The present disclosure provides systems and methods where an electron focusing device can be combined with a scintillation detector to better focus the electrons generated by a light sensing device. The scintillation detector can include a scintillation crystal that is covered by an inner light-reflecting coating layer where the scintillation crystal may emit photons due to measurement radiation(s). The light sensing device can include a photomultiplier that may receive the photons emitted by the scintillation crystal and convert them into the electrons generated. The electron focusing device can include a metal ring magnet or one or more conducting coils encircling the scintillation crystal that may create a magnetic field so as to focus the electrons generated by the light sensing device.