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Study of heavy ion tracks in soda glass
Nuclear Instruments and Methods 215 (1983) 535-537 North-Holland Publishing Company
STUDY
OF HEAVY ION TRACKS
IN SODA
535
GLASS
S h y a m K U M A R , J.S. Y A D A V , S. C H A N D E R and A.P. SHARMA l)epartment of Physics, Kurukshetra Umrerst(v, Kurukshetru 132 119, India Received 3 March 1983
The pre-annealed and pre-etched samples of a soda glass detector are irradiated to S°Ti, 5¢'1:e and 12')Xe beams of energy 4.9 MeV/N, 5.1 MeV/N and 0.9 MeV/N, respectively from the Joint Institute of Nuclear Research (JINR) Dubna (Moscow) USSR. These irradiated samples are etched in the new etchant (HF ,:18 vol.% + H,SOa 96 vol.% ~-H ,O in the ratio of 6 : 1 : 1 8 with small amount of Z n ) at 40°( ". The etch pit diameter and track length are measured for different etching times. The energ5 loss and range of these ions in soda glass are also computed theoretically. By the comparison of total etchable track length ~ith the theoretical range, the value of critical threshold for etchable tracks in soda glass is found to be (13.0 + 1) McV mg -I cm 2.
1. Introduction During the last two decades solid state nuclear track detectors have been increasingly used in various fields of science and technology because of their simple handling and low cost [1-3]. A m o n g SSNTDs, glass detectors have held a special place due to their superior homogeneity and transparency and also due to their higher threshold for track registration, they are less p r o n e to e n v i r o n m e n t a l effects. So, glass detectors can be preferably used in certain studies of nuclear physics, astrophysics and geophysics where e n v i r o n m e n t a l conditions can affect the detector response [4]. In the present work. the etchpit diameter and etched track length were measured as a function of etching time for ~° Ti, 56Fe and 129Xe ions of energy 4.9 M e V / N , 5.1 M e V / N and 0.9 M e V / N respectively in soda glass. The energy loss a n d range of these ions in soda glass were calculated theoretically and c o m p a r e d with experimental values of etched track lengths to obtain the critical energy loss (dE/dx)¢ for etchable tracks in soda glass.
2. Experimental details
a n d length were measured with a transmitted light microscope having an eye-piece screw micrometer with a least count of 0.215 p.m for a magnification of 900 × . A phase contrast technique was used to increase the precision of the measurements. The total error in diameter m e a s u r e m e n t due to statistical error, diffraction of light a n d microscope optical resolution was found to be within 0.5 p.m. The energy loss rate (dE/dX) for these ions is calculated by using the r a n g e - e n e r g y equations given by Mukherjee and Nayak [8] which give elemental stopping power. Assuming the validity of Bragg's additive rule, the stopping power of complex media [(dE/dX)~] E at the ion energy E in terms of the stopping powers of constituent elements (d E/d X), at the same ion energy E, are represented as
[ ( d E / d X ) , ] E = ~ I ~[Y,A,(dE/dX),]L-,
(I)
where A,. = 5".,(~]A,) is the molecular mass n u m b e r of the medium, A, and Y, are the mass n u m b e r and n u m b e r of atoms per molecule of the i t h atomic species respectively. E
Range=
Y'~
8E/[(dE/dX),]E,
(2)
E - k.'.
