PAW (Physics Analysis Workstation)

PAW (Physics Analysis Workstation)
Name	PAW (Physics Analysis Workstation)
Developer	CERN
Released	1986
Latest release	1990s
Programming language	FORTRAN, CERNLIB
Operating system	VAX/VMS, UNIX, Linux
Genre	Data analysis, Visualization
License	Proprietary/CERNLIB

PAW (Physics Analysis Workstation) is an interactive data analysis and visualization tool developed at CERN for high-energy physics experiments. It provided histogramming, curve fitting, and graphical presentation tightly integrated with the CERNLIB software collection, and was widely used at facilities such as DESY, SLAC, and Fermilab for analysis of detector data from collaborations like ALEPH, OPAL, and ATLAS. PAW influenced subsequent packages and workflows in particle physics computing at institutions including Brookhaven, LBNL, and KEK.

Overview

PAW combined interactive command-line control, scripted batch processing, and a graphics engine to manipulate multi-dimensional histograms, fits, and contours for experimental datasets from detectors such as UA1, UA2, and CMS. The environment relied on libraries from CERNLIB and made use of plotting devices standardized on X Window System terminals and printers used at European Organization for Nuclear Research sites. PAW was often deployed alongside data formats and services like ZEBRA and magnetic spectrometer outputs from experiments including WA2, LHCb, and T2K.

History and development

Development began in the mid-1980s under groups at CERN with contributions from physicists who had worked on earlier tools at SLAC and DESY. PAW evolved from needs identified during operation of experiments such as UA1 and LEP and was shaped by software strategies used in projects at Fermilab and Brookhaven during the development of detectors like CDF and D0. Maintenance and distribution were coordinated with the CERN Program Library releases and influenced by computing trends at ESA and academic centers like University of Oxford and University of Cambridge where analysis training took place. Over its lifecycle PAW adapted to platforms from VAX systems to early Linux clusters used in collaborations including ALICE and LHC prototype studies.

Architecture and features

PAW's architecture rested on a FORTRAN-based core linked into CERNLIB and using structured data management provided by systems such as ZEBRA and PAWNT session managers derived from work at CERN. Key features included multi-dimensional histogramming, fitting with minimization algorithms inspired by methods used at Brookhaven and SLAC, and a graphics macro language compatible with devices supported at DESY and KEK. Interactivity integrated with terminals running X Window System and print output for devices common at Fermilab and TRIUMF. PAW supported interfaces to data produced by experiments such as ALEPH, DELPHI, and L3, and incorporated numerical routines akin to those in libraries used at LLNL and LANL.

Usage and applications

Researchers at collaborations including ATLAS, CMS, ALICE, LHCb, CDF, and D0 used PAW for exploratory data analysis, quality assurance of detector runs, and production of publication plots presented at conferences such as ICHEP and EPSHEP. PAW was taught in computing schools run by CERN and used in analysis workflows at national labs like Brookhaven and universities such as UC Berkeley and Imperial College London. It was applied to calorimeter studies from experiments like NA49, tracking performance in setups from ZEUS, and Monte Carlo validation in generator comparisons involving software from GENIE and legacy packages used at SLAC.

Comparison with ROOT and successors

PAW preceded and contrasted with object-oriented successors such as ROOT developed at CERN and initiated by developers who had worked with PAW during LEP and LHC preparations. While PAW used procedural FORTRAN paradigms and relied on CERNLIB, ROOT adopted C++ and integrated I/O, histogramming, and graphics in an object model favored by groups at LBNL and Fermilab. Successors addressed scalability for large datasets from LHC experiments and incorporated modern software engineering practices from institutions like Microsoft Research collaborations with academic labs. Migration pathways involved conversion tools and training efforts coordinated by CERN and national laboratories such as KEK and DESY.

Legacy and influence

PAW's impact persists in analysis culture, pedagogy, and tool design within high-energy physics; its command paradigms and histogram conventions influenced standards adopted by ROOT and educational material used in summer schools at CERN and training programs at Fermilab and DESY. Many veterans from experiments like ALEPH, OPAL, ALEPH Experiment and infrastructure projects at CERN contributed to successor software, and institutions including Brookhaven and LBNL archived PAW macros and examples that continue to inform legacy data reprocessing for long-term preservation efforts coordinated among CERN, IN2P3, and national data centers. PAW's role in the transition from procedural libraries to object-oriented frameworks remains a notable chapter in computing histories at laboratories such as SLAC and KEK.

Category:Data analysis software