• Title/Summary/Keyword: Soft ray

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Mechanism of the X-ray and Soft Gamma-ray Emissions from the High Magnetic Field Pulsar: PSR B1509-58

  • Wang, Yu;Takata, Jumpei;Cheng, Kwong Sang
    • Journal of Astronomy and Space Sciences
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    • v.30 no.2
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    • pp.91-94
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    • 2013

  • We use the outer gap model to explain the spectrum and the energy dependent light curves of the X-ray and soft ${\gamma}$-ray radiations of the spin-down powered pulsar PSR B1509-58. In the outer gap model, most pairs inside the gap are created around the null charge surface and the gap's electric field separates the opposite charges to move in opposite directions. Consequently, the region from the null charge surface to the light cylinder is dominated by the outflow current and that from the null charge surface to the star is dominated by the inflow current. We suggest that the viewing angle of PSR B1509-58 only receives the inflow radiation. The incoming curvature photons are converted to pairs by the strong magnetic field of the star. The X-rays and soft ${\gamma}$-rays of PSR B1509-58 result from the synchrotron radiation of these pairs. The magnetic pair creation requires a large pitch angle, which makes the pulse profile of the synchrotron radiation distinct from that of the curvature radiation. We carefully trace the pulse profiles of the synchrotron radiation with different pitch angles. We find that the differences between the light curves of different energy bands are due to the different pitch angles of the secondary pairs, and the second peak appearing at E > 10 MeV comes from the region near the star, where the stronger magnetic field allows the pair creation to happen with a smaller pitch angle.

  • https://doi.org/10.5140/JASS.2013.30.2.091 인용 PDF KSCI

Evaluation of imaging reformation with cone beam computed tomography for the assessment of bone density and shape in mandible (Cone beam형 전산화단층영상에서 골의 형태와 밀도의 평가)

  • Hong, Sang-Woo;Kim, Gyu-Tae;Choi, Yon-Suk;Hwang, Eui-Hwan
    • Imaging Science in Dentistry
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    • v.38 no.1
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    • pp.49-56
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    • 2008

  • Purpose: Diagnostic estimation of destruction and formation of bone has the typical limit according to capacity of x-ray generator and image detector. So the aim of this study was to find out how much it can reproduce the shape and the density of bone in the case of using recently developed dental type of cone beam computed tomography, and which image is applied by new detector and mathematic calculation. Materials and Methods: Cone beam computed tomography (PSR 9000N, Asahi Roentgen Ind. Co., Ltd., Japan) and soft x-ray radiography were executed on dry mandible that was already decalcified during 5 hours, 10 hours, 15 hours, 20 hours, and 25 hours. Estimating and comparing of those came to the following results. Results: The change of inferior border of mandible and anterior border of ramus in the region of cortical bone was observed between first 5 and 10 hours of decalcification. The reproduction of shape and density in the region of cortical bone and cancellous bone can be hardly observed at cone beam computed tomography compared with soft x-ray radiography. The difference of decrease of bone density according to hours of decalcification increase wasn't reproduced at cone beam computed tomography compared with soft x-ray radiography. Conclusion: CBCT images revealed higher spatial resolution. However, contrast resolution in region of low contrast sensitivity is the inferiority of images' property.

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