论文标题
Mainz Microtron Mami的500 MEV正电子束的设计研究
Design study for a 500 MeV positron beam at the Mainz Microtron MAMI
论文作者
论文摘要
已经在Mainz Microtron Mami的应用物理区域实现了一个具有500 MeV的正电子束进行设计研究。将在Bremsstrahlung的一对转换后创建正电子，这是由855 MEV电子束AF Mami在钨转换器目标中产生的。从Bremsstrahung转换器目标本身中的两个可能的几何形状（I）成对转换中，以及（ii）Bremsstrahlung对在分离的铅箔中的转换，前者被详细考虑。正电子将是在外部开放电子束线弯曲磁铁中选择的能量，并用附加的扇形磁铁弯曲。两者之间的磁聚焦元素的设计旨在在屏蔽良好的正电子目标腔室中进行准备，该目标腔室距离目标梁约6 m，具有epsilon_v = 0.055 pi mm mrad（1 sigma）和epsilon_h = 0.12 pi mm mrad（1 sigma）的水平和垂直发射率，分别为10 micm sheg groms groms gromsos gromsos，egnibor mmrad（1 sigma）= 0.12 pi mmmmmmmmmmmm Monment。在公认的正电子带宽度为1 MeV时，垂直斑点的斑点是0.064 MRAD，大小为5.0 mm（FWHM），水平尺寸为0.64 MRAD，大小为7.7 mm（FWHM）。正电子产率为每秒13.1，1 MEV正电子能带宽度和1个Na电子束电流。
A design study has been performed for a positron beam with an energy of 500 MeV to be realized at the applied physics area of the Mainz Microtron MAMI. Positrons will be created after pair conversion of bremsstrahlung, produced by the 855 MeV electron beam af MAMI in a tungsten converter target. From the two conceivable geometries (i) pair conversion in the bremsstrahlung converter target itself, and (ii) bremsstrahlung pair conversion in a separated lead foil, the former was considered in detail. Positrons will be energy selected within an outside open electron beam-line bending magnet, and bent back by an additional sector magnet. Magnetic focusing elements in between are designed to prepare in a well shielded positron target chamber about 6 m away from the target a beam with horizontal and vertical emittances of epsilon_v = 0.055 pi mm mrad (1 sigma), and epsilon_h = 0.12 pi mm mrad (1 sigma), respectively, for a 10 micro m thick amorphous tungsten target and negligible momentum spread. At an accepted positron band width of 1 MeV, spots are expected vertically with an angular spread of 0.064 mrad and a size of 5.0 mm (FWHM), and horizontally with an angular spread of 0.64 mrad and a size of 7.7 mm (FWHM). The positron yield amounts to 13.1 per second, 1 MeV positron energy band width, and 1 nA electron beam current.
