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BERKALA FISIKA
Published by Universitas Diponegoro
BERKALA FISIKA adalah jurnal saintifik yang diterbitkan secara periodik 3 bulanan. Jurnal ini memuat kajian-kajian Fisika baik kajian teoretik maupun hasil eksperimen. Jurnal ini juga memberi ruang yang luas bagi kajian – kajian aplikasi fisika dalam bidang teknologi, ilmu-ilmu hayati dan kedokteran.
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286
Articles
Berkala Fisika Vol. 18 No. 3 Tahun 2015

Berkala Fisika, Tim Redaksi ( Jurusan Fisika Universitas Diponegoro Semarang )

BERKALA FISIKA 2015: Berkala Fisika Vol. 18 No. 3 Tahun 2015
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Abstract

Berkala Fisika Vol. 18 No. 3 Tahun 2015

STUDI PENGARUH UKURAN PIXEL IMAGING PLATE TERHADAP KUALITAS CITRA RADIOGRAF

Sudin, Ahmas ( Jurusan Fisika, Fakultas Sains dan Matematika, Universitas Diponegoro Jl. Prof. H. Soedarto, SH Tembalang, Semarang ) , Muhlisin, Zaenul ( Jurusan Fisika, Fakultas Sains dan Matematika, Universitas Diponegoro Jl. Prof. H. Soedarto, SH Tembalang, Semarang ) , Widiyandari, Hendri ( Jurusan Fisika, Fakultas Sains dan Matematika, Universitas Diponegoro Jl. Prof. H. Soedarto, SH Tembalang, Semarang )

BERKALA FISIKA 2015: Berkala Fisika Vol. 18 No. 3 Tahun 2015
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Abstract

This study aims is to determine the image on imaging plate which has a different pixel sizes. In this research, the X-ray apparatus and Computed Radiography (CR) which is used in the diagnostic field was used. The three imaging plate each having size of 0.097 mm, 0.115 mm and 0.168 mm with stepwedge objects on it was used. The exposure factor was adjusted at 64.5 kV and 16 mAs. The each of imaging plate were exposure three times. The results of each radiograph imaging plate were measured by using a densitometer. By measuring the Stepwedge radiograph, it was obtained the density and contrast value of each imaging plate. Contrast value for each imaging plate were compared to obtain the imaging plate that have a higher contrast value. This research resulted that each different pixel sizes on the imaging plate would generate a different image quality. Keywords: pixel, imaging plate, image quality, contras, density

STUDI PARAMETER REAKTOR BERBAHAN BAKAR UO2 DENGAN MODERATOR H2O DAN PENDINGIN H2O

Richardina, Very ( Jurusan Fisika, Universitas Diponegoro, Semarang ) , Budi, Wahyu Setia ( Jurusan Fisika, Universitas Diponegoro, Semarang ) , Tjiptono, Tri Wulan ( Badan Tenaga Atom Nasional Yogyakarta )

BERKALA FISIKA 2015: Berkala Fisika Vol. 18 No. 3 Tahun 2015
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Research about study of Pressurized Water Reactor (PWR) parameters using UO2 as fuel materials with moderator of H2O and coolant of H2O for heterogeneous infinite cylinder design  has realized. There is one of design to make nuclear reactor, it is a neutronic design. At neutronic design, first must calculations to determine group constants ( neutron cross section and the multiplication factor). The neutronic equations with one dimensional  transport theory for annulus geometry can be solved with WIMSD5B codes. Numeric method that used was one dimensional homogenization cell methods. To archieve   steady state or reactor, used enrichment of U235 between 2% until 3,2% with variation 0,05%. From the result with cluster methods with 32 groups and 10 regions, steady states of reactor at enrichment of U235 is 2,9% with effective multiplication factor (keff) = 1,006491. Keywords: PWR, reactor parameters, effective multiplication factor (keff), WIMSD5B

PEMETAAN PERCEPATAN GETARAN TANAH MAKSIMUM MENGGUNAKAN PENDEKATAN PROBABILISTIC SEISMIC HAZARD ANALYSIS (PSHA) DI KABUPATEN KEPAHIANG PROVINSI BENGKULU

