N4D4  Monte-Carlo Software Applications

Thursday, Nov. 5  16:30-18:10  Pacific Salon 3

Session Chair:  Garrett McMath, Los Alamos National Laboratory, United States; Gabriela Hoff, Univesidade do Estado do Rio de Janeiro (UERJ/IPRJ), Brazil

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(16:30) N4D4-1, A Channelized Hotelling Observer for Treaty-Verification Tasks

C. J. MacGahan1, M. A. Kupinski1, N. R. Hilton2, E. M. Brubaker2, W. C. Johnson2

1University of Arizona, Tucson, AZ, USA
2Sandia National Laboratories, Livermore, CA, USA
We apply the channelized Hotelling observer–a common tool used in medical image quality assessment–to the task of arms-control-treaty verification. The model does not aggregate information about the tested objects. Events are processed in list-mode format and only non-sensitive channels are updated with each detected event. This model includes a framework to incorporate nuisance parameters such as source location, orientation, and material age. To test this model, Monte Carlo simulations were performed with the GEANT4 toolkit. Photons were tracked from plutonium inspection objects developed by Idaho National Laboratory. We simulated the Fast-Neutron Imaging system designed by Oak Ridge National Laboratory and Sandia National Laboratories, which consists of 40x40 1cm2 liquid scintillator pixels with a plastic coded aperture. Observer models were evaluated using the area under the ROC curve.

(16:50) N4D4-2, Monte Carlo Simulation of Radionuclide Inventory of Irradiated Nuclear Fuel for Generation of Complex Fission Gamma Ray Fields

O. Huml1, P. Žlebcík2, L. Sklenka1, J. Rataj1, M. Štefánik1

1Dept. of Nuclear Reactors, Czech Technical University, Prague, Czech Republic
2National Radiation Protection Institute, Prague, Czech Republic
To provide complex real fission gamma ray field for testing detection systems of intervening mobile groups a new testing device MONTE-1 was developed at the training reactor VR-1 operated by the Czech Technical University in Prague. Three types of nuclear fuel elements were irradiated in the core of the VR-1 reactor to generate the fission gamma ray fields. The three types were fuel element IRT-4M, fuel rod EK10 and a fuel pellet used in PWRs. Depletion of the fuel elements was simulated by the MCNP code to estimate inventories of created radionuclides and their activities. Detailed MCNP model of the EK10 fuel rod and fuel pellet were prepared and implemented into existing parametrized model of the VR-1 reactor. Optimal irradiation conditions for measurements in real experiments with detection systems at the testing device MONTE-1 were selected based on the comparison of results. Calculated activities of selected radioisotopes were compared with real measurements. In addition, results of radionuclide inventories were used for other simulations of dose rate distributions in the area of experiments. This work was supported by the Ministry of the Interior of the Czech Republic within the security research program VG20132015119.

(17:10) N4D4-3, Validation of Mcnp6 Generated Bonner Sphere Responses to Complex Neutron Spectra

W. Erwin1, J. Clinton1, A. Decker2, J. McClory1

1Air Force Institute of Technology, Wright-Patterson AFB, OH, USA
2Nuclear Science and Engineering Research Center, West Point, NY, USA
This experiment sought to validate BSS response functions generated by MCNP6, the latest version of the radiation transport code published by Los Alamos National Laboratory. An MCNP6 model simulated a prompt fission (Watt) neutron spectrum for a LiI(Eu) scintillator encased in various diameter polyethylene spheres, generating a response matrix. Corresponding experimental data were collected at the Fast Burst Reactor (FBR) at White Sands Missile Range. The normalized detector responses for both simulated experimental spectra were found to be in excellent agreement, with a maximum variance of ± 5% for all detector/sphere combinations. The incident neutron spectra for both simulated and experimental runs were then deconvolved from the BSS data using MAXED, a maximum entropy unfolding code; the deviations between the unfolded simulated and experimental spectra were expected, given the relative simplicity of the MCNP neutron source when compared to the FBR.

(17:30) N4D4-4, Correction Factors to Convert Microdosimetry Measurements in Silicon to Tissue in C-12 Ion Therapy

D. Bolst, S. Guatelli, L. T. Tran, L. Chartier, M. L. F. Lerch, A. B. Rosenfeld

Centre For Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Autralia
Carbon therapy is a relatively new radiation treatment modality. It offers many advantages over traditional radiation therapy including excellent conformity in treatment, sparing healthy organs at risk. However a complication when delivering C-12 is that the relative biological effectiveness (RBE) varies greatly; this means that accurate RBE measurements of the radiation field are vital for treatment planning and for routine quality assurance (QA). One method of calculating RBE values is using the microdosimetric kinetic model (MKM) which uses microdosimetric measurements. Tissue equivalent proportional counters (TEPCs) are the gold standard in microdosimetry, able to simulate a micron sized volume using tissue equivalent gas. TEPCs have many drawbacks including wall effects, operation complexity and poor spatial resolution which are not ideal for the sharp dose profiles associated with C-12 therapy. As an alternative solution, the Centre for Medical Radiation Physics (CMRP), University of Wollongong, has adopted a solid state approach which addresses the limitations of the TEPC, however silicon microdosimeters are not without their shortcomings, namely a lack of tissue equivalence. In this work a method for converting the microdosimetric spectra obtained in silicon to tissue in C-12 therapy was developed based on comparing the energy deposition in silicon and muscle, calculated by means of Geant4. A scaling factor C was determined to scale the dimensions of silicon to an equivalent sized muscle volume. The scaling factor for converting silicon to muscle was found to be 0.58 with an additional low energy correction (LEC) factor which varied based upon the lineal energy of the C-12 peak. The comparison of the RBE derived from experimental TEPC measurements to RBE obtained from simulated microdosimetric spectra in silicon and converted to tissue reveals good agreement, proving the success of the developed method.

(17:50) N4D4-5, X-Ray Detector Simulation Pipelines for the European XFEL

T. Rüter1, S. Hauf1, M. Kuster1, A. Joy2, R. Ayers2, M. Wing2,3,4, C. H. Yoon1, A. Mancuso1

1European XFEL GmbH, Hamburg, Germany
2University College London, London, United Kingdom
3Deutsches Elektronensynchrotron (DESY), Hamburg, Germany
4Universität Hamburg, Hamburg, Germany
The European X-ray Free Electron Laser is a high-intensity X-ray light source currently being constructed in Hamburg, Germany, that will provide spatially coherent X-rays in the energy range between 0.25 keV – 25 keV. The LPD, DSSC and AGIPD detectors are being developed for the facility to provide megapixel imaging capabilities with a dynamic range spanning from single photon sensitivity to 105 photons per pixel.

Calibration of these detectors is challenging, as a large set of calibration parameters (up to 109) need to be taken into account. To aid in detector characterization and provide a drop-in replacement for data processing evaluation, the X-ray Camera Simulation Toolkit (X-CSIT) has been developed in collaboration with University College London. X-CSIT has been successfully integrated into the XFEL's computing framework Karabo and validation against pnCCD and LPD data has been performed.

Based on X-CSIT, a X-ray detector simulation pipeline (XDSP) can be assembled in Karabo to simulate a realistic detector response at a given experimental configuration. A XDSP for the SPB/SFX imaging experiment based on randomized calibration data of an AGIPD prototype module has been implemented and integrated into the experiment's start-to-end simulation framework simS2E. We present first results of this integration alongside a discussion of the possible effects on reconstruction algorithms.