particles we can call it was the surface detectors was. one thousand six hundred sixty tanks make up the surface detector at the pier that was the observatory. all of them are filled with water the detector covers an area of fifty by sixty kilometers it's the largest observatory ever built. when cosmic rays reach the earth's surface here they're registered by the water tanks a single cosmic ray can produce a particle shalah that stretches over several square kilometers and a small tenuously detected by different containers. but it's not the only way how we can figure out the showers are actually. when the particles go from the atmosphere inside the air molecules. so you have this energy