Hadi, Arif Ismul ( Jurusan Fisika, FMIPA Universitas Bengkulu, Bengkulu ) , Brotopuspito, Kirbani Sri ( Jurusan Fisika, FMIPA, Universitas Gadjah Mada, Yogyakarta )

BERKALA FISIKA 2015: Berkala Fisika Vol. 18 No. 3 Tahun 2015
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This study aims to analyze and map the peak ground acceleration using the approach of Probabilistic Seismic Hazard Analysis (PSHA) in the area. Earthquake catalog data obtained from BMKG, ISC and USGS began in 1914 until 2014. Declustering process using ZMAP ver.6 software. Identification and modeling of the seismic source uses three models of seismic sources: (1) to subduction earthquake source, (2) the source of the earthquake fault and (3) the source of the quake background. Parameters a-value and b-value is obtained by the Gutenberg-Richter recurrence law and maximum likelihood method, whereas the determination of the attenuation function and logic tree refers to the Revision Team of Indonesia Earthquake 2010. Peak ground acceleration values obtained using USGS-PSHA-07 software. The results showed that the value of the peak ground acceleration in the Kepahiang District for probability exceeded 10% and 2% in the 50 year design life of the building is 0.15 – 0.8 g and 0.25 – 1.3 g. Areas that are the red zone is the Ujan Mas Sub-district, Kepahiang Sub-district, Tebat Karai Sub-district, Seberang Musi Sub-district and Bermani Ilir Sub-district, while the regions are relatively safe from the red zone is the Merigi Sub-district, Kabawetan Sub-district and Muara Kemumu Sub-district. Red zone is an area adjacent to the Sumatran Fault of Musi Segment. Keywords: peak ground acceleration, PSHA, red zone and Sumatran Fault of Musi Segment.

STUDY OF ELECTROOPTICS BEHAVIOUR OF NAPHTHALENE AND ANTHRACENE

Firdausi, K Sofjan ( Jurusan Fisika, Universitas Diponegoro, Semarang ) , Khumaeni, Ali ( Jurusan Fisika, Universitas Diponegoro, Semarang ) , Richardina, Very ( Jurusan Fisika, Universitas Diponegoro, Semarang ) , Arianto, Fajar ( Jurusan Fisika, Universitas Diponegoro, Semarang ) , Budi, Wahyu Setia ( Jurusan Fisika, Universitas Diponegoro, Semarang )

BERKALA FISIKA 2015: Berkala Fisika Vol. 18 No. 3 Tahun 2015
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In this paper, we demonstrate electro-optics behaviour of naphthalene and anthracene using change of polarization of sample induced by external electric field. The source of light for polarization was 1 mW-he-ne Laser 633 nm. The induced external Electric field was produced by high DC voltage 0 – 7 kV. The samples were diluted in solutions-form using wash-benzene. The result shows that anthracene has higher polarizability than naphthalene, which is indicated by higher change of polarization in anthracene than naphthalene. The Assumption that potential difference is proportional to the distance between molecules is shown qualitatively by graphs of Van der Waals potential energy or force between molecules. In this case, anthracene has higher level Energy than naphthalene so that it can be used in visible excitation for environmental spectroscopy. Keywords: electro-optics, polarization, naphthalene, anthracene, Van der Waals potential energy 

PEMANFAATAN METODA INVERSI DAN PROBABILISTIC NEURAL NETWORK PADA DATA SEISMIK DALAM PENENTUAN ZONA RESERVOAR BATUGAMPING (CARBONATE BUILDUP) DI LAPANGAN SUKO, CEKUNGAN JAWA TIMUR UTARA

Novianto, Ardian ( Teknik Geofisika, Universitas Pembangunan Nasional “Veteran” Yogyakarta Jln. SWK 104 Condong Catur Sleman Yogyakarta )

BERKALA FISIKA 2015: Berkala Fisika Vol. 18 No. 3 Tahun 2015
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Abstract

