Spektra: Jurnal Fisika dan Aplikasinya
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A PRELIMINARY STUDY OF RADIATION QUALITY CORRECTION FACTOR (KQ) DETERMINATION FOR WELL-TYPE IONIZATION CHAMBER
Get PDFThis paper deals with the determination of the radiation quality correction factor (kQ) well-type ionization chamber for the measurement of Co-60 brachytherapy. The measurement of the brachytherapy source has been done in the hospital brachytherapy facilities. The measurement of air Kerma has been done using three different ionization chambers 0.6 cm3, 30 cm3, 80 cm3, which have calibration factor traceability for Co-60 and one well-type ionization chamber which calibrated for Ir-192. The determination of the radiation quality correction factor (kQ) was determined based on the results of the air Kerma ratio between measurements using ionization chambers, which have traceability to Co-60 and Ir-192 sources. The results of the measurement of the reference air Kerma rate (RAKR) obtained from the three chambers were 21.36, 19.87, 19.34 mGy.m2.h-1, while the results of measurements with ionization chambers get a value of 19.01 mGy.m2.h-1. The kQCal results from 0.6 cm3 ionization chamber get a value of 1.07. The kQCal value was compared with the value of Andreas Schuller’s et al. kQreff of 1.05 and get a deviation of 2.2%. Implementation of the booth kQ value on the results of the RAKR from the HDR1000Plus well-type ionization chamber in the measurement of brachytherapy in two different facilities gets a maximal deviation 1.7% with dose value from Treatment Planning System (TPS). The deviation was in the acceptable range of ±5%. Based on this, the use of radiation quality correction factor (kQ) value can be implemented as one method if it does not have the traceability factor calibration of the Co-60 brachytherapy source
THE COMPATIBILITY OF MODEL FOR LOW SHEAR FLOW ANALYSIS IN DEVELOPING PLASTICIZED HTPB-BASED BINDER
Get PDFIn developing flow behavior of plasticized prepolymer as liquid content of composite solid propellant, zero shear viscosity (ZSV) is a critical parameter that Goh-Wan equation is developed to model it recently [1]. Thus, this work aims to analyze the compatibility of the Goh-Wan equation toward the liquid content of propellant, characterize it, and determine the limit. In this work, a varied flow behavior index was obtained by using Hydroxy terminated polybutadiene (HTPB) and HTPB-DOA (Dioctyl adipate) system with the variable of its concentration, pre-heating, and pre-stirring methods as samples. Viscosity was measured at 2, 3, 4, and 5 rpm by using the disc spindle of Brookfield viscometer. For the minimum shear-rate investigation, as a limit of compatibility, other three sets of shear rates are applied, which are 0.6 – 5 rpm, 1 – 5 rpm, and 1,5 – 5 rpm. By functioning Goh-Wan equation (model 1) and Power-Law (model 2), a model was categorized as compatible if yields lower value of ZSV than the first experimental measured viscosity (η1st). Characterization was determined by a graph of plotting percentage difference of ZSV obtained from models 1 and 2 towards the index of flow behavior. The 3% of the difference between ZSV obtained from model 1 and η1st was set to be a minimum value for a set of applied shear-rate to be acceptable. It is reported that the Goh-Wan model is compatible with the liquid content of propellant and characterized by a perfect linear correlation. It is also found that a minimum applied shear rate of 1.5 rpm is acceptable for model compatibility
THE EFFECT OF COBALT CONTENT ON MAGNETIC PROPERTIES OF CoFe ALLOYS
Get PDFHard Disk Drive (HDD) as a data storage device when operated with high temperatures (around 66oC), its function will be constrained. The CoFe alloys have a large coercivity field and can be patterned in very small sizes that are suitable for HDD devices. In this study, Co1-x Fex cube alloy was used (x = 0.25; 0.30; 0.50; 0.75). Samples were treated with temperature changes to get the Curie temperature. The coercivity field value is obtained by giving the external field and temperature below Curie temperature and also above Curie temperature to the samples. The VAMPIRE software is a micromagnetic simulation program based on atomistic models. The results showed that Curie’s temperature decreased when Co content increased. The composition of Co0.25 Fe0.75 has the highest Curie temperature that is equal to 1075 K. The temperature Curie is not affected by the size of the cube. When the sample is given a temperature rise below the Curie temperature, the value of the coercivity field decreases. The value of the coercivity field is very difficult to determine when the temperature used is above the Curie temperature. The percentage of composition does not affect the coercivity field value. Therefore, cube-shaped CoFe material is very suitable for use as a material data storage device operated at temperatures below the Curie
