Catching some gamma rays in executive Mexico

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Three hundred hulk tanks, each holding some-more than 50,000 gallons of purified water, roost on the side of a Sierra Negra volcano in executive Mexico, standing 13,500 feet above sea level. Four photosensors distortion during a bottom of each tank.

The array of tanks is partial of the High-Altitude Water Cherenkov Gamma-Ray Observatory, or HAWC, a corner plan of Mexico and a United States. While the record is comparatively simple, a plan is ambitious: observing gamma and cosmic rays, and contributing to the search for dim matter.

Segev BenZvi, an assistant professor of physics, and fellow scientists are looking for very energetic gamma rays and cosmic rays that enter Earth’s atmosphere. When a high-energy rays interact, they create a “particle cascade”—a showering of high-energy particles—that falls to Earth.

BenZvi and colleagues on the project are study extremely high-energy molecule acceleration, from supernova remnants, black holes, proton stars, and pulsars—“objects with very, very large amounts of energy, some of that is being dumped into accelerating charged particles out in space,” he says. When they interact, they furnish gamma rays and vast rays.

HAWC is a “scaled-up” version of a classical production student experiment, he says, that uses a water tank in a lab to measure for muons—heavy, unstable versions of electrons that are the ground-level ruins of particle cascades.

But a plan is innovative in 3 ways: a high-altitude location brings improved attraction to a particles, that get absorbed by a atmosphere as they descend; a “optically isolated, densely packed” tanks; and a algorithms that let the scientists make use of a data they assemble.

Construction of a observatory began in 2011 during a site in the Parque Nacional Pico de Orizaba, a inhabitant park and home to the asleep volcano Pico de Orizaba, Mexico’s top peak. HAWC was rigourously non-stop last spring. When a experiments are complete, in about 10 years, the scientists will revive the area to as tighten to a original condition as they can. The park is a “cloud forest,” with one of the highest tree lines in a world. An environmentally supportive site, the timberland affects cloud formation and rainfall in areas south and west of a park. No trees were private in formulating the observatory.

The high-altitude location poses teenager hurdles for researchers, like crispness of breath, says BenZvi. “And shortness of temper, trust it or not,” he says. “You usually get really irritated. Your meditative isn’t very clear. we find that we get bad during doing basic arithmetic in my conduct when I’m adult there.”

The huge tanks—23 feet wide and some-more than 16 feet high—are a same kind of tanks used by Midwestern farmers to irrigate their fields. A military contractor who manufactures “light-tight” tents for soldiers in hostile domain creates a tanks’ hemispherical domes.

Local workers fabricated the tank array, and afterwards done 4,000 trips by lorry adult and down the mountain to transport a H2O to fill them—a volume of 55 million liters, or a homogeneous of a soda can’s value of H2O for each person vital in Mexico.

The tanks representation a air shower particles during belligerent level. There are about 100 million particles in a cascade during a peak. The number of particles decreases as the cascade descends. “It’s like a pancake of highenergy particles that moves toward a ground,” BenZvi says. When a particles strike the ground, they pierce by the tanks—and when high-energy particles pierce by water, they furnish ultraviolet light, known as a Cherenkov effect. The photosensors in a tank record a ultraviolet light. And from a settlement of times that the sensors in any tank are triggered, scientists can reconstruct the instruction of a particle pancake.

The information they collect might also shed some light, as it were, on dark matter.

“There is really clever evidence, from all kinds of measurements in astrophysics, that there is something called dim matter,” BenZvi says. “But it’s not clear what it is. We consider it’s a fundamental
particle or particles.”

But scientists don’t know how massive it is or what a interactions are. “So it’s wholly possible that some of a gamma rays and vast rays that we see are actually not constructed by neutron stars and supernovae and things like that—they’re actually produced when clumps of dark matter correlate and decay. That’s the idea,” he says.

When anomalies are found in astrophysical data, scientists consider either a source of the curiosity is a mistake in their model or a change of dark matter.

“And that’s kind of a name of a game,” says BenZvi. “It’s a tough game, as we can imagine. It’s arrange of like a fun about ‘unknown unknowns’—you don’t know what you’re not modeling.”

Telescopes offer another way to magnitude gamma rays. But they have a slight margin of view, taking in usually a few degrees of the sky during a time. HAWC records information from two-thirds of the sky each 24 hours.

“Over a march of one day, we can see radically a entire northern hemisphere,” says BenZvi, observant that a methods are complementary. “We’ve made the gamble on some-more coverage, less sensitivity; they make a gamble on more sensitivity, reduction coverage. If you have both forms of instruments running, we can demeanour for unexpected things with HAWC—we communicate with those guys through behind channels: ‘Hey, we see something interesting. Point your telescope there.’ And that’s how a lot of a margin works.”

Scientists are now processing their initial year’s value of data from HAWC, that they began to make open this spring. And they are expanding a array with some additional tanks—just a few, that will move with them a four-fold boost in sensitivity.

And there is speak of formulating a second observatory, presumably in Chile. The southern hemisphere provides a best vantage point for watching a core of the galaxy—and it’s “a really strong candidate for watching dark matter, since we believe there’s a super-massive black hole in a core of a galaxy, and so there should be a gravitational well there where dark matter is concentrated,” says BenZvi.

“If we have a HAWC in the southern hemisphere, literally the core of a universe will be right overhead,” he says.

Source: University of Rochester