Abstract The paper reports on features of so-called solid-state nuclear track detectors (SSNTDs), their calibration measurements performed with known ion beams, and their different applications for detailed studies of charged particle emissions from various high-temperatures plasma facilities

A Korman

A Szydlowski

E Skladnik-Sadowska

M Jaskola

M Sadowski

T Czyzewski

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CALIBRATION AND APPLICATION OF
NUCLEAR TRACK DETECTORS
FOR HIGH-TEMPERATURE PLASMA DIAGNOSTICS
M. Sadowski, A. Szydlowski, E. Skladnik-Sadowska, M. Jaskola,
T. Czyzewski, and A. Korman
The Andrzej Soltan Institute for Nuclear Studies (IPJ), 05-400 Otwock-Swierk, Poland.
Abstract
The paper reports on features of so-called solid-state nuclear track detectors (SSNTDs), their
calibration measurements performed with known ion beams, and their different applications
for detailed studies of charged particle emissions from various high-temperatures plasma
facilities.
1. Introduction
In 1959 E. Silk and R. Barnes revealed nuclear tracks induced by fission fragments in solid-
state (mica) [1]. Ever since nuclear tracks were observed in many others solid-state
materials, e.g. in plastics, some glasses, and crystals. Very soon these materials have found
application as solid-state nuclear track detectors (SSNTDs).
Taking into account sensitivity, resolution, and variability of their response, the best
SSNTD materials appeared to be optically clear amorphous, thermoset plastics (polymers),
which have high homogenity and isotropy, high optical transparency and uniformity. A
plastic material fulfilling those requirements was synthesized in 1978, and it was called CR-
39 (Columbia Resin) [2]. Others, more sensitive SSNTDs (improved versions of CR-39)
were manufactured in the eighties and they are commercially available as PM-355, PM-500,
PM-600 plastics.
It should, however, be noted that a thermoset material (such as CR-39) is usually
made within the extrusion and quenching process. Therefore, its quality and especially its
particle detection characteristics depend strongly on the applied technological procedures.
Hence, every newly acquired batch of SSNTD sheets should be carefully calibrated before
using for quantitative measurements of ions.
The main aim of this paper was to report on calibration of selected SSNTDs and to
present some examples of their applications, which might be of interest for many plasma
laboratories.
2. Calibration of SSNTDs
At the Andrzej Soltan Institute for Nuclear Studies (IPJ) various SSNTDs have been used
for several years as convenient tools for high temperature plasma corpuscular diagnostics.
Therefore, detailed calibration measurements of different types of SSNTDs have been
performed. The applied calibration procedure was as follows: Beams of selected ions, as
provided by different particle accelerators, were scattered by a suitable thin foil target (made
of pure Au, C, Al, etc.). The scattered ions were used to irradiate samples of the investigated
track detectors, and simultaneously they were monitored by Si-detectors (for determination
energy spectra and counting rates). After irradiation the samples were etched under
controlled conditions (in a 6.25 N water solution of NaOH, at 70oC) for different etching
times. The etching process was stopped every two hours, track parameters (mainly their
diameters) were measured with an optical microscope, and the etching process was renewed
for next 2 hours.
      Some results of the calibration studies concerning the CR-39 and PM-355 plastic track
detectors, irradiated with protons of energy changed from 0.9 MeV to 4.5 MeV in 0.2 MeV
steps, were presented in a paper [3], where a detailed description of the irradiation and
etching was also given. It should be noted that similar calibration measurements were
N  
 C R  - 39
T IM E  O F  E T C H IN G  (h )
0 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6
T
R
A
C
K
 D
IA
M
E
T
E
R
0
5
1 0
1 5
2 0
2 5
3 0
E = 2 .7 5 0  M e V
E = 2 .4 0 0  M e V
E = 2 .1 0 0  M e V
E = 1 .8 0 0  M e V
Fig. 1.  Evolution of track diameters (in µm) of different energy nitrogen ions
as a function of etching time.
performed in our laboratory sixteen years ago for SSNTDs of the cellulose-nitrate (CN) type.
The CN samples were then irradiated with deuterons of energy from 0.1 to 1 MeV [4].
The calibration diagrams
