State-of-the-art microcalorimeter spectrometers now contain large detector arrays with hundreds of individual pixels. Each individual pixel outputs a unique and non-linear response with respect to deposited energy. This work describes a pattern-recognition algorithm to combine these responses into a single energy-calibrated histogram, referred to as co-adding pixels. Photo-peaks from different pixels are matched together based upon how well the match aligns the centroids and heights of neighboring peaks. This usually results in around 100 co-adding calibration points from 30 to 300 keV for a several day acquisition of plutonium items with masses between 0.5 and 10 grams. An additional algorithm energy-calibrates this co-added spectrum using the fluoresced K x-ray emissions from a tantalum absorber and inherent x-ray escape peaks from the tin absorbers. Both algorithms operate without knowledge of the source and are fully automated. This work presents results from the acquisitions of high and low burnup plutonium, 10% enriched uranium, a 153Gd calibration source, and a 57Co+166mHo calibration source. In all measurements, resolution defined as the full-width at half-maximum (FWHM) of photo-peaks is preserved between the individual pixel and co-added spectra at around 65 eV for incident photon energies between 60 and 208 keV. The energy calibration algorithm is approximate and yields a calibration curve off by an average of around 200 eV for incident photon energies between 60 and 208 keV.

The algorithm used for isotope identification onboard a radioisotope identifier (RIID) plays a key role in obtaining a correct identification. The majority of RIIDs deployed by the United States Department of Homeland Security are based on NaI spectrometers. Their performance in isotope identification has been well-documented. It has been demonstrated that the secondary analysis of spectra by a trained spectroscopist is frequently necessary to resolve problems in the RIIDs identification. It is also clear that trained spectroscopists are capable of identifying complicated, multiple-line sources with even the poorest resolution detectors such as Nal. This paper seeks to understand the factors in detector performance such as energy resolution that play an important role in isotope identification.

Wavelet analysis is a mathematical technique that was presented in the mid-1980s to solve a variety of problems in signal analysis where the signal is aperiodic, noisy, transient, etc. More recently, wavelets have been applied to other problems such as feature detection and localization, making it a very promising tool for the analysis of gamma-ray spectra. Recent results have also shown that this technique has the potential to benefit over other approaches due to the fact that the signal can simultaneously be analyzed over multiple scales by using wavelet analysis, thus eliminating potential false isotope identifications from artifacts such as the Compton edge and backscatter peaks. This implies that this peak localization algorithm is no longer a function of detector resolution, which changes with energy. We will present our results evaluating the technique of wavelet analysis for low-resolution (NaI) gamma-ray spectra. Emphasis will be placed on wavelet selection and the incorporation of a simple algorithm to the problem of isotope identification.

Surveys were carried out at five different firing sites at Los Alamos National Laboratory to measure residual alpha emissions in earth contaminated with natural and depleted uranium. This contamination is caused by controlled experimental explosions during testing of the non fissile components of nuclear weapons. Two conclusions were reached: the first is that post shot clearing of the experimental areas is effective at removing contamination and the second is that the diminution of alpha emissions due to aging is small.

Recent design advances in airflow long-range alpha detector (LRAD) technology have improved the detectors` sensitivity, reduced their size and weight, and reduced their construction costs. These second-generation LRADs are also less influenced by fluctuations in background radiation. These advances now allow airflow LRAD systems to be lightweight, low-power, and portable, thereby increasing their usefulness to the radiation monitoring industry.

Long-range alpha detector (LRAD) systems are designed to monitor alpha sources and contamination by measuring the number of ions created in air by ionizing radiation. Traditional alpha detectors are designed to detect alpha particles directly and must be passed slowly within about 3 cm of an alpha source to operate effectively. LRAD detectors collect the ions created from alpha interactions with air. Therefore, they are better able to monitor equipment and complex surfaces and can be operated at a much greater distance from an alpha source than traditional alpha detectors. Furthermore, because LRAD detectors remain stationary during monitoring, they are less subject to operator error than traditional alpha detectors. This paper will discuss the basic operation as well as recent advances that have been made to LRAD Sample Monitors.

