Appendix 16. LAN PHA Documentation

 

Document Reference: John P. Townsend Jr., Feb. 1, 1991

 

A16.1 Introduction

 

This document describes the processing for the Pulse Height Analysis (PHA) portion of the Ulysses LAN experiment. The intended audience are the programmers and scientists charged with the operation, maintenance, and validation of the LAN PHA production processing. The reader is assumed to be familiar with the LAN experiment, including the major instrument components, the measuring techniques, and the LAN archive file contents and structure.

 

There are two separate components of the LAN experiment which are grouped in this document under the single generic rubric of PHA. The Composition Aperture (CA) system provides ion composition data using DE vs. E measuring techniques. The data set acquired by the CA system is referred to as the PHA event history. The Low Energy Magnetic/Foil Spectrometer (LEMS/LEFS) systems provide detailed energy spectra of measured electron and ion fluxes. The data subset acquired by the LEMS/LEFS systems for use in the PHA processing is referred to as the M and F Spectrum Accumulator (MFSA). These data sets are assembled into the LAN archive file and collectively drive the PHA processing.

 

The 3 main objectives of the LAN PHA process are:

 

1. Derive counting rates for individual ion species and energy bins for a specified time average interval. Rates are derived using both the PHA event history and the LAN archive WART count rates. The PHA event history provides the composition and energy information, and the WART count rates provide the actual ion population count rates. The rates are sectored for hydrogen, helium 3, and helium 4. All other species rates are unsectored. This output product is referred to as the track data set.

 

2. Obtain a matrix of averaged, normalized count rates for the entire 256 x 256 pixel PHA space for a specified time average interval. Normalized rates are obtained using the PHA event history and the LAN archive WART count rates. This output product is called the pulse data set.

 

3. Obtain averaged, sectored, normalized count rates for each of the four MFSA detectors (F', F, M', M) using the LAN archive MFSA 32 channel spectra and the MFSA count rates for a specified time average interval. This output product is referred to as the LAN MFSA data set.

 

The objectives of the LAN PHA process are accomplished through the LAN PHA system (see Figure A16-1 below). The system has two stages: the generation stage and the analysis stage. The generation stage consists of the program PHAGEN which produces the three output files of the PHA process from the LAN archive data. The analysis stage consists of multiple plots and pseudocolor displays of the three output files. The PHA system is suited to the similar yet distinct tasks of event identification within a large data set and event analysis concentrating on specific times. As such, the PHA system is designed to work in both rigid production environments and individual user environments. With regard to user environments, it is envisioned new products may be developed and possibly added to the LAN production with the consent of the team. The LAN PHA process is designed to be flexible and robust. Flexibility is obtained through user selectable run time options controlling the behavior of the process. By separation of the various component tasks and subprocesses, and the use of structured programming techniques, the PHA process aspires to be robust.

 

Figure A16-1 LAN PHA system design

 

 

The PHA system was developed in the VAX/VMS environment. However, the system is required to be portable among the LAN team member institutions using VAX/UNIX. Events at the production institution (UCBerkeley) have required the system to be ported to the SUN/UNIX environment as well. The recent FORTRAN 77 extensions in the SUN environment have reduced the porting concerns between VAX and SUN to four categories:

 

1. Binary files are incompatible between machine architectures. This requires a conversion of any data (input or output) which was produced on a different machine architecture than the host system.

2. Installation specific graphics. VAX with XWindows. Sun uses SunXWindows.

3. Installation specific I/O routines. Disk and tape I/O must be customized for each installation and conform with a standard interface.

4. Operating system dependencies.

 

• A16.2 Inputs
• A16.3 Outputs
• A16.4 Processing
• A16.5 Displays and Plots
• A16.6 Track Files - A Major Revision
• A16.7 PHAGEN Software (obsolete, removed from this site)