飞秒激光诱发的医用质子束特性的实验研究

Experimental study of femtosecond laser-induced medical energy proton beam

为了探索飞秒脉冲激光与固体靶相互作用中医用质子束特性,在超短超强激光装置"SILEX-I"上进行了医用高能质子束特性实验研究。实验利用HD810辐射变色膜片(RCF)、CR39核径迹探测器和Thomson离子谱仪分别在固体靶背表面法线方向测量了质子束的空间分布、束密度、产额和能谱。实验结果表明:质子束沿着靶背法线方向发射,与入射激光方向无关;质子束空间分布呈现环状、成丝和圆盘状分布,并且质子束存在较小的发射立体角;保持复合靶前表面的Au厚度不变,质子束流随着后表面的C8H8层厚度的增加而减小;质子束发射在一定能量处出现截止,截止能量的大小与靶厚度有关,即随靶厚度的增加而减小。

To study the characteristics of medical proton beam produced in the interaction of femtosecond pulse laser with solid targets,the proton beam behavior at the normal direction of the rear surface of the solid targets produced from ulintencity pulse laser was explored on SILEX-I laser facility.The spatial distributions of the proton beam with different target thicknesses were recorded by radiochromic film（RCF） HD810.The density and yield of the proton beam were recorded by nuclear track detector CR39.And the proton energy spectrum was measured by Thomson magnetic spectrometer.The results show that high energy protons jet only in the direction normal to the rear surface of target within a small cone angle.With the same thickness of Au layer,the proton beam flux decreases with the increasing of C8H8 layer thickness,and the corresponding spatial profile of proton beam shows ring-,filament-,and disc-like distributions.A sharp cutoff energy exists in the proton energy spectrum,and it depends on the target thickness and decreases with the increasing of target thickness.