11th Geant4 Space Users Workshop

26 Aug 2015, 08:00 → 28 Aug 2015, 18:00 Asia/Tokyo

Hiroshima Institute of Technology Hiroshima Campus, Hiroshima, Japan

The main workshop web page is here.
http://nsl.iis.it-hiroshima.ac.jp/geant4/

Wednesday 26 August

08:30 → 09:00 Registration

09:00 → 10:30 Welcome and general status reports

Convener: Nasser Barghouty (NSAS)

09:00 Welcome

Speaker: Prof. Yasushi Nagasaka (Hiroshima Institute of Technology)

09:15 JAXA status

Speaker: Dr Masanobu Ozaki (JAXA)

Slides JAXAreport2015_ozaki.pdf

09:40 ESA status

Speaker: Mr Petteri Nieminen (ESA)

ESA_Geant4_RD_activities_2015_PDF.pdf

10:05 INTA status

Speaker: Mr Sergio Ibarmia (INTA)

Slides ibarmia_Geant4atINTA_G4SUW2015.pptx

10:30 → 10:50 break

10:50 → 12:00 General status reports

Convener: Dr Masanobu Ozaki (JAXA)

10:50 Radiation Transport and Space-Radiation Related Efforts at NASA’s Marshall Space Flight Center

Speaker: Dr Nasser Barghouty (NASA MSFC)

Slides 11thGSUW_Space_Radiation.pptx

11:15 Applications of MRED for Predicting Single Event Effects

MRED (Monte Carlo Radiative Energy Deposition) is Vanderbilt University’s Geant4 application for simulating radiation events in semiconductors. Geant4 is comprised of the best available computational physics models for the transport of radiation through matter. Geant4 is a library of c++ routines for describing radiation interaction with matter assembled by a large and diverse international collaboration. MRED includes a model developed by researchers at Vanderbilt University for screened Coulomb scattering of ions (currently available in the latest Geant4 release), tetrahedral geometric objects, a cross section biasing and track weighting technique for variance reduction, and a number of additional features relevant to semiconductor device applications. The Geant4 libraries contain alternative models for many physical processes, which differ in levels of detail and accuracy. Generally, MRED is structured so that all physics relevant for radiation effects applications are available and selectable at run time. The underlying physical mechanisms for Single Event Effect (SEE) response are: 1) ionizing radiation-induced energy deposition within the device, 2) initial electron-hole pair generation 3) the transport of the charge carriers through the semiconductor device and 4) the response of the device and circuit to the electron-hole pair distribution and subsequent transport. Each of these occur on a different time scale and they are often assumed to be sequential, i.e., energy deposition determines the initial electron-hole pair generation, which in-turn impacts device and circuit response. We will provide a review of MRED applications that address issues as they relate to the mechanisms listed above.

Speaker: Prof. Robert Reed (Vanderbilt University)

Slides MRED.pdf

11:40 announcement

12:45 → 21:40 Social event

Thursday 27 August

09:00 → 10:30 Status reports from Geant4 developers

Convener: Dr Sebastien Incerti (CNRS)

09:00 Kernel and Geometry Updates

Speaker: Dr Makoto ASAI (SLAC)

Slides Geant4GeneralStatus.pptx

09:30 Parallelization features (MT, MPI, TBB)

Speaker: Andrea Dotti (SLAC National Accelerator Laboratory)

Slides Geant4_MT_Space_Users_Workshop_2015.pdf

10:00 Visualization and UI updates

Speaker: Koichi Murakami

10:30 → 11:00 break

11:00 → 12:40 Status reports from Geant4 developers

Convener: Andrea Dotti (SLAC National Accelerator Laboratory)

11:00 JPL mission activities and Geant4 applications for some of JPL mission

Speaker: Shawn Kang (Jet Propulsion Laboratory)

11:25 Standard Electromagnetic Physics Update

Speaker: Prof. Vladimir Ivantchenko (CERN, G4AI)

Slides Geant4EMStatus.pdf

11:55 Low-energy Electromagnetic Physics / Geant4-DNA Update

Speaker: Dr Sebastien Incerti (CNRS)

Slides SIncerti-G4SUW.pdf

12:25 Welcome - President of Hiroshima Institute of Technology

12:40 → 14:00 lunch break

14:00 → 15:20 Other developments

Convener: Dr Koichi Murakami

14:00 Integration of GPGPU for EM physics

Speaker: Prof. Akinori Kimura (Ashikaga Institute of Technology)

14:25 The Space Elevator and Geant4

The space elevator is coming closer to reality as strong materials research advances. Research into the dynamics of very long tethers, tether climber and power beaming technologies is underway and Geant4 has a substantial role to play in these efforts. Space elevator basics will be discussed, followed by a sketch of likely Geant4 applications to the study of radiation effects, magnetosphere environment and micrometeorite damage. The talk will conclude with a projected completion schedule and a summary of groups currently involved in the project.

