- Email: [email protected]
148Gd, 238U, 239Pu and 244Cm alpha particle energy analysis using tracks in solids
Radiation Measurements 34 (2001) 341–343
148
Gd,
238
U,
239
www.elsevier.com/locate/radmeas
Pu and 244Cm alpha particle energy analysis using tracks in solids
C. Ameroa , J.I. Golzarria , M. Izerroukenb , G. Espinosaa; ∗ a Instituto
de F sica, UNAM., Apdo. Postal 20-364, 01000 M exico D.F., Mexico b Centre de Recherche Nucleaire de Draria, Alger, Algeria
Received 28 August 2000; received in revised form 10 January 2001; accepted 9 March 2001
Abstract This paper presents advances in a procedure for alpha particle analysis using the nuclear tracks formed in solid-state materials. This method is based on the relationship between the energy deposited in the material by ionizing particles and the track developed after a well-established chemical process. The experimental study included alpha particles in the energy range from 3.2 to 5:8 MeV emitted by 148 Gd, 238 U, 239 Pu and 244 Cm. The quantitative results provide a clear signature to identify each one of the radioisotopes based on the formed track parameters. The track analysis is performed with a digital image analysis system associated with a PC mathematical processor. The wide range energy response makes this method a c 2001 Elsevier Science Ltd. All rights reserved. promising analysis system. Keywords: Isotope identi8cation; Nuclear tracks; CR-39
1. Introduction As is well known, by making use of the relationship between the etching track parameters and the energy deposited in CR-39, di:erent alpha particles can be identi8ed. (Espinosa et al., 1996; Ilic et al., 1993). Using the basic principle the development for alpha particle energy analysis is an interesting challenge, many authors had been developing several and di:erent methods in order to have an automatic alpha spectrometer using nuclear track methodology (NTM) (Abdel Moneim et al., 1993; Bondarenko et al., 1996; Campos Venutti et al., 1984; Fews and Henshaw, 1982; Izerrouken et al., 1999; Khayrat and Durrani, 1999; Yadav, 1995). This work is focussed on the procedure for analysis of alpha particles using nuclear track detectors (NTD) and automatization of the data analysis to 8nd the track diameter ∗ Corresponding author. Tel.: +52-5-56-22-50-51; +52-5-56-16-15-35. E-mail address: [email protected] (G. Espinosa).
fax:
distribution for each of the radioisotopes and corresponding energies.
2. Experimental and results CR-39 LantrackJ polycarbonate, 600 m thick with a protection cover of 150 m polyethylene, is the chosen material for the detection, basically because of its response to the energies of the sets of alpha particles from 148 Gd (3:2 MeV), 238 U (4:2 MeV), 239 Pu (5:1 MeV) and 244 Cm (5:8 MeV). Before the exposure, the protection cover polyethylene is removed. The irradiation was performed in air with a 1 mm aluminum collimator placed between the detectors and the sources, using only normal incidence ◦ (90 ) alpha particles on the detectors. The following chemical process to develop the track was used. The polycarbonate is pre-etched in a KOH, 6:25 M so◦ ◦ lution, at 70 C ± 1 C, prior to being exposed to radiation, in order to avoid irregularities and contaminants on the surface of the material (Espinosa and Moreno, 1979; Henshaw,
c 2001 Elsevier Science Ltd. All rights reserved. 1350-4487/01/$ - see front matter PII: S 1 3 5 0 - 4 4 8 7 ( 0 1 ) 0 0 1 8 0 - 9
342
C. Amero et al. / Radiation Measurements 34 (2001) 341–343
Fig. 1. Track distribution and Gaussian 8t for each one of the sources: (a) 148 Gd; (b) 238 U; (c) 239 Pu; and (d) 244 Cm (au = arbitrary units).
1989). After pre-etching, the detectors were irradiated and later on chemically etched in a KOH, 6:25 M solution, but ◦ ◦ in this case at 60 C ± 1 C for a period of 2–18 h, using new pieces for each etching time. Then, the detectors were washed in distilled water and read and analyzed by a digital image analysis system (DIAS) (Espinosa et al., 1996). To obtain the track diameter distribution, for each one of the elements, the following considerations were taken: (a) The circular tracks where the relationship of minor d and major D diameters (d=D) is between 0.9 and 1.0 are counted (Espinosa et al., 1996); (b) only the major diameter was considered for the analysis. With these two restrictions, the measurements were done for di:erent etching times from 2 to 18 h, for a period of 2 h each. From this experiment it was observed that the diameter distribution histogram is moving along the x-axis as function of the etching time. A Gaussian analysis of the track distribution for each etching time of the detectors was made, obtaining that the lowest value of the standard deviation is for 12 h of etching. Track diameter histogram distribution for the four elements with the optimum etching time (12 h) are shown in Fig. 1, and the corresponding Gaussian distribution curve of the four radioisotopes is shown in Fig. 2. The mean value and standard deviation is calculated using Microcalc OriginsJ software.
