Using Ngraph software, the parameters of various functions were deterÂmined by least squares analysis of fits to experimental efficiencies, εf of a coaxial HPGe detector for gamma rays in the energy range 59 keV to 1836 keV. When these parameters had been determined, their reliability was tested by the calculated goodness-of-fit parameter χ2cal It is shown that the function, where n = 3, gives satisfactory results.
Menggunakan perisian Ngraph, parameter pelbagai fungsi ditentukan dengan kaedah penyesuaian kuasa-dua terkecil untuk kecekapan ujikaji, εf dalam julat tenaga sinar gama 59 ke V ke 1836 ke V untuk satu pengesan HPGe sepaksi. Setelah parameter ini ditentukan, kebolehpercayaan yang fungsi, dimana n = 3 memberikan keputusan yang memuaskan.
From the weighted least-squares fit, two methods of calculation of χ2 test were derived and investigated. The first method which uses a mean weight yields the well known standard method. ie. χ2cal1 = (x)-1 Σ(x-xi)2 and the second method which uses the statistical weight yields χ2cal2 = Σ(x)-1 (x-xi)2. It is theoretically shown that each method has its own type of . ie. arithmetic mean for χ2cal1 and harmonic mean for χ2cal2. Application to the experimentally determined nuclear data, however showed that the two methods gave almost the same χ2cal values, I irrespective of x used. An approach to verify that the mean weight equals to (x)-1 in the standard method is also discussed.
Dari penyesuaian kedua-dua terkecil berpemberat, dua kaedah pengiraan ujian χ2 diterbitkan dan dikaji. Kaedah pertama yang menggunakan pemberat purata memberikan kaedah standard yang terkenal, iaitu χ2cal1 = (x)-1 Σ(x-xi)2 dan kaedah kedua yang menggunnakan pemberat statistik memberikan χ2cal2 = Σ(x)-1 (x-xi)2 . Ditunjukkan secara teori setiap kaedah mempunyai tersendiri, iaitu purata aritmatik untuk χ2cal1 dan purata harmonik untuk χ2cal2. Penggunaan teori ini kepada data nuklear ujikaji, walau bagaimanapun, menunjukkan yang kedua-dua kaedah memberikan nilai χ2cal yang hampir sama, bebas dari jenis x yang digunakan. Pendekatan untuk menentusahkan pemberat malar bersamaan dengan (x)-1 dalam kaedah piawai juga dibincangkan.
The activity of two liquid mixed radionuclide sources in NPL'S standard glass ampoules were determined by gamma-ray spectrometry measurement using a standard point source placed at 38.5 cm axially above the detector. A radio nuclide 137Cs was chosen, Results obtained were within 3% agreement with the calculated value. The same degree of deviation was obtained when the NPL standard source of equal geometry, chemical composition and density was used.
Keaktifan dua sumber radionuklid campuran cecair yang terkandung dalam bekas kaca piawai NPL ditentukan dengan kaedah pengukuran spektrometri sinar-gama menggunakan satu sumber titik piawai diletakkan pada 38.5 em di atas pengesan, Satu sumber radionuklid 137Cs dipilih. Keputusan yang diperoleh bersetuju dalam lingkungan 3% dengan nilai yang dikira. Darjah simpangan yang sama diperoleh apabila sumber piawai NPL yang sama dari segi geometri, komposisi kimia dan ketumpatan digunakan,
Measurement of the natural 40K body gamma-ray radioactivity via the whole-body counter (WBC) technique may yield the total body potassium (TBK) status, from which for example, the body cell mass can be derived (Moore et al. 1963). The accuracy of the derived TBK is of course critically dependent on the assumed value of the ratio 40K:TBK. Potassium chloride (KCI) has been widely used as the 40K calibration standard. In reviewing the literature (Burkinshaw 1967; Ross & Morris 1968; Havlik 1970, Young et al 1975; Manocha & Mohindra 1976; Holtzman 1977; Graham 1983; HMSO 1985-1986, Lykken et al 1987; Lan & Weng 1989; Fenwick et al. 1991), it is apparent that inconsistencies occur in the use of 40K activity per gram of natural potassium. It varies between 27.33 to 31.31 Bq per gram of potassium. The objectives of this study were to independently measure and calculate the 40K activity per gram of natural potassium in an attempt to reduce the uncertainty in the accepted figure. Experimentally the activity of 40K from a known amount of K was determined by measuring the 40K photon emission of an analar grade KCI sample solution and the absolute efficiency of the detection system at energy 1460 KeV. Both the photopeak count-rate and the absolute efficiency were measured using the gamma-ray spectroscopy technique. The 40K activity is also calculated from its half-life (IAEA 1989) and the number of atoms present in the sample. The measured and calculated values obtained were 30.18 ± 0.72 Bq g-1 and 31.00 ± 0.33 Bq g-1 respectively. The difference is of the order of 2.6%. The measured value is consistent with the literature values being close to the mean of the values, namely 29.77. In conclusion, it is believed that the experimental values reported in this work is one of the few experimentally determined results and it is reassuring to note that the experimental and theoretical values are in reasonable agreement.