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Different but related: the three US facilities battling for survival
The three major US nuclear-physics
facilities under threat by budget
difficulties – Brookhaven National
Laboratory’s Relativistic Heavy Ion
Collider (RHIC), the Continuous Electron
Beam Accelerator Facility (CEBAF) at the
Thomas Jefferson National Accelerator
Facility and the Facility for Rare Isotope
Beams (FRIB) under construction at
Michigan State University – have different
but related goals and technologies.
The RHIC is primarily designed to
study the “phase diagram” of nuclear
matter from almost baryon-free matter at
temperatures up to four trillion degrees
kelvin down to baryon-dense matter at
lower temperatures. “It is by far the most
powerful in the world in terms of intensity
and most versatile in terms of energy,” says Brookhaven’s associate director
Berndt Müller. Those capabilities stem largely from a series of upgrades
over the past decade that have increased the collider’s luminosity and the
precision of its detectors. “The RHIC we have now is a new machine in many
respects – in its ability to accelerate uranium to the detectors – with almost
no resemblance to 10 years ago, covering science that was not envisioned
we’re going here,” Brinkman told the
subpanel in Washington at a hearing,
adding that it “represents permanent
damage to the field”. But if Congress
and the Obama administration fail
to avoid the looming budget cuts
in the “financial sequester” – the
agreement to reduce government
spending across the board if the two
Space
NASA has signed an agreement
with the European Space Agency
(ESA) to collaborate on a space mission
to study dark matter and dark
energy. ESA’s $800m Euclid mission
is expected to launch in 2020 and
will spend six years measuring and
mapping around two billion galaxies
covering more than one-third of the
sky. NASA is now expected to provide
around $100m towards the construction
of the probe, with the space
agency’s involvement likely to extend
the science that can be achieved.
Dark energy, which makes up
around 73% of the universe, is
believed to be the driving force
behind the universe’s expansion but
is a substance about which we have
almost no knowledge. Dark matter,
meanwhile, accounts for a further
23% of the universe, with the rest
Still running CEBAF at Jefferson Lab currently seems to be safe.
sides cannot agree on a budget – then
the cuts look more of a reality. “We
didn’t spend much time on sequestration,”
says Tribble. “If it occurs,
it will be such a problem in all parts
of government that it’s impossible
to know what the impact will be on
nuclear physics.”
One concern is that the sequester
NASA joins Europe’s dark-energy mission
Helping hands
NASA is expected to
provide around
$100m towards the
European Space
Agency’s $800m
Euclid mission,
which will study dark
energy and dark
matter
ESA/C Carreau
being ordinary visible matter. “The
study of dark energy was identified
as an important scientific ques-
tion in the 2010 Decadal Survey of
Astrophysics by the National Academies
of Science,” NASA spokesman
James Harrington told Physics
World. “Euclid will make significant
progress in understanding the
nature of it.”
Euclid will be armed with two
state-of-the-art instruments – an
optical visual imager and a nearinfrared
spectrometer. For the
infrared instrument NASA will now
be providing 16 detectors, plus four
spares, to the tune of $50m. NASA
will be giving a further $50m to support
the 54 US scientists who will
now be joining the mission, the bulk
from the Jet Propulsion Laboratory
in Pasadena, California. “By pro-
News & Analysis
when it was constructed,” adds Müller.
Recent discoveries include a new form of
matter – a strongly coupled quark–gluon
plasma – that was created by collisions of
gold ions.
As for the FRIB, it will be complete in
2021 and be based on a high-powered
superconducting linear accelerator that
will be able to produce rare isotopes. The
FRIB will be the world’s most powerful
radioactive beam facility, able to make
nearly 80% of the isotopes predicted to
exist for elements up to uranium.
CEBAF, meanwhile, will provide a highintensity
continuous beam of electrons
using superconducting radio-frequency
technology. The facility is currently
undergoing a long shutdown as part of the
upgrade that will double the accelerator’s energy from 6 GeV to 12 GeV, with
the goal of starting its new science programme in 2015. The electron beam
in the upgraded facility can be split and delivered simultaneously to three
different experimental halls. According to Robert McKeown, deputy director
for science at the Jefferson lab, one of these halls will feature a “flagship
experiment” that will use a 9 GeV photon beam to search for exotic mesons.
could lead to a ban on starting any
new programmes at all. That could
affect the FRIB, which has not yet
received the necessary “critical decision
2” go-ahead from the DOE.
Even if that situation does not occur,
the field could lose so much financial
support that it might even have to
close two machines rather than one.
viding US-made detectors for the
mission and by having US scientists
working on the mission, both the
European and US science communities
will benefit,” says Harrington.
This is not the first time that
NASA and ESA have worked
together on a major mission, having
collaborated on the Hubble and
James Webb space telescopes as well
as on the Cassini and Huygens missions
to Saturn and the Herschel and
Planck observatories. “We welcome
NASA’s contribution to this important
endeavour, the most recent in a
long history of co-operation in space
science between our two agencies,”
says Álvaro Giménez, ESA’s director
of science and robotic exploration.
NASA says it hopes the experience
it gains on Euclid will help it with
the construction of the Wide-Field
Infrared Survey Telescope mission,
which is planned for launch in the
coming decade to study dark energy
and dark matter.
Gemma Lavender
Physics World March 2013 7
Thomas Jefferson National Accelerator Facility