Speaker: Dr Dennis Wright (SLAC)

Slides G4SE.pdf

14:50 Hadronic Physics Update

Speaker: Dr Dennis Wright (SLAC)

Slides SUW2015.pdf

15:20 → 15:50 break

15:50 → 17:30 Space missions - instruments and detectors (1)

Convener: Dr Tsunefumi Mizuno (Hiroshima University)

15:50 Geant4 Applications to High Energy Astrophysics

An astrophysical system harboring a strong gravity star such as a black hole or a neutron star accretes gas from the circumstellar environment, releasing enormous gravitational energy via accretion onto the deep potential. Since a large fraction of the accretion power is released in a form of X-ray radiation, X-ray spectral and temporal information is an important probe to study the energetic phenomena in the accreting system. Recent improvement in observational instruments allows us to obtain high-quality data (i.e. high statistics and high energy/timing/spatial resolutions) which contains information on the central engine and the circumstellar environment of black holes and neutron stars in great detail. However, precise comparison between the high-quality data and theoretical models requires careful treatment of X-ray generation in the accreted plasma and radiative transfer. In order to treat the radiative transfer precisely, we have developed a general-purpose calculation framework of radiative transfer based on Monte Carlo methods called MONACO (Odaka et al. 2011). MONACO depends upon the Geant4 toolkit library for particle tracking since the library has sophisticated treatment of the tracking in a complicated geometry. In addition, the universality of the Geant4 physical process handling enables us to introduce into MONACO our original code of physical processes that are optimized for astrophysical modeling. The framework currently provides three physics lists: (1) Cold matter—photoelectric absorption followed by fluorescence and scattering by electrons bound to neutral atoms or molecules are responsible for generating spectral features of X-ray reflection, (2) Photoionized plasma—photoionization and photoexcitation of various ion species result in emission lines and absorption lines, and (3) Comptonization—this process plays an important role in cooling a hot accretion flow through X-ray radiation. All of these processes have to be considered in a moving frame since bulk or random motion of the matter interacting with a photon produces a Doppler shift or broadening, which provides us with crucial information on physical conditions of the matter including its dynamics. We have applied this Monte Carlo framework to various astrophysical objects from galactic X-ray binaries (neutron stars or black holes) to extragalactic supermassive black holes. In this talk, we present the code design and how we apply the framework to real astrophysical problems. We then discuss issues arising when utilizing the Geant4 library for the astrophysical applications.

Speaker: Dr Hirokazu Odaka (ISAS/JAXA)

Slides geant4_suw11_odaka.pdf

16:15 In-orbit Performance Estimation of the Hard X-ray Imager onboard ASTRO-H with Monte Carlo simulations

The Hard X-ray Imager (HXI) is one of four instruments onboard 6th Japanese X-ray satellite, ASTRO-H, which is scheduled to be launched in FY 2015. Combined with hard X- ray telescopes, the HXI will realize imaging spectroscopy in hard X-ray band ranging from 5 keV to 80 keV with a sensitivity which is two orders of magnitude better than that of Suzaku/HXD. The HXI is composed of a stacked semiconductor detector module surrounded by BGO (Bi4Ge3O12) scintillators. The BGO scintillators work as the active shields to reduce background events caused by cosmic-ray particles and radio-activation. The main detector of the HXI consists of 4 layers of silicon (Si) detectors and 1 layer of cadmium-telluride (CdTe) detector. Such a stacked structure enables high detection efficiency throughout a wide energy range. The flight model of HXI have already been fabricated, and installed into the satellite. Thus, it is time for selection and prioritization of the targets, which will be observed a few months after the launch. In order to accurately evaluate feasibility of the observations, it is necessary to estimate effective area, in-orbit background rates and detection sensitivity based on the performance of the real detectors. Therefore, we have developed an accurate response function, which relates an output signal of the detector to an input signal from astrophysical objects. To construct the response function for HXI, Monte Carlo simulations based on Geant4 are adopted because Compton scattering and secondary X-ray emissions have non-negligible effects on the detector response in the hard X-ray band. Our simulator implements almost all passive materials as well as the semiconductor detectors and the active shields. In addition, the simulator treats charge transportation in the detector devices and readout noise. By utilizing this simulator, we have successfully reproduced the experimental data. Here, we will present a detail of our Monte Carlo simulator and discuss expected performance of the HXI.

