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Calibration studies and the application of nuclear track detectors to the detection of charged particles
Radiation Measurements 50 (2013) 258e260
Contents lists available at SciVerse ScienceDirect
Radiation Measurements journal homepage: www.elsevier.com/locate/radmeas
Calibration studies and the application of nuclear track detectors to the detection of charged particles A. Szydlowski, A. Malinowska*, M. Jaskola, A. Korman, K. Malinowski, M. Kuk National Centre for Nuclear Research, Andrzeja Sołtana 7, 05-400 Otwock, Poland
a r t i c l e i n f o
a b s t r a c t
Article history: Received 9 November 2011 Received in revised form 5 March 2012 Accepted 21 March 2012
This paper describes calibration studies of solid state nuclear track detectors (SSNTDs) of he CR-39/PM355 type. A dozen or so PM-355 detector samples were cut out from detector sheets delivered at different times and were irradiated with mono-energetic protons, deurerons and helium ions of energy ranging up to a few MeV. After that, the samples were etched and track opening diameters were determined as a function of particle energy and detector etching time. These studies were motivated by the application of the detectors in fusion experiments to measure energetic ions which escape high-temperature plasmas. The calibration diagrams obtained enable us to compare the relative sensitivities of detectors from different batches and to use these detectors in an optimal way. Ó 2012 Elsevier Ltd. All rights reserved.
Keywords: Solid-state nuclear track detectors PM-355 p, d, 4He-ions Calibration diagrams
1. Introduction Solid-State Nuclear Track Detectors have been used for corpuscular system diagnostics in various high-temperature plasma experiments for a long time (Bertalot et al., 1980; Muhling et al., 1984; Murphy and Strachan, 1985; Malinowska et al., 2008; Szydlowski, 2003, 2008, 2009). The calibration data obtained up to now are very useful for various studies, which have been performed using these detectors in the field of nuclear physics, as well as, for measurements of fast protons and other particles emitted from high-temperature plasmas generated in different facilities. Due to their specific properties, these detectors are able to cope very well with the harsh conditions of plasma facilities. In order to make such detectors more relevant for plasma experiments detailed calibration studies of the detectors in question are needed. Using monoenergetic ions from particle accelerators one can investigate track parameters (diameter, depth) as a function of ion energy, ion atomic number, and detector etching time. At our institute detailed calibration studies of the CR-39 detector and its new versions such as PM-355, PM-500 and PM-600 have been performed for a few years and spectroscopic properties of the detectors were evaluated (Szydlowski et al., 1999a, 2000, 2001). The PM-355 plastic appeared to be the best, especially for the detection of light ions including protons, deuterons, He-, and
* Corresponding author. Tel.: þ48 22 7180417. E-mail address: [email protected] (A. Malinowska). 1350-4487/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.radmeas.2012.03.013
heavier ions like: C, N, O, S, and therefore, we recommend this detector for measurements of fast particles escaping from hightemperature plasmas produced in various facilities. This report deals with the calibration studies of PM-355 detectors manufactured at different times in order to compare their sensitivity to the investigated ions. To this end the PM-355 detectors were purchased in a few batches from the Pershore Moulding Company (Catalog Page the Pershore Moulding Company, 1998) manufactured in the decade 2000e2010. Selected samples of the detectors cut from each batch were irradiated with Hþ-, Dþ- and 4 He-ions of energy ranging from 0.2 to a few MeV, which were provided by particle accelerators. 2. Experimental procedures In order to perform the intended calibration measurements of the purchased detectors, selected samples were irradiated with mono-energetic ions of different energies provided by various particle accelerators, but mainly by the “Lech” accelerator (Van de Graaff type) (Szydlowski et al., 1999b). During these irradiations the Hþ- and Dþ- ion energy values were changed in steps of 200 keV in the energy interval ranging from 200 keV to 2 MeV, and for 4Heions from 300 keV to 5 MeV. The irradiation was made at normal incidence by ions elastically scattered from a self-supporting gold foil of around 100 mg/cm2 in thickness. The scattered ion fluxes were measured using a Si surface barrier detector in order to control the energy spectra of the scattered ions and to measure counting rates over the track detector
A. Szydlowski et al. / Radiation Measurements 50 (2013) 258e260
259
Fig. 1. Sample pictures of openings of tracks produced in PM-355 detectors by 1 MeV projectiles, which have been observed after a 10-hour-long etching time; A - protons, B deuterons, C - 4He-ions.
