Measurement of the energy spectra of fission fragments using nuclear track detectors and digital image processing Guillermo Espinosa a , José I. Golzarri a , Victor M. Castaño b, * a Instituto de Física, Universidad Nacional Autónoma de México, A.P. 20-364, México D.F. 01000, México b Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Santiago de Querétaro, Querétaro 76230, México article info Article history: Received 9 December 2008 Received in revised form 12 January 2010 Accepted 17 April 2010 Keywords: Nuclear tracks Detectors Image processing Energy spectra abstract Energy spectra of fission fragments were determined using a Nuclear Track Methodology (NTM) sup- ported by digital image analysis and numerical data processing using a standard personal computer. The analysis of a californium ( 252 Cf) spectrum with this approach shows improvement compared with the values reported previously using the standard procedure, in terms of resolution and accuracy. This new method adds full automation to the technical advantages and cost effectiveness of an NTM. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction The impressive development in semiconductor technology during recent decades has had a significant influence on the tech- nology of detectors of ionizing radiation, leading to qualitative changes in the measurement criteria (Castaño and Espinosa, 1990; Espinosa and Castaño, 1990, 1991; Espinosa et al., 1992; Kahn and Durrani, 1973; Martínez et al., 1992; Schmitt and Pleasonton, 1996; Trejo et al., 1992). The pioneering work by Schmitt and Pleasonton (1996) is still considered a classic in the field. Kahn and Durrani (1973) had successfully introduced what at the time was a novel method, known as the Solid State Nuclear Track Detector (SSNTD) approach, to determine the energy spectrum of fission fragments (Espinosa et al., 1993, 1998; Viquez et al., 1991) and this field has grown impressively, not only in terms of the numerous applications which make use that technology, but also because of the modern phosphors and novel optical materials (Bernal et al., 2008; Cruz et al., 2007; García et al., 2007; Ramola, 2008) available today. In this study, an alternative method, which combines SSNTD methodology with modern image processing techniques (Bernal et al., 2008; Cruz et al., 2007; García et al., 2007; Ponomarev and Cucinotta, 2006; Ramola, 2008; Viquez et al., 1991) for deter- mining the energy spectrum of fission fragments of 252 Cf is presented and its advantages compared with those of the estab- lished methods. 2. Experimental The method is based on the relationship between the energy transferred to the material by the fission fragments of californium ( 252 Cf; 79.4 and 103.8 MeV) and the size distribution of nuclear tracks induced in the SSTND material by chemical processing (Castaño and Espinosa, 1990; Espinosa and Castaño, 1990, 1991; Kahn and Durrani, 1973; Schmitt and Pleasonton, 1996). Among the several nuclear track detector materials available, fused silica glass was chosen because of its energy response, commercial availability, homogeneity and reproducibility. The irradiation was applied in air, keeping close contact between the detectors and the source, by using only normal incidence (90  ) of the fission frag- ments onto the detectors. Following irradiation, the fused silica detectors were etched in a 8% vol. HF solution at 20  1  C for periods ranging from 5 to 60 min. The detectors were then washed in distilled water, dried in air and analyzed using a Digital Image Analysis System (DIAS; Castaño and Espinosa, 1990; Espinosa et al., 1992; Viquez et al., 1991) to obtain the nuclear track size distribution. The following assumptions were made: a) only the circular tracks in which the ratio of the smallest, d, to the biggest, D, diameters (d/D) lying between 0.9 and 1.0 were taken into account (Espinosa et al., 1998; Viquez et al., 1991); b) only the biggest tracks present were considered for the analysis. With these two restrictions, the * Corresponding author. Tel.: þ52 442 2340820; fax: þ52 442 2381165. E-mail address: castano@fata.unam.mx (V.M. Castaño). Contents lists available at ScienceDirect Radiation Measurements journal homepage: www.elsevier.com/locate/radmeas 1350-4487/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.radmeas.2010.04.011 Radiation Measurements 45 (2010) 786e788