HADRONIC SHOWER SIMULATION WORKSHOP
896(2007); http://dx.doi.org/10.1063/1.2720452View Description Hide Description
Geant4 is a toolkit for the simulation of the transport of radiation through matter. With a flexible kernel and choices between different physics modeling choices, it has been tailored to the requirements of a wide range of applications.
With the toolkit a user can describe a setup’s or detector’s geometry and materials, navigate inside it, simulate the physical interactions using a choice of physics engines, underlying physics cross‐sections and models, visualise and store results.
Physics models describing electromagnetic and hadronic interactions are provided, as are decays and processes for optical photons. Several models, with different precision and performance are available for many processes. The toolkit includes coherent physics model configurations, which are called physics lists. Users can choose an existing physics list or create their own, depending on their requirements and the application area. A clear structure and readable code, enable the user to investigate the origin of physics results.
Application areas include detector simulation and background simulation in High Energy Physics experiments, simulation of accelerator setups, studies in medical imaging and treatment, and the study of the effects of solar radiation on spacecraft instruments.
896(2007); http://dx.doi.org/10.1063/1.2720453View Description Hide Description
Four of the most‐used Geant4 hadronic models, the Quark‐gluon string, Bertini‐style cascade, Binary cascade and Chiral Invariant Phase Space, are discussed. These models cover high, medium and low energies, respectively, and represent a more theoretical approach to simulating hadronic interactions than do the Low Energy and High Energy Parameterized models. The four models together do not yet cover all particles for all energies, so the Low Energy and High Energy Parameterized models, among others, are used to fill the gaps.
The validity range in energy and particle type of each model is presented, as is a discussion of the models’ distinguishing features. The main modeling stages are also described qualitatively and areas for improvement are pointed out for each model.
896(2007); http://dx.doi.org/10.1063/1.2720454View Description Hide Description
Geant4 is a software toolkit for the simulation of the passage of particles through matter. It has abundant hadronic models from thermal neutron interactions to ultra relativistic hadrons. An overview of validations in Geant4 hadronic physics is presented based on thin‐target measurements. In most cases, good agreement is available between Monte Carlo prediction and experimental data; however, several problems have been detected which require some improvement in the models.
896(2007); http://dx.doi.org/10.1063/1.2720456View Description Hide Description
MARS 15 is a Monte Carlo code for inclusive and exclusive simulation of three‐dimensional hadronic and electromagnetic cascades, muon, heavy‐ion, and low‐energy neutron transport in accelerator, detector, spacecraft, and shielding components in the energy range from a fraction of an electron volt up to 100 TeV. Main features of the code are described in this paper with a focus on recent developments and benchmarking. Newest developments concern inclusive and exclusive nuclear event generators, extended particle list in both modes, heavy‐ion capability electromagnetic interactions, enhanced geometry, tracking, histograming and residual dose modules, improved graphical‐user interface, and other external interfaces.
896(2007); http://dx.doi.org/10.1063/1.2720458View Description Hide Description
The performance of the Monte Carlo code system PHITS is validated for heavy ion transport capabilities by performing simulations and comparing results against experimental data from heavy ion reactions of benchmark quality. These data are from measurements of secondary neutron production cross sections in reactions of Xe at 400 MeV/u with lithium and lead targets, measurements of neutrons outside of thick concrete and iron shields, and measurements of isotope yields produced in the fragmentation of a 140 MeV/u 48Ca beam on a beryllium target and on a tantalum target. A practical example that tests magnetic field capabilities is shown for a simulated 48Ca beam at 500 MeV/u striking a lithium target to produce the rare isotope 44Si, with ion transport through a fragmentation‐reaction magnetic pre‐separator. The results of this study show that PHITS performs reliably for the simulation of radiation fields that is necessary for designing safe, reliable and cost effective future high‐powered heavy‐ion accelerators in rare isotope beam facilities.
896(2007); http://dx.doi.org/10.1063/1.2720459View Description Hide Description
MCNPX (Monte Carlo N‐Particle eXtended) is a general‐purpose Monte Carlo radiation transport code with three‐dimensional geometry and continuous‐energy transport of 34 particles and light ions. It contains flexible source and tally options, interactive graphics, and support for both sequential and multi‐processing computer platforms. MCNPX is based on MCNP4c and has been upgraded to most MCNP5 capabilities. MCNP is a highly stable code tracking neutrons, photons and electrons, and using evaluated nuclear data libraries for low‐energy interaction probabilities. MCNPX has extended this base to a comprehensive set of particles and light ions, with heavy ion transport in development. Models have been included to calculate interaction probabilities when libraries are not available. Recent additions focus on the time evolution of residual nuclei decay, allowing calculation of transmutation and delayed particle emission. MCNPX is now a code of great dynamic range, and the excellent neutronics capabilities allow new opportunities to simulate devices of interest to experimental particle physics, particularly calorimetry. This paper describes the capabilities of the current MCNPX version 2.6.C, and also discusses ongoing code development.
