Some people just overreact to events. I take a stroll through Dr. Mason's lab - no touching, no attempts to conjure up the dead, or transmogrify some innocent civilian, or anything like that - and he's upset. Upset enough to install a deadly apparatus to keep people out. Hey, Doc, there's a non-lethal device that already does that: it's called a lock.
And here's some unsolicited advice: think of the legal ramifications, and perhaps consult an attorney. Imagine that some poor soul, new to town, wanders up the steps. "Hmm," he thinks, "Mason Labs. Perhaps this establishment sells victuals. Perhaps I could find employment here." He finds a locked door and goes away. Or: he finds an unlocked door, enters, and a plasma field reduces his body to its component molecules. His litigious relatives sue Mason Labs as a corporate entity and sue Dr. Mason in his personal capacity for failure to display an adequate sign explaining the consequences of entry. By the end of the process, the blood fruit thingie could end up the property of some yahoo from the Mainland. That wouldn't end well for anyone.
So here's another, related piece of advice: if you want to keep people out of a house, make it look forbidding. One of those really tall gothic castle structures, perhaps. Or take a cue from some of your fellow scientists: put a big mechanical lobster out front, or a mutant thing with tentacles over the door. People notice those kinds of things, and they take a hint. No need for the Death Ray. Just a helpful suggestion.