Guilherme, S. Pessanha, M.L. Carvalho, J.M.F. dos Santos, J. Coroado, Spectrochim. Acta B 65 (4) (2010) 328–333. [6] S.B. Dabagov, Phys.-Usp. 46 (10) (2003) 1053–1075. [7] M.A. Kumakhov, F.F. Komarov, Phys. Rep. 191 (5) (1990) 289–350. [8] C.A. MacDonald, X-ray Optics Instr. 2010 (2010) 1–12. [9] P.J. Schields, D.M. Gibson, W.M. Gibson, N. Gao, H. Huang, I.Y. Ponomarev, Powder Diffr. 17 (2) (2002) 70–80. [10] N. Gao, K. Janssens, Polycapillary X-ray optics, in: K. Tsuji, J. Injuk, R. Van Grieken (Eds.), X-Ray Spectrometry: Recent Technological Advances, Wiley, Chichester, 2005, pp. 89–110. [11] Ch. Zarkadas, A.G. Karydas, Spectrochim. Acta B 59 (2004) 1611–1618. [12] G. Buzanich, P. Wobrauschek, C. Streli, A. Markowicz, D. Wegrzynek, E. ChineaCano, S. Bamfor, Spectrochim. Acta B 62 (2007) 1252–1256. [13] L. Cheng, X. Ding, Z. Liu, Q. Pan, X. Chu, Spectrochim. Acta B 62 (2007) 817– 823. [14] www.lnf.infn.it/xlab/index.html. [15] D. Hampai, S.B. Dabagov, G. Cappuccio, G. Cibin, V. Sessa, Spectrochim. Acta B 64 (2009) 1180–1184. [16] D. Hampai, S.B. Dabagov, G. Cappuccio, A. Longoni, T. Frizzi, G. Cibin, V. Guglielmotti, M. Sala, Opt. Lett. 33 (23) (2008) 2743–2745. [17] D. Hampai, A. Liedl, C. Polese, G. Cappuccio, S.B. Dabagov, EXRS 2014 (oral presentation). [18] A. Liedl, C. Polese, D. Hampai, G. Della Ventura, A. Marcelli, S.B. Dabagov, F. Bellatreccia, EXRS 2014 (poster). [19] D. Hampai, L. Marchitto, S.B. Dabagov, L. Allocca, S. Alfuso, L. Innocenti, Nucl. Instr. Meth. Phys. Res. Sect. B 309 (2013) 264–267. [20] D. Hampai, S.B. Dabagov, C. Polese, A. Liedl, G. Cappuccio, Spectrochim. Acta B 101 (2014) 114–117. [21] C. Polese, S.B. Dabagov, A. Esposito, D. Hampai, A. Gorghinian, A. Liedl, M. Ferretti, AIP Adv. 4 (2014) 077128.
Please cite this article in press as: C. Polese et al., Proposal for a prototype of portable lXRF spectrometer, Nucl. Instr. Meth. B (2015), http://dx.doi.org/ 10.1016/j.nimb.2015.02.043
Contents lists available at ScienceDirect
Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb
Proposal for a prototype of portable lXRF spectrometer C. Polese a,b,⇑, S.B. Dabagov a,c,f, A. Esposito a, A. Liedl a,d, D. Hampai a, C. Bartùli b, M. Ferretti e a
INFN – LNF, XLab Frascati – Via E. Fermi, 40, I-00044 Frascati, Italy Dip. DICMA, Univ. Roma ‘‘Sapienza’’, Via Eudossiana 18, Roma, Italy c RAS P.N. Lebedev Physical Institute, Leninsky pr. 53, 119991 Moscow, Russia d Dip. Scienze, Univ. Roma3, Largo San Leonardo Murialdo 1, Roma, Italy e ITABC, CNR, Montelibretti, Roma, Italy f National Research Nuclear University MEPhI, Kashirskoe shosse 31, 115409 Moscow, Russia b
a r t i c l e
i n f o
Article history: Received 23 December 2014 Received in revised form 10 February 2015 Accepted 12 February 2015 Available online xxxx Keywords: Micro-XRF Polycapillary optics Cultural heritage
a b s t r a c t lXRF is a powerful instrument for non-destructive characterization of materials of cultural interest. At the XLab Frascati Laboratory this technique is already well performed thanks to the polyCO set equipment allowing simultaneous lXRF 2D mapping. However, due to the strict demand for in situ analysis in this particular field, a new portable lXRF spectrometer equipped with a full polycapillary lens conjugated with a transmission anode X-ray tube is proposed. Many cultural objects are characterized by elements (Ag, Sn, etc.) with high energy fluorescence K-lines. Thus, the capability of a full lens to deliver a high energy fraction of X-ray spectrum, in order to excite the fluorescence K-lines of such elements, is tested. Ó 2015 Elsevier B.V. All rights reserved.