Fig. 2. Gaussian distributions for the four elements (au = arbitrary units).
The energy resolution was calculated by the following equation (Skvarc, 1997; Izerrouken et al., 1999). KE (E1 − E2 )=(D1 − D2 ) = KD; E 0:5(E1 + E2 ) where E1 and E2 are the energies of incident alpha particles, D1 and D2 are the mean track diameter corresponding to
C. Amero et al. / Radiation Measurements 34 (2001) 341–343 Table 1 Track diameter D for the four alpha particle energies after 12 h of etching time and the energy resolution E (Mev)
D (m)
KE=E
3.2 4.2 4.2 5.1 5.1 5.8
20:04 ± 0:73 18:14 ± 1:31 18:14 ± 1:31 15:74 ± 0:89 15:74 ± 0:89 14:09 ± 0:67
0.18 0.11 0.07
each energy and KD is the width of the distribution. D1 , D2 and KD, are determined by 8tting the track size distribution from Fig. 2 using the Izerrouken et al. procedure. The results are shown in Table 1. 3. Conclusions The nuclear track detectors can be very useful for alpha energy analysis. Digital image analysis systems are very helpful to measure automatically the track diameter distribution, and the PC mathematical processors make an automatic and fast procedure for the alpha particle energy identi8cation. Being the nuclear track methodology another option for alpha spectroscopy with a reasonable resolution and cost. Acknowledgements The authors wish to thank to Dr. E. Ley-Koo for his useful comments. This work was partially supported by DirecciLon General de Intercambio AcadLemico, UNAM.
343
References Abdel Moneim, A.M., Addel Naby, A., El Ekkad, F.A., 1993. Alpha particle spectrometry with a new polymeric track detector (PM-355). Nucl. Tracks Radiat. Meas. 21, 235–238. Bondarenko, O.A., Salmon, P.L., Henshaw, D.L., Fews, A.P., 1996. Performance of alpha particle spectroscopy using a Tasrak detector. Radiat. Meas. 26, 59–64. Campos Venutti, G., Diociaiuti, M., Grisanti, G., Risica, S., 1984. Use of an interactive image analysis system (IBAS) to analyze alpha particle track energies in cellulose nitrate nuclear track detectors. Nucl. Tracks Radiat. Meas. 8, 199–202. Espinosa, G., Moreno, A., 1979. Alpha detection by SSNTD’s. Proceedings of the 10th International Conference on SSNTD. Lyon, France. Academic Press. New York, pp. 777–784. Espinosa, G., Gammage, R.B., Meyer, K.E., Dudney, C.S., 1996. Nuclear track analysis by digital imaging. Radiat. Prot. Dosim. 66, 363–366. Fews, A.P., Henshaw, D.L., 1982. High resolution alpha particle spectroscopy using CR-39 plastic track detector. Nucl. Instrum. Methods 197, 517–529. Henshaw, D.L., 1989. Application of solid state nuclear track detectors to measurements of natural alpha radioactivity in human body tissues. Nucl. Tracks Radiat. Meas. 16, 253–270. Ilic, R., Sutej, T., Skvarc, J., Humar, M., 1993. Current Research on Nuclear Track in Solids at J. Stefan Institute. Nucl. Tracks Radiat. Meas. 21, 397–403. Izerrouken, M., Skvarc, J., Ilic, R., 1999. Low energy alpha particle spectroscopy using CR-39 detectors. Radiat. Meas. 31, 141–144. Khayrat, A.H., Durrani, S.A., 1999. Variation of alpha particle track diameter in CR-39 as a function of residual energy and etching conditions. Radiat. Meas. 30, 15–18. Skvarc, J., 1997. The e:ect of mechanical stress on charged particle track etching in CR-39 polymer. Ph.D. Theses, University of Ljubljana, Slovenia. Yadav, J.S., 1995. Charged particle identi8cation using CR-39 detectors. Radiat. Meas. 24, 115–128.
