Ruskov E, Glebov V Yu, Darling T W, Wessel F J, Conti F, Valenzuela J C, Rahman H U, Beg F N
Magneto-Inertial Fusion Technologies, Inc., Tustin, California 92612, USA.
Laboratory for Laser Energetics, Rochester, New York 14623, USA.
Rev Sci Instrum. 2019 Jul;90(7):073505. doi: 10.1063/1.5090785.
Detection of secondary D(t, n)He neutrons produced when thin argon or krypton gas shells implode on a deuterium gas target is a very challenging task because the secondary neutron yield is a small fraction of the primary neutron yield and because the implosion is often accompanied by an intense hard X-ray burst. We built a large volume neutron time of flight (nTOF) detector using liquid scintillator (xylene solvent with small quantities of wavelength shifting PPO + bis-MSB fluors) in an attempt to increase the detection probability for secondary neutrons in our staged Z-pinch experiments at the 1 MA Zebra pulsed-power generator. Two fast, gated microchannel plate photomultiplier tubes detect the light created in 21 liters of liquid. The hard X-rays were successfully suppressed in the recorded nTOF traces, but we found no evidence of secondary neutrons. The signal quality from the primary D(d, n)He neutrons was higher compared to the signal quality from a plastic scintillator nTOF, thus providing a more reliable estimate of the deuterium ion temperature at the pinch stagnation time. Cross-calibration with a silver activation detector enables standalone neutron yield measurement.
探测薄氩气或氪气壳层向氘气靶内爆聚时产生的次级D（t，n）He中子是一项极具挑战性的任务，因为次级中子产额只是初级中子产额的一小部分，而且内爆聚过程通常伴随着强烈的硬X射线爆发。我们在1兆安斑马脉冲功率发生器上进行的多级Z箍缩实验中，使用液体闪烁体（含有少量波长转换剂PPO + 双-MSB荧光剂的二甲苯溶剂）构建了一个大体积中子飞行时间（nTOF）探测器，试图提高对次级中子的探测概率。两个快速、门控微通道板光电倍增管探测21升液体中产生的光。在记录的nTOF轨迹中，硬X射线被成功抑制，但我们没有发现次级中子的迹象。与塑料闪烁体nTOF相比，初级D（d，n）He中子的信号质量更高，从而能更可靠地估计箍缩停滞时刻的氘离子温度。与银活化探测器的交叉校准实现了独立的中子产额测量。
