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Etching characteristics of phosphate glass track detector
T r a ~ Radla~. Mm:., Vol. 22, Nm I--4, pp 183-186, 1993
l~evi~ ScimceLid Primed ia Otmt k/Ism. 0969-S07S~ $6.00+.00
Pel'llllmOll
ETCHING CHARACTERISTICS OF PHOSPHATE GLASS TRACK DETECTOR S. C. WANO*and P. B. PIuc~ *Insutute of [-hgh Energy Physics, P.O. Box 2732, Beijmg, China; and tPhymcs Depm~,ent, Umvenity of Cahforma, Bodceley, CA 94720, U~.A.
ABSTRACT The etching characteristics of phosphate glass VG-13 have been studied in various etching conditions using relativistic heavy ions SSSU,197Au and *StLs. The addition of KF to HBF4 solution obviously increases the sensitivity of VG-13. The effects of concentration of KF on S and V m were studied. For La ions (z/~:63), S was measured to be about 1.15.
KEYWORDS Phosphate glass; etching; potassium fluoride; sensitivity. INTRODUCTION It was found recently that some phosphate glasses have excellent track recording characteristics and have been applied to several research fields with suecese ( Price eL ,l., 1987a, 1987}), Wang et ai., 1987 ). Phosphate glsm is a very prospective detector both in cosmic ray and nuclear physics. VG-13 is a phosphate track detector with high semfitivity and high charge resolution. In this paper we report the etching characteristics of VG-13 and the effect of adding KF to HBF4 on etching behaviors. EXPERIMENTAL METHOD The glass samples were irradiated with 223 GeV U ions (z/p = 106), 197 GeV Au ions (z/O = 90), 83 GeV La ions (z/~ = 72) and 126 GeV La ions (z/p = 63) from Lawrence Berkeley Laboratory Bavalac Accelerator. After etching in various etchants, the cone lengths and mouth sizes of etch pits were measured m6ng a Leitz Metalloplan microscope with a 53x oil ~ o n objective and S (=V~/Ve) and V e were calculated by applying standard expression for pit geometry. RESULTS AND DISCUSSION The effects of etchant concentration and temperature on S and Vf HBF4, HF sad HNO8 are most commouly used etchants for VG-13. HBF4 has the highest etching sensitivity among them. The effects of the concentration of HBF4 on V e and S for VG-13 in 55°C HBF4 solution are shown in Fig.1 and Fig.2. For VG-13 etched in HBF4 solution, Ve increases linearly with the concentration of HBF4 when it is beyond 30%. S increases with the concentration at first, then trends to be fiat. S and V I for VG-13 etched in 49% HBF4 at different etching temperatures were meamu~. The results are given in Fig.& Ve obeys an Arrheulus relation,as expected from chemical kinetics. Experimental data of VG-13 fit to an equation of InVa = 33.1 - 11.2 x IOS/T. The activation energy for the etching reaction was calculated to be 0.97eV, whieh is in the same order of magnitude as polymer etched in alkali solution. The effect of fluoriO*~ As shown by Fig.2, for VG-13 etched in HBF4 S increases with the concentration of HBF,. Possibly, the sensitivity of VG-13 would keep increasing if more concentrated HBFi was used. However the maximum concentration of HBF4 commercially available is about 49%. KF is a water-dieso]vable fluoride. When
183
184
S.C. WANG and P. B. PRICE
100 0.2
~0.I
40
__f
~
0 20
>-s
6
v
eV/N Au
600MeV/N La
2
2"o 3"o 40
os5 ~ e v / ~ u
;o
I0
20
30
40
50
Concentration of HBF4 (%)
Concentration of HBF4 (%)
Fig.l The effect of concentration of HBF4 on Vg Fig.2 The effect of concentration of HBP4 on s for VG-13 etched in 55°C HBF4 solution, for VG-13 irradiated with 985 MeV/N U, 1000 MeV/N Au and 600 MeV/N La and etched in 55°C HBF4 solution.
I00
935MeV/N U
>II
10
1000MeV/N Au Jh | •
u
w--
600 MeV/N La w
0 10
' 20
" 30
40
" 50
v,--
" 60
70
Temperature (oC) Fig.3 The effect of etching temperature on S for VC~-13irradiated with 935 Mev/N U, 1000 MeV/N Au and 600 MeV/N La and etched in 49% HBF4 solution.
PHOSPHATB GLASS TRACK DETECTOR
18.~
100 ~VG-13+HBF4 50
VG-13÷KF÷HBF4
20
10 .-;/
5
;> II
2
d~
ce 39 _ /
/Jr / V 13+HF
1
0.5
0.2[' 0
Rodyne
20
.
1
80
~
50
80 100
200
z'/B Fig.4 Reduced track etch rate S-1 as a function of z'/~ for VG-13 etched in 10%KF+49%HBF4 (this work), 48%HF and 49%HBF4 (Price et al., 1987a), and Rodyne polycarbonate and CR-39 ( Salamon et a/.,1985). Here z" = zx exp(-130/sSlS).