1. Introduction X-ray fluorescence (XRF) spectrometry is widely used in in situ campaign for non-destructive characterization of materials of cultural interest [1]. Medium-Z elements (Ag, Sn, Sb, Ba etc.) are abundant in many different types of these materials such as paintings [2], glasses, and metals [3]. Their optimum detection involves the capability of exciting their fluorescence K-lines [4] by means of a high energy primary beam. Dealing with this kind of materials, the spatial resolution is also important because the details to be investigated can be very small [5] (Fig. 1). Advances in X-ray optics have made micro-beams available. Among them, polycapillary lenses [6–11] are very efficient in delivering high flux beams thanks to their peculiar geometry and large acceptance solid angle. They consists of many hollow glass channels that work by total external reflection (TER), as a guide for X-ray photons, and are arranged in barrel (focusing full-lenses) or half-barrel shapes (collimating semi-lenses). Commercial polyCO (XOS, IFG, XCT, etc.) act as a sort of low pass filter, suppressing the high energy fraction (>20 keV) of the beam [12,13], due to the severe energy dependence for TER critical angle (hc )
hc ðhxp Þ=E;
ð1Þ
⇑ Corresponding author at: INFN – LNF, XLab Frascati – Via E. Fermi, 40, I-00044 Frascati, Italy.
namely inverse proportional to the photon energy (hc < 1 for E > 2 keV). By theoretical calculation we can estimate a gain in the radiation density with respect to a pinhole focusing in the same size spot at the same distance according to the equation [6]:
G¼
X2l kT ; X2p
ð2Þ
where Xl is the solid angle captured by the lens at the input focal distance (IFD), Xp is the solid angle viewed in the spot obtained with the pinhole at distance L from the source, and kT is the polyCO transmission efficiency. In this paper we present the preliminary results in achieving relatively high energy micro-beams for portable systems. The rationale is to harden the input spectrum by means of filters and to use the central section of the lens, more efficient at high energies. 2. Experimental setup and preliminary results The measurements were carried out at XLab Frascati [14], a LNF INFN facility [15] dedicated to the study and characterization of Xray optics, with particular attention for polyCO lenses, and various X-ray analytical techniques [16,17], such as lXRF, lXRF 2D/3D imaging, X-ray micro-tomography (l-CT) [18,19], total reflection X-ray fluorescence (TXRF) [20], and X-ray diffraction (XRD).
http://dx.doi.org/10.1016/j.nimb.2015.02.043 0168-583X/Ó 2015 Elsevier B.V. All rights reserved.
Please cite this article in press as: C. Polese et al., Proposal for a prototype of portable lXRF spectrometer, Nucl. Instr. Meth. B (2015), http://dx.doi.org/ 10.1016/j.nimb.2015.02.043
2
C. Polese et al. / Nuclear Instruments and Methods in Physics Research B xxx (2015) xxx–xxx
Fig. 1. Picture of a medieval enameled silver plate.
Fig. 3. Transmission of the polyCO.
Fig. 2. Spectra of the primary beam and the focused one, normalized with respect to the total count rate.
