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: (54)Mn, (57)Co, (60)Co, (88)Y, (109)Cd, (134)Cs, (137)Cs, and (152)Eu at distances of 5 and 10cm 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 88-1836keV.