GEOPHYSICAL FORENSIC FOR ARCHAEOLOGICAL EXPLORATION IN MUAROJAMBI, INDONESIA
Get PDFIn July 2011, archaeological exploration tried to apply the physics method for the first time in Muarojambi, Indonesia. We combined physics with geosciences and called it geophysical forensic. Our method is known as Ground Penetrating Radar (GPR). GPR used high-frequency electromagnetic (EM) waves between 10-3000 MHz to imaging subsurface based on dielectric permittivity’s physical parameters. Changes in the electrical properties, rock magnetism, and water content of the material under the surface will provide a response recorded on the radargram as a function of distance to time (two-way travel time). Data processing performs to reduce the noise recorded when collecting data. We have successfully obtained four GPR lines; three lines gathered near Gumpung Temple and one line at Telago Rajo Pool. The GPR method succeeded in giving a subsurface image and possibility of the archaeological objects near the Gumpung Temple and Telago Rajo Pool
THE ACCELERATION RESPONSE SPECTRUM AND EFFECTIVE DURATION OF LEBAK EARTHQUAKE JANUARY 23, 2018 IN JAKARTA REGION
Get PDFJakarta is the capital city of Indonesia with a very high population density low to the upper distribution of buildings which causes many areas of Jakarta to have a high vulnerability to natural disasters, one of which is an earthquake. One of the earthquakes felt this year was Lebak Banten Earthquake January 23, 2018, with a magnitude 6.1 at 13.34 local time. The depth of the earthquake was 61 Km at -7.09o S - 106.03o E, in the South Indian Ocean of Java Island. The epicenter was 43 km from Cilangkahan Village, Malingping Sub-district, Lebak District, Banten. We analyze the ground motion characteristics in the Jakarta area using 3 component acceleration data at Jakarta City Hall Office (JAKO) and Tanjung Priok Maritime Station (JATA) with dynamic statistical analysis method. The effective duration and earthquake response spectrum are determined using the acceleration data. In this study, the active period of the earthquake was calculated using the Trifunac and Brady method. The results of the analysis show that the most significant acceleration spectrum at JAKO station is found in component E of 0.07742 g in the period of 0.54 s while for the most significant acceleration spectrum JATA station found in component N of 0.04572 g in the period of 0.58 s. The effective duration obtained at JAKO stations was 56.76 s and JATA station 63.47 s. These results indicate that in the case of the Lebak earthquake, the further region from the epicenter of the earthquake has an effective duration which is relatively longer
INTERNET OF THINGS OF ELECTRONIC SEAL BASE ON GPRS SHORT MESSAGE SERVICE AND THINGSPEAK
Get PDFThe field of metrology is mainly legal metrology; seals are closely related to the guarantee or validity of a measuring instrument. Seals are designed so that it is not easy for other parties to open the seal. Seal damage must be identified as soon as possible. The application of the Internet of Things (IoT) is needed in the process of sending data in real-time. IoT technology can be applied to electronic seals to know and record the condition of the measuring device. Broken seals caused by irresponsible parties can cause losses to consumers and owners of measuring instruments. Electronic seals are expected to be able to detect seal damage caused by abuse of authority or fraud. The broken seal will send data to the server as well as SMS (Short Message Service) to the related party. Electronic seals can send damage data via SMS within 20 seconds with a success rate of 92% and sending data through the ThingSpeak web server within 40 seconds with a success rate of 82%
PROTON DRIPLINE FOR ISOTONE N = 18, 20, AND 22 USING MODIFIED RELATIVISTIC MEAN FIELD (MRMF) MODEL
Get PDFDetermining the position of one- and two-proton dripline for isotone of N = 18, 20, and 22 has been studied through Modified Relativistic Mean Field (MRMF). The model exemplifies three impacts, namely isovector-isoscalar coupling, tensors, and electromagnetic exchange through five parameter set variations. The position of one- and two-proton dripline for the isotones is predicted by applying two methods, which are two-proton separation energy, and Fermi energy. The research shows that the prediction of one- and two-proton dripline for isotone of N = 18, and N = 20 is positioned at Z = 22 and Z = 26 consecutively. Then, the prediction of one- and two-proton dripline for isotone of N = 22 has two positions, Z = 26 and Z = 28. The calculation result indicates that the position prediction for isotone of N = 18, N = 20, and N = 22 is following the research result conducted by Nazarewicz with RMF+NLSH model [1]. Meanwhile, isovector-isoscalar coupling, tensors, and electromagnetic exchange do not affect massively for the position prediction of two-proton dripline. However, the three methods affect one-proton dripline