Computer simulation of the space charge dominated beam dynamics for external injection into the JINR Phasotron
A project of increasing the beam intensity of the 660 MeV JINR proton Phasotron up to 50 µA by an external injection of the H − beam with energy of 5 MeV is now under design. Computer simulation of the space charge dominated beam dynamics in Phasotron is reported. As follows from the simulation, the capture efficiency does not change too much when the beam space charge is taken into account.
The magnetic analogue method as used in the study of a cyclotron central region
Abstract The shape of the electric field in a given electrode configuration can be found with the help of a magnetic analogue. In the study of the central particle trajectories of a cyclotron, where a detailed knowledge of the electric accelerating fields is essential, this method appears to be particularly useful. A detailed discussion of the method itself is presented. A computer-controlled apparatus has been built to perform the necessary measurements. The mensuring procedures, the subsequent checks and corrections that are applied and the use of the fields in the orbit integrations are reviewed.
rPET detectors design and data processing
Small animal PET systems based on rotating planar detectors posses some interesting advantages for high sensitivity, high resolution imaging. We have designed the rPET detectors based on MLS crystals assembled on a 30times30 matrix optically coupled to a flat-panel PS-PMT. Weighted position readout circuits pre-process the 64 signals from the 8times8 anodes matrix, which are digitized using a charge-integrating converter. The amplification electronics, including the trigger output for coincidence detection, and the high voltage supply are integrated in a three PCBs stack that forms the base attached to the back of the PMT. The whole assembly is enclosed in a light tight, lead (Pb) shielded aluminum box. The detectors are mounted on a rotating gantry with more than 180 degrees rotation span. The digitized events are screened and histogramed, and a modified center of gravity algorithm removes from the position calculation those signals with poor signal to noise ratio. Apparent mean crystal size on the 511 keV field-flood images is 0.6 mm, mean peak-to-valley ratio is better than 8, and intrinsic resolution is 1.5 mm at the central row, with the energy window wide open. Sensitivity (CPS) for a pair of these detectors set in coincidence at 160 mm distance is 1%