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DOE OSTI2013

Environment scattering in GADRAS.

Radiation transport calculations were performed to compute the angular tallies for scattered gamma-rays as a function of distance, height, and environment. Green s Functions were then used to encapsulate the results a reusable transformation function. The calculations represent the transport of photons throughout scattering surfaces that surround sources and detectors, such as the ground and walls. Utilization of these calculations in GADRAS (Gamma Detector Response and Analysis Software) enables accurate computation of environmental scattering for a variety of environments and source configurations. This capability, which agrees well with numerous experimental benchmark measurements, is now deployed with GADRAS Version 18.2 as the basis for the computation of scattered radiation.

Thoreson, Gregory G.↗

DOE OSTI2014

Development of a Focusing DIRC Detector for Particle Identification

We have constructed a prototype Direct Ring Imaging $\check{C}$erenkov (DIRC) detector in our optics lab to study its performance for identifying pions and kaons. This type of detector will be used for the Belle II experiment now under construction at the KEK laboratory in Japan. To test our prototype, we have constructed a cosmic ray telescope (CRT) that is able to trigger on and reconstruct cosmic ray tracks. We require that the tracks traverse the DIRC detector and study the resulting detector response.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2014

Testing for the Photon Doppler Broadening Data Sampling Bug in MCNP5/X

MCNP5/X has the capability to perform photon Doppler broadening to incorporate the effect of bound electrons on photon scattering. This effect is generally important if energy spectra or detector responses are desired for photons in the tens to hundreds of keY energy range. In the Fall of 2011, a diligent MCNP user noticed that the sampling routines in MCNP were inconsistent with t he data for sampling which atomic shell t he electron is bound. The data are provided in probability density function (PDF) format, whereas MCNP sampled the data as if they are in a cumulative density function (CDF) format, leading to erroneous results.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2013

Annual Report: Property Improvement in CZT via Modeling and Processing Innovations

The objective of this project is to develop growth models of CZT crystals from the melt using vertical gradient freeze (VGF) or vertical Bridgman growth as a typical process. Further, the project will perform critical experiments including single crystal growth to validate the growth models and to provide detailed data for modeling and simulation. Ideally, the project will develop growth models that will provide, for the first time, choices for optimal CZT single crystal growth from the melt based on model input. The overarching goal that guides this research proposal is to produce large, single crystals of CZT with good yield and reproducible properties. In our view this depends on 1) understanding crystal growth processes, including annealing and cool-down processing, and 2) understanding the role of defects on detector response since it is not possible, yet, to produce defect-free materials. Models of defect structure and formation are addressed. Validated models and experiments on reducing defects in melt-grown crystals are used to guide our understanding of growth processes and in-furnace annealing plus cool-down.

36 MATERIALS SCIENCE↗

DOE OSTI2014

GADRAS isotope ID user s manual for analysis of gamma-ray measurements and API for Linux and Android .

Isotope identification algorithms that are contained in the Gamma Detector Response and Analysis Software (GADRAS) can be used for real-time stationary measurement and search applications on platforms operating under Linux or Android operating sys-tems. Since the background radiation can vary considerably due to variations in natu-rally-occurring radioactive materials (NORM), spectral algorithms can be substantial-ly more sensitive to threat materials than search algorithms based strictly on count rate. Specific isotopes or interest can be designated for the search algorithm, which permits suppression of alarms for non-threatening sources, such as such as medical radionuclides. The same isotope identification algorithms that are used for search ap-plications can also be used to process static measurements. The isotope identification algorithms follow the same protocols as those used by the Windows version of GADRAS, so files that are created under the Windows interface can be copied direct-ly to processors on fielded sensors. The analysis algorithms contain provisions for gain adjustment and energy lineariza-tion, which enables direct processing of spectra as they are recorded by multichannel analyzers. Gain compensation is performed by utilizing photopeaks in background spectra. Incorporation of this energy calibration tasks into the analysis algorithm also eliminates one of the more difficult challenges associated with development of radia-tion detection equipment.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2015

