Introduction Rates of Radiation Defects in Electron Irradiated Semiconductor Crystals of n-Si and n-GaP
Abstract: We take the concentration of radiation defects concentration Ndef to be the difference between the carrier concentration of semiconductors before n0 and after irradiation n(D) at the dose D, delivered at room temperature. By application of an appropriate fitting function to the dose dependent curves of the Ndef (D), it was demonstrated that the empiric exponential law of the form Ndef=n0(1-exp(-D/D0)) gives the best agreement with the experimental data, irrespective of the electron energy and irradiation dose. The results showed that the formation of radiation defects in the samples studied is not a linear process and ΔNdef/ΔD are found to decrease exponentially with increasing irradiation dose, according to their particular character....
Read MorePhoto-review of NRPM 2019 conference
Please visit NRPM 2019 Conference website, where photo-review is available.
Read MoreGroup 2014-2019 investigations
Development of a new type of Vibrating Wire Monitor (VWM), which has two mechanically coupled wires (vibrating and target), is presented. The new monitor has a much larger aperture size than the previous model of the VWM, and thus allows us to measure transverse beam halos more effectively. A prototype of such a large aperture VWM with a target wire length of 60 mm was designed, manufactured, and bench-tested. Initial beam measurements have been performed at the Fermilab High Intensity Neutrino Source facility, and key results are presented. Fig. 1. (a) Photo of the Large Aperture Vibrating Wire Monitor (LA-VWM). (b) Beam profile, measured by the LA-VWM in the horizontal direction at the Fermilab High Intensity Neutrino Source facility. Measurements of secondary particles/photons reflected/generated from an oscillating wire in synchronism with the wire oscillation frequency are proposed. The differential signal on wire maximal deviations at oscillation process can provide a fast signal proportional to beam profile gradient. Idea of using such “Resonant Target” for beam transverse gradient profiling was tested with lightening the oscillating wire by a laser. Fig. 2. (a). Layout of experiment: 1 – vibrating wire of VWM with wire length 80 mm, 2 – wire oscillation generating magnet poles, 3 – laser, 4 – photodiode. (b) Forward and backward scan of the vibrating wire sensor. Red line – differential signal from photodiode at ultimate positions of wires during oscillations. Green line – averaged signal of 1000 measurements of photodiode at ultimate positions of wires, Blue line – vibrating wire oscillation frequency also depends on reflecting on wire photon numbers. Proton/ion beams of multiple charge/mass ratios can be very complex. Orthogonal X-Y projections are often inappropriate to represent these profiles. An array of vibrating wires, rotating around the beam axis is under development. The mechanical implementation is described. An algorithm to reconstruct the profile is proposed. The tradeoffs between the number of wires, the rotation angles, the response time and the profile resolution are discussed. Fig. 3. (a). Numerals indicate: (1) – measured beam, (2) –frame of monitor, (3) – vibrating wires, (4) –support flange with gear teeth on the flange rim, (5) – loading gear with shaft translated rotation, (6) inclination axis supporting lips, (7) – gearbox-transmitter translate inclination axis rotation to the shaft (8). (b). Test distribution of the beam to be measured. Two types of neutron monitors with fine spatial resolutions are proposed based on vibrating wires. In the first type, neutrons interact with a vibrating wire, heat it, and lead to the change of its natural frequency, which can be precisely measured. To increase the heat deposition during the neutron scattering, the use of gadolinium layer that has the highest thermal neutron capture cross-section among all elements is proposed. The second type uses the vibrating wire as a “resonant target.” Besides the measurement of beam profile according to the average signal, the differential signal synchronized with the wire oscillations defines the beam profile gradient. The monitor’s spatial resolution is defined by the wire’s...
Read MoreAPRD organizes a conference on June 17-20 “Nuclear and Radiation Physics and Materials”
International conference “Nuclear and Radiation Physics and Materials” will be held on June 17-20 at YSU (Yerevan State University) organized by A. Alikhanyan National Laboratory (Applied Physics Researches Division); University of Notre Dame, USA; National Research University “High School of Economics”, (NRU HSE), Russia; Ministry of Science and Education, Science Committee of Armenia. The conference has several sections listed below: 1. NUCLEAR PHYSICS Mechanisms of nuclear reactions and nuclear structure Low and Medium Energy Nuclear Physics Techniques and methods of nuclear experiment. Mechanisms of nuclear reactions and nuclear structure Low and Medium Energy Nuclear Physics Techniques and methods of physical and nuclear experiment. 2. NUCLEAR AND RADIATION METHODS AND TECHNOLOGIES Production and use of radioactive isotopes Radiation Technology New promising materials and methods for their production Experimental equipment and methods for studying radiation processes in materials 3. RADIATION PHYSICS OF MATERIALS Physics of non-metallic and metallic materials Use of radiation beams Nanostructure materials science New radiation applications in physics, biology and ecology. THE ORGANIZERS A. Alikhanyan National Science Laboratory (ANSL), Armenia University of Notre Dame, USA National Research University “High School of Economics”, (NRU HSE), Russia Ministry of Science and Education, Science Committee of Armenia STEERING COMMITTEE Chairman: Ani Aprahamian – Alikhanyan National Science Laboratory, University of Notre Dame, USA Vice Chairman: Gennady Bondarenko, NRU HSE, Russia Committee members: V.V. Harutyunyan, ANSL, Armenia Kh.V. Manukyan, University of Notre Dame, USA V.M. Tsakanov, CANDLE, Armenia R.B. Kostanyan, National Academy of Sciences, Armenia G.A. Karyan, ANSL, Armenia S.V. Rogozhkin, NRC “Kurchatov Institute ITEP, Russia V.V. Andreev, N.E. Bauman Moscow State Technical University, Russia P. Zukowski, Lublin University of Technology, Poland P.A. Selishchev, University of Pretoria, South Africa V.N. Mordkovich, IMTHPM, Moscow, Russia More info on official website of NRPM...
Read MoreTwo works were presented at international conference “Radiation Physics of Solid State” (Sevastopol, Crimea).
2018 was marked with attending on XXVIII conference of “Radiation Physics of Solid State” in the city of Sevastopol. Below are presented works published in Conference proceedings. Арутюнян Севастополь 2018 Алексанян Севастополь...
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