Table 1: The sensitizing effect of KF for VG-13 Etching condition
Ve
S
(.Ih) U(228GeV)Au(I TGeV) L(SSOeV) 45uC 49%HBF4 35°C 5%KF-I-49%HBF4 45°C 10%KF+49%HBF4
0.11 0.022 0.078
28.4:1:1.6 42.7-4-1.9 40.6-1-2.6
6.9-4-0.8 11.3:~c0.9 10.3-4-0.8
1.8-4-0.0 2.5::k0.2 2.2-4-0.0
KF is added to 49% HBF4, the solution is getting muddy. VG-13 was etched in 49% HBF4 with different an~ount of KF added and S and V e were measured. The effect of KF in 49% HBF4 on S and V# is given in Table 1. The i~.nsitising effect of KF is very obvious and S keeps constant approximately when concentration of KF is between 2% - 10%. Besides KF, other fluorides of alkali metals, such as RbF and C.4F, have idmilar as~,dtizing effect. Fig.4 compares the response of VG-13 etched in 10%KF+49%HBF4 with the response of VG-13 etched in pure 49%HBF4 and in 48%HF. The curve for VG-13 etched in 10%KF+49%HBF4 is smooth fit to ~ values of S for various ions and energies of ions. As the curves show, VG-13 etched in 10%KF+49%HBF4 is more sensztive than VG-13 etched in pure 49%HBF4, or Rodyne polycarbonate for particles of z / ~ > 70. When VG-13 is etched in 49%HBF4, tracks of 1.28 GeV La ions (z/Bffi63) in VG-13 look very shallow and it is hard to measure their track parameters. However when VG-13 is etched in 10%KF+49%HBF4 solution, the tracks of La ions look much darker and S was measured to be about 1.15.
N T m ~/t-4.-N
186
S.C. WANG md P. B. PRICE REFERENCES
Price,P.B., H.-S.Park, G.G~bie~, J.Duch, and M.H.Salsmon (1957a). VG-13 : A nuclear track recordinE glass detector with uniquely hi rh resolution. Nttd. l ~ r . MeW. B ~ 60-67. Price, P.B., L.M.Cook sad k.Marker (19871)). Phospluste glare for identification of heavy ions. Na'~xre, ~5,7000,157-1U. Wans,S.C., P.B.Price, S.W.Bsrwick, K.J.Moody and E.K.Hulet,(1987). Radioactive decay of n4U via Ne and Mg e m i J ~ . Ph~.P~v.C, 36.8, 2717-2720. Salamon,M.H., P.B.Price, M.Tincknell, and S.L. Guo (1985). Charge resolution of plastic track detectors used to identify relativistic nuclei. Natl. Instr. Metl,., ~c0.,~4.
l~evi~ ScimceLid Primed ia Otmt k/Ism. 0969-S07S~ $6.00+.00
Pel'llllmOll
ETCHING CHARACTERISTICS OF PHOSPHATE GLASS TRACK DETECTOR S. C. WANO*and P. B. PIuc~ *Insutute of [-hgh Energy Physics, P.O. Box 2732, Beijmg, China; and tPhymcs Depm~,ent, Umvenity of Cahforma, Bodceley, CA 94720, U~.A.
ABSTRACT The etching characteristics of phosphate glass VG-13 have been studied in various etching conditions using relativistic heavy ions SSSU,197Au and *StLs. The addition of KF to HBF4 solution obviously increases the sensitivity of VG-13. The effects of concentration of KF on S and V m were studied. For La ions (z/~:63), S was measured to be about 1.15.
KEYWORDS Phosphate glass; etching; potassium fluoride; sensitivity. INTRODUCTION It was found recently that some phosphate glasses have excellent track recording characteristics and have been applied to several research fields with suecese ( Price eL ,l., 1987a, 1987}), Wang et ai., 1987 ). Phosphate glsm is a very prospective detector both in cosmic ray and nuclear physics. VG-13 is a phosphate track detector with high semfitivity and high charge resolution. In this paper we report the etching characteristics of VG-13 and the effect of adding KF to HBF4 on etching behaviors. EXPERIMENTAL METHOD The glass samples were irradiated with 223 GeV U ions (z/p = 106), 197 GeV Au ions (z/O = 90), 83 GeV La ions (z/~ = 72) and 126 GeV La ions (z/p = 63) from Lawrence Berkeley Laboratory Bavalac Accelerator. After etching in various etchants, the cone lengths and mouth sizes of etch pits were measured m6ng a Leitz Metalloplan microscope with a 53x oil ~ o n objective and S (=V~/Ve) and V e were calculated by applying standard expression for pit geometry. RESULTS AND DISCUSSION The effects of etchant concentration and temperature on S and Vf HBF4, HF sad HNO8 are most commouly used etchants for VG-13. HBF4 has the highest etching sensitivity among them. The effects of the concentration of HBF4 on V e and S for VG-13 in 55°C HBF4 solution are shown in Fig.1 and Fig.2. For VG-13 etched in HBF4 solution, Ve increases linearly with the concentration of HBF4 when it is beyond 30%. S increases with the concentration at first, then trends to be fiat. S and V I for VG-13 etched in 49% HBF4 at different etching temperatures were meamu~. The results are given in Fig.& Ve obeys an Arrheulus relation,as expected from chemical kinetics. Experimental data of VG-13 fit to an equation of InVa = 33.1 - 11.2 x IOS/T. The activation energy for the etching reaction was calculated to be 0.97eV, whieh is in the same order of magnitude as polymer etched in alkali solution. The effect of fluoriO*~ As shown by Fig.2, for VG-13 etched in HBF4 S increases with the concentration of HBF,. Possibly, the sensitivity of VG-13 would keep increasing if more concentrated HBFi was used. However the maximum concentration of HBF4 commercially available is about 49%. KF is a water-dieso]vable fluoride. When
183
184
S.C. WANG and P. B. PRICE
100 0.2
~0.I
40
__f
~
0 20
>-s
6
v
eV/N Au
600MeV/N La
2
2"o 3"o 40
os5 ~ e v / ~ u
;o
I0
20
30
40
50
Concentration of HBF4 (%)
Concentration of HBF4 (%)
Fig.l The effect of concentration of HBF4 on Vg Fig.2 The effect of concentration of HBP4 on s for VG-13 etched in 55°C HBF4 solution, for VG-13 irradiated with 985 MeV/N U, 1000 MeV/N Au and 600 MeV/N La and etched in 55°C HBF4 solution.
