Instrumentation and Bunkers
Trinity’s planners knew how important it would be to shield personnel from potential effects of the atomic test. Extreme light, heat, and exposure to radiation were known as possible, but no one knew how much would occur when the bomb went off. 
Engineers built a number of bunkers surrounding the Trinity Site. The bunkers were able to see the explosion from different angles, giving the recording equipment the most holistic points of view. 
The bunkers were built up with earth on the three sides exposed to the explosion. The sloped sides would be able to direct the blast wave up and around the bunker and the people sheltering within. 
In addition to sheltering people, the bunkers also housed equipment vital in recording every aspect of the blast. Here, cables and wires are connected to the bunker. 
This aerial view looks down on one of the bunkers, showing as the closer square. This view shows the earth slopes built up around the bunker and the entrance on the left side. 
These view ports in the front of the bunker enable people and cameras inside to watch the test. 
Wiring was strung on telephone poles to and from recording instruments and the operators. The pegs in the poles where the wires connect are porcelain caps that insulate the wire and pole from the ground. 
Cameras recording the explosion were positioned every which way due to the uncertainty about what exactly would happen when the bomb went off. 
Moveable shelters were installed for equipment that couldn’t be sheltered in the bunker. 
Equipment such as seismographs were installed directly into the ground to obtain the most accurate information when the bomb went off. 
The equipment connected to the recording instruments were complex and required a great deal of familiarity to run properly. Miles of cable and tons of equipment all needed testing and calibration before the explosion. 
The hardware for the instruments on site needed to be hardy and extremely durable to survive the explosion. 
A technician checks the wiring and set up of a camera. This camera is aimed out of the port in the bunker, visible behind the technician. 
The cameras at Trinity were extremely advanced for the time and were capable of recording images at less than millisecond intervals. 
The cameras at Trinity were not just to record the explosion. Leaders at Trinity knew that they were making history and were invested in recording the project for posterity. 
A technician sets up a freestanding instrument on a tripod. 
In addition to the instruments on the ground, balloons and other aerial instruments were launched from the Trinity Site to record data in the air.
A complex set of labs, test instrumentation, bunkers, buildings and roads appeared where there had previously been only a few ranch houses and corrals in a near empty desert. Test equipment had to be designed, acquired, located, set up, protected, cabled, connected, calibrated and tested.
Starting in November 1944, military engineers built protective bunkers for instruments and people at 10,000 yards to the south, north, and west of ground zero. South 10,000 was used as the control bunker with the automatic triggering device that would start the timing sequence. It had a wooden periscope for viewing the explosion from inside the bunker. The lead scientist, Dr. J. Robert Oppenheimer, was at this bunker while other key personnel, such as Major General Groves, watched from the base camp.
The three bunkers have been dismantled. The small bunker still visible from the road 800 yards to the west of the tower held seismic and radiation detecting equipment. Instruments had three primary purposes:
– Capture the implosion, the simultaneity or time between detonation, and the release of gamma rays from the nuclear reaction.
– Measure the amount of nuclear energy and intensity of the gamma rays from the explosion.
– Measure damage, blast pressure, earth shock, and heat.
Technicians set up dozens of field experiments that included barrage balloons and fifty Mitchell 35mm and FASTAX high speed cameras to record the test. Cameras faced upwards at mirrors that faced ground zero. Hundreds of miles of wires were strung between base camp, the instrumentation, and the control bunker to carry signals from the automatic triggering system that turned on instrumentation and carried data signals back to protected recorders. Each experiment and device had to be activated on its own schedule at different points in the count down.