Limestone particularly Carbonate Buildup is one type of reservoir potential as a hydrocarbon accumulation. Problems often encountered in the analysis are the type of reservoir porosity deployment complexity that is very different from other rocks. The understanding of porous area as a zone of a reservoir in the body Carbonate buildup will provide an overview in the development and determination of drilling new wells. Identification of potential zones in carbonate buildup can be done with the approach of the seismic data inversion process and multi-attribute with neural network method. Seismic inversion process is the reverse of the forward modeling process which will produce Acoustic impedance value that describes not only the boundary between the layers but also a layer of rock itself (Layer Properties). Validation of the results of the inversion process is done by creating a density map using multi-attribute process with probabilistic neural network method. The results of the inversion and multi-attribute process is expected to provide an overview of the deployment area having a large porosity which can serve as a reservoir zone. The results from the combination of the two methods showed that the reservoir zone is in the central part of carbonate buildup that field through the development of new drilling process can be directed at the zone. Keywords: AI inversion, Multi-attribute PNN, Carbonate Buildup

INTERPRETASI MODEL ANOMALI MAGNETIK BAWAH PERMUKAAN DI AREA PERTAMBANGAN EMAS RAKYAT DESA CIHONJE, KECAMATAN GUMELAR, KABUPATEN BANYUMAS

Sehah, Sehah ( Jurusan Fisika, Fakultas MIPA, UNSOED, Jalan Dr. Suparno 61 Purwokerto ) , Raharjo, Sukmaji Anom ( Jurusan Fisika, Fakultas MIPA, UNSOED, Jalan Dr. Suparno 61 Purwokerto ) , Prasetyo, Chandra Adi ( Jurusan Fisika, Fakultas MIPA, UNSOED, Jalan Dr. Suparno 61 Purwokerto )

BERKALA FISIKA 2015: Berkala Fisika Vol. 18 No. 2 Tahun 2015
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Measurement of magnetic data has been done in the area of ​​the gold mining in the village of Cihonje, the district of Gumelar, the regent of Banyumas in May to June 2013. Based on the modeling that has been conducted on the local magnetic anomalies along cross section of AB obtained six models of subsurface rock, while for along cross section of AB obtained five models. Based on the modeling results, rock formations that developed in the research area are Tapak formation, Halang formation, andesite-basaltic, and the alternating formation of the sandstones with some other rocks. The magnetic susceptibility of subsurface rock in the research area are interpreted ranged from 0.0039 to 0.0174 cgs units with the average magnetic susceptibility of rocks is estimated equal to 0.0099 cgs units that interpreted as the alternating formation of sandstone and claystone from Halang formation. The mineralization of gold ore is estimated to occur in almost of all subsurface rocks, but the most dominant mineralization is estimated to occur in the Halang formation especially on the alternating formation of sandstone and claystone. The gold ore mineralization occurs in the form of veins of pyrite, chalcopyrite, galena, and the others, that fill the cracks and the pores of the rocks. Keywords: magnetic anomaly, gold mining, Village of Cihonje

PENGARUH GAIN TERHADAP FWHM DAN FWTM PADA CITRA B-MODE ULTRASONOGRAM (USG)

Amitasari, Ria ( Jurusan Fisika, Universitas Diponegoro, Semarang ) , Suryono, Suryono ( Jurusan Fisika, Universitas Diponegoro, Semarang ) , Adi, Kusworo ( Jurusan Fisika, Universitas Diponegoro, Semarang )

