Please see the following link for more information;

On-Site

https://www.diamond.ac.uk/Users/Experiment-at-Diamond/IT-User-Guide/At-DLS/Access-data.html

Off-Site

https://www.diamond.ac.uk/Users/Experiment-at-Diamond/IT-User-Guide/Not-at-DLS/Retrieve-data.html

Within 40 days of session

Use Globus online

https://www.diamond.ac.uk/Users/Experiment-at-Diamond/IT-User-Guide/Not-at-DLS/Retrieve-data/in40days/Globus.html 

After 40 days of session

Use TopCAT/icat (https://icat.diamond.ac.uk/#/login)

https://icat.diamond.ac.uk/#/help

NB. The root directory for your visit is named "topdir"