Judul: Penentuan Kurva Efisiensi Detektor Sinar Gamma Dengan Menggunakan Simulasi Monte Carlo
Abstrak: Pengukuran radioaktivitas pada sebuah sampel memegang peranan penting dalam bidang proteksi radiasi pada instalasi-instalasi nuklir. Untuk keperluan tersebut biasaoya digunakan metode spektrometri sinar gamma dengan menggunakan sebuah detektor semikonduktor gennanium. Dalam menggunakan metode tersebut, puncak kurva efisiensi dari sinar gamma pada setiap jenis sampel yang akan diukur harus diketahui terlebih dahulu.
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Judul: Radiasi gamma dari cesium 134 pada tanah
Abstrak: Nilai efisiensi pada pengukuran radiasi gamma sangat dipengaruhi oleh faktor geometri. Pengukuran ini dilakukan terhadap tanah yang dicampur dengan cesium-134 dengan radionuklida yang teratur pada spektrometer gamma. Campuran tanah dengan 134Cs dicacah menggunakan spektrometer gamma pada berbagai ukuran wadah sampel yaitu silinder dengan ukuran 0,2 liter dan 2 liter dan menggunakan Marinelli beaker dengan ukuran 0,5 liter, 1 liter, 2 liter dan 3 liter. Luas permukaan wadah yang kontak dengan detektor juga mempengaruhi nilai efisiensi. Semakin besar nilai perbandingan luas permukaan wadah yang kontak dengan detektor terhadap seluruh luas permukaan sampel maka menjadi semakin besar nilai efisiensi.
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Judul: Filogeni Timun Laut Famili Stichopodidae (Kelas Holothuroidea) Berdasarkan Karakter Morfologi
Abstrak: Stichopodidae is one of the commercial holothuroid families and distributes widely in tropical shallow waters around the world. External and internal morphology as well as spicules are used to differentiate holothuroid species. However, these characters possessed high similarity among the Stichopodidae members. Evolution based on morphological characters can be used to determine the character states that subsequently applied in the phylogenetic analysis. However, the evolutions of those characters are still under debatable. Based on the previous phylogenetic studies, there is still no morphological study of Stichopodidae. Therefore, this study was conducted to describe the phylogenetic relationship of Stichopodidae, to determine plesiomorph, synapomorph, homoplasy and key characters of species from Stichopus and Thelenota (Stichopodidae). The specimens used in this study were derived from Oceanography Research Center-Indonesian Institute of Sciences (LIPI), collected from Indonesian shallow waters. They consisted of nine species from Family Stichopodidae (ingroup) and two species from Family Holothuriidae (outgroup). Maximum parsimony and PAUP 4.0b was applied to construct the phylogenetic tree based on 78 morphological characters. The result showed two phylogenetic trees which separate the genus of Stichopus and Thelenota into two consistent clades (bootstrap 99% and 100%, respectively). The species position of each genus was stable. The two genus from Stichopodidae had the same number of synapomorph characters, and four plesiomorph characters occurred in the family level. Stichopus had ten homoplasy characters, while Thelenota did not have this characters. Six of nine species had the autapomorph characters that was used in constructed the identification key of Stichopodidae.
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