Design of Antiproton Target for FAIR

Production and collection of antiprotons will be one of the many important experiments that will be done at the FAIR. The SIS100 will deliver a bunched proton beam with, intensity = 2 ◊ 10 11 protons, bunch length = 25 ns and particle energy = 29 GeV. The design of a production target that will survive over an extended period of time is a very important and difficult problem. Figure 1 shows the proposed target geometry which is the same as used previously in the CERN antiproton pro- duction experiments. It consists of 6 iridium cylinders, each 1 cm long and having a radius of 2 mm with a small gap of 50 µm between two neighboring pieces. This avoids bending of the target as a result of expansion due to heating. The iridium part is enclosed in a solid graphite casing that is followed by an aluminum cover. The advantage of using graphite is that it has much lower absorption cross section for antiprotons. The dimensions of the different parts of th e target are shown in the figure. The proton beam is incident at the left face of the target, the protons generate a shower of secondary particles that deposit their energy in the targ et. The energy deposition is calculated using the FLUKA code and the results are plotted in Fig. 2. The focal spot size of the beam is characterized with a = 1.5 mm in this case. The antiprotons generated in the target will be collected on the right side of the target using a magnetic horn.