Estimating thickness of the inner dead-layer of n-type HPGe detector

In this study, a procedure to estimate thickness of the inner dead-layer of an n-type coaxial HPGe detector is described. Experimental measurements are carried out with standard point sources: ⁵⁴Mn, ⁵⁷Co, ⁶⁰Co, ⁸⁸Y, ¹⁰⁹Cd, ¹³⁴Cs, ¹³⁷Cs, and ¹⁵²Eu at distances of 5 and 10 cm from source to detector. Shape and dimensions of a high-purity germanium (HPGe) detector are determined by radiography to characterize the geometry accurately for Monte Carlo simulation. The role of thickness of the inner dead-layer on full energy peak efficiency is illustrated by MCNP5 code, and it is observed that slope coefficient of efficiency curve has a linear relationship with thickness of the dead-layer. The adjustment of dead-layer yields good agreement, with relative deviation of ≤3%, between experimental efficiency and simulated efficiency in the energy range of 88–1836 keV. - Highlights: • This study aims a linear function of the efficiency versus energy depend on the variable of the dead-layer. • The interpolation thickness of the inner dead-layer was estimated to be approximately twice the nominal value by the manufacturer. • The response function showed a good agreement between experimental and simulation using the adjustment of inner dead-layer.