area. The fluxes of the projectiles that hit the detector samples did not exceeded 2 O 4 104 particles/cm2, so that the densities of tracks produced over the detector surface were not excessively overcrowded and the track overlap effect was negligible. The energy spread of the elastically scattered particles depended mainly on the total energy loss in the target material and ranged from about 30 keV (for 200 keV protons) to 20 keV (for 2 MeV protons). For deuterons and helium ions these values were almost 2e3 times higher. The irradiated samples were treated by a chemical etching procedure. The samples were etched in steps in a 6.25 N water solution of NaOH, at a temperature of 70 1 C for different etching times. The etching procedure was interrupted every 2 h, the samples were washed and dried, and track parameters were
Fig. 2. Evolution of track opening diameters as a function of incident 4He-ion energy and etching time as measured for PM-355 track detectors from different deliveries. Lines are drawn to guide the eye.
measured under an optical microscope. After such an analysis the etching process was renewed for a further period of 2 h. It was estimated that the track diameters were measured with an accuracy of 0.5 mm. 3. Experimental results and discussion In Fig. 1 we present photos of tracks openings produced in the PM-355 detectors by mono-energetic protons, deuterons and 4Heions. Comparing these tracks one can see that openings are sufficiently regular in shape that they can be scanned automatically using an optical microscope equipped with a CCD camera and suitable software (Nikon Imaging System). In Figs. 2e4 we assemble the results of the detailed calibration measurements which were carried out for protons, deuterons and 4 He-ions in the period 2000 O 2010. The diagrams demonstrate specific maxima, which are shifted to higher ion energies for longer etching times. It was also found earlier that the location of the maximum is defined by the thickness of the external detector layer removed during the bulk etching process, and the range of the projectile in the detector material. This means that tracks are etched out to the largest diameters only when the etching solution has unconstrained access to the end part of the particle trajectory where the concentration of detector material defects is highest. This takes place after removal (by the etching) of the detector external layer of a thickness equal to the projectile range.
Fig. 3. Evolution of track opening diameters as a function of incident deuteron energy and etching time as measured for a few different batches of PM-355 track detectors. Lines are drawn to guide the eye.
260
A. Szydlowski et al. / Radiation Measurements 50 (2013) 258e260
describes the evolution of the diameters of openings of tracks induced by 4He - ions of the same energy. These calibration diagrams (Fig. 5) reveal that the diameters of openings of the etchpits, which were produced by mono-energetic 4He - ions, increase linearly versus the etching time within a certain range of this time. A critical value of the etching time is that at which an external layer of the detector equal to the ion range in the detector material is removed by the bulk etching process.
4. Summary and conclusions The most important results of these studies which were carried out during the last 10 years can be summarized as follows:
Fig. 4. Evolution of track opening diameters as a function of incident proton energy and etching time as measured for a few batches of PM-355 track detectors. Lines are drawn to guide the eye.
One can see that the calibration characteristics, which were determined for each individual detector batch differ significantly (Figs. 2e4). This means that samples taken from different deliveries present tracks of different sizes even when they are irradiated with the same ions and etched for the same time. This confirms the supposition that various manufacturing procedures were used to produce these detectors (Durrani and Bull, 1987; Durrani, 2001). The suggestion recommending the precise calibration of each detector delivery seems to be well-founded. The diagrams of track opening diameters (Figs. 2e4) show that the PM-355 detectors purchased in 2010 reveal tracks almost 30% larger than the detectors produced in 2000. This difference is more evident for 4He-ions tracks then for tracks induced by protons and deuterons. The ratios of 4He-ions track opening diameters in these two detectors Ø(2010)/Ø(2000) are in the range 1.30e1.35 and do not noticeably depend on the detector etching time, whereas for the deuteron tracks this ratio is equal to about 1.25. The diagrams expressing track diameter evolution as a function of etching time are presented in Fig. 5. Each curve in this figure
Fig. 5. Evolution of 4He-ions track opening diameters expressed as a function of the etching time. Lines are drawn to guide the eye.
