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Special Containment Procedures: SCP-XXXX is contained in a cuboid cell 10 m by 10 m by 10 m. The interior of the cell maintains an ultra-high vacuum to prevent particle annihilation, and specialised equipment to re-initialise vacuum in case of an external breach. On the ceiling there are annihilation detectors every square meter, totalling 100 detectors for redundancy and location of an anti-matter source. All objects in the containment cell will be labelled with a black plus sign on a red background; this is to prevent objects from going into the anti-matter universe. SCP-XXXX is located in a dimensional unit in the Marie Byrd Land portion of Antarctica to prevent casualties if an incident were to occur. SCP-XXXX is not to be within range of any type of explosives and or high-speed projectiles, all guards assigned are to be equipped with melee weapons.
Description: The exterior SCP-XXXX is a shipping container with standard dimensions with one door. The interior of SCP-XXXX holds two dimensional doorways, one to the interior of the container and the other to a parallel universe, that will henceforth be referred to as Anti-Earth. Contrasting the exterior, the interior has two doors on the end faces, each close in front of the dimensional doors. The interior is grated on the walls and ceiling whilst the floor there is space for potential cargo and forklift. The atmosphere inside is toxic air and ventilation is not to be attempted due to the annihilation hazard, due to this all personnel entering SCP-XXXX are to wear airtight hazmat suits.
The dimensional doorways have a liquid-like surface tension that requires 20 Newtons of force for an object or person to pass through. The doorway decreases the energy emitted by electromagnetic radiation by 54%, therefore light can not travel between both universes without being observed from the inside of the container.
The Anti-Earth is identical to the Earth although the atomic structure is in contrast: Whilst Earth is made up of atoms containing protons (positive charge), neutrons (no charge) and electrons (negative charge) whilst the anti earth is made up of atoms containing anti-protons (negative charge), anti-neutrons (no charge) and positron (positive charge). When atoms from Anti-Earth are transported to Earth; all anti-atoms undergo immediate annihilation destroying the atoms and converting them into pure energy, therefore preventing atoms from one universe from getting to the other is essential as a gamma ray burst with the energy of a nuclear bomb would occur in any object more than 0.5 grams crossed. To prevent cross universe contamination all items and people entering SCP-XXXX are to wear a plus or minus according to their universe's (anti-)proton charge with a red background. Both versions of SCP Foundation on Earth and Anti-Earth have identical containment procedures for SCP-XXXX.
SCP-XXXX was discovered in the African port of Abidjan, the previous owner had described 'floating water' in the container to a college, this message was flagged and both the sender and recipient were given amnestics. The suspected reason for the anomalous properties of the container is the previous cargo it once carried; the cargo in question is an anti-matter trap for a particle accelerator, henceforth referred to as SCP-XXXX-1. SCP-XXXX-1 was recovered and tested for no anomalous properties although to prevent a similar incident SCP-XXXX-1 was incinerated.
