Data collected during an experiment on an ISIS instrument is saved to disk as an "ISIS raw data file"
The exact format the data is stored in will depend on the year the data was collected and whether the experiment was performed on a neutron or muon instrument.
The data will be in one of two possible formats:
1. Original ISIS RAW format. This is a locally created binary based format and files in this format will have the extension ".raw". Analysis programs such as Open GENIE or Mantid can be used to read the files.
2. NeXus based data file. The data is stored using the NeXus Data Format with its underlying HDF5 representation. The file contents can be viewed using generic HDF5 utilities such as HDFView or analysis programs such as Open GENIE or Mantid
The data will have been stored using the NeXus format - details of the file layout and how to read them into programs can be found on the Muons web pages