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Dear
Colleague:
Welcome to Quantum, a periodic e-newsletter for
professionals working with magnetic technologies. Quantum
is designed to keep you up to speed on applications, case
histories, and evolutions of quantum magnetometers in a variety
of disciplines.
In this
issue:
Award Winner
–
10 Minute Survey
(Top)
As many of you may remember,
GEM requested our users' help in completing a 10 minute survey
designed to evaluate our users' interests in upcoming
technologies and communications offerings.
The results are now in and we
are pleased to announce that Kamil Rozimant from the Department
of Applied and Environmental Geophysics, Faculty of Science,
Comenius University of Bratislava, Slovakia was our award
winner.
Congratulations to our award
winner, and our thanks to all whom participated. We are actively
following up on your technology and communication preferences
for upcoming product and newsletter releases.
New Upgrades from GEM
- 5 Second Sampling, More Memory and Reduced GPS Costs
(Top)
GEM has recently reviewed its
ground offerings and decided to upgrade its core geophysical
data acquisition system, the GSM-19 Overhauser "Walking"
magnetometer. Now, when you purchase a Walking magnetometer, 5
second sampling is now included as a valid survey setting.
Previously, this was an option that was purchased separately.
This change means that the
Overhauser magnetometer is directly comparable to optically
pumped devices, with the exception of GEM's K-Mag, which is the
world's most sensitive commercial ground magnetometer /
gradiometer. The Overhauser magnetometer is also much less
expensive than caesium devices, providing excellent value for
our users.
However, GEM's upgrades do not
stop there:
- Our memory has now been
standardized at 16 Mbytes (please see specification sheets for
comparable number of readings). And in addition, GEM now
offers a single upgrade of another 16 Mbytes for a total
volume of 32 Mbytes. The new memory upgrade is also offered at
a new cost that is more than 50 percent less than our previous
memory combinations. These memory upgrades provide more than
enough capacity for DGPS post-processing operations.
- 3D-GPS support is now
provided through the availability of an elevation option. This
serves two functions, namely, enabling professionals to 1)
construct topographic maps of their survey sites (to within
vertical positioning errors that are approximately 3 times the
horizontal positioning errors); and 2) utilize 3D data in data
modeling.
- Our integrated GPS option
has been reduced in price by 40 percent in support of the
increasing number of users who want to add this option to
their surveying methods, and thereby increase survey
efficiency and lower costs.
As well, additional Version 7
upgrades are designed to make all of GEM's magnetometers /
gradiometers more efficient through enhanced data output. Now,
data can be easily output to ASCII-format files that are
compatible with industry-standard software packages from Encom,
Geosoft and Intrepid. Moreover, output is programmable so the
user has the choice of the final arrangement of data in the
output file. This gives additional flexibility and convenience
for data processing work.
As GEM moves forward into the
future, we continue to listen to our users' requests for new
functionality and we are pleased that the new capabilities from
GEM upgrades are receiving positive attention from all users of
magnetometers and gradiometers.
Since its
inception in 1980, GEM has provided proactive support to earth
science groups through delivery of the latest magnetometers for
ground and airborne applications. And our loyal customers have
continued to support us throughout this period for a variety of
reasons.
"Over the
last 25 years, GEM has provided solutions that help earth
science professionals address their challenges in many
disciplines," said Dr. Ivan Hrvoic, President of GEM. "Whether
searching for minerals, researching earthquakes or helping
academics meet their scientific and teaching goals, our focus is
always on enhancing magnetic technologies. The widespread use of
our technologies (more than 100 countries worldwide) is one of
the best testimonials we can provide as to GEM’s success in
meeting customer needs."
The
company’s offerings focus on Overhauser, Proton Precession and
optically pumped Potassium instruments – the only company
worldwide that provides such an extensive portfolio of total
field magnetometers for mineral exploration, near surface
geophysics, earthquake research and other applications.
Many
professionals are using the Overhauser magnetometer – a
GEM-developed technology that is now a global standard based on
its data quality, efficiency and low power consumption. In
addition, traditional Proton Precession technologies have found
new life at GEM through a Research and Development program
resulting in the highest sensitivity and robust Proton
instrument today.
The
Potassium magnetometer is another example of a novel technology
that delivers the highest sensitivity and sampling rates for
both airborne and ground work. In the air, the Potassium system
is used for acquisition of very high-quality magnetic and
gradient data in either fixed-wing or helicopter applications.
On the ground, it serves as either a base station or a portable
unit that can be towed behind a sled or all terrain vehicle
(ATV), depending on project needs.
GEM
Advanced Magnetometers delivers magnetometers and gradiometers
with built-in GPS for high-sensitivity, accurately-positioned
ground, airborne and stationary surveys. Each instrumentation
system offers unique benefits in terms of acquisition of
high-quality data. These core benefits are complemented by GPS
navigation options with metre, sub-metre and centimetre
positioning. In addition to a 25-year history of innovation in
magnetometer design and manufacturing, GEM is known for its
customer service and support.
