Space Oddities by Harry Cliff

Author:Harry Cliff [Cliff, Harry]
Language: eng
Format: epub
Publisher: Knopf Doubleday Publishing Group
Published: 2024-03-26T00:00:00+00:00

Unexpected Guests

Deep within the sprawling Fermilab site, a side road runs through forest and shrubland to a small artificial hill. In one side of its grassy dome, a gray metal door marked “Caution—Radiation Controlled Area” opens into a chamber filled with racks of electronics and scattered with cardboard boxes of old computer kit. Though the space looks abandoned, the continuous roar of fans and pumps suggests that something is still going on beneath the hill. A trapdoor in the floor reveals what: a subterranean vault filled by a huge metal sphere, the three-story-high, eight-hundred-ton MiniBooNE detector.

Though now dormant, MiniBooNE[*3] remains a star character in an unfolding neutrino drama, one that promises to upend our understanding of nature’s most elusive building blocks. Inside the sphere are 250,000 gallons of ultrapure mineral oil surrounded by 1,280 amber orbs—light detectors—which once watched patiently for flashes of light in the dark liquid, a sign that a neutrino had made contact with an atom.

MiniBooNE sits on an invisible line that slices across the Fermilab site, starting at a target area about 550 meters to the south. Here, protons accelerated by the lab’s fifteen-hundred-foot circumference “Booster” ring smash into a target with enough violence to break the mighty bonds holding their constituent quarks together, rupturing the protons into a spray of exotic particles. Among the subatomic shrapnel are the pions we discussed earlier, as well as kaons. Each is made from a quark and an antiquark glued together by the strong force. They are then magnetically funneled into a fifty-meter tunnel. As they fly through the empty space, they decay, transforming into muon neutrinos and their electrically charged muon cousins. Finally, a wall of steel and concrete absorbs everything except the neutrinos themselves, which whiz on unhindered, forming a beam that passes through steel, concrete, earth, and rock alike.

The purpose of MiniBooNE was to follow up on an anomaly found by a similar experiment, a thousand miles away at Los Alamos, New Mexico, in the late 1990s. The Liquid Scintillator Neutrino Detector (LSND) had seen something that was hard to explain using our current understanding of the science: muon neutrinos transforming into electron neutrinos over far shorter distances than was thought possible. As we saw earlier, neutrinos can indeed change their stripes as they travel. But such effects are usually only apparent once they have covered relatively large distances. LSND was positioned a mere thirty meters from a source of muon neutrinos; they shouldn’t have had enough time to perform their Jekyll and Hyde transformation by the time they arrived at the detector. Nevertheless, despite starting off with an almost pure beam of muon neutrinos, the team at Los Alamos saw strong evidence that electron neutrinos were mysteriously appearing in their detector.

Their result suggested something potentially earth-shattering: the hidden influence of yet another, fourth type of neutrino. We’ve already met the three standard flavors—electron, muon, and tau. Many theories predict the existence of an even more intangible variety, a so-called sterile neutrino. We previously talked about

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.