Principal goal of these preliminary measurements was to characterize the primary beam focused by the optics and to evaluate its efficiency in exciting high energies fluorescence K-lines. An Oxford Apogee W anode X-ray tube, set at 50 kV and 1 mA, was used. The outcoming spectrum was recorded by placing a SDD detector (to be used also in the prototype: 10 mm2 active area, 450 lm thickness, FWHM 175 eV @ 5.9 keV) at 39 cm from the tube focus. The spectrum was corrected for the detector energy efficiency, and the time acquisition was 120 s. A filter made of a 70 lm thick sheet of stainless steel (Fe 74%, Cr 18%, Ni 8%) and a 60 lm thick sheet of copper was placed at the entrance of the lens, in order to enhance the high energy fraction of the spectrum. The polycapillary full-lens parameters correspond to the input focal distance (IFD) of 56.5 mm, the output focal distance (OFD) of 44 mm, the length of 12 cm, the input diameter of 4 mm, and a 100 lm focal spot size. The nominal values of OFD and beam size have been verified by taking some CCD images at various distances from the lens. The polyCO lens reduces the bremsstrahlung component at high energies and shifts its maximum to lower values (from 19 to 14 keV) (Fig. 2). The polyCO results to have a good efficiency in the energy range of 6–20 keV (Fig. 3) [21].
The spectra of focused beam with and without filter are shown in Fig. 4. It is evident that the filtering allows enhancing the high energy fraction of the primary beam. To estimate the setup capability of exciting high energy fluorescence K-lines, some XRF spectra for a standard bronze alloy have been recorded. Fig. 5 shows a comparison between the XRF spectra recorded filtering the primary beam, using a pinhole, the above mentioned polyCO and another full-lens optimized for high energies (HE) and with similar geometrical parameters. The first lens results to be not efficient in the high energy region, but both the polyCO provide a better excitation in the low energy region with respect to the pinhole. Fig. 6 shows, for the HE lens, the improvement in the excitation given by the filter. In this case the intensities of the two XRF spectra have been normalized in order to be comparable, because the unfiltered spectrum has been recorded at 60 lA. According to the experimental results, the first polyCO provides a gain of 3 orders of magnitude for Cu Ka and 1 over 10 keV, while the HE polyCO 4 orders for copper and even 3 up to 25 keV. It is evident that a lens with such parameters as the HE one could be suitable for the realization of a portable lXRF spectrometer able in the detection of high energy K-lines.
3. Prototype proposal To further improve the high flux beam focused by a polyCO, a transmission anode X-ray tube [11] could be used. It is characterized by a strongly reduced focus-window distance, and this property combined with the use of a fifth generation micro-lens, optimized for the transmission of high energy photons and with low IFD (<25 mm), would lead to capture a larger acceptance angle. To realize such a prototype, we propose a Moxtek transmission W anode X-ray tube: 50 kV, 200 lA, focal spot size 400 lm, 0.25 mm thick Be window, 92° emission solid angle, and a total weight of 950 g (important for the portability). The target is recessed of 2.29 mm from the front end, but with the lens of an input diameter smaller than the external Al collimator diameter (4.5 mm) it is possible to get closer to the target. As an alternative, also a polyCO like the HE one could be used by placing it closer than its optimum IFD value and using only its central section, which consists of channels with a low curvature radius and therefore is more efficient for the total reflection of the higher energy photons.
Please cite this article in press as: C. Polese et al., Proposal for a prototype of portable lXRF spectrometer, Nucl. Instr. Meth. B (2015), http://dx.doi.org/ 10.1016/j.nimb.2015.02.043
C. Polese et al. / Nuclear Instruments and Methods in Physics Research B xxx (2015) xxx–xxx
3
Fig. 4. Spectra of the focused primary beam, with (red line) and without (black dashed line) filter, normalized with respect to the total count rate. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 5. XRF spectra of a standard bronze alloy, with a pinhole (black), the polyCO optimized for low energies (blue) and the one for higher energies (red). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 6. XRF spectra of a standard bronze alloy obtained with the HE polyCO, with (red) and without (black) filter. The intensities have been normalized with respect to the total count rate. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Please cite this article in press as: C. Polese et al., Proposal for a prototype of portable lXRF spectrometer, Nucl. Instr. Meth. B (2015), http://dx.doi.org/ 10.1016/j.nimb.2015.02.043
4
C. Polese et al. / Nuclear Instruments and Methods in Physics Research B xxx (2015) xxx–xxx
4. Conclusion A preliminary study on the possibility of obtaining high energy beams and a spatial resolution of 100 lm by means of a full polyCO, for their application in in situ XRF analysis of materials of cultural interest, has been carried out. Filtering the beam proved to efficiently harden the primary focused beam, and the entire setup has resulted to be capable in exciting the K-lines of medium-Z elements (<30 keV). Hence, to realize a portable lXRF system we propose the use of a transmission anode tube combined with a polyCO similar to the tested one, placed closer than its IFD to the target. Such a tube would also allow to entirely exploit the potentiality of microlenses (soon manufactured at XLab Frascati), optimized for high energies and with lower IFDs. Acknowledgments One of the authors (SD) would like to acknowledge the support by the Ministry of Education and Science of RF in the frames of Competitiveness Growth Program of NRNU MEPhI, Agreement 02.A03.21.0005. References [1] C. Seccaroni, P. Moioli, Fluorescenza X. Prontuario per l’analisi XRF portatile applicata a superfici policrome, Nardini Editore, Firenze, Italy, 2002.