148
Gd,
238
U,
239
www.elsevier.com/locate/radmeas
Pu and 244Cm alpha particle energy analysis using tracks in solids
C. Ameroa , J.I. Golzarria , M. Izerroukenb , G. Espinosaa; ∗ a Instituto
de F sica, UNAM., Apdo. Postal 20-364, 01000 M exico D.F., Mexico b Centre de Recherche Nucleaire de Draria, Alger, Algeria
Received 28 August 2000; received in revised form 10 January 2001; accepted 9 March 2001
Abstract This paper presents advances in a procedure for alpha particle analysis using the nuclear tracks formed in solid-state materials. This method is based on the relationship between the energy deposited in the material by ionizing particles and the track developed after a well-established chemical process. The experimental study included alpha particles in the energy range from 3.2 to 5:8 MeV emitted by 148 Gd, 238 U, 239 Pu and 244 Cm. The quantitative results provide a clear signature to identify each one of the radioisotopes based on the formed track parameters. The track analysis is performed with a digital image analysis system associated with a PC mathematical processor. The wide range energy response makes this method a c 2001 Elsevier Science Ltd. All rights reserved. promising analysis system. Keywords: Isotope identi8cation; Nuclear tracks; CR-39
1. Introduction As is well known, by making use of the relationship between the etching track parameters and the energy deposited in CR-39, di:erent alpha particles can be identi8ed. (Espinosa et al., 1996; Ilic et al., 1993). Using the basic principle the development for alpha particle energy analysis is an interesting challenge, many authors had been developing several and di:erent methods in order to have an automatic alpha spectrometer using nuclear track methodology (NTM) (Abdel Moneim et al., 1993; Bondarenko et al., 1996; Campos Venutti et al., 1984; Fews and Henshaw, 1982; Izerrouken et al., 1999; Khayrat and Durrani, 1999; Yadav, 1995). This work is focussed on the procedure for analysis of alpha particles using nuclear track detectors (NTD) and automatization of the data analysis to 8nd the track diameter ∗ Corresponding author. Tel.: +52-5-56-22-50-51; +52-5-56-16-15-35. E-mail address: [email protected] (G. Espinosa).
fax:
distribution for each of the radioisotopes and corresponding energies.
2. Experimental and results CR-39 LantrackJ polycarbonate, 600 m thick with a protection cover of 150 m polyethylene, is the chosen material for the detection, basically because of its response to the energies of the sets of alpha particles from 148 Gd (3:2 MeV), 238 U (4:2 MeV), 239 Pu (5:1 MeV) and 244 Cm (5:8 MeV). Before the exposure, the protection cover polyethylene is removed. The irradiation was performed in air with a 1 mm aluminum collimator placed between the detectors and the sources, using only normal incidence ◦ (90 ) alpha particles on the detectors. The following chemical process to develop the track was used. The polycarbonate is pre-etched in a KOH, 6:25 M so◦ ◦ lution, at 70 C ± 1 C, prior to being exposed to radiation, in order to avoid irregularities and contaminants on the surface of the material (Espinosa and Moreno, 1979; Henshaw,
c 2001 Elsevier Science Ltd. All rights reserved. 1350-4487/01/$ - see front matter PII: S 1 3 5 0 - 4 4 8 7 ( 0 1 ) 0 0 1 8 0 - 9
342
C. Amero et al. / Radiation Measurements 34 (2001) 341–343
Fig. 1. Track distribution and Gaussian 8t for each one of the sources: (a) 148 Gd; (b) 238 U; (c) 239 Pu; and (d) 244 Cm (au = arbitrary units).
1989). After pre-etching, the detectors were irradiated and later on chemically etched in a KOH, 6:25 M solution, but ◦ ◦ in this case at 60 C ± 1 C for a period of 2–18 h, using new pieces for each etching time. Then, the detectors were washed in distilled water and read and analyzed by a digital image analysis system (DIAS) (Espinosa et al., 1996). To obtain the track diameter distribution, for each one of the elements, the following considerations were taken: (a) The circular tracks where the relationship of minor d and major D diameters (d=D) is between 0.9 and 1.0 are counted (Espinosa et al., 1996); (b) only the major diameter was considered for the analysis. With these two restrictions, the measurements were done for di:erent etching times from 2 to 18 h, for a period of 2 h each. From this experiment it was observed that the diameter distribution histogram is moving along the x-axis as function of the etching time. A Gaussian analysis of the track distribution for each etching time of the detectors was made, obtaining that the lowest value of the standard deviation is for 12 h of etching. Track diameter histogram distribution for the four elements with the optimum etching time (12 h) are shown in Fig. 1, and the corresponding Gaussian distribution curve of the four radioisotopes is shown in Fig. 2. The mean value and standard deviation is calculated using Microcalc OriginsJ software.
