$171
million Fermilab Undertaking
A 'Smashing' Project in Illinois, Minnesota
by Craig Barner
An experiment that will involve hundreds of physicists from
32 different universities and research institutes has resulted
in a $171 million project at the Fermi National Accelerator
Laboratory in Batavia, Ill.
The experiment seeks to determine whether the neutrino, a
shadowy subatomic particle, has mass, said Dixon Bogert, a
physicist and deputy project manager for civil construction.
Though the existence of the neutrino was postulated in the
1930s and first confirmed in the 1950s, the particle is so
light that no measurement has been made of its mass.
Previous experiments have revealed three different types of
the particle - electron, muon and tau neutrino - and observations
from nature suggest that a neutrino of one type might sometimes
change into a neutrino of another and back again, a process
known as neutrino oscillation. The experiment seeks to confirm
the oscillation takes place to answer whether neutrinos have
mass.
The Neutrinos from the Main Injector, or NuMI, experiment
might result in developing spin-off knowledge, such as shedding
light on fundamental issues about the nature of matter and
energy like the sun and nuclear fusion.
"It (neutrino oscillation) is related to fusion processes
and other things like that," Bogert said.
Sitework at the laboratory 40 mi. southwest of Chicago began
in 1999, and construction is expected to finish in February,
said Elaine McCluskey, Fermilab construction manager. Scientific
instruments and materials will then be installed, and the experiment
is expected to start in 2005 and could last one to two decades.
Physics for Construction Professionals
The Fermilab project's parameters are immense because construction
is taking place in two states, on land and below ground where
facilities to be used for the NuMI experiment are already located.
A proton beam will be extracted from the facility's underground
main injector and shot into a target of carbon blocks, Bogert
said. The collision between the quarks that make up the protons
and those that make up the carbon will rain out a variety of
particles, such as two-quark states of matter called pi mesons.
These will be focused with cylindrical magnets and dart through
a 2,200-ft.-long, 6-ft.-diameter steel pipe lined in concrete.
During flight, the anti-down quarks that make up the particles
change into anti-up quarks and W particles. W particles, in
turn, decay into muons and muon neutrinos.
These particles will shoot through blocks of metal surrounded
by concrete to absorb the muons, and the muon neutrinos will
zip through a detector made of 200 planes of steel equipped
with scintillators to verify the muon-type neutrinos have been
produced. Finally, the beam will project through 450 mi. of
solid earth to Soudan, Minn., where another detector of 484
planes is located and already installed in an abandoned iron
mine a half-mile underground.
"In Minnesota, the expectation is we're not going to get
many muon neutrinos, but instead a high number of electron neutrinos
and tau neutrinos," Bogert said. "They have a different
signature than the muon neutrino."
Each neutrino bullet will take less than a second to travel
between the Fermilab gun and the Minnesota target because the
beam travels at the speed of light. The injector cycles every
1.9 seconds.
Project Elements
Several major elements make up the project at Fermilab to
carry out the experiment.
Two shafts were opened with explosives, including one to service
the target area and another to service the detector space, McCluskey
said. Excavators were used to push debris in a container, and
a crane removed the spoils.
A 4,150-ft.-long tunnel was mined and includes space for the
two halls, in addition to a chamber between them for the absorber
blocks. After the tunnel ends, the beam continues on to its
target.
A tunnel-boring machine created the 21.5-ft.-diameter tunnel,
and Lombard, Ill.-based S.A. Healy Co. served as the general
contractor for this project element.
Above each shaft, structures have been built, the Target building
and the Minos -Main Injector Neutrino Oscillation Search - building
above the detector area. They will house equipment for the experiment,
including a 30-ton crane in the Target structure that will be
used to lower the carbon blocks, and two 15-ton cranes in Minos
that will bring down the detector planes.
Park Ridge, Ill.-based Ragnar Benson Inc. served as the general
contractor on the service buildings and outfitting.
Bridge cranes in the tunnel allow materials to be moved once
they have been brought down.
A Material Project
Material distribution was an important issue partly because
activity occurred above and below ground.
And, a large quantity of materials go into the project, McCluskey
said. About 25,000 cu. yds. of concrete - an amount requiring
1,000 truckloads - was used to line the decay pipe alone. Additional
concrete was needed for the target pit and tunnel walkways.
Considerable exertion went into stockpiling materials in the
tunnel during the early stages of construction, said Phil Stearney,
project manager for Ragnar Benson.
