The POSH intense keV Positron Beam

In 2000, the intense variable energy keV positron beam POSH was completed. Its intensity of 4 x 10^8 positrons/s made it the most intense beam in the world. In March 2000, the POSH beam was succesfully coupled to a new ACAR target chamber and operative for depth-selective 2D-ACAR studies in the (sub-)micron range, using an Anger cameras-based detection system.

In the near future, it is expected that the POSH beam will be coupled to a positron microprobe.

Fig 1: POSH-ACAR facility. 1) two position-sensitive detectors (Anger cameras) which are commonly put at a total distance of 23.5 m; 2) conventional (22Na-based) ACAR chamber; 3) POSH tube; 4) HV electrostatic accelerator (0-25 keV); 5) rotatable insert.

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