The pre-annealed and pre-etched samples of soda glass were .exposed vertically to -S°Ti, S6Fe a n d 129Xe b e a m s of energy 4.9 M e V / N , 5.1 M e V / N and 0.9 M e V / N respectively from the heavy ion cyclotron at J I N R D u b n a , USSR [5,61. These exposed samples were etched in the new etchant (48 vol.% H F + 96 vol.% H 2 S O , ~ + H , O in the ratio of 6 : 1 : 1 8 with a small a m o u n t of Z n ) [7] at 40°C by using a thermostatically controlled i n c u b a t o r within + I°C. The track diameter 0 1 6 7 - 5 0 8 7 / 8 3 / 0 0 0 0 - 0 0 0 0 / $ 0 3 . 0 0 ~ 1983 N o r t h - H o l l a n d
where the range is in m g / c m 2, (dE/dX) is in MeV r a g - i cm 2 and E o corresponds to Vc) = (e2/h) where I~) is the electron vekx:ity in the hydrogen atom. 8 E = 0.05 MeV (small energy interval over which d E / d X is assumed to be constant). Range in microns = Range ( m g / c m 2) × 10.0/density. (3)
S. h ' u m o r t't al. / th,at:v m n tracl, ~ m soda glass
536
6° r
XQ
Sodo gtess
3Or
+ Zn (smell omount ) Ot g,C'C
O F, ~
i ~n
E
x,
¢a
20
~0
f~
wX
I0[
0 L,-/~ - ", 0 40
.................................. BO 120 160 200 Zt,O 280 Etch,ng time (Seconds)
~ 360
320
"!!
, 400
0Lo
Fig. 1. Variation of etch pit diameter with etching time for ~(}'li (4.9 MeV/N), 5~'Fe (5.1 MeV/N) and ~2'~Xe(0.9 MeV/N).
,3
2~
3',~
I, ,.o
Ron§e
-~'0
?0-
,
7c
I,i ~o
.
90
',,u m )
Fig. 3. Variation of energy loss rate d E / d X with penetration
depth of ~(}'['i. ~'~'Fe and 12'~Xe ions in soda glass (calculated theoretically). 3. R e s u l t s a n d d i s c u s s i o n
Fig. 1 shows, the variation of etch pit diameter with etching time for the ions 5°Ti. 5~'Fe and 129Xe with energies 4.9 M c V / N , 5.1 M e V / N and 0.9 M c V / N , respectively. For 5°Ti and 5~Fe, the slope of the etchpit diameter versus etching time curves increases continuously, but for 129Xe, the slope of this curve decreases continuously. "l'his is because for tracks of 5"I'i ions of energy' 4.9 M e V / N and S~'Fe ions of energy 5.1 M e V / N , the energy loss increases with penetration depth until the energy is degraded to = 1.5 M e V / N (the position of the Bragg peak in the range versus energy loss curvc) and after this, energy loss starts decreasing [6.9]. But for 12'~Xe of energy 0.9 M e V / N , the energy loss decreases continuously with penetration depth and so does the slope of track diameter versus etching time curves.
24"
~'.r r
f
l
"~--°
s6! 8.t
/~/ '
~
o /j//
/"
/ /
/
- ~zlE
//~ ,, /
-
"I ol 40!
j~
~
J Fe
_
~_.___
.~ _ _~___~ L_%~ L obs
I-corrected
--o-
---o--
T,
~
-~c--
Xe
"
//~/~ .~//~
tc
~_ . - "~z~..-.a, . . . . .
,__ -~-~
-e-
16Elchont .
HF48VoI'Io:H250/, 96%:H20 : 6 ' 18 ~'Zn (srnoII quonh|y)ot LG*C 0 [ -~ 0
. . . . . . . . . . . . . . . . . . . . . . . . . 60 120 180 210 30G E~ch,rg hme (seconds) ¢:~
360
I. = L,b, +
Vht-- Vb(t-- t,).
(4)
where Vb is the bulk etch rate, t is the etching time and t is the complete etching time (time required for the tracks to be etched completely). The value of t¢ for ~°Ti (4.9 M e V / N ) , S~'Fe (5.1 M e V / N ) and 129Xe (0.9 M e V / N ) is found to be 4.4, 4.2 and 1.1 min, respectively. The total etched track lengths for the 5°Ti ion of energy 4.9 M e V / N , S~'Fe ions of 5.1 M e V / N and I~"~Xe ions of 0.9 M e V / N after correction turn out to be (53.5 ± 1) p.m, (59.6 _+ 1) p.m and (21.2 _+ 0.5) p.m, respectively. By comparing the values of the total etchablc track lengths of these ions with the theoretical value c,f the range of these ions at the same energy, the value of the critical threshold (dE/dX), for etchahle tracks in soda glass is found (fig. 3) [10]. The value of (dE/dX)~ for these ion tracks is found to be within (13.0 ! 11 MeV nag t c m 2. The authors are thankful to the authorities of J I N R Dubna (USSR) for providing the exposed samplcs. One of us (SKy is thankful to the authorities of CSIR (India) for providing financial assistance.
