Radiation Pressure effects on ion Acceleration on the GEMINI laser

We report on the absolute calibration of amicro channel plate (MCP) detector, installed asdetector in a Thomson parabola spectrometer. Thecalibration delivers the relation between a registeredcount numbers in the CCD camera (on which the MCPphosphor screen is imaged) as a result of the impact ofan ion beam onto the MCP. The particle response ofthe whole detection system was evaluated by usinglaser accelerated ions with proton energies up to 3MeV and carbon ion energies up to 16 MeV. In orderto obtain an absolute measurement of the number ofions incident on the MCP detector, slotted CR-39track detector was installed in front of the MCP. Thesignal registered on the MCP due to ions propagatingthrough the CR-39 slots is compared to the number ofparticles counted on the adjacent CR-39 stripes afterthe etching. The calibration of the response of MCPhas been extended to higher energy ions and protonson the basis of a simple model validated bycomparison with the calibration data. This sensitivedetection set-up makes it possible to measure in asingle laser shot the ion spectrum in absolute terms.