Torgasin Konstantin

Analysis of SNIP Algorithm for Background Estimation in Spectra Measured with LaBr3: Ce Detectors

LaBr3:Ce scintillating detectors exhibit excellent properties for γ-ray spectroscopy such as high energy resolution and operation under room temperature as well as MHz counting rates. On the other hand, sever background radiations exist due to the internal contamination of radioactive materials that are very difficult to be avoided during the manufacture. To decrease the effect of these background levels, some analytical techniques, e.g. background subtraction, should be applied. In the present work, we investigate the efficiency of the sensitive nonlinear iterative clipping peak (SNIP) method for background estimation and subtraction. Optimization of the clipping window is discussed for range of energy up to 3 MeV. Enhancement of energy resolution up to 50% was obtained.

Monte Carlo Calculations of γ-Rays Angular Distribution Scattering from 11B in (γ, γ) Interaction

An investigation of angular distribution of scattered gamma-rays is important to get information about an efficient arrangement of γ-ray detectors and it is necessary to design a real detection system of the inspection system by using a (γ, γ) interaction. Angular distribution of scattered gamma radiation from 11B at 4,440 keV from transition J π (5/2− → 3/2−) has been simulated by extended GEANT4. In the simulation, seven LaBr3:Ce detectors were recording the scattered photons from nuclear resonance fluorescence (NRF) process in a plane perpendicular to the incident polarized γ-ray beam. The γ-ray beam was assumed to be monoenergetic and linearly polarized with energy spread of 5%. All the LaBr3:Ce detectors were similar in the diameter of 1.5 in. and length of 3 in., positioned at seven different directions. Angular distribution of the scattered γ-rays is discussed in terms of the detectors’ positions with respect to the target and incident γ-ray beam. The result, which indicates the largest count rate from NRF signals is backward (135° and 225°) and forward (45° and 315°) directions with respect to the incident gamma-ray, is useful when using the NRF process in inspection of the special nuclear materials (SNM) like 235U and 239Pu.

Development of a field measurement system for the Bulk HTSC SAU

To realize a short-period strong-field undulator, we proposed a high temperature superconducting bulk staggered array undulator (Bulk HTSC SAU) and proceeded proof of principle experiments and numerical studies. We have succeeded to generate periodic transverse magnetic fields whose strength was controlled by an external solenoid field. At the same time, we revealed a problem; at both ends of undulator, field distribution is substantially distorted. We proposed several approaches of field correction. To verify the effectiveness of these field correction methods, it is necessary to measure the magnetic field distribution precisely, not only inside of the undulator but also both ends. For this purpose, we developed a rotary measurement system to measure the magnetic field distribution at the end of the undulator. Multiple Hall sensors are placed on a circuit board at equal intervals from the centre of the board. By rotating and moving the board, the probe can measure axial field in 3D space on the undulator ends. In this paper, we deliver specifics of the system.

Design Study for Direction Variable Compton Scattering Gamma Ray

A monochromatic gamma ray beam is attractive for isotope-specific material/medical imaging or non-destructive inspection. A laser Compton scattering (LCS) gamma ray source which is based on the backward Compton scattering of laser light on high-energy electrons can generate energy variable quasi-monochromatic gamma ray. Due to the principle of the LCS gamma ray, the direction of the gamma beam is limited to the direction of the high-energy electrons. Then the target object is placed on the beam axis, and is usually moved if spatial scanning is required. In this work, we proposed an electron beam transport system consisting of four bending magnets which can stick the collision point and control the electron beam direction, and a laser system consisting of a spheroidal mirror and a parabolic mirror which can also stick the collision point. Then the collision point can be placed on one focus of the spheroid. Thus gamma ray direction and collision angle between the electron beam and the laser beam can be easily controlled. As the results, travelling direction of the LCS gamma ray can be controlled under the limitation of the beam transport system, energy of the gamma ray can be controlled by controlling incident angle of the colliding beams, and energy spread can be controlled by changing the divergence of the laser beam.