1,280 research outputs found
Refactoring, reengineering and evolution: paths to Geant4 uncertainty quantification and performance improvement
Ongoing investigations for the improvement of Geant4 accuracy and
computational performance resulting by refactoring and reengineering parts of
the code are discussed. Issues in refactoring that are specific to the domain
of physics simulation are identified and their impact is elucidated.
Preliminary quantitative results are reported.Comment: To be published in the Proc. CHEP (Computing in High Energy Physics)
201
Quantifying the unknown: issues in simulation validation and their experimental impact
The assessment of the reliability of Monte Carlo simulations is discussed,
with emphasis on uncertainty quantification and the related impact on
experimental results. Methods and techniques to account for epistemic
uncertainties, i.e. for intrinsic knowledge gaps in physics modeling, are
discussed with the support of applications to concrete experimental scenarios.
Ongoing projects regarding the investigation of epistemic uncertainties in the
Geant4 simulation toolkit are reported.Comment: To be published in the Proceedings of the 13th ICATPP Conference on
Astroparticle, Particle, Space Physics and Detectors for Physics
Applications, Villa Olmo, Como, 3-7 October 201
Research in Geant4 electromagnetic physics design, and its effects on computational performance and quality assurance
The Geant4 toolkit offers a rich variety of electromagnetic physics models;
so far the evaluation of this Geant4 domain has been mostly focused on its
physics functionality, while the features of its design and their impact on
simulation accuracy, computational performance and facilities for verification
and validation have not been the object of comparable attention yet, despite
the critical role they play in many experimental applications. A new project is
in progress to study the application of new design concepts and software
techniques in Geant4 electromagnetic physics, and to evaluate how they can
improve on the current simulation capabilities. The application of a
policy-based class design is investigated as a means to achieve the objective
of granular decomposition of processes; this design technique offers various
advantages in terms of flexibility of configuration and computational
performance. The current Geant4 physics models have been re-implemented
according to the new design as a pilot project. The main features of the new
design and first results of performance improvement and testing simplification
are presented; they are relevant to many Geant4 applications, where
computational speed and the containment of resources invested in simulation
production and quality assurance play a critical role.Comment: 4 pages, 4 figures and images, to appear in proceedings of the
Nuclear Science Symposium and Medical Imaging Conference 2009, Orland
Early results in the treatment of proximal humeral fractures with a polyaxial locking plate
Objectives: We report early results using a second generation locking plate, non-contact bridging plate (NCB PH®, Zimmer Inc. Warsaw, IN, USA), for the treatment of proximal humeral fractures. The NCB PH® combines conventional plating technique with polyaxial screw placement and angular stability. Design: Prospective case series. Setting: A single level-1 trauma center. Patients: A total of 50 patients with proximal humeral fractures were treated from May 2004 to December 2005. Intervention: Surgery was performed in open technique in all cases. Main outcome measures: Implant-related complications, clinical parameters (duration of surgery, range of motion, Constant-Murley Score, subjective patient satisfaction, complications) and radiographic evaluation [union, implant loosening, implant-related complications and avascular necrosis (AVN) of the humeral head] at 6, 12 and 24weeks. Results: All fractures available to follow-up (48 of 50) went to union within the follow-up period of 6months. One patient was lost to follow-up, one patient died of a cause unrelated to the trauma, four patients developed AVN with cutout, one patient had implant loosening, three patients experienced cutout and one patient had an axillary nerve lesion (onset unknown). The average age- and gender-related Constant Score (n=35) was 76. Conclusions: The NCB PH® combines conventional plating technique with polyaxial screw placement and angular stability. Although the complication rate was 19%, with a reoperation rate of 12%, the early results show that the NCB PH® is a safe implant for the treatment of proximal humeral fracture
Geant4-related R&D for new particle transport methods
A R&D project has been launched in 2009 to address fundamental methods in
radiation transport simulation and revisit Geant4 kernel design to cope with
new experimental requirements. The project focuses on simulation at different
scales in the same experimental environment: this set of problems requires new
methods across the current boundaries of condensed-random-walk and discrete
transport schemes. An exploration is also foreseen about exploiting and
extending already existing Geant4 features to apply Monte Carlo and
deterministic transport methods in the same simulation environment. An overview
of this new R&D associated with Geant4 is presented, together with the first
developments in progress.Comment: 4 pages, to appear in proceedings of the Nuclear Science Symposium
and Medical Imaging Conference 2009, Orland
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