|
|
 |
| |
|
|
|
Registration Properties of LR-115 NTDs and their use in Radon Level Determination and Equivalent Dose Evaluation |
|
|
|
PP: 275-283 |
|
|
|
doi:10.18576/jrna/100309
|
|
|
|
Author(s) |
|
|
|
E. H. Ghanim,
Kh. Shnishin,
A. Hussien,
H. M. El Samman,
M. Shehata,
M. El Ghazaly,
A.El-Sersy,
|
|
|
|
Abstract |
|
|
| Cellulose Nitrate (LR-115) Nuclear Track Detectors (NTDs) were irradiated systematically with alpha particles from a 241Am alpha source with an energy range of about 1 to 5 MeV at an incident angle 90o. Etching characteristics and registration properties were studied. The alpha tracks in LR-115 films were measured with an optical microscope attached to an eyepiece micrometer with a precision division of ±0.22 μm. The main parameter is the bulk etch rate (VB), which was carried out that controlled during the track formation. The dependence of VB on etchant concentration and temperature was extensively investigated. The activation energy, Eb, of etching for the studied detectors was calculated, and an average value of Eb = 0.93 ± 0.03 eV was extracted. The registration parameters were performed. The used plastic foils were pre-sparked to clear the alpha track diameter openings. The registration properties of pre-sparked LR-115 NTDs were enhanced up to the value of 5.0 MeV -energy. The Response function, V, as a function of residual range, R, and restricted energy loss (REL350) was deduced. In addition, the registration parameters and the excess etch-rate ratio (V-l) of alpha tracks were achieved. The dependence of response, V, and the excess etch-rate ratio (V-l) upon R as well as REL350, was investigated. Also, it is clear that response V was decreased rapidly, and the excess etch-rate ratio (V-l) was increased in a power fitting formula. The relation between (V-l) and REL350 obeys a power law that agrees well with some previous works.
The radon concentration, CRn, was related to track densities using an AB-5 calibrated monitor through a calibration factor, k, of LR-115 detectors. A radon concentration chamber was designed and attached with an AB-5 monitor to determine the calibration factor, k. The average value of k was found to be k = 0.0599 track cm-2d-1 per Bq m-3. Also, the equilibrium factor, F, was calculated experimentally with the empirical equation of the open and closed cup mode technique for track ratio. The equilibrium factor, F, was calculated as F = 0.45. The LR-115 detectors were used in the radon level determination as CRn and radon equivalent dose, Deq, in some dwellings in the Menoufia zone in Egypt. The minimum detectable value of equivalent dose to the maximum value was 0.4 - 0.6 mSv/y in two different modes of measurement. An average value of radon equivalent dose was deduced as Deq.= 0.5 mSv/y. An average value of radon-annual equivalent dose in houses was found to be = 0.72 mSv/y. Results of this study are discussed within the framework of nuclear track formation theories and the etching concepts mechanism.
|
|
|
|
|
|
|
|
