Adding AIDA to Geant4

This document is intended to become a proposal to the Geant4 architecture board, after discussion by the AIDA developers.

Introduction

AIDA is a set of abstract classes which allow analysis code to be written independent of any particular analysis tool. A particular AIDA compliant analysis tool can be selected at link time with no changes to analysis code.

Currently AIDA is used by a number of examples and tutorials in the Geant4 distribution, but there are a number of problems:

1. The example are not consistent in their use of AIDA.
2. The same code needs to be repeated in each analysis module.

This proposal aims to address these problems, and at the same time make it easier to use AIDA with Geant4.

Goals

The goals of this proposal are to:

1. Update the examples and tutorials to use AIDA consistently.
2. Add a simple set of interactive commands for interactively viewing histograms and n-tuples, and for storing histograms and n-tuples to disk.
3. Document clearly how to use various AIDA compliant tools with Geant4.
4. Introduce no new external dependences on Geant4
5. Make it possible for geant4 kernel code to contain diagnostic histograms, which would be turned off by default but which could be activated on demand (optional).

These goals can be achieved without forcing users to use AIDA, it will be just as easy to use any other analysis tool as it is now.

Implementation

In order to achieve these goals we propose the following:

• Add the AIDA header files to the Geant4 analysis section
• Add two new public classes to the analysis section
  • AIDAAnalysisManager - Can be used directly or extended by the user. Will replace a large amount of duplicate code in the examples, and provide a consistent example of how to use AIDA with Geant4.
  • AIDACommandManager -  A Geant4 command interpreter to allow a simple set of AIDA commands to be used from the Geant4 command prompt.
• Add a default dummy implementation of AIDA. This is a very short implementation of the AIDA interfaces used by default if no real AIDA implementation is provided. This will allow Geant4 to be compiled, linked and run with no real AIDA implementation present.

AIDA Commands

The following minimal set of AIDA commands should be implemented initially. More commands could be added later.

AIDAAnalysisManager