PIXELAV

PIXELAV
Name	PIXELAV
Developer	Lawrence Berkeley National Laboratory, Berkeley Lab
Released	2008
Latest release version	2.7
Programming language	C++, Fortran, Python
Operating system	Linux, macOS, Windows
License	proprietary / open-source hybrid

PIXELAV PIXELAV is a specialized simulation framework developed for detailed modeling of semiconductor pixel detectors used in high-energy physics and astrophysics. It integrates physical models and numerical methods to replicate charge transport, electric fields, radiation damage, and readout electronics behaviors observed in experiments such as those at CERN, SLAC National Accelerator Laboratory, and Fermilab. The project connects collaboration networks across institutions like Lawrence Berkeley National Laboratory, Brookhaven National Laboratory, University of California, Berkeley, Oxford University, and DESY.

Overview

PIXELAV provides a modular toolkit for simulating pixelated sensor systems deployed in experiments including Large Hadron Collider, ATLAS experiment, CMS experiment, ALICE experiment, and space missions such as Fermi Gamma-ray Space Telescope. The software couples solid-state physics models relevant to Silicon, Germanium, and compound semiconductors with device-scale geometries employed by collaborations like LUX-ZEPLIN, Hyper-Kamiokande, and IceCube Neutrino Observatory. PIXELAV's scope overlaps with detector simulation frameworks such as Geant4 and readout-focused projects like ROCm and ROOT while emphasizing microphysics and signal formation for pixel architectures used by HL-LHC, Belle II, and ILC communities.

Design and Architecture

The architecture separates front-end components: geometry description, electric-field solver, charge-transport engine, radiation-damage module, and readout emulation. Geometry is specified with constructs analogous to GDML-driven descriptions used by ATLAS Inner Detector and CMS Tracker, enabling interoperable layouts for hybrids, bump-bonded sensors, and monolithic active pixel sensors (MAPS) employed by ALICE ITS. Field solutions draw upon methods used in device simulators by Synopsys and concepts from TCAD while maintaining interoperability with experiment software stacks like Gaudi and CMSSW. The codebase uses parallelization strategies familiar to projects at Argonne National Laboratory and Oak Ridge National Laboratory, leveraging libraries adopted by LHCb and NOvA.

Simulation and Modeling Capabilities

PIXELAV models carrier generation from ionizing tracks based on physics implemented in Geant4 routines and experimental parametrizations used by CLEO and BaBar. Carrier drift, diffusion, trapping, and detrapping are implemented with mobility models validated against measurements from groups at CERN Micro-Strip Sensors Group and University of Manchester. Radiation damage is handled via defect-level models inspired by studies at Institute for Microelectronics Barcelona and Julich Research Centre, reproducing effects reported by CMS Tracker Upgrade and ATLAS IBL teams. The readout chain emulates preamplifier response, shaping, time-walk, and threshold dispersion comparable to modules from Medipix and Timepix families used in CERN instrumentation.

Performance and Validation

Validation campaigns compare PIXELAV outputs with test-beam data from facilities such as CERN SPS, DESY Test Beam Facility, and Fermilab Test Beam Facility, and with laboratory measurements by groups at University of Geneva and University of Bonn. Performance metrics include cluster size, charge-sharing distributions, timing resolution, and hit-efficiency figures analogous to those reported by ATLAS Pixel Detector and CMS Pixel Detector performance papers. Computational performance leverages strategies from Intel and NVIDIA GPU-accelerated workflows used in CMS and ATLAS reconstruction, providing scalable runtimes for array sizes similar to those in HL-LHC pixel upgrades.

Applications and Use Cases

PIXELAV supports detector design optimization for projects like ATLAS IBL, CMS Phase-2 Tracker, and X-ray Astronomy instruments; sensor prototyping for Muon g-2 and NA62; and radiation-hardness studies for ESA and NASA missions. It has been used to predict charge-collection efficiency for 3D silicon sensors and to assess timing performance for low-gain avalanche detectors (LGAD) employed by CMS MIP Timing Detector. The framework assists electronics groups in designing front-end ASICs similar to ROC chips, and it informs integration teams coordinating with facilities such as CERN Integration Facility and KEK.

Development History and Contributors

PIXELAV originated from collaborative efforts at Lawrence Berkeley National Laboratory in the mid-2000s, drawing on expertise from instrumentation groups at University of California, Berkeley, University of California, Santa Cruz, and SLAC. Contributors include researchers affiliated with ATLAS, CMS, LHCb, Belle II, and national laboratories including Brookhaven National Laboratory and Fermilab. Development evolved alongside parallel projects like Allpix Squared and KDetSim, incorporating methods validated by test-beam consortia such as those organized by CERN RD50 and RD53.

Licensing and Availability

PIXELAV is distributed under a hybrid model: core modules are available to collaborating institutions under permissive terms used by collaborations like ATLAS and CMS, while specialized components may be subject to institutional licenses maintained by Lawrence Berkeley National Laboratory and partner labs such as Brookhaven National Laboratory. Source access, binaries, and documentation are provided to experimental collaborations and accredited research groups, following distribution practices similar to ROOT and Geant4 while respecting export-control and institutional IP policies implemented at U.S. Department of Energy labs.

Category:Simulation software