The aim of the first part of this study is to find red blood cell (RBC) diameter by using nuclear track detector CR_39 SSNTDs. Three pieces of the detector of thickness (100µm) were irradiated by alpha particles from 241Am source with energies (2.5, 3.5 and 4.5) MeV. Blood samples were collected from two groups RBC1 (21 years old) and RBC2 (28 years old) donor peoples. Blood samples were smeared over the detectors and after one hour etched with the NaOH solution for 6.25 N at 70 ͦC. The first sample of RBC1 which has a diameter 7.2µm was smeared on the detector that has energy 3.5Mev and the detector was etched to 4.5 hr, which is the same time when the track alpha particles diameters matched with red blood cells diameters. The second sample of RBC2 which has a diameter 6.96μm was smeared on the detector that has energies 2.5 and 4.5 MeV. Matching occurred between the diameters in the energy of 4.5MeV at the time of the 5hr etching, while in the energy 2.5MeV matching occurred at time etched 4 hr.
The second part of the study aimed to find the absorbed energy of alpha particle by the RBC using CR-39. This was achieved through three other pieces of non-irradiated detectors and placing red blood cells on them and then irradiated with alpha particles from 241Am source with incident energies (3.5, 4 and 4.5) MeV. The detectors of the cells were cleaned after irradiation and etched by the chemical solution to a time of etching for a maximum of 5 hr. The diameters of the cells have been measured to calculate the energy passing through the cells and detectors to find the absorbed energy through the difference between the energies of the incident alpha (3.5, 4 and 4.5) Mev and alpha passing through the cell and the detectors. The value of alpha energy absorbed by red blood cells in the three energies was 0.25 MeV.