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FROM LEFT: PHOTOMASTER/SHUTTERSTOCK; JEAN LACHAT/UCHICAGO NEWS; FERMILABPortable Detector Shakes
Up Neutrino World
❯
NEUTRINOS ARE THE BOO
RADLEYS OF PHYSICS. These
tiny, electrically neutral
particles are shy to a fault. Sixty-
five billion of them pass through
every square centimeter of Earth’s
surface each second, and nearly
all exit the other side without
making their presence known.
Catching them in flight typically
requires special detectors weighing
thousands of tons.
“They are harder to detect
than anything else we know in particle physics,” says
astrophysicist Juan Collar of the University of Chicago.
Collar is part of a team called COHERENT that
changed the game in August by making the first tabletop
neutrino detector.
The instrument is 100 times more sensitive than previous
technology, Collar says. It works via an interaction between
neutrinos and atoms theorized more than 40 years ago:
As neutrinos bounce off atoms, they cause atomic nuclei
to jiggle. The detector’s first measurements confirmed this
predicted effect for the first time.
New discoveries could be in store as the device now
checks other features of neutrinos, including their
electromagnetic properties. And Collar hopes that even-
smaller detectors could be useful for monitoring nuclear
reactors, which spew out neutrinos. DEVIN POWELLPig Cells That
Won’t Go Retro
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MORE THAN 100,000 Americans
need an organ transplant, and
roughly 20 die daily while waiting.
Since the early 20th century, scientists have
envisioned a workaround in which we
could use pig organs, but those so-called
xenotransplants have never been human-
compatible. This year, bioengineers at
Harvard University and technology startup
eGenesis reached an important milestone
in making that vision reality.
Pigs carry retroviruses, which replicate
by permanently inserting their genes in
the DNA of a host species. And in lab
experiments, these porcine endogenous
retroviruses (PERVs) tended to leap from
pig to human cells. In a paper published
in August in Science, scientists addressed
this potential biohazard by knocking out
the retroviral DNA with the gene editing
technology CRISPR-Cas9. After cloning
PERV-free embryos, the team implanted
them in sows and raised piglets. The little
oinkers were completely retrovirus-free.
Now, the team is adapting the
technique to make other essential genetic
modifications, such as knocking out
molecules that trigger immune systems
to reject organs. “We are working
on building a ‘pig 2.0’ with advanced
immune compatibility,” says Luhan Yang,
eGenesis’ co-founder and chief scientific
officer. Humanized with a hand from
CRISPR, their organs could match our
needs. JONATHON KEATSJuan Collar helped make a
portable neutrino detector
(top), a far cry from current,
huge detectors (above).