Radiation Safety Aspects of Linac Operation with Bremsstrahlung Converters

This chapter provides a discussion of radiation safety aspects of operation of electron linear accelerators equipped with bremsstrahlung converters. Electron accelerators with 3, 6, 9 and 15 MeV electron beams are discussed. High-energy photon and photoneutron production during linac operation was analyzed using Monte Carlo methods. Radiation dose rates for different configurations of linacs were evaluated and compared with experimental results

Computational Feasibility Study of Dual Photon/Neutron Imaging Technique

Non-destructive testing (NDT) is crucial for industrial applications, particularly when imaging of internal components or structures is desired Current NDT imaging techniques, such as x-rays, focus primarily on isolating unique shapes. Rarely are these methods capable of distinguishing materials or material composition Potential application in the car industry for testing and examining the functional durability of products − Vehicle engines are composed of a combination of low-z and high-z materials with significant variation in density − Being able to determine the location of material during operation eliminates the need to disassemble an engine during stud

Time Encoded Imaging of Neutrons and Photons Using CLYC Detector Equipped with a Dual Mode Collimator

Information about a radiation source’s position is essential for methods of simultaneous detection of neutrons and photons. The detection system that is capable of spatial mapping of radiation in two dimensions was developed. A single Cs2LiYCl6:Ce3+ detector enriched in 7Li isotope (C7LYC) was equipped with a hybrid dual-mode rotational collimator. The collimator was designed as a coded aperture (a modified uniformly redundant array) using lead and plastic components. C7LYC scintillator enables segregation of neutron signals from photon signals, and neutron and photon energy measurements. Radiation measurements were performed at different angular positions of the collimator using a single detector. Maximum likelihood expectation technique was utilized to generate the image of an assayed radiation source. Time encoded imaging of neutron and photon sources was demonstrated using this detection system

Gamma Ray Measurements Using Unmanned Aerial Systems

Gamma ray measurements involved in monitoring technologies of field conditions are of vital importance for environmental safety and radiation protection. This chapter addresses the method of cooperative gamma sensing using multiple unmanned aerial systems. Section 1 provides an introduction. The design of semiconductor and scintillation gamma ray sensors integrated into aerial robotic platforms is discussed in Section 2, along with the fusion of time-stamped radiation data with position information using the real-time kinematic positioning technique. Section 3 addresses the multirobot contour mapping of radiation fields. Computer simulation of radiation contour mapping is discussed in Section 4. Experimental verification of the contour mapping and source-seeking algorithm is described in Section 5. Section 6 summarizes results of the project

Gamma Ray and Neutron Sensors for Remote Monitoring Using Aerial Robotic Platforms

Remote radiation sensing technologies are essential for radiation safety and environmental security measures. The use of unmanned aerial systems equipped with gamma-ray and neutron sensors enables monitoring of ionizing radiation in hard to reach hazardous zones where the contamination is unknown. To keep personnel away from the radiation exposure by using remote measurement techniques, these sensors should be integrated into robotic platforms, and the analysis of sensor’s signals should be automated and carried out onboard. Two sensors were integrated into an octocopter aerial platform to address this need: a semiconductor Cadmium Zinc Telluride gamma-ray sensor and an elpasolite Cs2LiYCl6:Ce3+ scintillator based gamma/neutron sensor. To allow easy deployment in the field, both radiation sensors were designed as plug-and-play components using the Robot Operating System for onboard processing of the sensor’s data and for fusion of the processed data with the real time kinematic GPS information

Study of pulse shape discrimination for a neutron phoswich detector

A portable phoswich detector capable of differentiating between fast neutrons and thermal neutrons, and photons was developed. The detector design is based on the use of two solid-state scintillators with dissimilar scintillation time properties coupled with a single optical sensor: a 6Li loaded glass and EJ-299-33A plastic. The on-the-fly digital pulse shape discrimination and the wavelet treatment of measured waveforms were employed in the data analysis. The instrument enabled neutron spectrum evaluation

Wavelet-Based Analysis of Neutron-Induced Photon Spectral Data

Neutron-based methods of non-destructive inter- rogation of objects for the purpose of their characterization are well-established techniques, employed in the field of bulk material analysis, contraband detection, unexploded ordnance, etc. The characteristic gamma rays produced in nuclear reactions initiated by neutrons in the volume of the irradiated object (inelastic neutron scattering, thermal neutron capture, and activation) are used for the elemental identification. In many real-world applications, an automated spectral analysis is needed, and many algorithms are used for that purpose. The Applied Physics Institute at Western Kentucky University has recently started to employ a mathematical spectrum analysis technique based on wavelets that simultaneously provides quick, accurate, and objective analysis of gamma ray spectra. This paper will provide a brief overview of wavelets and multiwavelets, and of the wavelet-based analysis algorithm. Examples will be given using neutron- induced photon spectra measured using high resolution and low resolution detectors

Computational study of radiation doses at UNLV accelerator facility

A Varian K15 electron linear accelerator (linac) has been considered for installation at University of Nevada, Las Vegas (UNLV). Before experiments can be performed, it is necessary to evaluate the photon and neutron spectra as generated by the linac, as well as the resulting dose rates within the accelerator facility. A computational study using MCNPX was performed to characterize the source terms for the bremsstrahlung converter. The 15 MeV electron beam available in the linac is above the photoneutron threshold energy for several materials in the linac assembly, and as a result, neutrons must be accounted for. The angular and energy distributions for bremsstrahlung flux generated by the interaction of the 15 MeV electron beam with the linac target were determined. This source term was used in conjunction with the K15 collimators to determine the dose rates within the facility