Where We'll Be
–
SEG 2005 and AGU
2005
(Top)
As part of our program to stay
in touch with our customers, we will be on hand at two upcoming
conferences in the United States in the next few weeks. These
include the Society of Exploration Geophysicists annual meeting
in Houston, and the American Geophysical Union's upcoming
meeting in San Francisco.
Some of the technologies that
GEM will be featuring include:
- GEM has recently upgraded
its Ground Magnetometer systems to enable its customers to
perform surveys even more efficiently and effectively through
new 5 times per second sampling; new data formats and
integrated GPS.
- The company's Airborne
Magnetometers, based on the unique Potassium technology, were
also upgraded and customers are now acquiring data on Unmanned
Airborne Vehicles (UAVs) and an innovative 4-Sensor
gradiometer towed platform.
We cordially invite you to
visit GEM's booth and learn about these new technologies in
person at SEG in Houston from October 6 to 9, 2005. GEM's booth
number is 2261 .... located conveniently across from the
Internet cafe.
Or, if you prefer, drop in and
see us at the AGU meeting from December 6 through 10 in San
Francisco. We will be at booth 013 ... again located
conveniently across from the Internet cafe.
Our focus at the AGU will be
similar to the SEG with the exception that we will also be
featuring our Earthquake Research technologies. A poster
describing these technologies and their implementation at a site
in Mexico will be on display on Friday, December 9 on Level 2.
The number of the poster is T51B - 1339.
The
Tri-Directional Helicopter Gradiometer from GEM was the first
three-axis gradiometer developed globally. Since its inception
in the mid 1980s, the system has been outfitted with optically
pumped Potassium sensors and has evolved into a reliable
platform for different applications, including mineral
exploration.
Tridirectional Sensor with
Helicopter and Sample High Resolution Data
This special
gradiometer consists of a three-armed towed bird configured with
4 sensors for calculation of magnetic gradients, including
vertical and horizontal across and along track gradients.
Additional components include GPS for accurate positioning of
the bird during flight. Data capture is either to the GSMP-30A
acquisition console or a 3rd party unit.
Currently,
the gradiometer is being flown by a major airborne contracting
company in Western Canada. As we hear more about the results and
quality, we'll be sure to keep our interested readers informed.
Several
researchers from St. Petersburg are now in the works of
preparing a book about the use of magnetic prospecting in
archaeology - specifically with the GEM GSM-19 Overhauser
magnetometer / gradiometer. As noted by the researchers, "We
like your instrument, it was the main one for all our
investigations since 1993. Now, we use two of them; one is
recording the temporal changes of Earth's magnetic field."
The book will
be in English and will be entitled, "Magnetic Prospecting in
Archaeology.Ten Years of Using the Overhauser GSM-19WG
Gradiometer." It will be about 70 pages with many illustrations
and photos (with some of them in colour). The objective is to
provide a high quality, attractive volume for archaeologists
planning to use magnetic prospecting for the investigation of
their sites. Although the authors previously published a smaller
booklet, they have decided for the new edition as there are many
new examples to show.
It will start
with a short introduction part on the principles of magnetic
survey in archaeology, but the major focus will be on examples
of the application of the instrument in archaeology in many
countries, where we worked since we bought the first GEM
instrument in 1993, and the second one in 2004. This includes
Denmark, Norway, Greece, Egypt, Syria, Ukraine, Germany, Sweden,
Estonia, and Russia.
The issue
date is currently set for next April when the researchers'
colleague, Olfert Voss, archaeologist from the National Museum
in Copenhagen, whom has contributed to magnetic prospecting in
Denmark for the last 13th seasons, celebrates his 80th birthday.
Olfert is considered to be the Danish "chief"; he is the main
member of the geophysical team when work is in Denmark.
Earthquake Prediction
- SuperGrad Talk at the Balkan Geophysical
Congress
(Top)
Interest
continues to be expressed in GEM's SuperGrad system for
earthquake prediction monitoring and research. The latest
interest is from Romania which recently hosted the Balkan
Geophysical Congress in Bucharest.
During the
Congress, GEM was pleased to make several presentations,
including a Commercial Presentation on GEM's Technologies, and a
new scientific paper describing the latest work in installing a
SuperGrad earthquake research system in Oaxaca, Mexico. To
download the paper, click
here.
Members of the
Romanian scientific community are highly interested in SuperGrad
for its ability to monitor larger earthquakes such as those
encountered in Romania. During discussions, the scientists
expressed a strong interest in having an installation in place
soon.
Based on these
discussions, GEM has decided to add a Romanian SuperGrad station
to complement its existing stations in Israel and Mexico. (A
second Israeli installation will also be set up in a region more
tectonically active than the initial site.)
In Romania,
installation is planned for the Romanian "hot" area in the
province of Vrancea. Earthquakes happen at great depths in
Vrancea ... down to 200 km. However, the SuperGrad is proposed
to have the ability to detect any "big" earthquake (M7 or more)
at depths over 100 km and close to 200 km. Detection is by ULF
(1 to 10 mHz) magnetic gradients and total magnetic fields.
