Playing the Magnetic Field
By Dean Woodbeck
January 2001 Alumnus
We take an elevator to the ground floor of the Dow Environmental Sciences
and Engineering Building, unlock the door to a lab, walk around the corner,
and run into a sauna.
Well, it looks like a sauna--albeit a very large one--with tongue-and-groove
planks on the walls and ceiling. But where's the stove?
In reality, this room is as shielded as a room can be from the Earth's
magnetic field. Behind that wood planking is transformer steel.
"Basically, in here you couldn't get a compass to tell you which
way is north," said Jimmy Diehl, professor of geology. "There
is virtually no magnetic field."
"We use Scotch tape for our sample holders, but sometimes we have
to replace it because it is too magnetic," pointed out Sue Beske-Diehl,
professor of geology.
No magnetic field? Magnetic Scotch tape? What's the deal, Diehls?
The geologists need the field-free room as they study the magnetic properties
of very small particles and samples. As they study sediment from the floor
of Lake Superior, for example, they test tiny core samples--no bigger
than a box for a lapel pin. When they are finished, they can tell you
the story behind the sample--how long ago it was deposited, whether the
climate at the time was warm or cold, and other variations.
"We can tell you what's happened since the glaciers left Lake Superior,"
Sue said.
The Diehls are geologists, but there is a lot more to their story. They
job-shared almost before the term existed.
"We share one faculty position and we have since the beginning,"
more than 20 years ago, Jimmy said.
Back in the late 1970s, Tech was interested in hiring Sue, based on the
work she was doing as a post-doctoral student at the University of Minnesota.
With both spouses in the same specialty, the Diehls knew finding two full-time
faculty positions in the same place would be difficult.
"Sue asked the department head about sharing a position and he said,
'no way,' " Jimmy laughed.
"So I told him about the advantages to the department," Sue
said, "that we would have more time for students and that we could
teach a wider variety of courses. Finally, he said, 'let's go talk to
the dean.' "
The dean sent her to the provost--Dale Stein (now president emeritus
of Tech). "He had just read an article about this new concept of
job-sharing," Sue said. "He made it happen."
Now their careers at Michigan Tech are approaching 25 years, during which
they have shared a faculty position and responsibility for their two children.
"Jimmy would stay home in the morning and I'd stay in the afternoon,"
Sue said. "The only thing it did was take away some research time.
Our careers may have expanded much more (if both had been full-time),
but who knows? It has allowed our lives to have a balance."
Back at the sauna--er, shielded room--the Diehls are showing off their
new superconducting rock magnetometer. The machine's innards are cooled
to 4.2 degrees Kelvin, allowing sensors to detect and amplify changes
in magnetic field of samples.
They Scotch tape a sample to a mylar rod, which is then inserted into
the supercooled sensors. The magnetic properties are measured four times
as the sample rotates. A dedicated computer collects and interprets the
data.
The machine and the room were made possible by a grant from the National
Science Foundation and from private funds that helped to equip the Dow
building.
"We received funds for the instrument from NSF," Jimmy said,
"but none for the room. The instrument without the room would be
sort of crazy, so Tech increased its cost-share and funded the room."
In a room where you test for magnetic properties, all of your equipment
must be non-magnetic. The venting is all plastic (PVC) pipe. Storage cabinets
have no metal hardware. No magnetic materials could enter the room, at
a time when labs in the new building were still under construction.
"This room (the 'sauna') was built in February 1999, but they still
had to construct the lab around the room," Jimmy said. "We didn't
want people to put their hammers on the roof; we lived in fear that they
would do something that would degrade this thing. Next door, they had
these huge steel pipes sitting next to the wall; the field in this room
went up astronomically."
There has been a renewed interest in magnetic properties as scientists
have discovered a connection with climate change.
"Magnetic properties tend to be quicker responders to climate change,
in some cases." Jimmy said.
While they have done extensive work in the Great Lakes region over the
years, the Diehls have also benefitted from recent renewed interest in
Lake Superior. They have hooked up with the five-year Keweenaw Current
(KITES) program, led by Tech chemistry prof Sarah Green, and the Lake
Superior Ecosystem Research (LaSER) Center, headed by Michigan Tech biology
professor Charlie Kerfoot.
"Charlie is going out in boats and getting core samples," Jimmy
explained. "We can open up the cores and do a sub-sampling of a cube
of mud. We measure the direction of magnetism, and other magnetic properties,
and we can integrate that into a story."
"We'll even look at the smaller area lakes, like Lake Annie, which
may be able to give us a good climate record from the last 10,000 years,"
Sue said. "We may be able to get an idea of dry and wet periods and
their durations. The more we know about past climates, the more we'll
be able to predict what happens in the future."
Oil-bearing rock may have a magnetic personality, as well, providing
another use for this basic scientific research. Smaller oil companies
have begun using magnetics for prospecting because it is cheaper than
seismic tests.
The Diehls are also working with Bill Rose, another geology professor,
in his work on volcanic ash.
"If you can correlate volcanic ash in two different sediment cores,"
Sue said, "you can get a good timeline, which is another environmental
indicator."
As their professional lives heat up with this supercooled machine, their
home life slows down a bit. "Our son just started college,"
Jimmy said, "so we're exploring how life goes on." Not surprisingly,
even this discussion has geological underpinnings. "I'd like to get
Sue to Hawaii," Jimmy says. "I think the big island of Hawaii
is such a great geological setting."
Sue Beske-Diehl and Jimmy Diehl and their superconducting
rock magnetometer.