在SINR回旋加速器质谱计中磁场的非电垫补

Non-electrical shimming of the magnetic field in the SINK minicyclotron AMS

我所承担的国家自然科学基金重大项目——“超灵敏小型回旋加速器质谱计研制”的目标是研制一台方便、实用、小型、低能的回旋加速器质谱计,用于^(14)C质谱分析。该质谱计具有高的倍频次数和低的磁场强度等特点。被测粒子需在16次倍频下加速100圈左右,这对磁场的等时性提出了很高的要求。由于质谱计的小型化要求,我们采用非电垫补(即机械修正)的办法来调整磁场分布,使之满足等时性要求。在垫补的实现过程中,磁场分布的测量是一个关键的环节,要求在峰值场为0.37T的低场下,达到万分之一的测量精度。为此,需要在测量工具的制作和安装;仪器的调整及测量数据的处理方面做大量的工作。

A non-electrical shimming of magnetic field has recently been completed in the SINR minicyclotron AMS. After shimming five times , deviation of the isochronous field is 1×10-4 -3×10-4. The accumulated maximum phase shift of the central particle is about ±10°under high harmonic operation of 16 and with turn number of 100. Amplitude of the first harmonic has been lowered down to less than 1×10-4T. It tooks only 50 minutes for the magnetic field measuring device to get a whole map of the magnetic field with 1° step.