Search for Magnetic Monopoles with the NO$\nu$A Far Detector

The magnetic monopole is a hypothetical particle, which is an important field configuration in many Grand Unified Theories, and whose mass may vary from 10 4 to 10 18 GeV. The quantization of magnetic charge derived by Dirac in 1931 suggests the heavy ionization nature of magnetic monopoles. The NO$\nu$A collaboration is using the NO$\nu$A far detector - the largest scintillator detector in the world - to search for signals of relic monopoles that might have been produced in the early universe. To achieve this, we have simulated the propagation of non-relativistic monopoles with a uniform distribution of velocity within the range 10 -4 ≲β≲ 0.2 , and the corresponding detector response. To record potential monopole-like events, we have developed a data-driven trigger system with two monopole triggers (the fast monopole trigger and the slow monopole trigger). This analysis focuses on the data recorded by the fast monopole trigger, which is sensitive to monopoles with velocity β ≳ 10 -3 . We have performed a blind analysis on a total live time of 1628.2 hours of data recorded by the fast monopole trigger. We present the updated flux limits with 90% CL (confidence level) as a function of monopole mass and velocity.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2017

PCF File Format.

PCF files are binary files designed to contain gamma spectra and neutron count rates from radiation sensors. It is the native format for the GAmma Detector Response and Analysis Software (GADRAS) package [1]. It can contain multiple spectra and information about each spectrum such as energy calibration. This document outlines the format of the file that would allow one to write a computer program to parse and write such files.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

DOE OSTI2018

Enhancing GADRAS Source Term Inputs for Creation of Synthetic Spectra

The Gamma Detector Response and Analysis Software (GADRAS) team has enhanced the source term input for the creation of synthetic spectra. These enhancements include the following: allowing users to programmatically provide source information to GADRAS through memory, rather than through a string limited to 256 characters; allowing users to provide their own source decay database information; and updating the default GADRAS decay database to fix errors and include coincident gamma information.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2018

Magnetic field map for T977 tertiary beam

This note describes the final magnetic field model and a simplified momentum reconstruction and its uncertainties being used for the analysis of the 2010 data for T977 (MINERvA test beam ex- periment) at the Fermilab Test Beam Facility. The results from analysis of those data are published in “MINERvA neutrino detector response measured with test beam data,” [Aliaga et al.(2015)] which has open access availability, and is also available as arXiv:1501.06431. The beamline used for this experiment was designed by MINERvA in collaboration with experts at the Fermilab Test Beam Facility. Support for constructing the beamline was provided by Fermilab, including support to MINERvA personnel and also a wide range of technical help from across Fermilab.

43 PARTICLE ACCELERATORS↗

DOE OSTI2018

Prototype Stilbene Neutron Collar II

A neutron collar using stilbene organic scintillator cells for fast neutron counting is described for the assay of fresh low enriched uranium (LEU) fuel assemblies. The prototype stilbene collar has a form factor similar to standard He-3 based collars and uses an AmLi interrogation neutron source. This report describes the simulation, using a custom LLNL developed MCNPX, of list mode neutron correlation data on various fuel assemblies. Some of these fuel assemblies have neutron absorbers (burnable Gd poisons) and partial defect s (DU, Fe, Pb pins). Calibration curves (doubles vs 235 U linear mass density) are presented for fast (with Cd lining) mode of operation. The modeling incorporates LLNL developed neutron crosstalk correction algorithms and stilbene light output detector response quench function. Pileup issues are addressed using the LLNL code GamGen / RadSrc to estimate the flux of alpha decay gammas from the fuel assemblies on the stilbene cells with and without Pb shielding. One panel of the prototype collar using 10 high-efficiency 4”x2” stilbene cells from Inrad Optics, using LLNL developed technology, has been constructed and calibrated for optimal PSD and data acquisition electronics. Several sources (AmLi, AmBe, Cf, DD, and DT) have been measured with the single panel and the measured data is consistent with the modeling. A novel part of our work was to determine the light output (LO) quench function for the Inrad 4” x 2” stilbene crystals through a LLNL-MCNPX simulation based optimized fitting of the measured LO data.

