Marking a major innovation in muon detectors used in the studies of interiors of structures like pyramids and caves, a new muon detector has been developed matching the bigger ones in terms of performance yet with a smaller size.

The details of the innovation were covered in the address of Alain Bonneville at the American Geophysical Union Fall Meeting in San Francisco on Thursday. He is a geophysicist at Pacific Northwest National Laboratory

Muons are elementary particles produced by the collision of cosmic rays with atmospheric molecules and are invisible to the naked eye. Earth receives a constant stream of muons at various angles and they pass through earth and rock. That is why detecting them gives a broad idea of the internal structures of rocks and other materials.

Deeper Structural Analysis

Already, elementary particles have been quite effective in exploring underground areas of pyramids and volcanoes in deciphering their deeper structures.

However, the method was beset with a shortcoming in not being able to communicate the changes happening in the density of the internal structures.

In a technological breakthrough, the Pacific Northwest National Laboratory, or PNNL created a miniature version of the muon detector. It is the largest supporter of research in physical sciences in the United States.

The mini muon detector answers the need for "seeing" changes in density variations at the underground and in the objects' internal structures.

Made of plastic components and optical fibers, these detectors carry signals to electronics by accounting for each muon passing through the device. The density change is understood from the variation in the number of muons hitting the detector at a given period as in the case of a plume of carbon dioxide.

Small Detector Created

The PNNL's mini detector carries smaller dimensions such as the diameter of six inches and length of three feet. It is capable of going down thousands of feet underground via horizontal boreholes, to do good imaging and monitor carbon dioxide storage sites pretty well.

The testing of mini detector's output was made by pitting it against large detectors in a tunnel at Los Alamos National Laboratory, where the scientists found the results on par with the larger machines.

With data converting into the image, the device can be used in tracking carbon dioxide or leakage underground. The scope extends further into applications on a variety of subsurface imaging areas.

Solar Storm Analysed

Meanwhile, a muon tracking telescope-array in India's Ooty detected cosmic ray showers. The GRAPES-3 facility noticed a surge in muon intensity and a corresponding weakening of the earth's magnetic field after a solar storm hit the earth on June 22, 2015.

The details were published in the journal Physical Review Letters by the Indo-Japanese collaboration that made the study.

According to the researchers, a coronal mass ejection (CME) reached earth on June 22, 2015, after the solar flares in the sunspot 12371 at the sun's central disc and caused radio blackouts and Aurora Borealis.

The data revealed that CME weakened the earth's magnetic field after the burst of high-energy cosmic rays.

Calling it unique, the team said the muon tracking study offered the advantage of assessing the impact of solar storms and space weather at distances twice the radius of the earth.

This was unlike satellite-based studies, which are constrained by the limitation of yielding very localized information that is within their vicinity.

"Galactic cosmic rays producing a muon burst were bent in the space surrounding the Earth over a volume that is 7 times that of the Earth, and hence they serve as a monitor of the solar storm over this volume. This is in stark contrast to the satellite-based measurements that provide only in situ information," said S.K. Gupta, head of the GRAPES-3 experiment that is based in Tata Institute of Fundamental Research, Mumbai.

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