Compact broadband high-resolution Compton spectroscopy for laser-driven high-flux gamma rays

A compact broadband Compton spectrometer with high spectral resolution has been designed to detect spectra of laser-driven high-flux gamma rays.The primary detection range of the gamma-ray spectrum is 0.5 MeV-13 MeV,although a secondary harder gamma-ray region of13 MeV-30 MeV can also be covered.The Compton-scattered electrons are spectrally resolved using a curved surface detector and a nonuniform magnetic field produced by a pair of step-like magnets.This design allows a compact structure,a wider bandwidth,especially in the lower-energy region of 0.5 MeV-2 MeV,and optimum spectral resolution.The spectral resolution is 5%-10% in the range 4 MeV-13 MeV and better than 25% in the range 0.5 MeV-4 MeV(with an Al converter of 0.25 mm thickness and a collimator of 1 cm inner diameter).Low-Z plastic materials are used on the inner surface of the spectrometer to suppress noise due to secondary X-ray fluorescence.The spectrometer can be adjusted flexibly via a specially designed mechanic al component.An algorithm based on a regularization method has also been developed to reconstruct the gamma-ray spectrum from the scattered electrons.