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Publikācija: Electron Emission Standed Nanodosimetry and Gas Detection

Publication Type Conference paper
Funding for basic activity Unknown
Defending: ,
Publication language English (en)
Title in original language Electron Emission Standed Nanodosimetry and Gas Detection
Field of research 1. Natural sciences
Sub-field of research 1.3 Physical sciences
Authors Jurijs Dehtjars
Kristīne Perovicha
Marina Romanova
Keywords nanodosimetry, gas sensor, electron emission
Abstract Radiation and gases are employed for medical treatment and diagnostics. Radiation therapy is aimed to deliver a dose to the target organ, dosimetry providing verification and the feedback for quality of the procedure. Nanodosimetry (ND) is a cutting edge and is targeted to measure absorbed dose in a nanovolume of the radiated substance. There are several reasons that ND is of a great importance: (i) biological effects by radiation depend on dose absorbed by DNA pairs sized to a nanoscale; (ii) radiation therapy is trended to apply high dose gradients (Gy/(µm…nm)), surviving of the cells depending on the gradient value; (iii) nanoparticles as the radiation scattering centers are expected to reach local micro- nano- scaled treatment that minimally influences risk organs/cells. In spite of the ND significance there are not detectors for direct radiation measurement in nanovolumes. To reach the solution the detector should be nanosized, nanoobjects being candidates for this. Readout from them must not be interfered by the measurement to get a reliable result. Therefore, contactless technologies are preferable for ND. The specific gases exhausted by patients are indexes of some diseases. Because a concentration of the gases is not high their molecules are accumulated by the absorber, its properties being altered and are available to measure. To increase a sensitivity of the gas absorbing sensor its signal should be powered by a density of the absorbed molecules. The considered above peculiarities of the both ND and gas sensors could be combined within electron emission (EE) based devices. Low energy photons (~ 5eV) induce EE at its prethreshold, electrons escaping from a depth ~10-100 nm. Moreover, an electron emission current (I) dependence on the electron work function (j) is close to the parabolic law. In such a case absorption of the gas molecules that are capable to alter j should supply a high level response of I. The research demonstrates novel results on EE availability for ND of high energy electrons and gamma photons as well as detection of isopentane and benzene gases.
Reference Dehtjars, J., Perovicha, K., Romanova, M. Electron Emission Standed Nanodosimetry and Gas Detection. In: Advanced Research Workshop "Technological Innovations in CBRNE Sensing and Detection for Safety, Security, and Sustainability", Armenia, Yerevan, 29 Sep-1 Oct., 2012. Yerevan: 2012, pp.53-53.
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