Impressions from MC2005 J. Apostolakis G. Folger

Talk overview The conference The radiation Transport tools ‘present’ Applications Themes and topical issues

Conference overview About 200 participants: providers, users,.. Organisation –Plenaries on MC tools –Parallel sessions on Methods & data advancements (electron/gamma, neutron, hadron) Verification & computer implementation Applications in particular areas –Reactor, medical including dosimetry,.. Wide diversity –Several session in parallel –This summary is a personal viewpoint And relies on notes, as talk presentations not yet available

Codes / Tools / Toolkit Several teams present: M CNP 5 M CNPX F LUKA G EANT 4 P HITS ‘Missing’ E GS (nrc/5) Penelope Tripoli MARS … Different ‘philosophies’ MCNP 5/X, FLUKA –Standard ‘tool’/code driven by input files –Built-in ‘tallies’ chosen by flags –‘Flat’ geometries Delineated by surfaces –Yet more physics options being made available Geant4 –Toolkit –Hierarchial geometry, …

MCNP5 Neutrons, , , protons,.. Long line of codes (60s to now) From Los Alamos National Laboratory –Team of 12 code developers & 4 on data –Funding from ASCI program Capability evolution Great emphasis on Quality Assurance –Revised implementation in F90 Profit from large supercomputer facility –Especially for validation Traditional strengths, include Neutron treatment using data –For E <~ 150 MeV Variance reduction techniques Latest improvements Push for proton radiography –Extend protons up to 50 GeV New intra-nuclear cascade as option –INCL4 (Liege) New data –ENDF/B-VII Built-in parallelization –MPI and OpenMP Generating weights fast –With PARTISN code

MCNPX Is eXtended version of MCNP4C –Transports 34 particle types up to TeV energies Uses –evaluated data libraries (p, n,  - nuclear) –Physics models where libraries are not available –Option for crossover at 20MeV, or as needed (some data up to 150MeV) Written in F90 Many options for radiation tallies, biasing –Weight window generator –Options for sources –Pulse-height (with variance reduction) & coincidence tallies Physics enhancements –CEM 2K and INCL4 (cascade), in addition to older Bertini, HETC, Fluka, Isabel models –  doppler broadening –  – nuclear models Awards for bug reports –‘certificate’ and $$ Support NAG/IBM/Intel f90 complr Parallel computation –For all particles (uses MPI) –High speedup for criticality calculations Future plans –Magnetic fields –Delayed neutrons & g –CAD input with spline tracking

7-Can HEU Test Problem Air HEU Aluminum ~5% Enriched

PHITS Simulate –hadron-neucleus with E up to 200 GeV –Nucleus-nucleus from 10 MeV/n to 100 GeV/nucleon –Transport heavy ions, hadrons & leptons Neutrons down to eV Features –JQMD for nucleus- nucleus using molecular dynamics –JAM hadronic cascade –Photons, electrons and low-energy neutrons as in MCNP4C. From RIST, Japan

FLUKA Tool known at CERN – so just a few remarks Compare to data for  -scopic data only ‘Not a toolkit’ –Physics models are fully integrated –Self-consistent: full cross-talk between EM, hadronics, neutrons (with effort for same level of accuracy) –Correlations preserved enabling predictivity –‘No programming is necessary’ Recent extensions for heavy ions Numerous comparisons & applications –Including CERF, TARC, ATLAS, Atmosphere, AMS, Borexino –Talks on E deposition in LHC magnets,, CERF comparisons

Geant4 One plenary and over 12 parallel talks Much interest –Applications –Methods Some concerns from users –Many choices available –Difficulty to get going without good guidance

A number of other tools –Deterministic tools treating neutrons

Summary - Codes Fewer codes represented –Missing MVP, MCP, MCBEND, TRIPOLI, EGS, ITS, VIM, TART, … More complex questions –Burn-up, activation Remove bridge between MC and depletion codes –Correlated sources and tallies –(Anti)coincidence of events across multiple regions –Moving geometry, stochastic geometry –2 & 3 D graphical output necessary

Selected topics

Summary - Geometry setup GUIs are becoming popular CAD is making progress –Tools to convert to solids start to appear –Still need to achieve arbitrary surface spline NURBS –Would like to see these tools become OpenSource

CAD input H. Tsige-Tamirat Forschungszentrum Karlsruhe Input from STEP/IGES files –Thinned with engineer’s help Tool to read CAD file, process & create MCNP input file –Uses open source CAD as toolkit for reading –Addresses overlaps and gaps (‘voids’) –Created in C++, using MVC Status –Working for realistic JET example Other efforts underway –Delegating navigation to CAD system (speed issues) –Tesselating BREP solids From *Summary talk* GUIs are becoming popular CAD is making progress –Tools to convert to solids start to appear –Still need to achieve arbitrary surface spline NURBS –Would like to see these tools become OpenSource

Human phantoms

Distributions centers Codes primarily available from –Radiation Safety Information Computational Center (RSICC) at Oak Ridge National Laboratory (ORNL). –OECD / NEA (European Nuclear Energy Agency) Nuclear Data Bank computer program services Conditions for distributions are evolving –Personal licenses (not site as in past)

Applications Significant interest in medical applications –Dedicated session on ‘Tomographic Models for Radiation Protection dosimetry’ Reactor applications –Several sessions –Emerging applications for Accelerator Driven Space applications Much interest in CAD-input

Other notable / novel Intercomparisons of ‘tools’ at times MCNP, Geant4, Fluka, data –For proton therapy applications –For accelerator driven applications Novel approach to MC –Using Field Programmable Gate Arrays for Ultra-high Speed Monte Carlo Computation –A.S.Pasciak, J.R.Ford.

Unusual applications Enhanced electron and photon fluxes in thunderstorms –T. Torii (JNDI), T. Sugita (SSL), T. Nishijima, Z.-I. Kawasaki (Osaka U) Japan

Uman, M.A. : The Lightning Discharge (Academic Press, 1987) Japanese Winter Thunderclouds Have Charged Areas in Low Altitude. Altitude & Distribution of Thundercloud Electric Charges

Simulation of the Generation of EM Shower by Muon Irradiation μ ＋ （２ GeV) Emission of massive knock-on electrons μ - （２ GeV) Elevation Angle: 30°, Number of Histories ： 5 E-Field ： Winter Thundercloud (Tri-pole) Deposition energy in the atmosphere is calculated by using Geant4 code. Muon beam thundercloud

Other topics from the Conference Summary Comments

Summary- Data/libraries More users produce their own data Need better QA of data Little evidence of effort on emerging needs –Delayed gamma, neutron –Improved secondary particle production including correlations Library repository, with graphics good idea –NADS: //nuclear/llnl.gov/CNP/nads

Summary – Physics & Methods New physics models continue to emerge –Users getting frustrated with too wide choices –Provide recommendations Methods improvements –Variance reduction with pulse-height tallies –Some tough issues remain Effort to speed up –Parallelism, some re-write code for this –Algorithm efficiency

Summary - Applications About 25% of talks Codes need to provide results & errors –Users need “convergence score card” –Normality checks, 2 nd moment of analysis, trends Users training more of an issue –Codes have options –Users unaware of “easy” solutions Application work should begin with related benchmark simulation –Eliminate time consuming mistakes

Summary - Benchmarks Not enough benchmark papers –Perhaps most important aspect of MC development Need way to gather results –Web site to post papers Mix “component” benchmarks with integral –Integral result can mask offsetting errors/deficiencies ( e.g. Geant4) Develop quantitative metric for comparisons –Standard toolkit good start, some concern as well