Proposed Radiation Effects Facility Beam Line

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Proposed Radiation Effects Facility Beam Line for
the K150 Cyclotron
Courtney Knaup Emporia State University REU 2007
Cyclotron Institute, Texas AM University Advisor
Dr. Henry Clark
Beam Line Layout, Cave and Testing Station
Beams Available
Upon completion of the recommissioning project,
the Cyclotron Institute can expand the Radiation
Effects Facility (REF) program by adding a
dedicated beam line and experimental cave on the
K150 cyclotron. The beam line layout, testing
station and radiation shielding walls have been
designed. The computer code Transport was used
to determine the number of electromagnets needed
and their optimal positions along the beam line
so that both defuse and focused beam spots can be
produced at the target location. A list of ions
at energies produced by the K150 cyclotron has
been determined for the Single Event Effects
(SEE) experimenters.
Radiation Effects
The SEE experimenters require a wide variety of
ions and energies in order to effectively test
their computer chips. The curve in the figure
above shows the maximum E/A as a function of Q/M
for the K150 cyclotron. To reduce tuning time
between ion changes, sets of ions at similar Q/M
ratios have been determined.
The design of the experimental area allows plenty
of room for work space, radiation shielding, and
an entrance labyrinth which allows for easy
access and the containment of secondary radiation
produced by the beam.
Computer chips in aerospace equipment receive
high levels of radiation from solar flares,
cosmic rays and the Earth's Van Allen radiation
belts. The performance of these chips can be
tested with the accelerated beams from the K150
cyclotron which are similar in ion type and close
to the energies experienced in space.
Due to space limitations, an "all in one"
in-air/vacuum chamber testing station has been
re-designed. The K500 REF beam line uses two
separate areas one for in-air testing and one
for vacuum testing. the new design allows the
beam line to be much shorter while not
compromising its usefulness.
Aerospace engineers plot the number of upsets as
a function of LET to understand how well their
computer chips will respond in the radiation
fields of the earth. Upset cross sections tend to
follow the pattern shown in the figure above
which includes three parts the threshold, knee
and saturation regions. With ions having range of
100 microns and LET up to 60 MeV/mg/cm2,
engineers can test "In-air" and up to LETs into
the saturation region with the K150 accelerated
beams.
Beam is transported along the beam line from the
K150 cyclotron. The quadrupole magnet pairs focus
and/or defocus the beam and the dipole magnet
bends the beam into the experimental area. The
computer code Transport was used to determine
the optimal positions for quadrupole magnet pairs
2, 3 and 4. The magnetic fields of the quadrupole
magnet pairs can be set so that the beam spot at
the testing station is either diffuse or focused.
The diagrams above show the phase space of the
beam along the beam path for a diffuse beam spot
scenario. This structure is required for the SEE
experiments and ensures that their computer chips
are uniformly irradiated.
The charts above show the linear energy transfer
(LET) as a function of range for ions accelerated
to 5, 14, and 25A MeV/nucleon. The 14 and 25
MeV/nucleon ions have enough energy to allow
experimenters to test in air.