The paper aims to propose the maximum track length (Lmax) measurement as an alternative approach to evaluate and extract the bulk etch rate (Vb) of the nuclear detector PADC CR-39, and compare it with the results obtained by the removal layer thickness measurement of the etched detector. The alternative Lmax-method mainly relies on the measuring the length of the etched tracks, their maximum values and saturation times from the obtained track profile images. The detectors were irradiated with different energies of alpha particles emitted from the 241Am source and then etched in a 6.5 N NaOH solution at 701oC for different successive time intervals. In order to calculate Vb, the maximum length of the tracks and their saturation times were determined corresponding to the energies of the alpha particles used. A direct proportion between the maximum length of the tracks and the energy of the alpha particle was observed. However, the value of Vb is found to be 1.3440.0202 m h-1 obtained using the Lmax-method, and it was consistent with that computed by the method based on the measurement of the thickness difference of the etched detector which was 1.3540.065 m h-1.

PADC detector --- SSNTDs --- Bulk Etch rate --- CR-39 --- Track Length.

In the present work, we have determined the bulk-etch rates of lexan polycarbonate (C16H14O3)n nuclear track detector at different temperatures to deduce its activation energy, the effects of gamma irradiation on this detector in the dose range of 23 – 71.3 kGy have been studied by using the etching technique. The bulks etch rates increase and the activation energies for bulk etching decrease with the increase in gamma dose. These results have been explained on the basis of chain scission of the detector due to gamma irradiation.

في هذا البحث تم حساب معدل القشط لسطح كاشف الاثر النووي للحاله الصلبة Lexan Polycarbonate الصيغة الكيميائية (C16H14O3)n عند درجات حرارة مختلفة لاستخراج طاقة التنشيط لمعدلات القشط لسطح الكاشف،وكما تم دراسة تأثير جرع مختلفة من اشعة كاما (23-71.3 KGy) على معدلات القشط لسطح الكاشف من خلال استخدام تقنية القشط بمحلول قاشط . حيث وجد ان معدل القشط لسطح الكاشف تزداد وطاقة التنشيط تقل بزيادة جرعة اشعة كاما ويعود السبب في ذلك الى ان اشعة كاما تعمل على شق سلاسل البوليمرية لمادة الكاشف

Lexan polycarbonate --- Gamma radiation --- etching technique --- Bulk-etch rate --- activation energies for bulk etching.

In this paper, the bulk etch rate, VB of the CR-39 detector employed, was found experimentally to be equal to 1.49µmh-1. Detector samples were irradiated with alpha particles energies from 1 to 5MeV and incident angles from 20◦ to 90◦. After etching in a 6.25N NaOH solution kept at (70±1) ˚C, the lengths of major and minor axes of the alpha track openings were measured, and the track etch rate, VT for normal and oblique incidence was calculated. The relationship between VT and the track depth, x of the alpha particle in the detector for normal incidence was studied. Track length, L and track length growth rate, dL/dt were also calculated. These data were used altogether to derive a V function, which took the functional form of the Brun’s function with new constants (a1=0.091, a2=1.2, a3=1.6, a4=1.61, a5=1.425). Experimental V function was compared with those computed by TRACK-VISION program, and a good agreement with three of them was found

في هذا البحث، تم حساب معدل القشط العام ((VB عمليا للكاشف CR-39 المستخدم في هذه الدراسة إذ وجد انه يساوي 1.49µmh-1. تم تشعيع نماذج من الكاشف بجسيمات الفا طاقاتها من (1-5 MeV) وزوايا سقوطها من (20◦-90◦)، ثم قشطها بمحلول NaOH تركيزه 6.25N ودرجة حرارته (70±1) ˚C. تم قياس اطوال المحاور الكبيرة والصغيرة لفتحات الاثر ومن ثم حساب معدل القشط على طول الاثر (VT)، ودراسة العلاقة بين ((VT وعمق الاثر (x) لجسيمات الفا في مادة الكاشف عند السقوط العمودي، وحساب طول الأثر (L) ومعدل نمو طول الاثر .(dL/dt) استخدمت البيانات العملية اعلاه لاشتقاق دالة جديدة (V) والتي أخذت شكل دالة Brun بثوابت جديدة.(a1=0.091, a2=1.2, a3=1.6, a4=1.61, a5=1.425) وأخيرا تمت مقارنة نتائج الدراسة الحالية للدالة (V) مع نتائج الدوال الموجودة في برنامج TRACK-VISION ووجد تطابق جيد مع ثلاث منها

CR-39 --- Bulk etch rate VB --- Track etch rate VT --- Major and minor axes --- Track length L --- V function --- CR-39، معدل القشط العام VB، معدل قشط الاثر VT، المحاور الكبيرة والصغيرة، طول الأثر L، الدالة V.