Jones E A, Smith F A, Goodhead D T, Oriel J
Department of Medical Electronics and Physics, St Bartholomew's Medical College, London, UK.
Phys Med Biol. 1988 Dec;33(12):1385-97. doi: 10.1088/0031-9155/33/12/004.
The proton beam from an AN700 van de Graaff accelerator has been used to bombard solid targets of C, TiB2, SiC, SiN, Al and Au in the energy range 250-700 keV. A study of target surface contamination, the nature of the angular dependence in the x-ray emission and the dependence of the x-ray yield on proton energy has been undertaken. Our findings suggest that the optimum target angle is 30 degrees with respect to the incident proton direction and the detector angle 90 degrees to the target surface. In a vacuum of 10(-5) Torr (approximately 1.33 mPa) and at proton currents of 50-100 muA, a carbon deposit can be expected to build up with time on the target surface to reduce the characteristic x-ray intensity from the target. In the comparison between the energy dependent yields of CK and AlK x-rays, we find a slightly smaller dependence on energy than that predicted by the empirical cross section formula of Paul (1984) although the latter is not expected to be valid down to Z = 6.
来自一台AN700范德格拉夫加速器的质子束已被用于轰击碳、二硼化钛、碳化硅、氮化硅、铝和金的固体靶，能量范围为250 - 700千电子伏特。已对靶表面污染、X射线发射中角依赖的性质以及X射线产额对质子能量的依赖性进行了研究。我们的研究结果表明，相对于入射质子方向的最佳靶角度为30度，探测器与靶表面的角度为90度。在10^(-5)托（约1.33毫帕斯卡）的真空中，且质子电流为50 - 100微安时，预计随着时间推移靶表面会形成碳沉积物，从而降低来自靶的特征X射线强度。在碳K和铝K X射线的能量相关产额的比较中，我们发现其对能量的依赖性略小于保罗（1984年）的经验截面公式所预测的，尽管预计后者在原子序数低至Z = 6时并不适用。