Speaker: Kouichi Hagino (ISAS/JAXA)

16:40 Development and Verification of the Response Function for the BGO Active Shields onboard ASTRO-H

The Hard X-ray Imager (HXI) and the Soft Gamma-ray Detector (SGD), onboard instruments of Japanese 6th X-ray observatory, ASTRO-H, are surrounded by the large number of BGO (Bi$_4$Ge$_3$O$_{12}$) scintillators for active shielding. These active shields are very important to reduce the non X-ray background such as cosmic rays and/or gamma-rays from radioisotopes produced by activation of the detector materials themselves so that we can achieve much higher sensitivity in the hard X-ray and soft gamma-ray band. In addition to the active shielding as the primary purpose, we can utilize the shield detectors of SGD as the all-sky monitor with very large effective area for the transient phenomena such as gamma-ray bursts and soft gamma-ray repeaters. In this year, we have finished to fabricate the flight model of HXI and SGD and we have performed the pre-flight calibrations, and now, we are in the stage to develop and verify the gamma-ray response function of the detectors. The gamma-ray response of BGO active shields is very complicated because they consist of various types of shape of large BGO crystals and incident gamma-rays would suffer multiple scattering in the detector, and also resulting yield of scintillation lights changes depending on the incident position of the gamma-rays. To reproduce such complicate gamma-ray response, we developed Geant4-based Monte-Carlo simulator including geometries of individual detector components. For the BGO active shields, we implement measured energy resolution and energy threshold to reproduce the energy spectra and anti-coincidence triggers for the main detector. We also apply the simple empirical model to calculate the variation of the light yield depending on the incident position of gamma-rays. We confirmed that our developed gamma-ray response successfully reproduce the measurement within roughly 10% accuracy at this moment. In this contribution, we present a detail of our Monte-Calro simulator and performance of the BGO detectors of HXI and SGD as both active shield and all-sky monitor.

Speaker: Dr Masanori Ohno (Hiroshima University)

Slides 20150827_G4Workshop_BGOsimulation_v1.pdf

17:05 The localizing algorithm of gamma-ray bursts and evaluation of systematic error in Suzaku Wide-band All-sky Monitor using Geant4

The Wide-band All-sky Monitor (WAM) on board the X-ray astronomical satellite Suzaku consists of four sides of BGO scintillation counters within the Hard X-ray Detector. Thanks to large effective area (800 cm2 at 100 keV) and field of view of ∼ 2π st, the WAM has detected transient objects, such as Gamma-Ray Bursts (GRBs) and Solar flares, approximately 300 event per year. However, the WAM itself can not determine the position of incident photons since the WAM is a non-imaging detector. The energy response of the WAM has strong dependency on the incident angle (Terada IEEE ’07) and thus the position is required for the spectral analyses. Currently, all spectral results with WAM are obtained only by flaring events whose positions are measured by other missions. Actually, we have perfomed spectral analysis of only 10% of all detected GRBs by the WAM, which observed simultaneously with other satellite. In order to estimate locations of rest GRBs only with WAM, we performed Monte-Calro simulation using Suzaku mass model reproduced entire satellite besed on Geant4 toolkit and found out counts of the WAM in detail for each incident angle. And, we developed the method of estimating location by the WAM four sides independently. We verified our method using 32 GRBs whose locations are revealed by other satellites and found that an average of difference of azimuthal angles is approximately 7◦, except for direction of refrigerant tank which has large amount of material. Moreover, we also estimated the systematic errors in the response matrix we derived by this method using the same datasets. When spectrum fitted by Band function that model reproduce GRB spctra well, estimated systematic error of alpha, beta, Epeak, and flux are 25%, 3%, 18%, and 29% respectively. Our results show a probability that spectral analysis of new 1800 events is available.

