Measurement method for laser-accelerated multi-hundred-MeV protons utilizing multiple Coulomb scattering in an emulsion cloud chamber

We have developed a measurement method for laser-accelerated multi-hundred-MeV-class protons using an emulsion cloud chamber (ECC), which consists of a stack of nuclear emulsion films and scatterer plates. Based on multiple Coulomb scattering (MCS) theory depending on the incident energy of protons, we have constructed a regression model to inversely estimate the incident energy by means of support vector regression (SVR) with a radial basis function. The prediction accuracy was approximately 10% (standard deviation) for protons with energies up to 0.3 GeV in a 25 layer ECC with 0.5 mm thick tungsten plates, corresponding to a 2 cm thick compact detector.