论文标题
$^{14} $ n（n，p）$^{14} $ c横截面的$^{14}的测量
Measurement of the $^{14}$N(n,p)$^{14}$C cross section at the CERN n_TOF facility from sub-thermal energy to 800 keV
论文作者
论文摘要
背景：$^{14} $ n（n，p）$^{14} $ c反应引起了中子捕获疗法的兴趣，在中子捕获疗法中，与氮相关的剂量是由于低能中的中子而引起的主要成分，而在天体物理学中，14N在Sprocess中充当中子毒。在部分能量范围内获得的现有数据之间存在几个差异：热能，KEV区域和共振区域。目的：首次在单个测量中测量从热到共振区域的14n（n，p）14c横截面，包括第一个共振的表征，并提供麦克斯韦平均横截面（MAC）的计算。方法：飞行时间技术。 CERN中子飞行时间（N_TOF）设施的实验区域2（EAR-2）。 $^{10} $ b（n，$α$）$^7 $ li和$^{235} $ u（n，f）反应作为参考。两个同时运行的检测系统，一个梁上，另一个偏离梁。用R-Matrix代码Sammy的共鸣描述。结果：横截面已从次热能到800 keV解决两个第一个共振（在492.7和644 KEV）。热横截面（1.809 $ \ pm $ 0.045 b）比最近的两个测量值低一个以上的标准偏差，但与ENDF/B-VIII.0和JEFF-3.3评估相一致。横截面的1/V能量依赖性已被确认为数十个KEV中子能量。第一个共振在492.7 keV处的低能尾部低于评估值所建议的，而整体共振强度与评估相符。结论：我们的测量允许首次在广泛的能量范围内确定$^{14} $ n（n，p）横截面。我们已经获得了从亚热能到800 keV的高精度（2.5％）的横截面，并使用这些数据计算了Kt = 5至KT = 100 KEV的MAC。
Background: The $^{14}$N(n,p)$^{14}$C reaction is of interest in neutron capture therapy, where nitrogen-related dose is the main component due to low-energy neutrons, and in astrophysics, where 14N acts as a neutron poison in the s-process. Several discrepancies remain between the existing data obtained in partial energy ranges: thermal energy, keV region and resonance region. Purpose: Measuring the 14N(n,p)14C cross section from thermal to the resonance region in a single measurement for the first time, including characterization of the first resonances, and providing calculations of Maxwellian averaged cross sections (MACS). Method: Time-of-flight technique. Experimental Area 2 (EAR-2) of the neutron time-of-flight (n_TOF) facility at CERN. $^{10}$B(n,$α$)$^7$Li and $^{235}$U(n,f) reactions as references. Two detection systems running simultaneously, one on-beam and another off-beam. Description of the resonances with the R-matrix code sammy. Results: The cross section has been measured from sub-thermal energy to 800 keV resolving the two first resonances (at 492.7 and 644 keV). A thermal cross-section (1.809$\pm$0.045 b) lower than the two most recent measurements by slightly more than one standard deviation, but in line with the ENDF/B-VIII.0 and JEFF-3.3 evaluations has been obtained. A 1/v energy dependence of the cross section has been confirmed up to tens of keV neutron energy. The low energy tail of the first resonance at 492.7 keV is lower than suggested by evaluated values, while the overall resonance strength agrees with evaluations. Conclusions: Our measurement has allowed to determine the $^{14}$N(n,p) cross-section over a wide energy range for the first time. We have obtained cross-sections with high accuracy (2.5 %) from sub-thermal energy to 800 keV and used these data to calculate the MACS for kT = 5 to kT = 100 keV.