Speaker: Takeshi Fujinuma (Saitama University)

Friday 28 August

09:00 → 10:40 Space missions - instruments and detectors (2)

Convener: Prof. Robert Reed (Vanderbilt University)

09:00 A study of gamma-ray production from neutron capture on gadolinium

Speaker: Dr Takatomi Yano (Kobe Univ.)

Slides G4SpaceUserWorkshop_yano_ver2.pdf

09:25 ESA Space Radiation Instrument Developments

In this presentation an outline of ESA radiation monitoring instrumentation developments is given, with emphasis on the Geant4 analysis performed in support of the instrument design phase on one hand and on the data analyses efforts on the other hand. Typically, extensive effort is spent on optimising the instrument characteristics with Geant4 and releted radiation engineering tools, while in-flight data analysis and conversion from count rates to fluxes requires the use of accurate response functions, also derived by Monte Carlo methods. Examples given here include the Standard Radiation Environment Monitor (SREM), the Next Generation Radiation Monitor (NGRM), Rad-hard Electron Monitor for the JUICE mission (RADEM), Highly Miniaturised Radiation Monitor (HMRM), Energetic Particle Telescope (EPT), Space Application of TimePix Radiation Monitor (SATRAM), and the 3D Energetic Electron Spectrometer (3DEES). Some typical issues encountered and techniques used to solve these will be described.

Speaker: Dr Petteri Nieminen (ESA)

09:50 Geant4 and the Next Generation of Space-Borne Cosmic Ray Experiments

Speaker: Dr Mohammad Sabra (NASA/MSFC)

Slides Geant4SUW2015.ppt

10:15 CIRSOS - Collaborative Iterative Radiation Shielding Optymisation System

The CIRSOS system is an ESA funded R&D project aimed to develop a full radiation simulation framework in order to help S/C and P/L engineers through a SW system that: - Efficiently supports collaborative and iterative radiation analyses - Provides interfaces with industrial radiation design tools - Allows end-to-end radiation simulation, starting from the definition of the high energy particle environment, performing particle propagation through complex 3D geometrical models (via Geant4) and ending with deep dielectric charging effects modelling (via SPIS) Some of the most relevant advantages of CIRSOS for the radiation community include: - A user-friendly GUI to manage the entire system - A database controlled geometry managing - Material properties built-in databases - High-energy radiation and charging simulation capabilities (independent or coupled) - Parametric Geant4 analyses - Interface to SPENVIS and OMERE environment tools - Interface to FASTRAD and ESABASE2 modelling tools - Parallel simulation on multiple host / multiple processor - Built-in post-processing tools - Built-in geometry visualization tools

Speaker: Mr Sergio Ibarmia (INTA)

Slides ibarmia_CIRSOS_G4SUW2015.pptx

10:40 → 11:10 break

11:10 → 12:30 Radiation effects & single event effects

Convener: Mr Sergio Ibarmia (INTA)

11:10 Geant4 Simulations of Space Radiation Sensors at The Aerospace Corporation

Geant4 is a vital tool for understanding and calibrating the response of space-borne radiation sensors at The Aerospace Corporation. In the year since the last Geant4 Space Users' Workshop, we have focused on using the code to continue improving our understanding of the response, both foreground and background, of sensors aboard the Van Allen Probes and the Lunar Reconnaissance Orbiter (LRO). On the Van Allen Probes, we have tuned our model of the Relativistic Proton Spectrometer (RPS) to reproduce the observed response as closely as possible, in order to design and quantify cuts to reject contamination in the sensor’s very difficult primary measurement of penetrating energetic protons (60 MeV and up). We have also discovered a signal that is consistent with extremely energetic electrons (around 100 MeV) in the Earth’s magnetosphere, possibly from the decay of pions and muons resulting from cosmic-ray interactions with the Earth’s atmosphere, and are investigating. Also aboard the Van Allen Probes, we have completed modeling of the response of the three electron sensor heads of the Magnetic Electron Ion Spectrometers (MagEIS), and are using these to improve calibration of our measurements in the presence of penetrating and scattered background. Aboard LRO, we have continued to improve our model of background response of the Cosmic Ray Telescope for the Effects of Radiation (CRaTER), and have begun investigating the effects of varying amounts of water in the shallow lunar regolith on its observations of “albedo” protons produced at the moon by cosmic-ray interactions. We have also modeled the responses of single-element microdosimeters installed in a variety of spacecraft.

