The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration has performed measurements with a fission time projection chamber (fissionTPC) to study the fission process by reconstructing full three-dimensional tracks of fission fragments and other ionizing radiation. The amount of linear momentum imparted to the fissioning nucleus by the incident neutron can be inferred by measuring the opening angle between the fission fragments. Using this measured linear momentum, fission fragment angular distributions can be converted to the center-of-mass frame for anisotropy measurements. Angular anisotropy is an important experimental observable for understanding the quantum mechanical state of the fissioning nucleus and vital to determining detection efficiency for cross section measurements. Neutron linear momentum transfer to fissioning $^{235}$U, $^{238}$U, and $^{239}$Pu and fission fragment angular anisotropy of $^{235}$U and $^{238}$U as a function of neutron energies in the range 130 keV--250 MeV are presented.

中文翻译：

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使用 NIFFTE 裂变时间投影室测量的中子诱导裂变碎片角分布、各向异性和线性动量传递

中子诱导裂变碎片跟踪实验 (NIFFTE) 合作使用裂变时间投影室 (fissionTPC) 进行了测量，通过重建裂变碎片和其他电离辐射的完整三维轨迹来研究裂变过程。可以通过测量裂变碎片之间的张角来推断入射中子赋予裂变核的线性动量的量。使用这种测量的线性动量，裂变碎片角分布可以转换为各向异性测量的质心框架。角各向异性是理解裂变核的量子力学状态的重要实验观测值，对于确定横截面测量的检测效率至关重要。