SPAGINS: Semi-empirical PArameterization for fragments in Gamma Induced Nuclear Spallation

From empirical phenomena of fragments distributions in nuclear spallation reactions, the semi-empirical formulas named as SPAGINS are constructed to predict fragments cross sections in high energy $\gamma$ induced nuclear spallation reactions (PNSR). In constructing the SPAGINS formulas, theoretical models including the TALYS toolkit, the SPACS, and Rudstam formulas were employed to study the general phenomenon of fragment distributions in PNSR with incident energy from 100 MeV to 1000 MeV. Considering the main characteristics of PNSR, the SPAGINS formulas modify the EPAX and SPACS formulas, and are verified can reproduce the measured data well. The SPAGINS formulas provide a new effective tool to predict fragment productions in PNSR.