To use these detectors optimally, especially in spectroscopic measurements, each new batch of the PM-355 material should be carefully calibrated. The detectors bought recently reveal bigger tracks than those purchased earlier and this could result from different technological procedures used by the producer to manufacture the CR-39/PM-355 material.
Acknowledgements We like to thanks Dr N. Keeley for a critical reading of the manusctipt and for the constructive suggestions.
References Bertalot, L., Herold, H., Jager, U., Mozer, A., Oppenlander, T., Sadowski, M., Schmidt, H., 1980. Mass and energy analysis and space resolved measurements of ions from Plasma Focus device. Phys. Lett. 79A, 389. Durrani, S.,A., 2001. Nuclear tracs: a succes story of the 20th century. Radiat. Meas. 34, 5e13. Durrani, S.,A., Bull, R.K., 1987. Solid State Nuclear Track Detection: Principles, Methods and Applications. Pergamon Press, AERE, Harvell, Oxon UK. Muhling, E., Schumacher, U., Paretzke, H.G., 1984. Thermonuclear fusion product diagnostics by nuclear track detectors. Nucl. Tracks 9 (2), 113e117. Murphy, T.J., Strachan, J.D., 1985. Spatially resolved measurement of alpha particle emission from PLT plasma heated by ICRH. Nucl. Fusion 25 (3), 383e386. Malinowska, A., Szydlowski, A., Zebrowski, J., Sadowski, M.J., Scholz, M., Paduch, M., Jaskola, M., Korman, A., 2008. Measurements of fusion-produced protons by means of SSNTDs. Rad. Meas. 43, S295eS298. Nikon Imaging System-Elements BR 3.10 (NIS-Elements BR version3.10) http:// www.nis-elements.com/. Catalog Page Pershore Moulding Company, 1998. Szydlowski, A., Czyzewski, T., Jaskola, M., Sadowski, M., Korman, A., Kedzierski, J., Kretschmer, W., 1999a. Investigation of response of CR-39, PM-355, and PM-500 types of nuclear track detectors to energetic carbon ions. Rad. Meas. 31, 257e260. Szydlowski, A., Czyzewski, T., Fijal, I., Jaskola, M., Korman, A., Sadowski, M., Kedzierski, J., 1999b. Experimental methods used in calibration of solid state nuclear track detectors. Journ. Techn. Phys. 40 (1), 415e418. Szydlowski, A., Sadowski, M., Czyzewski, T., Jaskola, M., Korman, A., Fijal, I., 2000. Detection characteristics of PM-355 solid-state nuclear track for normal incident light ions within MeV energies. Nucl. Instr. Methods B 171, 379e386. Szydlowski, A., Banaszak, A., Czyzewski, T., Fijal, I., Jaskola, M., Korman, A., Sadowski, M., Kretschmer, W., 2001. Advantage of PM-355 nuclear track detector in light-ion registration and high temperature plasma diagnostics. Rad. Meas. 34 (1e6), 325e329. Szydlowski, A., 2003. Application of CR-39 track detectors for corpuscular diagnostics of high-temperature plasmas. Rad. Meas. 36, 35e42. Szydlowski, A., Malinowska, A., Sadowski, M.J., Jaskola, M., Karman, A., Van Wassenhove, G., Bonheure, G., Schweer, B., the the TEXTOR team, Ga1kowski, A., Ma1ek, K., 2008. Measurements of fusion-reaction protons in TEXTOR tokamak plasma by means of solid-state nuclear track detectors of the CR-39/PM-355 type. Rad. Meas. 43, S290eS294. Szydlowski, A., Badziak, J., Fuchs, J., Kubkowska, M., Parys, P., Roisinski, M., Suchanska, R., Wolowski, J., Antici, P., Mancic, A., 2009. Application of solidstate nuclear track detectors of the CR/PM-355 type for measurements of energetic protons emitted from plasma produced by an ultra-intense laser. Rad. Meas. 44, 881e884.
