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Improvements to a Java based software package developed at Pacific Northwest National Laboratory (PNNL) for display and analysis of radioxenon spectra acquired by the International Monitoring System (IMS) are described here. The current version of the Radioxenon JavaViewer implements the region of interest (ROI) method for analysis of beta-gamma coincidence data. Upgrades to the Radioxenon JavaViewer will include routines to analyze high-purity germanium detector (HPGe) data, Standard Spectrum Method to analyze beta-gamma coincidence data and calibration routines to characterize beta-gamma coincidence detectors. These upgrades are currently under development; the status and initial results will be presented. Implementation of these routines into the JavaViewer and subsequent release is planned for FY 2011-2012., Published in Proceedings of the 2010 Monitoring Research Review - Ground-Based Nuclear Explosion Monitoring Technologies, 21-23 September 2010, Orlando, FL. Volume II. Sponsored by the Air Force Research Laboratory (AFRL) and the National Nuclear Security Administration (NNSA). U.S. Government or Federal Rights License

Traditional radioxenon measurements have been done by ground-based fixed systems, however in recent years there has been an increased need for systems capable of quick deployment or even complete mobility. Using the Pixie-4 data acquisition (DAQ) system can help reduce the electronics footprint of both current systems, like the radioxenon Radionuclide Laboratory 16 (RL-16) and the Swedish Automatic Unit for Noble Gas Acquisition (SAUNA), as well as future systems. Pacific Northwest National Laboratory (PNNL) has developed a Linux based Nyx graphical user interface (GUI) for Pixie-4 cards. The Nyx software can be installed on various Linux platforms and is written in C++. This software offers a rich user interface for configuring and operating the Pixie4 card and PNNL designed high voltage (HV) cards. Nyx allows one to quickly get a nuclear detector operational by maintaining the core diagnostic features built into the Pixie-4 cards. First, Nyx maintains the multitude of adjustable parameters accessible in the Pixie-4 cards, which allows one to customize settings to take full advantage of a particular detector. Nyx also maintains an oscilloscope feature which is extremely useful to optimize settings and to verify proper detector behavior and is often the first feature used in Nyx during detector setup. Finally, Nyx allows the user to collect data in several formats including full pulse shapes to basic histograms. Overall, it is the corner stone for the transition of beta-gamma systems to a state-of-the-art digitizing DAQ system., Published in Proceedings of the 2010 Monitoring Research Review - Ground-Based Nuclear Explosion Monitoring Technologies, 21-23 September 2010, Orlando, FL. Volume II. Sponsored by the Air Force Research Laboratory (AFRL) and the National Nuclear Security Administration (NNSA). U.S. Government or Federal Rights License

Monitoring changes in atmospheric radioxenon concentrations is a major tool in the detection of an underground nuclear explosion. Ground-based systems like the Automated Radioxenon Sampler /Analyzer (ARSA), the Swedish Unattended Noble Gas Analyzer (SAUNA) and the Automatic portable radiometer of isotopes Xe (ARIX), can collect and detect several radioxenon isotopes by processing and transferring samples into a high-efficiency beta-gamma coincidence detector. The high-efficiency beta-gamma coincidence detector makes these systems highly sensitive to the radioxenon isotopes 133Xe, 131mXe, 133mXe, and 135Xe. The standard analysis of the 2-dimensional beta-gamma energy spectra uses regions of interest (ROI) to determine the amount of a particular radioxenon isotope present by summing the counts in region. This method relies on the peaks of interest falling within energy limits of the region. Some potential problems inherent in this method are the reliance on stable detector gains and a fixed resolution for each energy peak. In addition, when a high activity sample is measured, there will be more interference among the ROI, in particular within the 133Xe, 133mXe, and 131mXe regions. A solution to some of these problems can be obtained through spectral fitting of the data. Spectral fitting is simply the fitting of the peaks using known functions to determine the number and relative peak positions and widths. By knowing this information it is possible to determine which isotopes are present. The area under each peak can then be used to determine an overall concentration for each isotope. Using the areas of the peaks, several key detector characteristics can be determined: efficiency, energy calibration, energy resolution, and ratios between interfering isotopes (Radon daughters)., Published in Proceedings of Monitoring Research Review (30th): Ground-Based Nuclear Explosion Monitoring Technologies, Portsmouth, VA, on 23-25 Sep 2008, p733-738 sponsored by the National Nuclear Security Administration (NNSA) and the Air Force Research Laboratory (AFRL). The original document contains color images.

The Automated Radioxenon Sampler/Analyzer (ARSA) (Hayes 1999), built by Pacific Northwest National Laboratory (PNNL), can collect and detect several radioxenon isotopes. The ARSA is very sensitive to (133)Xe, (131m)Xe, (133m)Xe, and (135)Xe due to the compact high-efficiency beta-gamma coincidence detector it uses. As detection technology improves and more emphasis is placed on system automation, QA/QC checks become of increasing importance. By automating the QA/QC checks, the reliability of the data sets is ensured without the necessity of monitoring. Often, the automated QA/QC checks will be done on site, where radio-xenon gas is not readily available so it is important to be able to use sealed point sources as an alternative. Immediately after the initial calibration of the detector, a (137)Cs source, which has a 661.7-keV gamma-ray, is used to generate both gamma and beta spectra. The two spectra are saved to file, are called the template spectrum, and will be used as the template to perform on site QA/QC checks. The QA/QC check will automatically find the start and end points of the beta spectrum and compare them with those from the template spectrum. A similar method is used for the gamma spectrum; however, in a gamma spectrum the 661.7-keV peak can be used for the high energy end. If the points do not match, a gain and offset can be calculated to make the QA/QC spectra match the template spectra. A second and more advanced method is to take a beta-gamma coincidence spectrum for the template spectrum. A comparison of the QA/QC beta-gamma coincidence spectrum to the template spectrum will be used to determine what if any adjustments need to be made on the gain and offset. A detailed discussion of the QA/QC checks will be included in the paper., Presented at 29th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, Denver, CO 25-27 Sep 2007, sponsored by the National Nuclear Security Administration (NNSA) and the Air Force Research Laboratory (AFRL). Published in proceedings of the same p739-746. The original document contains color images.