The EGS4 Code System

Abstract

In the seven years since EGS3 was released it has been used in a wide variety of applications. As users have pushed it to new extremes, a broad range of improvements and corrections have been made. Perhaps the greatest strength of the EGS system is a structure which allows users to develop extensions and/or implement improvements made by others. With the release of EGS4 we have undertaken to re-establish a well-defined version of the system so that we can all benefit from each other's efforts. This report consists of five chapters and seven appendices. Chapter 1 is an introduction to EGS34 and to this report in general. Chapter 2 is an update of a similar chapter in the old EGS3 report (SLAC-210), where all the gory details of the physics are gathered together. Detailed knowledge of the contents of Chapter 2 is not essential in order to use EGS, but a sophisticated user should be aware of its contents. In particular, details of the restrictions on the range of applicability of EGS are dispersed throughout the chapter. The first-time user of EGS should skip Chapter 2 and come back to it later if necessary. With the release of the EGS4 version, we have made a deliberate attempt to present more examples in order to help the user ‘get started”. These are given as a series of tutorial User Codes in Chapter 3, which lead into several more sophisticated User Codes in Chapter 4. The first-time EGS user should glance through the “official” EGS4 User Manual provided in Appendix 2, and then proceed to work through the tutorials in Chapter 3. Chapter 5 presents a summary of the changes that were made in going from EGS3 to EGS4. As such it provides a nice record for the authors. However, it may prove useful to EGS3 users who want to know if the changes might affect their previous understanding of a particular simulation. Appendix 1 presents a detailed set of flow diagrams for the EGS4 code, photocopies of which can be joined together to make each subroutine complete. They have proven very useful to us during the changeover from EGS3 to EGS4. Appendices 2 and 3 are detailed User Manuals for EGS4 and PEGS4, respectively. They should be the most heavily used parts of this report and, therefore, have also been placed on the EGS4 distribution tape. Great effort was made to create these manuals such that they can be printed out on virtually any printer (there are 60 lines per page and a ‘1 eject nnnn’ at the top of each to facilitate page ejection). Admittedly the print is small in the appendices, but the user can print better copies of the manuals if so desired. Appendix 4 is a guide to Mortran3 for EGS4 users. We strongly urge any serious user of EGS to make the investment in learning to use Mortran3-it will not only save you time in the long run, but there are classes of problems that really require that you use Mortran3 macros. To facilitate use of Mortran3, we have included Appendix 5 which gives an overview plus all the details needed to run the entire Mortran3, PEGS4, and EGS4 package. Appendix 6 describes the contents of the EGS4 distribution tape. Lastly, Appendix 7 is the annotated bibliography mentioned above.