42 ENGINEERING↗

DOE OSTI2018

Developing a simulation tool for evaluating in-motion detector systems [Slides]

In order to combat the illicit trafficking of nuclear materials, Radiation Detection Systems (RDS) are used to scan pedestrians, vehicles, cargo, luggage, and other conveyances. Many of these systems are used in an “in-motion” configuration where the detector or target are moving past the other. Current modeling and simulation tools lack the ability to produce time-series detector response profiles for in-motion applications.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

DOE OSTI2015

GADRAS Isotope ID User's Manual for Analysis of Gamma-Ray Measurements and API for Linux and Android

Isotope identification algorithms that are contained in the Gamma Detector Response and Analysis Software (GADRAS) can be used for real-time stationary measurement and search applications on platforms operating under Linux or Android operating systems. Since the background radiation can vary considerably due to variations in naturally-occurring radioactive materials (NORM), spectral algorithms can be substantially more sensitive to threat materials than search algorithms based strictly on count rate. Specific isotopes or interest can be designated for the search algorithm, which permits suppression of alarms for non-threatening sources, such as such as medical radionuclides. The same isotope identification algorithms that are used for search applications can also be used to process static measurements. The isotope identification algorithms follow the same protocols as those used by the Windows version of GADRAS, so files that are created under the Windows interface can be copied directly to processors on fielded sensors. The analysis algorithms contain provisions for gain adjustment and energy linearization, which enables direct processing of spectra as they are recorded by multichannel analyzers. Gain compensation is performed by utilizing photo-peaks in background spectra. Incorporation of this energy calibration tasks into the analysis algorithm also eliminates one of the more difficult challenges associated with development of radiation detection equipment.

61 RADIATION PROTECTION AND DOSIMETRY↗

DOE OSTI2019

Search for the Higgs and Physics Beyond the Standard Model with the CMS Electromagnetic Calorimeter

The Compact Muon Solenoid (CMS) Experiment is a general purpose particle detector experiment at the Large Hadron Collider (LHC) at the European Laboratory for Nuclear Research (CERN). The LHC is the world’s highest energy particle collider, providing proton-proton collisions up to a center-of-mass energy of 13 TeV. The primary aim of the LHC and the CMS Experiment is to discover new physics at this high energy frontier. In 2012, the discovery of the Higgs boson at the LHC marked a crucial milestone in the Standard Model (SM) of particle physics and ushered in the beginning of a new era of exploration at the high energy frontier. Since this discovery, two key areas of study were the characterization of the new particle to confirm that it is, indeed, the predicted SM Higgs boson and also the examination of possible deviations from the SM that may hint at new physics. As a member of the CMS collaboration, the main interest of PI Orimoto has been the study of electromagnetic objects (electrons and photons) as a critical ingredient in the characterization of the Higgs boson, and as a window into physics beyond-the-SM (BSM). To this end, the Orimoto group has led numerous physics analyses ranging from SM Higgs boson studies, searches for exotic production and decay of the Higgs boson, as well as searches for supersymmetric particles. Moreover, the Orimoto group has made significant contributions to the CMS electromagnetic calorimeter (ECAL), the sub-detector responsible for the precise measurement of the energies of electrons and photons. The Orimoto group’s contributions have been recognized with many leadership roles and high profile conference presentations. This report outlines the group’s products and accomplishments from the award period (June 2013 through July 2018).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2019

Modeling of Pyroprocessing Hot Cell for Process Monitoring Evaluation

In this report, we examine studies undertaken to determine the applicability of applying measurements with a neutron counter within a pyroprocessing hot cell. The studies focus on the modeling of the hot cell and neutron counter in Monte Carlo N- Particle Code (MCNP) to determine expected radiation effects and applicability of neutron counters. The neutron counter of focus was the High Dose Neutron Detector (HDND) developed at Los Alamos National Laboratory (LANL). We studied the HDND to determine what would be the detector response under normal background conditions with operating process equipment as well as the background’s potential effect on counting applications involving a U/TRU ingot produced by the pyroprocessing electrorefiner. To perform this task, we were required to develop models of the pyroprocessing process cell and unit operations and generate source terms for various different times in the process. The data for the pyroprocessing materials came from SNL’s Safeguards and Security Process Model (SSPM) as part of MPACT’s advanced integration mission. This report will discuss the development of the pyroprocessing process cell and unit operations models in MCNP as well as various simulations to determine the applicability of the HDND for process monitoring efforts in the hot cell.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

DOE OSTI2018

MicroBooNE low-energy excess signal prediction from unfolding MiniBooNE Monte-Carlo and data