420
Fig. 2. Variation of observed and corrected track length for ~"'I'i (4.9 M e V / N ) , ~'Fe (5.1 M e V / N ) a n d 1"gXe (0.9 M e V / N )
with etching time.
Fig. 2 shows the variation of observed track lengths L + , and corrected track length I , with etching time. The observed track length first increases with etching time and after a certain value of etching time, t., called the complete etching time, the observed track length becomes constant. The observed track length is corrected for surface etching and over etching. "[he corrected track length is obtained using the formula
References
[I] P.B. Price and R.L. Fleischer. Annl. Rev. Nucl. Sci. 21 (1971) 295.
S. K u m a r et aL / Heaw" ton tracks :n soda gh:ss
[2] R.A. Akber, H.A. Khan and A.U. Baljwa. Nucl. Instr. and Meth. 160 (1979) 295. [3] J.S. Yadav, K.L. Gomber, V.P. Singh and A.P. Sharma. Int. J. Appl. Rad. and Iso. 31 (1980) 713. [4] J.S. Yadav, V.P. Singh, K.L. Gomber and A.P. Sharma. Proc. 10th Int. Conf. on SSNTDs (1980) p. 199. [5] J.S. Yadav and A.P. Sharma, Nucl. Track 3 (1979) 119. [6] J.S. Yadav. PhD thesis. Kurukshetra University, India (1982).
537
[7] K.L. Gomber, J.S. Yadav. V.P. Singh and A.P. Sharma. ('an. J. Phys. 59 (1981) 693. [8] S. Mukherjee and A.K. Nayak. Nucl. Instr. and Meth. 159 (1979) 421. [9] G. Fiedler, J. Aschenbach. W. Otto, T. Rantenherg, U. Steinhausar and G, Siegert. Nucl. Instr. and Meth. 147 (1977) 35. [101 K.K. Dwivedi. Thesis, I.I.T. Kanpur, India.
STUDY
OF HEAVY ION TRACKS
IN SODA
535
GLASS
S h y a m K U M A R , J.S. Y A D A V , S. C H A N D E R and A.P. SHARMA l)epartment of Physics, Kurukshetra Umrerst(v, Kurukshetru 132 119, India Received 3 March 1983
The pre-annealed and pre-etched samples of a soda glass detector are irradiated to S°Ti, 5¢'1:e and 12')Xe beams of energy 4.9 MeV/N, 5.1 MeV/N and 0.9 MeV/N, respectively from the Joint Institute of Nuclear Research (JINR) Dubna (Moscow) USSR. These irradiated samples are etched in the new etchant (HF ,:18 vol.% + H,SOa 96 vol.% ~-H ,O in the ratio of 6 : 1 : 1 8 with small amount of Z n ) at 40°( ". The etch pit diameter and track length are measured for different etching times. The energ5 loss and range of these ions in soda glass are also computed theoretically. By the comparison of total etchable track length ~ith the theoretical range, the value of critical threshold for etchable tracks in soda glass is found to be (13.0 + 1) McV mg -I cm 2.
1. Introduction During the last two decades solid state nuclear track detectors have been increasingly used in various fields of science and technology because of their simple handling and low cost [1-3]. A m o n g SSNTDs, glass detectors have held a special place due to their superior homogeneity and transparency and also due to their higher threshold for track registration, they are less p r o n e to e n v i r o n m e n t a l effects. So, glass detectors can be preferably used in certain studies of nuclear physics, astrophysics and geophysics where e n v i r o n m e n t a l conditions can affect the detector response [4]. In the present work. the etchpit diameter and etched track length were measured as a function of etching time for ~° Ti, 56Fe and 129Xe ions of energy 4.9 M e V / N , 5.1 M e V / N and 0.9 M e V / N respectively in soda glass. The energy loss a n d range of these ions in soda glass were calculated theoretically and c o m p a r e d with experimental values of etched track lengths to obtain the critical energy loss (dE/dx)¢ for etchable tracks in soda glass.
