This older article about the test they did with ordinary protons, indicates the outer frame measures "2.00 meters in length, 0.87 meters in width, and 1.85 meters in height" and comes in under 1000kg https://ep-news.web.cern.ch/content/cerns-base-step-leap-for...
Nope, it's pretty compact. The first image in CERN's photo gallery shows it being loaded into that truck: https://cds.cern.ch/record/2957407?ln=en
Of course, it's compact because it only has to last so long. CERN's press release discusses needing a generator and a cryocooler in the truck for longer trips: https://home.cern/news/press-release/experiments/base-experi...
This older article about the test they did with ordinary protons, indicates the outer frame measures "2.00 meters in length, 0.87 meters in width, and 1.85 meters in height" and comes in under 1000kg https://ep-news.web.cern.ch/content/cerns-base-step-leap-for...
There's a photo towards the end which shows the equipment in the truck, it seems to be about the size of a mini fridge or a half rack.