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"Penelitian ini bertujuan untuk menghitung kontribusi dari elektron kontaminan dalam medium air. Kontaminasi elektron pada berkas foton 6 dan 10 MV telah ditentukan dengan menggunakan metode analitik berdasarkan variasi dosis kedalaman fraksional (FDD) terhadap ukuran lapangan. Variasi terhadap ukuran lapangan turut dipertimbangkan untuk masing-masing jarak fokus ke permukaan (SSD) dan peralatan pengubah sifat berkas (beam modifier). Dari penelitian ini telah ditemukan bahwa dosis elektron kontaminan (dinormalisasi terhadap FDD maksimum) tidak dipengaruhi oleh SSD, menurun dengan kedalaman, dan meningkat dengan ukuran lapangan. Lebih lanjut, elektron kontaminan berkontribusi terhadap dosis permukaan dan bervariasi dari 12.8% hingga 33.5% untuk berkas foton 6 MV dan dari 10.7% hingga 34.2% untuk berkas foton 10 MV dalam lapangan terbuka dengan ukuran lapangan dari 5 cm hingga 40 cm pada SSD 100 cm. Penggunaan tray menaikkan dosis permukaan hingga 46.1% untuk berkas foton 6 MV dan 47.8% untuk berkas foton 10 MV khususnya pada ukuran lapangan 40 x 40 cm2, namun demikian pemakaian filter wedge telah dibuktikan mengurangi dosis elektron kontaminan. Hasil-hasil ini menggambarkan bahwa kontribusi elektron kontaminan terhadap dosis serap total harus dipertimbangkan dalam perhitungan dosimetri.

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The main purpose of this work was to calculate the contribution of the contaminant electrons in water medium. The electron contamination in 6 and 10 MV photon beams was determined by using analytical method which is based on variations of fractional depth dose (FDD) with field size. Variations with field size were independently considered for each source to surface distance (SSD) and beam modifiers. It was found that the maximum electron contaminant dose (normalized to its maximum FDD) was independent of SSD, decreased with depth, and increased with field size. Further, the electron contaminant contributed to the surface dose varied from 12.8% to 33.5% for 6 MV photon beam and from 10.7% to 34.2% for 10 MV photon beam in open field with field sizes from 5 cm to 40 cm at 100 cm SSD. The use of the tray increased the surface dose up to 46.1% for 6 MV photon beam and 47.8% for 10 MV photon beam particularly for the collimator setting of 40 x 40 cm2. The presence of the wedge filter was found to reduce the contaminant electron dose. These results illustrated that the contribution of the contaminant electrons to the total absorbed dose should be included into dosimetry calculation."

"Electrons in a single electron transistor (SET) are transported one by one from source to drain based on the coulomb blockade mechanism. The transport rate is sensitively influenced by the presence of event a single electron charge located near the quantum dot. Based on this characteristic, we propose a Double Quantum Dot (DQD) SET to manipulate the presence of an electron in Quantum Dot (QD) as an implementation of a single-electron logic concept. The existence of an electron in the QD is used to represent logic 0 (no electron in QD) or logic 1 (an electron in QD). The logic states are sensed by a SET charge detector. Design of circuit based on DQD and SET charge detector are simulated by using SIMON 2.0 software. From the simulation, we have successfully developed a two-bit logic circuit by controlling the presence of an electron in DQD. We found that the existence of an electron in QD can be controlled by application of a gate voltage larger than 190µV. Gate should be separated from QD by a non-tunnel capacitor of 500 aF. No larger than 1 aF of interdot tunnel capacitance is required to isolate the QD from one to another. The existence of an electron in QD is successfully detected by SET based charge detector."