BERKALA FISIKA 2015: Berkala Fisika Vol. 18 No. 2 Tahun 2015
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The effect of gain to The Width at Half Maximum (FWHM) and Full Width at Tenth Maximum (FWTM) on B-mode image ultrasonogram (USG) has been investigated. The aim of this research is to determine the effect of gain on the spatial resolution according the measurements of FWHM and FWTM. The evaluated resolution type is axial and lateral. This research used phantom multipurpose multi tissue with gain (30 dB, 35 dB, 40 dB, 45 dB, 50 dB, 55 dB and 60 dB) on frequency variation source 6,2 Mhz, 8 MHz dan 10MHz. The axial and lateral resolution images were obtained by using USG which uses B-Mode imaging. The measurement was made by using digital image and calculated objectively with MATLAB. The measurement of FWHM and FWTM was obtained from IP-PSF analysis (In Plane-Point Spread Function) using approximation for the Gaussian function. The result shows that there is influence from gain on FWHM and FWTM. The decreasing gain resulted in decreasing of FWHM and FWTM. The decreasing of FWHM and FWTM represents better spatial resolution, and vice versa. Keywords: FWHM, Gain, Point Spread Function, Spatial resolution, USG,

GENERATOR PEMBANGKIT PLASMA DENGAN KONFIGURASI ELEKTRODA BATANG TIPIS DAN JARUM

Wardaya, Asep Yoyo ( Jurusan Fisika, Universitas Diponegoro, Semarang ) , Nur, Muhammad ( Jurusan Fisika, Universitas Diponegoro, Semarang )

BERKALA FISIKA 2015: Berkala Fisika Vol. 18 No. 2 Tahun 2015
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The application of plasma generator has been developed for everyday live because it can generate high electric field and induced current, even by only 12 volt of potential difference. The advantages of the plasma generator are mainly caused by configuration form of its electrodes which is usually very sharp and asymmetric form. In this paper, plasma generator has been discussed using electrodes configuration of the thin rod and needle in two dimensional planes. The result shows that the plasma generator can produce various high electric fields, which highest field at the tip of needle electrode. In case of configuration of needle electrode, it will be produced saturated current due to their asymmetric electrodes, while in case of thin rod electrode; it will be no saturated current due to symmetric electrode. Keywords: plasma generator, thin rod and needle configuration electrodes, electric field, saturated current.

OPTIMASI PEMBANGKIT LISTRIK TENAGA ARUS LAUT MENGGUNAKAN SISTEM TURBIN SAVONIUS TERMODIFIKASI

Rahmi L, Halida ( Jurusan Fisika, Universitas Jenderal Soedirman, Jl. Dr. Soeparno 61 Purwokerto 53123 ) , Dharmala S, Budi ( Jurusan Fisika, Universitas Jenderal Soedirman, Jl. Dr. Soeparno 61 Purwokerto 53123 ) , Gediana, Almas ( Jurusan Fisika, Universitas Jenderal Soedirman, Jl. Dr. Soeparno 61 Purwokerto 53123 ) , Yusup, Agus ( Jurusan Fisika, Universitas Jenderal Soedirman, Jl. Dr. Soeparno 61 Purwokerto 53123 ) , Septria, Wenty ( Jurusan Fisika, Universitas Jenderal Soedirman, Jl. Dr. Soeparno 61 Purwokerto 53123 )

BERKALA FISIKA 2015: Berkala Fisika Vol. 18 No. 2 Tahun 2015
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Difficulty of access to service and installation of the electrical network in the area around a coast becomes a factor causing uneven distribution of power network. Therefore, a new prototype of Sea Flow Power Plant was prepared using a modified Savonius turbine. The modified Savonius turbine is a vertical wind turbine, which is modified into a horizontal turbine and made two pairs of turbines in different directions. Advantage of this turbine can optimally capture the come and back flows. Preparing prototype of the turbine is conducted after collecting data of the sea flow velocity surrounding Teluk Penyu - Cilacap, that is followed by manufacturing a modified Savonius turbine and prototype of PLTAL. Performance test reveals that the prototype can generate P =0,3 Watt, the velocity of turbine rotation ω = 44.42 rad/s, the turbine torque M = 0,0064 Nm and the diameter of turbine d = 0,32 m.  The sea flow velocity is often naturally changed leading to the turbine rotation change. It is found that the power and the turbine rotation increase with increasing the sea flow velocity.  At the sea flow velocity of  1,5 m/s, the prototype of PLTAL has good performance and very potential as a source of alternative electrical energy in the future. Keywords: Savonius turbine,  sea flow, electrical energy, power plant.

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