2. Experimental details
a n d length were measured with a transmitted light microscope having an eye-piece screw micrometer with a least count of 0.215 p.m for a magnification of 900 × . A phase contrast technique was used to increase the precision of the measurements. The total error in diameter m e a s u r e m e n t due to statistical error, diffraction of light a n d microscope optical resolution was found to be within 0.5 p.m. The energy loss rate (dE/dX) for these ions is calculated by using the r a n g e - e n e r g y equations given by Mukherjee and Nayak [8] which give elemental stopping power. Assuming the validity of Bragg's additive rule, the stopping power of complex media [(dE/dX)~] E at the ion energy E in terms of the stopping powers of constituent elements (d E/d X), at the same ion energy E, are represented as
[ ( d E / d X ) , ] E = ~ I ~[Y,A,(dE/dX),]L-,
(I)
where A,. = 5".,(~]A,) is the molecular mass n u m b e r of the medium, A, and Y, are the mass n u m b e r and n u m b e r of atoms per molecule of the i t h atomic species respectively. E
Range=
Y'~
8E/[(dE/dX),]E,
(2)
E - k.'.
The pre-annealed and pre-etched samples of soda glass were .exposed vertically to -S°Ti, S6Fe a n d 129Xe b e a m s of energy 4.9 M e V / N , 5.1 M e V / N and 0.9 M e V / N respectively from the heavy ion cyclotron at J I N R D u b n a , USSR [5,61. These exposed samples were etched in the new etchant (48 vol.% H F + 96 vol.% H 2 S O , ~ + H , O in the ratio of 6 : 1 : 1 8 with a small a m o u n t of Z n ) [7] at 40°C by using a thermostatically controlled i n c u b a t o r within + I°C. The track diameter 0 1 6 7 - 5 0 8 7 / 8 3 / 0 0 0 0 - 0 0 0 0 / $ 0 3 . 0 0 ~ 1983 N o r t h - H o l l a n d
where the range is in m g / c m 2, (dE/dX) is in MeV r a g - i cm 2 and E o corresponds to Vc) = (e2/h) where I~) is the electron vekx:ity in the hydrogen atom. 8 E = 0.05 MeV (small energy interval over which d E / d X is assumed to be constant). Range in microns = Range ( m g / c m 2) × 10.0/density. (3)
S. h ' u m o r t't al. / th,at:v m n tracl, ~ m soda glass
536
6° r
XQ
Sodo gtess
3Or
+ Zn (smell omount ) Ot g,C'C
O F, ~
i ~n
E
x,
¢a
20
~0
f~
wX
I0[
0 L,-/~ - ", 0 40
.................................. BO 120 160 200 Zt,O 280 Etch,ng time (Seconds)
~ 360
320
"!!
, 400
0Lo
Fig. 1. Variation of etch pit diameter with etching time for ~(}'li (4.9 MeV/N), 5~'Fe (5.1 MeV/N) and ~2'~Xe(0.9 MeV/N).
,3
2~
3',~
I, ,.o
Ron§e
-~'0
?0-
,
7c
I,i ~o
.
90
',,u m )
Fig. 3. Variation of energy loss rate d E / d X with penetration
depth of ~(}'['i. ~'~'Fe and 12'~Xe ions in soda glass (calculated theoretically). 3. R e s u l t s a n d d i s c u s s i o n
Fig. 1 shows, the variation of etch pit diameter with etching time for the ions 5°Ti. 5~'Fe and 129Xe with energies 4.9 M c V / N , 5.1 M e V / N and 0.9 M c V / N , respectively. For 5°Ti and 5~Fe, the slope of the etchpit diameter versus etching time curves increases continuously, but for 129Xe, the slope of this curve decreases continuously. "l'his is because for tracks of 5"I'i ions of energy' 4.9 M e V / N and S~'Fe ions of energy 5.1 M e V / N , the energy loss increases with penetration depth until the energy is degraded to = 1.5 M e V / N (the position of the Bragg peak in the range versus energy loss curvc) and after this, energy loss starts decreasing [6.9]. But for 12'~Xe of energy 0.9 M e V / N , the energy loss decreases continuously with penetration depth and so does the slope of track diameter versus etching time curves.