Vrancea is
some 300 km away from the capital, Bucharest, but a big
earthquake in Vrancea could endanger the capital and cause many
casualties. A precursor detected by the SuperGrad would be used
to issue an early warning (few hours before the earthquake) and
save many lives.
The Balkan Geophysical Congress
held in Bucharest was an excellent forum for magnetics with
three sessions, including a poster session. One of the
highlights was a presentation from our Turkish colleague,
Muzaffer Ozpu Arisoy, a researcher at Cumhuriyet University. The
talk is entitled, "Evaluation of Different Receiver Orientations
and Receiver Separations in Magnetic Gradiometer Method."
Mr. Arisoy's presentation
reviews the role of differential gradiometer measurements,
typically referred to as "gradients" in the working literature.
It includes mathematical formulations for the various field
values, a discussion of the roles of different "gradients" for
resolving objects, and mathematical models for various sensor
separations.
To download your copy, click
here.
The Chinese Earthquake Administration is taking
delivery on a substantial order for GSM-90 EUROMAG
magnetometers. The systems will be employed across China
as part of its earthquake monitoring program.
CEA ordered the GSM-90 F1 model,
so called because it samples up to one sample a second (standard
monitoring period described by geomagnetic organizations and
bodies, such as Intermagnet.
Before discussing the
orientation guidelines for Potassium sensors, it is important to
understand the concept of "dead zones". Specifically, dead zones
occur when the angle between the magnetic field and the sensor
axis are such that no magnetic measurement can be obtained.
The presence of dead zones
means that there is an optimal operating window for optically
pumped magnetometers (i.e. in which optimal orientation can be
obtained).
In all optically pumped
magnetometers, there is an interplay of optical polarization and
Radio Frequency (RF) depolarization of the two energy levels
present (i.e. for alkali metals) ... resulting in ampltitude
modulation of the polarizing light.
Light polarization requires a
colinear magnetic field whereas RF depolarization works with the
magnetic field at a right angle. As a consequence, 0 and 90
degree directions of the magnetic field are forbidden; they fail
in either polarization or depolarization.
The dead zone effect covers
more than several degrees around each of the "forbidden" angles;
hence angles close to 0 or 90 degrees are not very efficient and
the spectral lines are weak. We recommend operation between 10
to15 and 75 to 80 degrees.
Potassium has 4 spectral lines
and we only use one of them, at the lowest frequency in any
field. This line is the strongest for angles up to 45 degrees.
For angles above 45 degrees, line number 4 is strongest (but
this is irrelevant since we do not use this line). Line number 1
is the strongest at about 30 to 35 degrees.
Say the inclination in your
area was 65 degrees (i.e. 25 degrees off vertical). This is
close enough for very good results if you install the
magnetometer sensors vertically.
For inclination angles that are
near horizontal, simple geometrical consideration will tell you
that the horizontal installation of sensors will not work if the
sensor axes are in the East-West direction. Even for North -
South direction of the sensor axes, the angle would be some 65
degrees ... which is less favourable than 25 degrees.
Customer Service
- Update Your Warranty Online for Fast
Access to Updates
(Top)
GEM is pleased to offer the
longest warranty in the geophysical instrumentation industry as
a demonstration of its confidence in the quality of its
products. All GEM products are waranteed to the original
purchaser against defective parts and workmanship for two (2)
years from the date of original shipping. A summary document of
the precise TERMS and CONDITIONS is provided at
http://www.gemsys.ca/GEM_warranty_card.htm
As part of its customer service
program, GEM recently implemented an Online Maintenance
capability for all customers using its magnetometers. Click the
link above and you will also see a series of entry fields at the
bottom of the form. Simply complete the form and submit and your
warranty will be forwarded directly to us.
Then, you will be all ready for
any updates that GEM prepares – a timely way to acquire new and
upgraded features via the Internet.
The Last Word – Comments from Our
Customers
(Top)
As usual,
we leave the last word to our customers – our key focus in
ensuring that we continue to serve the market effectively and to
our customers’ satisfaction.
"Always enjoy reading your information,
and your usual courtesy in responding to
questions. Wish you were nearby.
Jerome Maverick
"GEM magnetometers functioned as specified during several
months of surveying in the Amazon jungle of Brazil. Local
operators could easily be trained to operate the
magnetometers reliably. The low angle magnetic field of
the region could be effectively detected with the sensor
in a horizontal orientation."
David Allen
Project Geophysicist (former)
Fugro Ground Geophysics
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Copyright 2005. GEM Systems, Inc. Advanced Magnetometers.
All rights reserved with the exception of organizations that
have contributed links to this issue. Our thanks to the contributors who have
made this edition possible, and who are identified in the text of related articles
or through their company websites. Note that some quotes relating
to industry-specific trends may have been obtained from public-domain
sources, and are not intended to promote GEM Systems,
Inc. Other examples may not necessarily reflect GEM products;
rather these examples are intended to illustrate the use of
magnetics and magnetometry for selected applications.
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