January 12th, 2021

лошадь, диаграмма, Фейнман

Детекторы рентгеновского излучения для будущих медицинских установок

Detectors for the future of X-ray imaging: https://arxiv.org/abs/2101.03493
Magnus Aslund, Erik Fredenberg, M. Telman, Mats Danielsson
In recent decades, developments in detectors for X-ray imaging have improved dose efficiency. This has been accomplished with for example, structured scintillators such as columnar CsI, or with direct detectors where the X rays are converted to electric charge carriers in a semiconductor. Scattered radiation remains a major noise source, and fairly inefficient anti-scatter grids are still a gold standard. Hence, any future development should include improved scatter rejection. In recent years, photon-counting detectors have generated significant interest by several companies as well as academic research groups. This method eliminates electronic noise, which is an advantage in low-dose applications. Moreover, energy-sensitive photon-counting detectors allow for further improvements by optimising the signal-to-quantum-noise ratio, anatomical background subtraction or quantitative analysis of object constituents. This paper reviews state-of-the-art photon-counting detectors, scatter control and their application in diagnostic X-ray medical imaging. In particular, spectral imaging with photon-counting detectors, pitfalls such as charge sharing and high rates and various proposals for mitigation are discussed.
лошадь, диаграмма, Фейнман

Тень позади резерфордовского рассеяния и вектор Гамильтона

Очередная симпатичная методическая статейка от Зураба Силагадзе.

A shadow of the repulsive Rutherford scattering and Hamilton vector: https://arxiv.org/abs/2101.03543
D.A. Shatilov, Z.K. Silagadze
The fact that repulsive Rutherford scattering casts a paraboloidal shadow is rarely exploited in introductory mechanics textbooks. Another rarely used construction in such textbooks is the Hamilton vector, a cousin of the more famous Laplace-Runge-Lenz vector. We will show how the latter (Hamilton's vector) can be used to explain and clarify the former (paraboloidal shadow).
Comments: 8 pages, 2 figures, to be published in European Journal of Physics