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In nuclear physics research and applied research in nuclear technology HPGe detector isprimarily used to detect energy and strength of rays.As with higher resolution,high detection efficiency andgreater detection of x-ray detection range(a few KeV to several MeV),HPGe detector has been widelyapplied to all kinds of ventures measuring.Most crucial metrics for HPGe are energy efficiency resolutionand detection efficiency,detect efficiency is directly related to the physical measurement accuracy,HPGewith significant meaning for the study of detection efficiency.For different measurement purpose thedetector has different definitions.Laboratory HPGe has high detection efficiency and energy resolution,it isused for testing high precision gamma ray measurement of the totipotency vrukh very sharp,even if morecomplicated rays or more of the nuclein issued by the rays incident,the majority of the totipotency vrukhhave been able to separate in isolation,totipotency vrukh easily recognized,and a full spectrum of oftenoccupy a lot of road and totipotency vrukh,the number of factors affecting relatively few, troposcatter andother interference radiation pulse to a lesser extent does not affect to the totipotency peakcounts.totipotency vrukh, symmetricmatrices also easily distinguished peak area easier.In this paper, the high-low HPGe detector and the shielding layer including Pb bricks, iron Fe,oxygen-free copper, polyethylene, the thickness of the selection and detection efficiency simulation.Germanium detector in the simulation of high detection efficiency and keep the shield, we use the lowbackground high purity germanium (HPGe) detector to test the material in theγradiation of naturalradionuclides.Such as rocks, polyethylene, lead, radioactive photoelectric tubes and asked to meet uBq / kgof the specific activity of radioactive levels.Adopted by the CERN to develop and lead high-energy physicsMonte Carlo for numerical simulation software toolkit geant4, paper simulated detection efficiency ofgermanium crystals, shielding the detection efficiency of different thickness: including lead thickness 5cm,10cmiron thickness of 2cm, 4cm, 6cm, 8cm, 10cm, polyethylene thickness of 2cm, 4cm, 6cm, 8cm, 10cm,oxygen-free copper thickness of 2cm, 4cm, 6cm, 8cm, 10cm.Through simulation, obtained with differentshielding thickness ofγ-ray detection efficiency and establish a very low background HPGe detectorγ-rayshielding system, suitable for the selection of low background radiation level of the material, reducingdarkmatter, the background radiation measurement system is of great significance level.
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