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Scientists probing for dark matter signatures deep in the Earth

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Scientists probing for dark matter signatures deep in the Earth

Boston (MA) – MIT physicist Jocelyn Monroe is fascinated with dark matter. The only problem is, she’s having a hard time finding any. Leading theories state that a functioning dark matter detector would detect non-dark matter collision 10 billion billion times more often than it would a single dark matter collision. So, to address this rarified reality, she’s been designing a much better dark matter detector.

One of the most pesky things about dark matter is … well, it hasn’t been detected yet. It doesn’t show up in conventional sensors the way normal matter does. And even though some theories state 95% or more of the universe is comprised of dark matter and energy, dark matter can’t be seen with just any form of matter-based sensing equipment. Scientists are theorizing that it can only be detected by collisions with normal matter. And, bolstered by the fact that no one has seen it to date, scientists say such collisions happen very infrequently.

The preferred method for detection are neutron interactions that occur deep within the Earth. The collision of a dark-matter particle with regular matter produces a tiny, brief flash of light. Even when placed a mile or more beneath the surface, the number of normal matter collisions is 19 orders of magnitude (10 billion billion times) more frequent.

Discernment

Monroe and her team developed a new neutron detector which, when placed alongside a traditional neutron detector, should weed out all of the non-dark-matter collisions, leaving only real candidates aside for true study.

While nobody knows what dark matter is made of, astronomers are convinced it does exist. They see gravitational attractions which pull against visible matter in such a way that they cannot be explained without dark matter.

Monroe says, “I think probably in the next five years, someone will see a candidate [for a dark-matter particle].” According to Monroe, some experiments have already claimed evidence of dark matter interactions, but so far those claims are “surprising and unconfirmed.” They are also not generally accepted by scientists. Monroe hopes to change that.

Initial experiments

Experiments with the new detector were carried out first at the Los Alamos National Laboratory. Her team exposed the device to a neutron source for calibration. Next, it will be sent to an undisclosed underground laboratory (which may possibly be the Deep Underground Science and Engineering Laboratory located in an old gold mine in South Dakota). The team is looking for the deepest place on the Earth they can find as the Earth itself will shield many neutrons, reducing the number of collisions that must be considered by the discerning detector.

Dark energy

In related news, earlier this week NASA pre-announced a “new findings on dark energy” event, scheduled for next Tuesday, December 16, 2008. Dark energy is the yin to dark matter’s yang, so to speak. While dark matter exhibits gravitational effects, it does not have any interactions with the electromagnetic force. It has been estimated that a little over 20% of the matter in the universe is dark matter, while nearly 75% of the energy is dark energy. This accounts for nearly 95% of the total energy density of the known universe.

Scientists tell us it’s surely there, we just can’t see it or detect it … “yet,” says Monroe.