24"
~'.r r
f
l
"~--°
s6! 8.t
/~/ '
~
o /j//
/"
/ /
/
- ~zlE
//~ ,, /
-
"I ol 40!
j~
~
J Fe
_
~_.___
.~ _ _~___~ L_%~ L obs
I-corrected
--o-
---o--
T,
~
-~c--
Xe
"
//~/~ .~//~
tc
~_ . - "~z~..-.a, . . . . .
,__ -~-~
-e-
16Elchont .
HF48VoI'Io:H250/, 96%:H20 : 6 ' 18 ~'Zn (srnoII quonh|y)ot LG*C 0 [ -~ 0
. . . . . . . . . . . . . . . . . . . . . . . . . 60 120 180 210 30G E~ch,rg hme (seconds) ¢:~
360
I. = L,b, +
Vht-- Vb(t-- t,).
(4)
where Vb is the bulk etch rate, t is the etching time and t is the complete etching time (time required for the tracks to be etched completely). The value of t¢ for ~°Ti (4.9 M e V / N ) , S~'Fe (5.1 M e V / N ) and 129Xe (0.9 M e V / N ) is found to be 4.4, 4.2 and 1.1 min, respectively. The total etched track lengths for the 5°Ti ion of energy 4.9 M e V / N , S~'Fe ions of 5.1 M e V / N and I~"~Xe ions of 0.9 M e V / N after correction turn out to be (53.5 ± 1) p.m, (59.6 _+ 1) p.m and (21.2 _+ 0.5) p.m, respectively. By comparing the values of the total etchablc track lengths of these ions with the theoretical value c,f the range of these ions at the same energy, the value of the critical threshold (dE/dX), for etchahle tracks in soda glass is found (fig. 3) [10]. The value of (dE/dX)~ for these ion tracks is found to be within (13.0 ! 11 MeV nag t c m 2. The authors are thankful to the authorities of J I N R Dubna (USSR) for providing the exposed samplcs. One of us (SKy is thankful to the authorities of CSIR (India) for providing financial assistance.
420
Fig. 2. Variation of observed and corrected track length for ~"'I'i (4.9 M e V / N ) , ~'Fe (5.1 M e V / N ) a n d 1"gXe (0.9 M e V / N )
with etching time.
Fig. 2 shows the variation of observed track lengths L + , and corrected track length I , with etching time. The observed track length first increases with etching time and after a certain value of etching time, t., called the complete etching time, the observed track length becomes constant. The observed track length is corrected for surface etching and over etching. "[he corrected track length is obtained using the formula
References
[I] P.B. Price and R.L. Fleischer. Annl. Rev. Nucl. Sci. 21 (1971) 295.
S. K u m a r et aL / Heaw" ton tracks :n soda gh:ss
[2] R.A. Akber, H.A. Khan and A.U. Baljwa. Nucl. Instr. and Meth. 160 (1979) 295. [3] J.S. Yadav, K.L. Gomber, V.P. Singh and A.P. Sharma. Int. J. Appl. Rad. and Iso. 31 (1980) 713. [4] J.S. Yadav, V.P. Singh, K.L. Gomber and A.P. Sharma. Proc. 10th Int. Conf. on SSNTDs (1980) p. 199. [5] J.S. Yadav and A.P. Sharma, Nucl. Track 3 (1979) 119. [6] J.S. Yadav. PhD thesis. Kurukshetra University, India (1982).
537
[7] K.L. Gomber, J.S. Yadav. V.P. Singh and A.P. Sharma. ('an. J. Phys. 59 (1981) 693. [8] S. Mukherjee and A.K. Nayak. Nucl. Instr. and Meth. 159 (1979) 421. [9] G. Fiedler, J. Aschenbach. W. Otto, T. Rantenherg, U. Steinhausar and G, Siegert. Nucl. Instr. and Meth. 147 (1977) 35. [101 K.K. Dwivedi. Thesis, I.I.T. Kanpur, India.