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Sains Malaysiana 43(6)(2014):
953–958
UV-VIS Spectral
Evaluation of CR-39 Detector Exposed with Diagnostic
Dosage
(Penilaian
Spektrum UV-Vis Pengesan CR-39
Terdedah dengan Dos Diagnostik)
Z. NUR SHA’DAH*1, S.M. ISKANDAR1, A.R. AZHAR1, M.J. SUHAIMI1, R. NUR LINA1 & M.K. HALIMAH2 1School of Physics, Universiti Sains
Malaysia, 11800 USM, Penang, Malaysia
2Department of Physics, Faculty of
Science, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
Received: 3 November
2013/Accepted: 28 December 2013
ABSTRACT
The effects of the X-ray irradiation
and chemical etching on the physical and optical properties of CR-39
plastic detectors were investigated for different doses of X-ray. CR-39
detectors were etched in the solution of the 3 M of NaOH after irradiation for
revelations of the track. The tracks formed on CR-39
either by irradiated X-ray or due to the effect of environment. The changes in
the thickness after exposed have significant decrease in 60 kVp and started to
increase in range of 70 kVp up to 100 kVp due to the formation of oxidation
layer on surface by free radicals. The optical band gaps before etching and
after etching were determined by using Ultraviolet-visible (UV-Vis)
spectroscopy. The optical band gap is attributed to the indirect transition due
to its amorphous nature which is significantly decline trend energy in increase
of the energy fluence of radiation. The Urbach’s energy, is defined as the
width of the tail localized states in the forbidden band gap which change
increment trend as increase in dose delivered due to the distortion structure
of the CR-39 in terms of the electron charges in valences
electron hence attributes to the induced modification of angle bond between the
neighboring atoms.
Keywords: CR-39;
optical band gap; X-ray irradiation
ABSTRAK
Kesan sinar-X pada beberapa pengesan
plastik CR-39 dan punaran kimia telah dikaji dalam dos sinar-X
yang berbeza dalam aspek perubahan sifat fizikal dan sifat optik. CR-39
terpunar dalam cecair NaOH 3 M selepas sinaran untuk pendedahan runut terbentuk
pada CR-39 sama ada oleh sinaran-X atau kerana kesan alam
sekitar. Perubahan ketebalan pendedahan mempunyai peningkatan penurunan yang
beerti pada 60 kVp dan memulakan peningkatan dalam julat 70kVp sehingga 100 kVp
ekoran daripada pembentukan lapisan pengoksidaan di permukaan oleh radikal
bebas. Jurang jalur optik sebelum dan selepas punaran telah ditentukan dengan
menggunakan spektrofotometer Ultralembayung-nampak (UV-Vis)
yang dikatakan oleh peralihan secara tidak langsung disebabkan sifat amorfus
yang ketara menolak trend tenaga di dalam peningkatan fluensi tenaga radiasi.
Tenaga Urbach, ditakrifkan sebagai hujung lebar keadaan setempat dalam jurang
jalur yang terlarang yang menukar trend kenaikan sebagai peningkatan dalam dos
dihantar disebabkan oleh struktur herotan CR-39
dalam jangka caj elektron dalam elektron valen dan mengakibatkan pengubahsuaian
teraruh sudut ikatan di antara atom jiran.
Kata kunci: CR-39; jurang jalur
optik; sinar-X
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