A method to improve radioactive waste drum activity estimation in Segmented Gamma Scanning (SGS) systems was developed for homogenous content. We describe a method to quantify the activity of spatially distributed gamma-emitting isotopes (‘hot spots’) in homogenous content waste drums without the use of a collimator. Instead of averaging all the detector's readings we treat it as many different spatial samples as if we have multiple detectors surrounding the waste drum ("virtual detectors"). From these readings, we form a general linear model. Next, we derive the Maximum Likelihood Estimator (MLE) for the multiple sources position and activity. We solve this hyper-dimensional search problem using an Alternating Projections (AP) technique which transforms the problem into a simpler one-dimensional maximization problem. We tested this method using a mathematical simulation with a various number of sources, at random activities and positions for several energy bands. The preliminary results are consistent and show large improvement of the accuracy with comparison to industrial SGS systems and the same accuracy as new methods which exploits the spatial samples. Furthermore, since this method eliminates the need for heavy led collimator, none of the sources is blocked for the whole measurement period, which provides increased count rates and decreases the total measurement time.

Radiation Portal Monitors (RPMs) are radiation detection devices which provide passive, non-intrusive means for fast screening of transportation of vehicles, baggage and passengers for the presence of nuclear and radiological materials.This paper presents two novel methods for enhancing the performances of RPMs. These methods are based on the analysis of the special pattern of the readings from the RPM detector. The pattern is generated when a moving radiation source is measured while the background is stagnant. This pattern provides an opportunity to employ methods based on the Matched Filter (MF) algorithm and the Generalized Likelihood Ratio Test (GLRT).Estimation of the radioactive source location in the vehicle improves the statistics furthermore.

The silicon photomultiplier (SiPM) is a novel photo-sensor technology. This paper presents the design optimization process for implementing this technology in a scintillator-based radiation detector. The device provides the advantages of low current consumption, small dimensions, and high gain. These properties make SiPM of great interest for applications involving portable instrumentation. However, a novel approach to establish a set of parameters and their limits is required to optimize the performance of this new technology in radiation detection applications. The trade-offs and the influences of factors such as the photon detection efficiency (PDE), dynamic range (DR), various scintillation crystal characteristics, and light-reflecting materials are discussed. This study investigates the incorporation of CsI(Tl) scintillation crystals with SiPMs based on measurements and results for different photo-coupling configurations, and the obtained achievements are described. A method for evaluating the photon collection efficiency of scintillator-SiPM-based detectors is proposed.

Silicon photomultiplier (SiPM) is a novel photosensor technology. This paper presents the design optimization process for implementing this technology in a scintillator based radiation detectors. The device provides the advantages of low current consumption, small dimensions, and high gain. These properties make the SiPM of great interest for applications involving portable instrumentation. However, a novel approach to establish a set of parameters and their limits is required to optimize performance of this new technology in radiation detection applications. The trade-offs and the influence of factors, such as Photon Detection Efficiency (PDE), dynamic range (DR), various scintillation crystal characteristics, and light reflecting materials, are discussed. This study investigated the incorporation of CsI(Tl) scintillation crystals with SiPM, based on measurements and results for different photo-coupling configurations and the obtained achievements are described. A method for evaluating the photon collection efficiency for Scintillator-SiPM based detectors is proposed.

In this paper a method for improving the signal to noise ratio (SNR) is described. This method is based on matched filter algorithm. The prospective application for the described method would be in Radiation Portal Monitors (RPM), where the signal is observed to have a fixed pattern. The comparison of the proposed method to the traditional integration is presented. The improvement in the SNR is shown to be a factor of 10.

The homeland security nuclear/radiological threat, accentuates the need for a Spectroscopy Personal Radiation Detector (SPRD). The CsI(Tl) capacity to discriminate the energy-lines of a gamma-radiation source along side with robust nature, makes these detectors suitable for isotope identification under harsh environmental conditions. However the CsI(Tl) detectors are also known for the temperature dependence of their response presenting itself in varying pulse time constant and crystal light yield. When observing a detection system as a whole this dependence appears as spectrum gain shift. For a radioisotope identification device it is paramount to correctly evaluate and compensate for any variation in spectrum parameters that may result in a faulty identification result. This work presents a theoretical analysis along side its practical application aiming at handling temperature transients. Step by step method for constructing a comprehensive scintillation detector temperature gain compensation schema will be presented and an application example will be demonstrated. Experimental lab work combined with digital signal processing techniques, including system identification and digital filtering methods are being used throughout this work and implemented for the solution of the real life problem of scintillation detector temperature gain compensation.