I think an IoP [Bulky, so +2] providing:
"Channelling: Nuclear Energy" [-2]
Stunt: "The Power of Science" - substitute Scholarship for Conviction when using Proton Pack. [-1]
Total cost: -1
The ghost trap would be IoP (no bonus, assuming character already has Proton Pack):
"Rituals: Quantum Entanglement" [-2]
Stunt: "The Power of Science" - substitute Scholarship for Lore when using Ghost Trap. [-1]
I might prefer that he ghost trap simply be a component of a Taken Out result when subduing a ghost using the Proton Pack.
I think Discipline should remain as the "Casting" skill for a Proton Pack - this should ensure that the less-focused Ghostbusters *will* be causing Fallout damage.
Looking over the base FATE rules for
Spirit of the Century, I might have an easier solution... I'd been thinking about allowing my players to use SotC stunts on a case-by-case basis as mortal stunts. I don't think any of them are terribly more powerful than what's already suggested in DFRPG, and it would really expand the list for those players who don't feel comfortable making up something that isn't already in the rulebook. At any rate, I ran across the rules for gadgets again, and I think they might suffice...
First, there's a series of stunts for gadgets, most notably: Personal Gadget, Universal Gadget, Custom Firearm and Weapon of Destiny.
Second, for those who don't want to spend the refresh cost, the SotC SRD has rules for purchasing gadgets (which is right in line with how the GBI franchise rights are supposed to go... proprietary equipment is supposed to be purchased from and serviced by GBI, not the players.)
So, a proton pack might start out as the equivalent of a flame thrower (a rifle-like "gun" attached by hose to a backpack-like device, which deals significant damage and can "spray" it's attacks). As a standardized Personal Gadget, we can give it three upgrades: Miniaturization (as pseudo-scientifically described in the movies, it's effectively a portable particle accelerator), Special Effect (it can be used to grapple ghosts and other ectoplasmic creatures at range), and Alternate Usage (damage counts as both fire and electricity), for example.
PKE meters might be part of a "Ghostbusters Utility Belt" Universal Gadget -- Alternate Usage (Use Alertness or Scholarship in place for Lore for Mystic Perception) -- while leaving the rest of the Universal Gadget undefined until needed.
A trap doesn't even have to be a gadget... It could just be a specialized item. We could treat it, effectively, as a thrown and remotely activated "explosive" with a special effect that imposes the "Trapped" aspect on ectoplasmic creatures. First "grappling" them with the proton packs, of course, makes it easier to trap them, due to all the resulting aspects imposed from the "grappling".
Now, according to the SRD rules, the cost of purchasing a gadget is equal to the base cost of the item +2 for each upgrade... Very Pricey. A single proton pack might have a resources cost of Good (+3) +6 -- One better than Legendary! (No wonder Ray needed to take out a second mortgage on his house!... Aspects to the rescue!) Even the utility belt might have a cost of Good or Great. Of course, having the option to take them as stunts ameliorates the cost to a large degree.
