Photo/Illutration The Great Pyramid of Giza outside Cairo (Asahi Shimbun file photo)

KASUGA, Fukuoka Prefecture--Japanese researchers plan to bombard the Great Pyramid of Giza outside Cairo with cosmic rays to confirm if there is a mysterious internal “chamber” that a previous survey detected.

The team from Kyushu University expects to arrive in Egypt soon to scan the massive structure, built around 2500 B.C. and believed to be the tomb for the pharaoh Khufu.

“The previously discovered cavity is way too large from an archaeological perspective,” said Sakuji Yoshimura, who heads the overall research project involving other universities. “We are very keen to verify the findings.”

Tadahiro Kin, an associate professor of radiation metrology at Kyushu University, and other researchers will scan the pyramid with a method called muon radiography, which is much like X-ray imaging.

Muons are subatomic particles generated when protons and other cosmic rays strike the atmosphere. An area about the size of a person's palm receives a muon per second.

While muons can pass through even bedrock 1 kilometer thick, the number of muons that penetrate objects can change depending on their density and thickness.

The technology will allow Kin's team to measure the thickness of stone blocks used to construct the pyramid.

A newly developed muon detector will operate for a month inside the Queen's Chamber, which is located in the lower part of the giant structure. The accumulated data will be combined with findings from a drone survey.

The pyramid stands 139 meters tall and has a square base with each side measuring 230 meters. A few other chambers, such as the King's Chamber and the Grand Gallery, are known to exist, but details of the internal construction remains a mystery.

Previously, an international research group including Nagoya University and the High Energy Accelerator Research Organization announced that they found a previously unknown cavity measuring more than 30 meters long at the pyramid's center using muon technology.

The finding was reported in British scientific journal Nature in November 2017.

But some researchers in Egypt are skeptical of the claim, and the Egyptian government asked Yoshimura, president of Higashi Nippon International University in Iwaki, Fukushima Prefecture, to verify the findings as he has long been involved in pyramid research.

In addition to Kyushu University, Tohoku University, the University of Tokyo and the Chiba Institute of Technology will be responsible for other parts of the research project under Yoshimura.

The project is due to end by this summer. The findings will be released around autumn.