Measurement of proton inelastic scattering cross sections on fluorine M. Chiari a,⇑ , A. Caciolli b , G. Calzolai a , A. Climent-Font c , F. Lucarelli a , S. Nava a a Department of Physics and Astronomy, University of Florence and INFN Florence, Sesto Fiorentino, Italy b Department of Physics and Astronomy, University of Padua and INFN Padua, Padova, Italy c CMAM, Universidad Autonoma de Madrid, Madrid, Spain article info Article history: Received 14 April 2016 Received in revised form 2 July 2016 Accepted 5 August 2016 Available online 23 August 2016 Keywords: Proton Fluorine Inelastic scattering EBS Teflon Aerosol samples abstract Differential cross-sections for proton inelastic scattering on fluorine, 19 F(p,p’) 19 F, from the first five excited levels of 19 F at 110, 197, 1346, 1459 and 1554 keV were measured for beam energies from 3 to 7 MeV at a scattering angle of 150° using a LiF thin target (50 lg/cm 2 ) evaporated on a self-supporting C thin film (30 lg/cm 2 ). Absolute differential cross-sections were calculated with a method not depen- dent on the absolute values of collected beam charge and detector solid angle. The validity of the mea- sured inelastic scattering cross sections was then tested by successfully reproducing EBS spectra collected from a thick Teflon (CF 2 ) target. As a practical application of these measured inelastic scattering cross sections in elastic backscattering spectroscopy (EBS), the feasibility of quantitative light element (C, N and O) analysis in aerosol particulate matter samples collected on Teflon by EBS measurements and spectra simulation is demonstrated. Ó 2016 Elsevier B.V. All rights reserved. 1. Introduction The knowledge of the cross sections for the inelastic scattering of MeV energy protons on nuclei with low lying nuclear levels (from a few to several hundreds of keV) can be important when performing quantitative analysis of thick multielemental samples with the elastic backscattering spectrometry (EBS) technique to efficiently disentangle overlapping shapes in the spectra due to both elastic and inelastic peaks. In particular, the knowledge of the proton inelastic scattering on fluorine, 19 F(p,p 1 ) 19 F and 19 F(p, p 2 ) 19 F, from the first two excited levels of 19 F at 110 and 197 keV, respectively, is indeed crucial for reliable EBS analyses of samples containing also nitrogen and oxygen other than fluo- rine; in fact, the energy of protons elastically backscattered by N and O at the typically used angles between 150° and 170° and for some proton energy ranges is very close to the energy of p 1 and p 2 protons. Thus, given the finite energy resolution of the par- ticle detection systems, the signals are actually undistinguishable and mistakes might happen. A similar situation happens when considering the 19 F(p,p 3 ) 19 F, 19 F(p,p 4 ) 19 F and 19 F(p,p 5 ) 19 F inelastic scatterings, from the third to fifth excited levels of 19 F at 1346, 1459 and 1554 keV, in the presence of lithium in the sample. In addition, neglecting the presence of the inelastic peaks of fluorine may induce the IBA practitioner to erroneously consider the pres- ence of nitrogen and oxygen in samples where these elements are absent, such as Teflon (CF 2 ), in order to achieve a simulation of an EBS spectrum, but inferring a wrong sample composition at the same time [1]. Moreover, the lack of inelastic scattering cross sections restricts the direct analysis of fluorine in thick samples by proton EBS up to a depth from the surface corresponding to an energy window of less than 100 keV, thus hampering the large probing depth that, in principle, can be achieved by using proton beams of increasing energy, for instance greater than 3 MeV. Whereas several papers have been published on the high energy proton elastic scattering on fluorine [2–7], also in recent years to meet the increasing demand of experimental values of elastic backscattering cross sections of high energy protons on light nuclei [8], only a few papers dealing with the inelastic scattering cross sections are presently available in the literature. In the 1970s, Thompson et al. [2] measured the cross section of the 19 F(p, p 2 ) 19 F reaction at 90° in the laboratory frame of reference and in the proton energy interval between 5.5 and 6.8 MeV, while Kuan et al. [3] obtained the (p,p 1 ), (p,p 3 ), (p,p 4 ) and (p,p 5 ) inelastic scat- tering cross sections from 5.8 to 5.9 MeV proton energy at a labo- ratory angle of 168°. Then, in the 1980s, Ouichaoui et al. [4] measured the (p,p 1 ), (p,p 2 ), (p,p 3 ) and (p,p 4 ) inelastic scattering cross sections from 2.70 to 2.99 MeV proton energy at laboratory angles of 158.3°, 144.6°, 122.3°, 94.65° and 66.8°. http://dx.doi.org/10.1016/j.nimb.2016.08.004 0168-583X/Ó 2016 Elsevier B.V. All rights reserved. ⇑ Corresponding author at: INFN Florence, Sezione di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino, Firenze, Italy. E-mail address: chiari@fi.infn.it (M. Chiari). Nuclear Instruments and Methods in Physics Research B 384 (2016) 37–41 Contents lists available at ScienceDirect Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb