Monte Carlo analysis of the influence of germanium dead layer thickness on the HPGe gamma detector experimental efficiency measured by use of extended sources

Study on Variation of HPGE Detector Dead Layer Thickness and its Effect on the Measurements of the Detector Response and Samples Characterization Using Monte Carlo Simulation

Volume 3: Nuclear Fuel and Material, Reactor Physics, and Transport Theory ◽

10.1115/icone26-82098 ◽

2018 ◽

Author(s):

K. Abd El Gawad ◽

Yushou Song

Keyword(s):

Monte Carlo ◽

Monte Carlo Method ◽

Layer Thickness ◽

Hpge Detector ◽

Dead Layer ◽

Nuclear Safeguards ◽

Detector Response ◽

Dead Layer Thickness ◽

235U Enrichment ◽

Good Agreement

The main objective of this work is to produce an optimal modeling for our aged Planar-HPGe detector using Monte Carlo method (MC). That optimization included the analysis of the germanium dead (inactive) layer thickness for our old detection system (planar-HPGe detector). DL is one of the important parameters needed in order to obtain the smallest discrepancy between simulated and experimental measurements of detector efficiency. Also, precise determination of 235U enrichment for UO2 samples which is necessary for purposes of nuclear materials verification in the field of nuclear safeguards. The thickness of Germanium dead layer (DL) can be vary by time as it is not well known due to the existence of a transition zone where photons are strongly attenuated and absorbed, that cannot contribute to the total photon energy absorption which causes a significant decrease in efficiency. Therefore, using data provided by manufacturers since long years (manufacture date) in the detector simulation model is not convenient. As a result, some strong discrepancies appear between measured and simulated efficiency, in addition to that non-accurate results for 235U enrichment determination. The Monte Carlo method applied to overcome this difficulty was to vary the thickness of dead layer step by step in simulation, a good agreement (minimum deviation) between estimated and experimental efficiency was reached when a suitable germanium dead layer thickness was chosen. Calculations and measurements were performed for radioactive nuclear material samples in the form of UO2 powder with different sizes and enrichments at different locations, under different gamma-lines emitted after a-decay of the 235U nuclei. Results indicated that a good agreement between simulated and measured efficiencies is obtained using a value for the germanium dead layer thickness approximately (2.45 mm) six in comparison with (0.389 mm) provided by the detector manufacturer.

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Assessment of the inactive dead layer thickness of old high-purity germanium detector: A study by Monte Carlo simulations and experimental verification

Radiation Protection and Environment ◽

10.4103/rpe.rpe_15_17 ◽

2017 ◽

Vol 40 (2) ◽

pp. 69

Author(s):

Narayani Krishnan ◽

S Anilkumar ◽

AmitK Verma ◽

Rajvir Singh

Keyword(s):

Monte Carlo ◽

Monte Carlo Simulations ◽

Layer Thickness ◽

Experimental Verification ◽

High Purity ◽

Germanium Detector ◽

Dead Layer ◽

High Purity Germanium Detector ◽

High Purity Germanium ◽

Dead Layer Thickness

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Dead layer thickness characterization of an HPGe detector by measurements and Monte Carlo simulations

Applied Radiation and Isotopes ◽

10.1016/j.apradiso.2011.11.014 ◽

2012 ◽

Vol 70 (3) ◽

pp. 538-542 ◽

Cited By ~ 32

Author(s):

A. Elanique ◽

O. Marzocchi ◽

D. Leone ◽

L. Hegenbart ◽

B. Breustedt ◽

...

Keyword(s):

Monte Carlo ◽

Monte Carlo Simulations ◽

Layer Thickness ◽

Hpge Detector ◽

Dead Layer ◽

Dead Layer Thickness

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Stochastic simulation study of HPGe detector response and the effect of detector aging using Geant4

Nuclear Technology and Radiation Protection ◽

10.2298/ntrp1701057t ◽

2017 ◽

Vol 32 (1) ◽

pp. 57-69

Author(s):

Hina Tariq ◽

Sikander Mirza ◽

Shakeel Rehman ◽

Nasir Mirza

Keyword(s):

Layer Thickness ◽

Circular Disk ◽

Dead Layer ◽

Detector Response ◽

Maximum Deviation ◽

Total Efficiency ◽

Dead Layer Thickness ◽

Extended Sources ◽

The Dead ◽

Cylindrical Volume

In this study the effect of detector aging in terms of increased dead layer thickness on detector efficiency has been studied using the Geant4 toolkit. Variation of energy deposition in the detector dead layer with the dead layer thickness has been quantified for various values of incident g-ray energy considering point isotropic as well as extended sources including the circular disk source and cylindrical volume sources. For the point isotropic source, the Geant4 computed values of energy loss per particle in the dead layer are found in good agreement with the corresponding published results with maximum deviation remaining below 2 %. New results for dependence of geometric, full-energy peak and total efficiency on dead layer thickness have been studied using Geant4 simulations for various values of g-ray energy, and for point isotropic and extended sources at various axial and lateral positions. These simulations yield an exponentially decreasing profile of detector aging sensitivity with an increase in g-ray energy for point isotropic, circular disk and cylindrical volume sources highlighting a larger decrease in efficiency due to aging for low energy photons.

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Investigation of Dead Layer Thickness in SrRuO3/Ba0.5Sr0.5TiO3/Au Thin Film Capacitors

MRS Proceedings ◽

10.1557/proc-655-cc3.2.1 ◽

2000 ◽

Vol 655 ◽

Cited By ~ 4

Author(s):

L. J. Sinnamon ◽

R. M. Bowman ◽

J. M. Gregg

Keyword(s):

Thin Film ◽

Dielectric Constant ◽

Layer Thickness ◽

Perovskite Phase ◽

Frequency Dispersion ◽

Dead Layer ◽

Parameter Ratio ◽

Thin Film Capacitors ◽

Dead Layer Thickness ◽

The Dead

AbstractThin film capacitors with barium strontium titanate (BST) dielectric layers of 7.5 to 950 nm were fabricated by Pulsed Laser Deposition. XRD and EDX analyses confirmed a strongly oriented BST cubic perovskite phase with the desired cation stoichiometry. Room temperature frequency dispersion (ε100 kHz / ε100 Hz) for all capacitors was greater than 0.75. Absolute values for the dielectric constant were slightly lower than expected. This was attributed to the use of Au top electrodes since the same sample showed up to a threefold increase in dielectric constant when Pt was used in place of Au. Dielectric constant as a function of thicknesses greater than 70 nm, was fitted using the series capacitor model. The large interfacial parameter ratio di / εi of 0.40 ± 0.05 nm implied a significant dead-layer component within the capacitor structure. Modelled consideration of the dielectric behaviour for BST films, whose total thickness was below that of the dead layer, predicted anomalies in the plots of d/ ε against d at the dead layer thickness. For the SRO/BST/Au system studied, no anomaly was observed. Therefore, either (i) 7.5 nm is an upper limit for the total dead layer thickness in this system, or (ii) dielectric collapse is not associated with a distinct interfacial dead layer, and is instead due to a through-film effect.

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