Contents lists available at SciVerse ScienceDirect
Radiation Measurements journal homepage: www.elsevier.com/locate/radmeas
Calibration studies and the application of nuclear track detectors to the detection of charged particles A. Szydlowski, A. Malinowska*, M. Jaskola, A. Korman, K. Malinowski, M. Kuk National Centre for Nuclear Research, Andrzeja Sołtana 7, 05-400 Otwock, Poland
a r t i c l e i n f o
a b s t r a c t
Article history: Received 9 November 2011 Received in revised form 5 March 2012 Accepted 21 March 2012
This paper describes calibration studies of solid state nuclear track detectors (SSNTDs) of he CR-39/PM355 type. A dozen or so PM-355 detector samples were cut out from detector sheets delivered at different times and were irradiated with mono-energetic protons, deurerons and helium ions of energy ranging up to a few MeV. After that, the samples were etched and track opening diameters were determined as a function of particle energy and detector etching time. These studies were motivated by the application of the detectors in fusion experiments to measure energetic ions which escape high-temperature plasmas. The calibration diagrams obtained enable us to compare the relative sensitivities of detectors from different batches and to use these detectors in an optimal way. Ó 2012 Elsevier Ltd. All rights reserved.
Keywords: Solid-state nuclear track detectors PM-355 p, d, 4He-ions Calibration diagrams
1. Introduction Solid-State Nuclear Track Detectors have been used for corpuscular system diagnostics in various high-temperature plasma experiments for a long time (Bertalot et al., 1980; Muhling et al., 1984; Murphy and Strachan, 1985; Malinowska et al., 2008; Szydlowski, 2003, 2008, 2009). The calibration data obtained up to now are very useful for various studies, which have been performed using these detectors in the field of nuclear physics, as well as, for measurements of fast protons and other particles emitted from high-temperature plasmas generated in different facilities. Due to their specific properties, these detectors are able to cope very well with the harsh conditions of plasma facilities. In order to make such detectors more relevant for plasma experiments detailed calibration studies of the detectors in question are needed. Using monoenergetic ions from particle accelerators one can investigate track parameters (diameter, depth) as a function of ion energy, ion atomic number, and detector etching time. At our institute detailed calibration studies of the CR-39 detector and its new versions such as PM-355, PM-500 and PM-600 have been performed for a few years and spectroscopic properties of the detectors were evaluated (Szydlowski et al., 1999a, 2000, 2001). The PM-355 plastic appeared to be the best, especially for the detection of light ions including protons, deuterons, He-, and
* Corresponding author. Tel.: þ48 22 7180417. E-mail address: [email protected] (A. Malinowska). 1350-4487/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.radmeas.2012.03.013
heavier ions like: C, N, O, S, and therefore, we recommend this detector for measurements of fast particles escaping from hightemperature plasmas produced in various facilities. This report deals with the calibration studies of PM-355 detectors manufactured at different times in order to compare their sensitivity to the investigated ions. To this end the PM-355 detectors were purchased in a few batches from the Pershore Moulding Company (Catalog Page the Pershore Moulding Company, 1998) manufactured in the decade 2000e2010. Selected samples of the detectors cut from each batch were irradiated with Hþ-, Dþ- and 4 He-ions of energy ranging from 0.2 to a few MeV, which were provided by particle accelerators. 2. Experimental procedures In order to perform the intended calibration measurements of the purchased detectors, selected samples were irradiated with mono-energetic ions of different energies provided by various particle accelerators, but mainly by the “Lech” accelerator (Van de Graaff type) (Szydlowski et al., 1999b). During these irradiations the Hþ- and Dþ- ion energy values were changed in steps of 200 keV in the energy interval ranging from 200 keV to 2 MeV, and for 4Heions from 300 keV to 5 MeV. The irradiation was made at normal incidence by ions elastically scattered from a self-supporting gold foil of around 100 mg/cm2 in thickness. The scattered ion fluxes were measured using a Si surface barrier detector in order to control the energy spectra of the scattered ions and to measure counting rates over the track detector
A. Szydlowski et al. / Radiation Measurements 50 (2013) 258e260
259
Fig. 1. Sample pictures of openings of tracks produced in PM-355 detectors by 1 MeV projectiles, which have been observed after a 10-hour-long etching time; A - protons, B deuterons, C - 4He-ions.
