Parameters of the proton beam facility
CYCLONE is capable of accelerating proton up to 65 MeV on a regular basis. As beam tuning and transport takes several hours, a system of 4 plastic blocs in polyethylene is used to lower the beam energy down to 14.4 MeV.
Different available energies have been calculated using SRIM code taking the different beam line item into account (beam diffusion foil, pressure window, air and transmission chamber).
With a combination of 4 blocs (2 – 4.2 – 8.2 and 16 mm), 16 different energies are possible at the DUT position (see table below):
In 2014, a new degrador of 1.1 mm thickness has been installed. This will allow us to achieve an energy of 10MeV, with a LET of 3.48 E-2 MeV/mg/cm2 and a range in Si of 0.71 mm.
Energy straggling (standard deviation of energy distribution with respect to the average energy) has been calculated using TRIM. The simulation was performed using 1000 protons at 62 MeV through the different beam line elements and the whole stack of energy degraders, with the final energy of 14.4 MeV, energy straggling is estimated to 1.09 MeV.
For beam flux, the health physics department sets the maximal limit to 2E8 part/s.cm². Lower beam flux can be reached by combination of ion production, puller position and Dee voltage adjustments. Typical flux of 50 part/s.cm² can be reached.
The needed homogeneity is reached using a lead foil with 250 µm placed close to the cave wall. This foil is under vacuum and is placed on a pneumatic jack activated through the user interface.
A +/- 10% homogeneity has been measured over 80mm in the horizontal direction and over 80mm in the vertical direction