Capabilities of the NIFFTE FissionTPC
R. J. Casperson
1 Introduction
Accurate neutron-induced fission cross section measurements are crucial for nuclear
reactor design and stockpile stewardship. Future nuclear reactors may use fast
neutrons, which would require higher precision measurements at higher incident
neutron energies [1–3]. Fission cross section measurements are often performed
in ratio, with 238 U or 235 U used as a reference reaction, and many of these past
measurements were performed with parallel-plate ionization chambers [4]. The
stacks of actinide foils are spaced close together to emphasize the large specific
ionization of fission fragments relative to α particles from the decay of the target
material.
Twin Frisch-grid ionization chambers [5, 6] go beyond conventional ionization
chambers, using multiple signals to enable a determination of the charged-particle
track angle. The detected angle contains information about the amount of actinide
target material traversed, and can be included in the estimation of fission fragment
detection efficiency.
The fission Time Projection Chamber (fissionTPC) was designed for full threedimensional charge cloud reconstruction by the NIFFTE (Neutron-Induced Fission
Fragment Tracking Experiment) Collaboration, applying technologies that have
been used since the 1970s for high-energy physics to low-energy nuclear physics
challenges. The fissionTPC has a two volume drift chamber with MICROMEGAS
of 2 mm pitch, typically operated with a blend of argon and isobutane [7]. Tracking
algorithms allow for vertexing of the charge cloud, providing a mass distribution for
actinide target, as well as angle and energy information of detected particles.
R. J. Casperson for the NIFFTE Collaboration ()
Lawrence Livermore National Laboratory, Livermore, CA, USA
e-mail: casperson1@llnl.gov
© This is a U.S. government work and not under copyright protection
in the U.S.; foreign copyright protection may apply 2021
J. Escher et al. (eds.), Compound-Nuclear Reactions, Springer Proceedings in
Physics 254, https://doi.org/10.1007/978-3-030-58082-7_38
301
R. J. Casperson
1 Introduction
Accurate neutron-induced fission cross section measurements are crucial for nuclear
reactor design and stockpile stewardship. Future nuclear reactors may use fast
neutrons, which would require higher precision measurements at higher incident
neutron energies [1–3]. Fission cross section measurements are often performed
in ratio, with 238 U or 235 U used as a reference reaction, and many of these past
measurements were performed with parallel-plate ionization chambers [4]. The
stacks of actinide foils are spaced close together to emphasize the large specific
ionization of fission fragments relative to α particles from the decay of the target
material.
Twin Frisch-grid ionization chambers [5, 6] go beyond conventional ionization
chambers, using multiple signals to enable a determination of the charged-particle
track angle. The detected angle contains information about the amount of actinide
target material traversed, and can be included in the estimation of fission fragment
detection efficiency.
The fission Time Projection Chamber (fissionTPC) was designed for full threedimensional charge cloud reconstruction by the NIFFTE (Neutron-Induced Fission
Fragment Tracking Experiment) Collaboration, applying technologies that have
been used since the 1970s for high-energy physics to low-energy nuclear physics
challenges. The fissionTPC has a two volume drift chamber with MICROMEGAS
of 2 mm pitch, typically operated with a blend of argon and isobutane [7]. Tracking
algorithms allow for vertexing of the charge cloud, providing a mass distribution for
actinide target, as well as angle and energy information of detected particles.
R. J. Casperson for the NIFFTE Collaboration ()
Lawrence Livermore National Laboratory, Livermore, CA, USA
e-mail: casperson1@llnl.gov
© This is a U.S. government work and not under copyright protection
in the U.S.; foreign copyright protection may apply 2021
J. Escher et al. (eds.), Compound-Nuclear Reactions, Springer Proceedings in
Physics 254, https://doi.org/10.1007/978-3-030-58082-7_38
301