area. The fluxes of the projectiles that hit the detector samples did not exceeded 2 O 4 104 particles/cm2, so that the densities of tracks produced over the detector surface were not excessively overcrowded and the track overlap effect was negligible. The energy spread of the elastically scattered particles depended mainly on the total energy loss in the target material and ranged from about 30 keV (for 200 keV protons) to 20 keV (for 2 MeV protons). For deuterons and helium ions these values were almost 2e3 times higher. The irradiated samples were treated by a chemical etching procedure. The samples were etched in steps in a 6.25 N water solution of NaOH, at a temperature of 70 1 C for different etching times. The etching procedure was interrupted every 2 h, the samples were washed and dried, and track parameters were
Fig. 2. Evolution of track opening diameters as a function of incident 4He-ion energy and etching time as measured for PM-355 track detectors from different deliveries. Lines are drawn to guide the eye.
measured under an optical microscope. After such an analysis the etching process was renewed for a further period of 2 h. It was estimated that the track diameters were measured with an accuracy of 0.5 mm. 3. Experimental results and discussion In Fig. 1 we present photos of tracks openings produced in the PM-355 detectors by mono-energetic protons, deuterons and 4Heions. Comparing these tracks one can see that openings are sufficiently regular in shape that they can be scanned automatically using an optical microscope equipped with a CCD camera and suitable software (Nikon Imaging System). In Figs. 2e4 we assemble the results of the detailed calibration measurements which were carried out for protons, deuterons and 4 He-ions in the period 2000 O 2010. The diagrams demonstrate specific maxima, which are shifted to higher ion energies for longer etching times. It was also found earlier that the location of the maximum is defined by the thickness of the external detector layer removed during the bulk etching process, and the range of the projectile in the detector material. This means that tracks are etched out to the largest diameters only when the etching solution has unconstrained access to the end part of the particle trajectory where the concentration of detector material defects is highest. This takes place after removal (by the etching) of the detector external layer of a thickness equal to the projectile range.
Fig. 3. Evolution of track opening diameters as a function of incident deuteron energy and etching time as measured for a few different batches of PM-355 track detectors. Lines are drawn to guide the eye.
260
A. Szydlowski et al. / Radiation Measurements 50 (2013) 258e260
describes the evolution of the diameters of openings of tracks induced by 4He - ions of the same energy. These calibration diagrams (Fig. 5) reveal that the diameters of openings of the etchpits, which were produced by mono-energetic 4He - ions, increase linearly versus the etching time within a certain range of this time. A critical value of the etching time is that at which an external layer of the detector equal to the ion range in the detector material is removed by the bulk etching process.
4. Summary and conclusions The most important results of these studies which were carried out during the last 10 years can be summarized as follows:
Fig. 4. Evolution of track opening diameters as a function of incident proton energy and etching time as measured for a few batches of PM-355 track detectors. Lines are drawn to guide the eye.
One can see that the calibration characteristics, which were determined for each individual detector batch differ significantly (Figs. 2e4). This means that samples taken from different deliveries present tracks of different sizes even when they are irradiated with the same ions and etched for the same time. This confirms the supposition that various manufacturing procedures were used to produce these detectors (Durrani and Bull, 1987; Durrani, 2001). The suggestion recommending the precise calibration of each detector delivery seems to be well-founded. The diagrams of track opening diameters (Figs. 2e4) show that the PM-355 detectors purchased in 2010 reveal tracks almost 30% larger than the detectors produced in 2000. This difference is more evident for 4He-ions tracks then for tracks induced by protons and deuterons. The ratios of 4He-ions track opening diameters in these two detectors Ø(2010)/Ø(2000) are in the range 1.30e1.35 and do not noticeably depend on the detector etching time, whereas for the deuteron tracks this ratio is equal to about 1.25. The diagrams expressing track diameter evolution as a function of etching time are presented in Fig. 5. Each curve in this figure
Fig. 5. Evolution of 4He-ions track opening diameters expressed as a function of the etching time. Lines are drawn to guide the eye.