Speaker: Dr Mark Looper (The Aerospace Corporation)

Slides looper_aerospace_geant4.pptx

11:35 Evaluation and Application of U.S. Medical Proton Facilities for Single Event Effects Test

The sudden closure of the Indiana University Cyclotron Facility (IUCF) has forced the space community to evaluate alternate medical proton cancer therapy center cyclotrons for single event effects (SEE) test in the 200 MeV regime. These new facilities offer increased reliability well adapted to medical needs, but create scheduling and technical challenges for those adapted to IUCF. A team of regular users is investigating these proton facilities for SEE and is currently performing initial tests to prove results. IUCF has been the primary source of 200 MeV regime protons for the space community since the early 1990s. The facility had supplied approximately 2000 annual hours of beam time prior to its closure in October 2014. The closure has resulted in a critical shortage of high energy proton test capability in the United States. To fill this gap, the authors have undertaken an evaluation of proton cancer treatment centers for their ability to provide proton beams suitable for SEE testing. The goal is to establish test capabilities to replace IUCF for the entire proton test capability. The complete paper will list all promising facilities and their critical attributes, discuss the unique differences between modern medical beams and those that had been typically used in proton SEE testing, and will report on preliminary test results from a typical medical proton facility. A simple, single replacement is not possible; therefore, short and long-term possibilities will be discussed. The fiscal climates related to developing a single IUCF-like facility are unlikely to happen, although it cannot be ruled out. With this is mind, the short term approach focuses on how to use a group of proton therapy facilities as an IUCF replacement.

Speaker: Prof. Robert Reed (Vanderbilt University)

Slides Proton_Facility.pdf

12:00 Simulation of medical proton accelerator

Speaker: Joseph Perl (SLAC)

Slides TOPAS_Hiroshima_20150828d_to_share.pdf

12:30 → 14:00 lunch break

14:00 → 15:40 Microdosimetry

Convener: Joseph Perl (SLAC)

14:00 Geant4-DNS use-cases

Speaker: Dr Sebastien Incerti (CNRS)

Slides SIncerti-G4SUW_-_G4DNA.pdf

14:25 Geant4 Monte Carlo simulation of absorbed dose and radiolysis yields enhancement from a gold nanoparticle under MeV proton irradiation

Gold nanoparticles have been reported as possible radio-sensitizer agents in tumor radiation therapy, in particular through the increase of local energy deposition in close vicinity of the nanoparticles and subsequent direct damage to cells and DNA. Moreover, indirect damage originating from the increased production of chemical species induced by such additional energy deposition events around nanoparticles could also significantly contribute to cellular damage. In this work, we present for the first time a Monte Carlo simulation calculating energy deposition and radical species production around a gold nanoparticle of 50 nm-diameter, using the general purpose Geant4 simulation toolkit. The simulations are performed for incident proton energies ranging from 2 MeV to 170 MeV, which are of interest for clinical proton therapy. The Geant4-DNA extension was adopted in this study to model both the very low energy physics processes, the physico-chemistry and chemistry processes. This work clearly shows that the concentration of chemical species (such as e-aq, H2, H•, •OH, H3O+, OH-, H2O2) in liquid water is significantly increased around a gold nanoparticle immersed in liquid water and irradiated by incident MeV protons.

Speaker: Ngoc Hoang Tran (Division of Nuclear Physics, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City, Vietnam.)

14:50 Toward construction of a neutron diffractometer for protein crystal with large unit cell at J-PARC ~ trial for improving data accuracy ~

Speaker: Dr Katsuaki Tomoyori (Japan Atomic Energy Agency)

Slides Geant42015-tomoyori.pdf

15:15 GPU Acceleration of Physics Models in Geant4-DNA

The Geant4-DNA extension enables quantitative estimation of biological effects by radiation. Its physics processes generate large amount of low energy secondary particles (~ a few eV). The simulation needs enormous computing time for tracking down to very low energy. This work presents the implementation of the physics modes of Geant4-DNA in GPU architecture. We have observed significant performance gain with the same accuracy as Geant4-DNA simulation.

Speaker: Shogo OKADA (KEK)

Slides G4CU-DNA_G4SpaceUserWorkshop_20150828.pdf

15:40 → 16:00 break

16:00 → 17:00 Radiation environments and shielding / workshop closing

Convener: Mr Petteri Nieminen (ESA)

16:00 Open discussion / requirements to Geant4

16:30 Closing remarks