The NEPOMUC upgrade and advanced positron beam experiments
The NEPOMUC upgrade and advanced positron beam experiments
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DOI：
10.1088/1367-2630/14/5/055027
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发表时间：
2012-05-31
影响因子：
3.3
通讯作者：
Schreckenbach, Klaus
中科院分区：
文献类型：
--
作者：
Hugenschmidt, Christoph;Piochacz, Christian;Schreckenbach, Klaus
FRMII的中子诱导正电子源NEPOMUC提供了每秒109个慢化正电子的高强度单能正电子束。提出了NEPOMUC升级的新布局，并讨论了在研究堆上运行堆内正电子源的约束条件。在新束管的尖端，80%富集Cd-113的Cd被用作中子- γ转换器，预计反应堆运行寿命为25年，从而确保正电子束实验的长期进行。该源由铂箔组成，这两种箔都产生正电子，通过对生产，并调节它们。这些薄膜的布局、电透镜以及用于正电子提取和光束形成的磁场都得到了改进。除了更高的光束强度外，预计光束亮度将至少提高一个数量级。目前和计划中的实验范围从核、原子和等离子体物理的基础研究到表面和固体物理的高灵敏度和元素选择研究，再到材料科学的应用。介绍了几台正电子能谱仪的升级改造和新的正电子束流实验。此外，一个新的开关和再调节装置将使我们能够从高强度的主光束切换到亮度增强的再调节正电子光束。
The neutron-induced positron source NEPOMUC at the FRMII provides a mono-energetic positron beam of high intensity of the order of 109 moderated positrons per second. The new layout of NEPOMUC upgrade is presented and the constraints for operating an in-pile positron source at a research reactor are discussed. Inside the tip of the new beam tube, 80% Cd-113-enriched Cd is used as a neutron-gamma-converter that has a projected lifetime of 25 years of reactor operation and thus ensures positron beam experiments in the long term. The source consists of Pt foils that both generate positrons, by pair production, and moderate them. The layout of these foils, the electric lenses and the magnetic fields for positron extraction and beam formation have been improved. In addition to a higher beam intensity, it is expected that the beam brightness will improve by at least one order of magnitude. The present and planned experiments range from fundamental studies in nuclear, atomic and plasma physics to high-sensitivity and element-selective investigations in surface and solid state physics to applications in materials science. The upgrade of several positron spectrometers as well as new positron beam experiments are presented. In addition, a new switching and remoderation unit will allow us to toggle from the high-intensity primary beam to a brightness enhanced remoderated positron beam.