To use these detectors optimally, especially in spectroscopic measurements, each new batch of the PM-355 material should be carefully calibrated. The detectors bought recently reveal bigger tracks than those purchased earlier and this could result from different technological procedures used by the producer to manufacture the CR-39/PM-355 material.
Acknowledgements We like to thanks Dr N. Keeley for a critical reading of the manusctipt and for the constructive suggestions.
References Bertalot, L., Herold, H., Jager, U., Mozer, A., Oppenlander, T., Sadowski, M., Schmidt, H., 1980. Mass and energy analysis and space resolved measurements of ions from Plasma Focus device. Phys. Lett. 79A, 389. Durrani, S.,A., 2001. Nuclear tracs: a succes story of the 20th century. Radiat. Meas. 34, 5e13. Durrani, S.,A., Bull, R.K., 1987. Solid State Nuclear Track Detection: Principles, Methods and Applications. Pergamon Press, AERE, Harvell, Oxon UK. Muhling, E., Schumacher, U., Paretzke, H.G., 1984. Thermonuclear fusion product diagnostics by nuclear track detectors. Nucl. Tracks 9 (2), 113e117. Murphy, T.J., Strachan, J.D., 1985. Spatially resolved measurement of alpha particle emission from PLT plasma heated by ICRH. Nucl. Fusion 25 (3), 383e386. Malinowska, A., Szydlowski, A., Zebrowski, J., Sadowski, M.J., Scholz, M., Paduch, M., Jaskola, M., Korman, A., 2008. Measurements of fusion-produced protons by means of SSNTDs. Rad. Meas. 43, S295eS298. Nikon Imaging System-Elements BR 3.10 (NIS-Elements BR version3.10) http:// www.nis-elements.com/. Catalog Page Pershore Moulding Company, 1998. Szydlowski, A., Czyzewski, T., Jaskola, M., Sadowski, M., Korman, A., Kedzierski, J., Kretschmer, W., 1999a. Investigation of response of CR-39, PM-355, and PM-500 types of nuclear track detectors to energetic carbon ions. Rad. Meas. 31, 257e260. Szydlowski, A., Czyzewski, T., Fijal, I., Jaskola, M., Korman, A., Sadowski, M., Kedzierski, J., 1999b. Experimental methods used in calibration of solid state nuclear track detectors. Journ. Techn. Phys. 40 (1), 415e418. Szydlowski, A., Sadowski, M., Czyzewski, T., Jaskola, M., Korman, A., Fijal, I., 2000. Detection characteristics of PM-355 solid-state nuclear track for normal incident light ions within MeV energies. Nucl. Instr. Methods B 171, 379e386. Szydlowski, A., Banaszak, A., Czyzewski, T., Fijal, I., Jaskola, M., Korman, A., Sadowski, M., Kretschmer, W., 2001. Advantage of PM-355 nuclear track detector in light-ion registration and high temperature plasma diagnostics. Rad. Meas. 34 (1e6), 325e329. Szydlowski, A., 2003. Application of CR-39 track detectors for corpuscular diagnostics of high-temperature plasmas. Rad. Meas. 36, 35e42. Szydlowski, A., Malinowska, A., Sadowski, M.J., Jaskola, M., Karman, A., Van Wassenhove, G., Bonheure, G., Schweer, B., the the TEXTOR team, Ga1kowski, A., Ma1ek, K., 2008. Measurements of fusion-reaction protons in TEXTOR tokamak plasma by means of solid-state nuclear track detectors of the CR-39/PM-355 type. Rad. Meas. 43, S290eS294. Szydlowski, A., Badziak, J., Fuchs, J., Kubkowska, M., Parys, P., Roisinski, M., Suchanska, R., Wolowski, J., Antici, P., Mancic, A., 2009. Application of solidstate nuclear track detectors of the CR/PM-355 type for measurements of energetic protons emitted from plasma produced by an ultra-intense laser. Rad. Meas. 44, 881e884.