896(2007); http://dx.doi.org/10.1063/1.2720460View Description Hide Description
We review the transport capabilities of the MCNP and MCNPX Monte Carlo codes in the energy regimes in which tabular transport data are available. Giving special attention to neutron tables, we emphasize the measures taken to improve the treatment of a variety of difficult aspects of the transport problem, including unresolved resonances, thermal issues, and the availability of suitable cross sections sets. We also briefly touch on the current situation in regard to photon, electron, and proton transport tables.
896(2007); http://dx.doi.org/10.1063/1.2720462View Description Hide Description
To evaluate the quality of general purpose particle interaction and transport codes widely used in the high‐energy physics community, express benchmarking is conducted. Seven tasks, important for high‐energy physics applications, are chosen. For this first shot, they are limited to particle production on thin and thick targets and energy deposition in targets and calorimetric setups. Five code groups were asked to perform calculations in the identical conditions and provide results to the authors of this report. Summary of the code inter‐comparison and verification against available experimental data is presented in this paper. Agreement is quite reasonable in many cases, but quite serious problems were revealed in the others.
896(2007); http://dx.doi.org/10.1063/1.2720463View Description Hide Description
The physics processes that are crucial for the description of hadronic shower development in calorimeters are π0 production, the release of protons in nuclear reactions and (in calorimeters with hydrogenous active material) elastic scattering of soft neutrons. In this paper, I discuss how we know that these elements are crucial, and I describe experimental data that are sensitive to a correct implementation of these elements in simulation codes. Therefore, these data should serve as benchmarks for (generic) validation of these codes. I also illustrate the practical importance of reliable shower simulations with some recent real‐life examples.
896(2007); http://dx.doi.org/10.1063/1.2720464View Description Hide Description
All too often we rely on Monte Carlo simulations without worrying too much about basic physics. It is possible to start with a very simple calorimeter (a big cylinder) and learn the functional form of π/e by an induction argument. Monte Carlo simulations provide sanity checks and constants. A power‐law functional form describes test beam results surprisingly well. The prediction that calorimeters respond differently to protons and pions of the same energy was unexpected. The effect was later demonstrated by the CMS forward calorimeter group, using the most noncompensating calorimeter ever built. Calorimeter resolution is dominated by fluctuations in π0 production and the energy deposit by neutrons. The DREAM collaboration has recently used a dual readout calorimeter to eliminate the first of these. Ultimate resolution depends on measuring neutrons on an event‐by‐event basis as well.
896(2007); http://dx.doi.org/10.1063/1.2720465View Description Hide Description
The aspects of hadron simulation affecting the calculation of unoscillated atmospheric neutrino fluxes is discussed. The method of simulating the atmospheric cascades is described. An evaluation of the errors on the atmospheric neutrino fluxes and various experimentally convenient ratios is presented. A new measurement of hadron production with the NA49 experiment at CERN is briefly reported.
896(2007); http://dx.doi.org/10.1063/1.2720466View Description Hide Description
One of the most promising approaches to determine the energy spectrum and composition of the cosmic rays with energies above 1015 eV is the measurement of the number of electrons and muons produced in extensive air showers (EAS). Therefore simulation of air showers using electromagnetic and hadronic interaction models are necessary. These simulations show uncertainties which come mainly from hadronic interaction models. One aim of this work is to specify the low energy hadronic interactions which are important for the muon production in EAS. Therefore we simulate extensive air showers with a modified version of the simulation package CORSIKA. In particular we investigate in detail the energy and the phase space regions of secondary particle production, which are most important for muon production. This phase space region is covered by fixed target experiments at CERN. In the second part of this work we present preliminary momentum spectra of secondary π+ and π− in p+C collisions at 12 GeV/c measured with the HARP spectrometer at the PS accelerator at CERN. In addition we use the new p+C NA49 data at 158 GeV/c to check the reliability of hadronic interaction models for muon production in EAS. Finally, possibilities to measure relevant quantities of hadron production in existing and planned accelerator experiments are discussed.
896(2007); http://dx.doi.org/10.1063/1.2720468View Description Hide Description
A brief description of recent progress in NEUGEN improvements is given. Comparison of various neutrino event generators based on a previous study is also made. Existing event generator models differ most strongly in the treatment of nuclear fsi, the focus of the paper.
896(2007); http://dx.doi.org/10.1063/1.2720469View Description Hide Description
The Main Injector Neutrino Oscillation search (MINOS) uses two detectors separated by 735 km to measure a beam of neutrinos created by the Neutrinos at the Main Injector (NuMI) facility at Fermi National Accelerator Laboratory. The experiment has recently reported an observation of νμ disappearance consistent with neutrino oscillations. We describe the manner in which the experiment’s results depend on the correct understanding and modeling of hadronic systems.
896(2007); http://dx.doi.org/10.1063/1.2720470View Description Hide Description
A comparison between the Geant4 Monte‐Carlo simulation of CMS Detector’s Calorimetric System and data from the 2004 Test‐Beam at CERN’s SPS H2 beam‐line is presented. The overall simulated response agrees quite well with the measured response. Slight differences in the longitudinal shower profiles between the MC predictions made with different Physics Lists are observed.