A smart measurement for a “no brane” result

What are and where are these 25% of the contents of the universe that we call "dark matter"? Could there be a hidden world, the physicists speak of "hidden brane", in which our ordinary matter could fall, passing at the same time on the "dark" side?

The STEREO experiment has just pushed back the limits of this new world, by more than an order of magnitude. The idea was to test the hypothesis that a neutron could convert into a hidden neutron, propagate through a hidden brane and reappear further into our usual world.

STEREO is installed at the ILL research reactor in Grenoble, France. The core of this reactor produces the highest continuous flux of neutrons in the world, making it a powerful source of hypothetical hidden neutrons.

10 m further, the STEREO detector contains 4 m3 of liquid scintillator, well isolated from the outside by thick shielding. It enables the regeneration and efficient detection of neutrons possibly emerging from a hidden brane.

In the end, no significant excess of neutrons was detected.

Surprisingly, the STEREO detector was not designed for this at all. The initial goal was to measure the interactions of neutrinos emitted by the reactor core. To do that, you have to be close to the core and sensitive to neutrons... which made STEREO an outstanding hidden brane tracker!

Re.: “Searching for Hidden Neutrons with a Reactor Neutrino Experiment: Constraints from the STEREO Experiment", by H. Almazán et al. Phys. Rev. Lett. (10.1103/PhysRevLett.128.061801)

ILL experiment : STEREO

ILL Contacts : Torsten Soldner, Mathieu Vialat

LPSC Grenoble Contact :  Jacob Lamblin