The weapons lab is where much of the aliens' more offensive technology is tested. This facility is located on the upper level of Mothership Zeta through a door leading from the observation deck. As the name indicates, the Lab is the place where alien weapons are being created, thus you can find many standard weapons as well as several unique versions of these weapons.
After passing through the door near the teleporter that has inconveniently been deactivated, you will enter a large room. Immediately, you should notice two alien turrets firing at you from the ceiling. Additionally, a couple of aliens and a guardian drone inhabit this room. If you head southwest, you can find a small room on the right (open it via the control panel just next to it) that holds the atomic pulverizer, which is a slightly upgraded version of the alien atomizer.
Continue through this passageway, and you will come to a three-way intersection. Left is a blocked passageway, right goes to a flight of stairs. Go up the stairs and then take the first left. You will find yourself on the platform from which the aliens you first encountered in this room were targeting you. On this level there is a healing archway to the left and a control panel for opening up the next area. After activating the control panel, go south down a set of stairs from the platform and then proceed to a another alien/drone-infested room via the east door. Continue on until you enter a room full of weapons and armor for the taking.
This is also the only place where experimental weapons drones can be found. Outside of the experimental drone room, the control panel for alien captive log 24 can be found. After your shopping spree, you can go through a door to the north and explore a range/training area, which allows you to receive Xenotech Expert perk. But to move onward with the mission, go to the southeast door into the experimentation lab.
To get this perk, you must find a "shooting range" in the weapons lab (a room with an alien atomizer and an alien disintegrator next to a switch). The ranges are in approximately the center of the map north-to-south, and on the eastern side. Activating the switch closest to the door summons brahmin, while activating the far switch teleports enemies abducted by the aliens to a second range.
In order to get the perk, 10 enemies must be killed with alien weapons consecutively. There are four types of enemies at the second range: