If you have an @anl.gov address, simply visit https://cels-anl.slack.com/signup and sign up using that address. You’ll automatically be added. This does not use your Argonne credentials. You will be sent a confirmation email to your Argonne address, after which you will set up a separate password for Slack.
If you don’t have an @anl.gov address, but you do have an Argonne account, see this document.
If neither of the above hold true, send a message to [email protected] and request an invitation. Let us know who you’re working with and we’ll get you added.
If you’re already on slack and want to invite someone, you can do that by typing /invite_people <email-address> and you’ll have the opportunity to invite them to any channels you’re a part of.
You can use Slack in the browser, or you can download the app for Windows, Mac, iOS, or Android. See https://slack.com/downloads for details. If your have “Self Service” installed on your Mac, you can get the app from that.