I00
935MeV/N U
>II
10
1000MeV/N Au Jh | •
u
w--
600 MeV/N La w
0 10
' 20
" 30
40
" 50
v,--
" 60
70
Temperature (oC) Fig.3 The effect of etching temperature on S for VC~-13irradiated with 935 Mev/N U, 1000 MeV/N Au and 600 MeV/N La and etched in 49% HBF4 solution.
PHOSPHATB GLASS TRACK DETECTOR
18.~
100 ~VG-13+HBF4 50
VG-13÷KF÷HBF4
20
10 .-;/
5
;> II
2
d~
ce 39 _ /
/Jr / V 13+HF
1
0.5
0.2[' 0
Rodyne
20
.
1
80
~
50
80 100
200
z'/B Fig.4 Reduced track etch rate S-1 as a function of z'/~ for VG-13 etched in 10%KF+49%HBF4 (this work), 48%HF and 49%HBF4 (Price et al., 1987a), and Rodyne polycarbonate and CR-39 ( Salamon et a/.,1985). Here z" = zx exp(-130/sSlS).
Table 1: The sensitizing effect of KF for VG-13 Etching condition
Ve
S
(.Ih) U(228GeV)Au(I TGeV) L(SSOeV) 45uC 49%HBF4 35°C 5%KF-I-49%HBF4 45°C 10%KF+49%HBF4
0.11 0.022 0.078
28.4:1:1.6 42.7-4-1.9 40.6-1-2.6
6.9-4-0.8 11.3:~c0.9 10.3-4-0.8
1.8-4-0.0 2.5::k0.2 2.2-4-0.0
KF is added to 49% HBF4, the solution is getting muddy. VG-13 was etched in 49% HBF4 with different an~ount of KF added and S and V e were measured. The effect of KF in 49% HBF4 on S and V# is given in Table 1. The i~.nsitising effect of KF is very obvious and S keeps constant approximately when concentration of KF is between 2% - 10%. Besides KF, other fluorides of alkali metals, such as RbF and C.4F, have idmilar as~,dtizing effect. Fig.4 compares the response of VG-13 etched in 10%KF+49%HBF4 with the response of VG-13 etched in pure 49%HBF4 and in 48%HF. The curve for VG-13 etched in 10%KF+49%HBF4 is smooth fit to ~ values of S for various ions and energies of ions. As the curves show, VG-13 etched in 10%KF+49%HBF4 is more sensztive than VG-13 etched in pure 49%HBF4, or Rodyne polycarbonate for particles of z / ~ > 70. When VG-13 is etched in 49%HBF4, tracks of 1.28 GeV La ions (z/Bffi63) in VG-13 look very shallow and it is hard to measure their track parameters. However when VG-13 is etched in 10%KF+49%HBF4 solution, the tracks of La ions look much darker and S was measured to be about 1.15.
N T m ~/t-4.-N
186
S.C. WANG md P. B. PRICE REFERENCES
Price,P.B., H.-S.Park, G.G~bie~, J.Duch, and M.H.Salsmon (1957a). VG-13 : A nuclear track recordinE glass detector with uniquely hi rh resolution. Nttd. l ~ r . MeW. B ~ 60-67. Price, P.B., L.M.Cook sad k.Marker (19871)). Phospluste glare for identification of heavy ions. Na'~xre, ~5,7000,157-1U. Wans,S.C., P.B.Price, S.W.Bsrwick, K.J.Moody and E.K.Hulet,(1987). Radioactive decay of n4U via Ne and Mg e m i J ~ . Ph~.P~v.C, 36.8, 2717-2720. Salamon,M.H., P.B.Price, M.Tincknell, and S.L. Guo (1985). Charge resolution of plastic track detectors used to identify relativistic nuclei. Natl. Instr. Metl,., ~c0.,~4.