One of the primary goals of MicroBooNE is to address the existence and underlying source of the MiniBooNE observed Low Energy Excess (LEE). The MiniBooNE LEE is the observation of an anomalous excess of νe charged current quasi-elastic-like events in the Booster Neutrino Beam at Fermilab. The true origin of those events could be attributed to either single electrons or single photons produced in the MiniBooNE Cherenkov detector, as the experiment lacked the ability to distinguish between the two. Using the ability of liquid argon time projection chambers to perform electron/photon separation, MicroBooNE aims to search for this excess in two exclusive channels: single photon and single electron. However before addressing either hypothesis the MiniBooNE LEE must be explicitly modeled in MicroBooNE. This requires that the MiniBooNE detector response, event reconstruction, selection and their collective effects be removed before mapping the observable excess to MicroBooNE. This note describes this “unfolding process,” and provides the end results of the true unfolded distributions for two well motivated LEE hypotheses: (a) electrons from an increased intrinsic νe charged current event rate and (b) single photons due to neutrino neutral current Δ production with subsequent radiative decay.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2019

Final Report on the NA-22 sponsored project from FY17-19: Next-Generation Correlated Fission Event Simulations

Through this multi-organization correlated fission physics research and development project, the CGMF and FREYA fission event generators have been implemented into the MCNP6.2 code and released to the public while a variety of dedicated differential experiments on correlated fission signatures have been performed to help validate the complex fission theory and physics implemented in these codes. In addition to enabling these new capabilities, a multitude of efforts in modeling and transport simulation has been directed toward a variety of applications including general nuclear nonproliferation, subcritical neutron multiplication, and nuclear criticality safety applications. While there is still much more to be done in the area of correlated fission physics, including the study of b-delayed fission observables, more robust validation and an extension into more application spaces, one of the key successes of this project can be summarized as the delivery of a newly demonstrated and consistently integrated simulation capability spanning several complex nuclear physics codes. From the special nuclear materials source term to the radiation transport to the time-coincident detector response modeling, new and existing users around the world, especially throughout the nuclear nonproliferation communities, can now begin to model these kinds of highly complex special nuclear material applications. Another successful aspect of this project included fruitful collaborations, mentoring opportunities and community outreach. One extended collaboration workshop was held in Santa Fe, NM in March 2017. Two other limited collaboration meetings took place including a brief gathering during the mid-project Schubert review at LANL and a single all-day special session on “Correlated Fission Physics, Transport and Applications” held during the 2019 Annual Meeting of the Institute of Nuclear Materials Management (INMM) in Palm Desert, CA. Finally, as part of this project, we have mentored 14 undergraduate students, PhD candidates, and postdoctoral researchers listed in Appendix A. The remainder of this report contains detailed information followed by highlights of the goals and accomplishments in Appendix B broken down by task within this project.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2020

Dose Calculations from Source Models and Gamma-Ray Spectra

Gamma-ray dose rates computed by two radiation source model-based methods and five measured spectrum-based methods are compared. With the exception of a Detective DX-100, which reported dose rates that are about 25% less than the mean, dose rates are generally within 10% of mean values. Methods for computation of dose rates employed by the Gamma Detector Response and Analysis Software (GADRAS) are described and critically evaluated. Results are presented for a feasibility evaluation that seeks to use spectra recorded inside vehicles to estimate the minimum dose outside the vehicles.

61 RADIATION PROTECTION AND DOSIMETRY↗

DOE OSTI2019

Demonstration of Comprehensive Ex-Vessel Fluence Capability

Several recent developments in the Consortium for Advanced Simulation of Light Water Reactors’ (CASL) Virtual Environment for Reactor Applications (VERA) were tested to highlight its capability to perform ex-vessel fluence and reaction rate calculations. VERA offers unique capabilities for integrating the deterministic neutronics code, MPACT, with Shift, a Monte Carlo code, to perform high-fidelity in-core and ex-core radiation transport. Applications such as pressure vessel fluence, ex-core detector response, and coupon irradiation analyses take advantage of this coupling. For these applications, MPACT performs the in-core radiation transport with temperature feedback and isotopic depletion through the direct coupling with the CTF subchannel thermal-hydraulics code. Then, MPACT provides the fission source to Shift for a follow-on fixed source radiation transport calculation that tallies all the ex-core responses of interest for each time-dependent statepoint. The variance reduction method, CADIS, which is implemented in Shift, allows for efficient performance of ex-core transport for calculation of ex-core quantities of interest. This milestone report identifies limitations to the current methodology in place and showcases VERA’s current capability to model ex-core quantities of interest.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