同位素10B靶的制备

Preparation of Isotopic 10B Target

  • 摘要: 为准确测量10B(n,α)7Li和10B(n,t2α)的反应截面,需制备质量厚度为50~350 μg/cm210B靶。本文系统研究了同位素10B靶的制备工艺,确定了“压片-烧结-蒸发”三步法制备10B靶。研究了基片温度对10B膜生长过程、结构和膜基结合力的影响,测试和分析了10B靶的不均匀性。结果表明,利用间歇式静电聚焦微调电子轰击法制备同位素10B靶,蒸发速率应低于0.02 μg/(cm2·s);灯丝平面与10B柱的最佳距离为10.5~11 mm;生长的10B膜随基片温度的升高而致密并逐步结晶,膜基结合力也更好,最佳基片温度约为300 ℃。对于尺寸为Ø80 mm同位素10B靶的制备,不均匀性可控制在10%以内。已经成功在Ta和Al基片上制备了厚度<350 μg/cm210B靶用于核物理实验测量。

     

    Abstract: In order to measure accurately the reaction cross sections of 10B(n, α)7Li and 10B(n, t2α), 10B targets with the thickness of 50-350 μg/cm2 should be prepared. The preparation technology of isotopic 10B target was studied. The three-step method of “pressing-sintering-evaporation” was determined. The effects of substrate temperature on the growth process, structure and adhesion of 10B film were studied. The inhomogeneity of 10B target was also measured and analyzed. The results show that the evaporation rate of isotopic 10B target prepared by intermittent electrostatic focusing fine-tuning electron bombardment method should be less than 0.02 μg/(cm2·s). The optimum distance between filament plane and 10B column is 10.5-11 mm. The growth of 10B film is compact and crystallizes gradually with the increase of substrate temperature, and the adhesion between film and substrate is better. The optimum substrate temperature is about 300 ℃. For the preparation of isotopic 10B target with the size of Ø80 mm, the inhomogeneity can be controlled within 10%. The 10B targets with the thickness less than 350 μg/cm2 were successfully fabricated on Ta and Al substrates, and used in the measurements of nuclear physics experiments.

     

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