[2] L. De Viguerie, P. Walter, E. Laval, B. Mottin, A. Sole, Angew. Chem. Int. Ed. 49 (2010) 1–5. [3] M. Ferretti, C. Polese, C. Roldan Garcia, Spectrochim. Acta B 83–84 (2013) 21– 27. [4] M. Ferretti, J. Anal. At. Spectrom. 29 (2014) 1753. [5] A. Guilherme, S. Pessanha, M.L. Carvalho, J.M.F. dos Santos, J. Coroado, Spectrochim. Acta B 65 (4) (2010) 328–333. [6] S.B. Dabagov, Phys.-Usp. 46 (10) (2003) 1053–1075. [7] M.A. Kumakhov, F.F. Komarov, Phys. Rep. 191 (5) (1990) 289–350. [8] C.A. MacDonald, X-ray Optics Instr. 2010 (2010) 1–12. [9] P.J. Schields, D.M. Gibson, W.M. Gibson, N. Gao, H. Huang, I.Y. Ponomarev, Powder Diffr. 17 (2) (2002) 70–80. [10] N. Gao, K. Janssens, Polycapillary X-ray optics, in: K. Tsuji, J. Injuk, R. Van Grieken (Eds.), X-Ray Spectrometry: Recent Technological Advances, Wiley, Chichester, 2005, pp. 89–110. [11] Ch. Zarkadas, A.G. Karydas, Spectrochim. Acta B 59 (2004) 1611–1618. [12] G. Buzanich, P. Wobrauschek, C. Streli, A. Markowicz, D. Wegrzynek, E. ChineaCano, S. Bamfor, Spectrochim. Acta B 62 (2007) 1252–1256. [13] L. Cheng, X. Ding, Z. Liu, Q. Pan, X. Chu, Spectrochim. Acta B 62 (2007) 817– 823. [14] www.lnf.infn.it/xlab/index.html. [15] D. Hampai, S.B. Dabagov, G. Cappuccio, G. Cibin, V. Sessa, Spectrochim. Acta B 64 (2009) 1180–1184. [16] D. Hampai, S.B. Dabagov, G. Cappuccio, A. Longoni, T. Frizzi, G. Cibin, V. Guglielmotti, M. Sala, Opt. Lett. 33 (23) (2008) 2743–2745. [17] D. Hampai, A. Liedl, C. Polese, G. Cappuccio, S.B. Dabagov, EXRS 2014 (oral presentation). [18] A. Liedl, C. Polese, D. Hampai, G. Della Ventura, A. Marcelli, S.B. Dabagov, F. Bellatreccia, EXRS 2014 (poster). [19] D. Hampai, L. Marchitto, S.B. Dabagov, L. Allocca, S. Alfuso, L. Innocenti, Nucl. Instr. Meth. Phys. Res. Sect. B 309 (2013) 264–267. [20] D. Hampai, S.B. Dabagov, C. Polese, A. Liedl, G. Cappuccio, Spectrochim. Acta B 101 (2014) 114–117. [21] C. Polese, S.B. Dabagov, A. Esposito, D. Hampai, A. Gorghinian, A. Liedl, M. Ferretti, AIP Adv. 4 (2014) 077128.
Please cite this article in press as: C. Polese et al., Proposal for a prototype of portable lXRF spectrometer, Nucl. Instr. Meth. B (2015), http://dx.doi.org/ 10.1016/j.nimb.2015.02.043