Traditional alpha-particle detectors are limited by relatively poor sensitivity, small size, and difficulty of operation. These factors result in laborious effort and imprecise results. In addition, it is difficult for these detectors to monitor the inside of pipes and large areas having nonuniform surfaces. To be effective, traditional monitors require the probe to be held less than 1 cm from the surface while scanning with a slow, steady, and continuous motion. Long-range alpha detector (LRAD) technology overcomes the limitations imposed by the short range of alpha particles and provides a detailed analysis of alpha contamination in a cost-effective manner. Using a combination of LRAD airflow and electrostatic methods, we have developed several monitors for the detection of alpha contamination on hands and arms, in surface soil, and for radon gas.

The authors have and are developing a series of practical alpha detectors for alpha characterization. These include soil surface monitors, pipe and duct monitors, air quality and radon monitors, tool monitors, and sample monitors. Two types of these monitors have been transferred to industry thus far for commercialization. Several of these systems have been fully field tested: for example, the soil surface monitor has been used to characterize 11 sites for 7 customers at 3 DOE facilities. Using a new but simple technology, these alpha detectors can be put to use in many areas where conventional alpha probes are impractical or insufficiently sensitive. Use of these alpha detectors in site characterization at the Uranium in Soil Integrated Demonstration at Fernald, at Los Alamos, and elsewhere will be discussed as well as their commercialization and possible further applications.

Conventional alpha detectors depend upon detecting the alpha particle directly. This is often difficult because typical alpha particles generated by uranium or plutonium travel less than 3 cm in air. In contrast, the long-range alpha detector (LRAD) technology relies on detecting the ions generated by alpha particles as they lose their energy in air, rather than detecting the alpha particles themselves. We have designed, built, and used LRAD-based airflow monitors to detect alpha contamination. The airflow monitor is composed of a sample chamber with air and ion filters at one end and an ion detector at the opposite end. A set of small fans is located just outside the ion detector to provide an airflow that transports the ions into the ion detector. Ambient air enters through the particulate and ion filters, passes over and through an object located in the sample chamber, through the ion detector, then leaves the system through the fans. The number of ions present is proportional to the amount of contamination on the object`s surface. This work describes the design, construction, and testing of the LRAD-based airflow monitors.

Long-range alpha detector (LRAD) systems are designed to monitor alpha contamination by measuring the ionization in air formed by the alphas. Recent tests have been performed to determine the sensitivity of LRAD systems to beta contamination and soil moisture levels. These results and the general technology are discussed in this paper. >

Soil surface monitors based on long-range alpha detector (LRAD) technology are being used to monitor alpha contamination at various sites in the Department of Energy complex. These monitors, the large soil-surface monitor (LSSM) and the small soil-surface monitor (SSSM), were used to help characterize sites at Fernald, Ohio, and active or inactive firing sites at Sandia National Laboratories and Los Alamos National Laboratory. Monitoring results are presented herein in chronological order.

Standard alpha detectors are severely limited when monitoring alpha contamination on large surfaces and the inside surfaces of pipes, ducts, and equipment. The Long-Range Alpha Detector (LRAD) system overcomes these problems by detecting the ion pairs created by an alpha particle in ambient air, rather than the alpha particle directly. These ion pairs are transported to a collection grid by either an air current or an electric field and create a small electric current (typically 10{sup {minus}13} to 10{sup {minus}14} A) that is read by an electrometer and displayed on a data acquisition system. This method of detection is used to create monitoring systems for both the environmental restoration and decontamination and decommissioning fields.

strongly supports academic freedom and a researcher's right to publish; as an institution, however, the Laboratory does not endorse the viewpoint of a publication or guarantee its technical correctness. ABSTRACT In support of national security, it is important to develop a technical understanding of handheld gamma-ray detectors used by field teams. Several commercially available detectors have been examined to determine their efficiency profile, resolution, stability, and ability to correctly identify a variety of isotopes. INTRODUCTION Several handheld detectors with isotope identification ability have been evaluated. Spectra have been acquired for a number of different radioisotopes using these detectors. These spectra were used to determine efficiency profiles and calibration stability information, and to assess the accuracy of automated isotope identification, with discouraging results. This paper is an extension of the work released in the paper " Evaluation of Handheld Isotope Identifiers " [1].