Fig. 2. Gaussian distributions for the four elements (au = arbitrary units).
The energy resolution was calculated by the following equation (Skvarc, 1997; Izerrouken et al., 1999). KE (E1 − E2 )=(D1 − D2 ) = KD; E 0:5(E1 + E2 ) where E1 and E2 are the energies of incident alpha particles, D1 and D2 are the mean track diameter corresponding to
C. Amero et al. / Radiation Measurements 34 (2001) 341–343 Table 1 Track diameter D for the four alpha particle energies after 12 h of etching time and the energy resolution E (Mev)
D (m)
KE=E
3.2 4.2 4.2 5.1 5.1 5.8
20:04 ± 0:73 18:14 ± 1:31 18:14 ± 1:31 15:74 ± 0:89 15:74 ± 0:89 14:09 ± 0:67
0.18 0.11 0.07
each energy and KD is the width of the distribution. D1 , D2 and KD, are determined by 8tting the track size distribution from Fig. 2 using the Izerrouken et al. procedure. The results are shown in Table 1. 3. Conclusions The nuclear track detectors can be very useful for alpha energy analysis. Digital image analysis systems are very helpful to measure automatically the track diameter distribution, and the PC mathematical processors make an automatic and fast procedure for the alpha particle energy identi8cation. Being the nuclear track methodology another option for alpha spectroscopy with a reasonable resolution and cost. Acknowledgements The authors wish to thank to Dr. E. Ley-Koo for his useful comments. This work was partially supported by DirecciLon General de Intercambio AcadLemico, UNAM.
343
References Abdel Moneim, A.M., Addel Naby, A., El Ekkad, F.A., 1993. Alpha particle spectrometry with a new polymeric track detector (PM-355). Nucl. Tracks Radiat. Meas. 21, 235–238. Bondarenko, O.A., Salmon, P.L., Henshaw, D.L., Fews, A.P., 1996. Performance of alpha particle spectroscopy using a Tasrak detector. Radiat. Meas. 26, 59–64. Campos Venutti, G., Diociaiuti, M., Grisanti, G., Risica, S., 1984. Use of an interactive image analysis system (IBAS) to analyze alpha particle track energies in cellulose nitrate nuclear track detectors. Nucl. Tracks Radiat. Meas. 8, 199–202. Espinosa, G., Moreno, A., 1979. Alpha detection by SSNTD’s. Proceedings of the 10th International Conference on SSNTD. Lyon, France. Academic Press. New York, pp. 777–784. Espinosa, G., Gammage, R.B., Meyer, K.E., Dudney, C.S., 1996. Nuclear track analysis by digital imaging. Radiat. Prot. Dosim. 66, 363–366. Fews, A.P., Henshaw, D.L., 1982. High resolution alpha particle spectroscopy using CR-39 plastic track detector. Nucl. Instrum. Methods 197, 517–529. Henshaw, D.L., 1989. Application of solid state nuclear track detectors to measurements of natural alpha radioactivity in human body tissues. Nucl. Tracks Radiat. Meas. 16, 253–270. Ilic, R., Sutej, T., Skvarc, J., Humar, M., 1993. Current Research on Nuclear Track in Solids at J. Stefan Institute. Nucl. Tracks Radiat. Meas. 21, 397–403. Izerrouken, M., Skvarc, J., Ilic, R., 1999. Low energy alpha particle spectroscopy using CR-39 detectors. Radiat. Meas. 31, 141–144. Khayrat, A.H., Durrani, S.A., 1999. Variation of alpha particle track diameter in CR-39 as a function of residual energy and etching conditions. Radiat. Meas. 30, 15–18. Skvarc, J., 1997. The e:ect of mechanical stress on charged particle track etching in CR-39 polymer. Ph.D. Theses, University of Ljubljana, Slovenia. Yadav, J.S., 1995. Charged particle identi8cation using CR-39 detectors. Radiat. Meas. 24, 115–128.