Applying plasma as an etching technique for CN-85 SSNTDs: Comparison study

This work compares the traditional etching technique using a water bath (WB) and plasma as a dry technique applied to CN-85 detectors as one type of solid-state nuclear track detectors (SSNTDs). That comparison will be achieved using different irradiation times with an Americium-241Alpha source (²⁴¹Am) of 5.486 MeV energy and 10 μCi activity. Three irradiation times, 10 s, 15 s, and 20 s, are applied. Small pieces of CN-85 detectors (1×1) cm² were used. For chemical etching with the WB technique, Sodium Hydroxide (NaOH) powder with a high purity (96 %) is used. In the dry etching technique, a non-thermal system of plasma is applied to etch CN-85 detectors. The Dielectric Barrier Discharge plasma system with dry air (DBD) is applied. Parameters of the etching process (the etching bulk rate (V_B), the track diameter (D_e), etching time (t_e), the track etching rate (V_T), the rate of track diameter (V_D), the ratio of etching rate (V), the critical angle of etching (θ_c) and the etching efficiency (ƞ)) for the CN-85 detector, applying WB and plasma, are estimated and compared. The tracks diameter was observed to increase with the increase in etching time for the two techniques at different irradiation times. Comparing the two applied etching techniques, it was observed that the track diameter growth rates in the plasma technique are higher than those in the WB technique as 9.78, 10.38, and 17.22 μm/min for the plasma technique compared to 0.328 μm/min for the WB technique at the three irradiation times. The plasma technique had an etching efficiency of ∼59 %, which is more efficient than the water bath technique (∼20 %) at a 15-s irradiation time. When the irradiation time increases to 20 s, the efficiencies of the plasma and water bath techniques become 54 % and 22 %, respectively. Hence, a dry etching plasma technique with SSNTD CN-85 with high efficiency compared to the water bath chemical technique is recommended for radiation dosimetry and radiation monitoring in wide applications such as the environment and nuclear medicine.