of the CR-39 and PM-355 type
track detectors exposed to
monoenergetic deuterons and 4He
ions were presented in later
papers [5-6]. Recently, the
SSNTDs mentioned above as
well as the modern PM-500 and
PM-600 plastics (together with
CN-films for a comparison), were
irradiates by heavier ions, such as
N+,  N+2,  N+3,  O+, and C +.
Parameters of the tracks induced
by those ions were measured as a
function of the etching time, ion
energy,  and its electric charge
(e.g. Fig.1.). We have also performed some calibration measurements with fast
monoenergetic neutrons. The SSNTD samples were irradiated with neutrons of energy 14.9
MeV and 5.2 MeV. Some of those samples were equipped with an additional converter layer
(neutron – proton) fixed in front of them. Neutron registration efficiencies were determined
for the CR-39, PM-355, and PM-500 plastic detectors, without and with a converter layer of
a different thickness (Fig.2.)
3.  Applications of SSNTDs
The SSNTDs described above appeared to be reliable efficient, and convenient tools for
quantitative measurements of energetic charged particles emitted from high-temperature
plasmas. In such experiments there usually appear strong electromagnetic interferences and
there are observed short emission times of pulsed particle beams accompanied by intense
pulses of the X-ray radiation. The SSNTDs can cope very well with such problems and
therefore they have found applications in many plasma facilities. The SSNTD samples were
installed, e. g. inside a Thomson-type ion analyzer, in order to register ion parabolae
obtained when primary ion beams are deflected by magnetic and electric fields of  the
spectrometer [7-8]. The samples of plastic SSNTDs were also installed, upon a semi-circular
       Fig. 2.   Responses   of   CR-39   and  PM-355
nuclear  track detectors to 5.2 MeV neutrons at
different distances from the neutron source
(detectors without  a  converted layer).
support placed in front of the electrode outlet within PF type facilities. Those SSNTDs were
placed at different   angles to the electrode axis in order to measure angular distributions of
fast ions, emitted from PF discharges [9-10] .
The SSNTD were also applied to register “ion pictures” formed within an ion
pinhole-camera [8-9]. Pieces of a SSNTD covered with absorption filters of different
thickness were used to determine energetic spectra of the D(d,p)T nuclear reaction protons
generated within PF devices [11-12].
4. Conclusions
The calibration characteristics of different SSNTDs, as obtained in our laboratory, make
those detectors more convenient for diagnostic purposes and detailed experimental studies
of primary ions, emitted from high temperature plasmas. Such calibrated SSNTDs can be
used e.g. for measurements of different nuclear reactions products, i.e.fast fusion protons,
energetic tritons, He-ions, and fast neutrons.
The calibrated SSNTDs can also be applied for energy and flux measurements of
pulsed plasma-ion streams generated by different plasma facilities including those used for
technological purposes, e.g. for ion implantation, surface treatment, metallic coating etc.
References
[1] E.C.H. Silk and  R.S. Barens: Phyl.Mag. 4, 970 (1959) .
[2] B.G. Cartwight, K. Shirk, P.B. Price: Nucl.Instr. and  Meth. 153, 457 (1978) .
[3] M. Sadowski, E.M. Al Mashhadani,  et al: Nucl. Instr. and Meth.. B 86, 311 (1996).
[4] T. Czyzewski, A. Szydlowski: J.Tech. Phys. 22 (2), 153 (1981).
[5] M. Sadowski, E.M. Al Mashhadani, et al.:Radiation Measurements 25, 175 (1995).
[6] M. Sadowski, et al.: Proc. 23rd EPS CF&PP, Vol. 20C, Part III, p.1144 (Kiev 1996).
[7] A. Mozer, M. Sadowski, H. Herold, H. Schmidt: J.Appl.Phys. 53(4), 2959 (1982).
[8] S. Denus, S. Czekaj, A. Szydlowski: Atomen-Energie Kerntechnik 44 (3), 189  (1984).
[9] M. Sadowski, et al.: Dense Z-Pinches, AIP Conf. Proc. 299, p.244 (London 1993).
[10] S. Czekaj, et al.: Proc. 11th ICPP CNFR, Vol. 2, p.593 (Kyoto 1986).
[11] U. Jager, L. Bertalot, H. Herold: Rev. Sci. Instr. 56(1), 77 (1985).
[12] E.M. Al Mashhadani, M. Sadowski, A. Szydlowski: Rus. J. Plasma  Phys. 20, 196 (1994).


CALIBRATION AND APPLICATION OF NUCLEAR TRACK DETECTORS FOR HIGH-TEMPERATURE PLASMA DIAGNOSTICS

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CALIBRATION AND APPLICATION OF NUCLEAR TRACK DETECTORS FOR HIGH-TEMPERATURE PLASMA DIAGNOSTICS

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