That would be correct, the integrator is part of the uv measurement system, the photocell on my olec is in the lamp head. The one you bought isn't missing the photocell necessarily if it was sold as part of a package with an al53 or al83 or something. Looking at an outdated price sheet from douthitt, a photocell will run you about $300. You got a really nice integrator that you likely won't find with a lamp, usually it's the 131, 121 or 111, so you didn't waste $25, though you should consider matching it up to what it was made to work with.