"It was a very large effort the first five months of the
job to get all the materials required for the tunnel work into
the tunnel so that we could build the building without having
a lot more material stocking to be performed later," he
added.
Designed for Science
Because of earth's curvature, the tunnel slopes downward 3.3
degrees, Bogert said.
The beam will be at its lowest point beneath Wisconsin and start
to rise as it approaches its northern Minnesota target.
"As we go under Wisconsin, the beam is 6 mi. down,"
he added.
The two shafts vary in depth due to the slope. The Target shaft
is 110 ft. deep, and the Minos shaft is 350 ft. deep.
Also because of the incline, dewatering was critical. Approximately
420,000 gallons of groundwater rushes toward the Minos hall,
the lowest point, each day.
A pump with backup electrical system was installed. And, a diesel-powered
auxiliary pump was put in just in case the first system goes
down.
"The water never stops coming, even if the pumps stop running,"
Stearney said.
Trench drains channel water into a 20-ft.-deep sump pit in the
Minos hall for efficient collection.
The shafts were lined in concrete to prevent water from dripping
into the chambers below and to provide a work surface for the
numerous risers.
The number of utility lines in the shafts is considerable. The
Minos shaft, for instance, has two vent risers, three pipe risers
and 24 conduit risers, and the Target shaft is also heavily
outfitted.
Swing stages were suspended to hold workers during utility-line
installation, Stearney said.
Shaft area was an issue because the space was used for hoisting,
in addition to a channel for utility lines. Despite the lines'
large number, they were not stacked but rather ring the shaft
edge.
"Fermi told us exactly where to put these lines,"
he added. "We had to stay out of the hoisting zone."
The location of the decay pipe in the tunnel was required to
be within .75 in. of tolerance, and a laser-guiding system was
used to place it.
Worker, Employee Protection
Several elements ensured the safety of construction workers
during construction and employees after project completion.
Construction could not occur in the above-ground structures
when workers were in the shaft and vice versa, and weekly
coordination meetings made certain subcontractors followed
these guidelines.
"We slated times for installing risers in the shaft,"
Stearney said. "We said, 'When we have the swing stages
in the shaft, we won't be doing anything else in the shaft.'"
A wall runs the entire depth of the shafts, creating two half
moons, and the stairs in one semicircle can be used for exiting
when the elevators in the other one cannot.
Keeping out fumes and proper ventilation were important.
Rather than gasoline, tuggers used to move materials before
installation of the bridge cranes were powered with diesel
fuel and had scrubbers. Air-handling units heat spaces with
electric power.
In addition, the tunnel was ventilated during construction
and for occupancy. Industrial fans were placed in the shafts
and halls, and four ventilation holes were drilled during
construction.
| KEY
PLAYERS |
| OWNER: |
Fermi National Accelerator
Laboratory/U.S. Department of Energy, Batavia, Ill. |
| GENERAL
CONTRACTOR (SERVICE BUILDINGS AND OUTFITTING): |
Ragnar
Benson Inc., Park Ridge, Ill. |
| GENERAL
CONTRACTOR (TUNNELING): |
S.A. Healy
Co., Lombard, Ill. |
| ARCHITECT/ENGINEER
(TUNNEL OUTFITTING): |
Montgomery
Watson Harza, Chicago |
| ARCHITECT/ENGINEER
(SERVICE BUILDINGS): |
Crawford,
Murphy & Tilly, Springfield, Ill. |
| ARCHITECT/ENGINEER
(CRANES AND PROCESS PIPING): |
Fermilab,
Batavia, Ill. |
| CONSULTING
ENGINEER: |
Hanson
Professional Services, Springfield, Ill. |
Useful Sources
Find out about the Neutrinos from the Main Injector project
by visiting
www-numi.fnal.gov/
on the Internet.
View the NuMI excavation by visiting
www-visualmedia.fnal.gov/VMS_Site/s_videonews.html
on the Internet.
See a 12-minute video about detecting neutrino oscillations
by visiting vmsstreamer1.fnal.gov/VMS_Site_02/VMS/MINOS/MINOS.ram
on the Internet.
'It was a very large effort the
first five months of the job to get all the materials required
for the tunnel work into the tunnel so that we could build
the building without having a lot more material stocking to
be performed later.'
- Phil Stearney, Ragnar Benson Inc.
'The water never stops coming,
even if the pumps stop running.'
- Phil Stearney, Ragnar Benson Inc.
|
print this page
e-mail this page
