Absolute Full-energy Peak Efficiency Research Articles

Integrated absolute full energy peak efficiency: A measure of photon registration efficiency

Integrated absolute full energy peak efficiency (IAFEPE) is a measure of photon registration efficiency using the γ-ray spectrometry method. We have derived appropriate formulas and theoretical explanations of IAFEPE for the first time. IAFEPE is a definite integral (Riemann integral) of the photon registration efficiency function within the detection energy range. IAFEPE, along with associated quantities such as mass integrated absolute full energy peak efficiency and surface integrated absolute full energy peak efficiency, allows for the quantitative validation of measurement conditions.

Dependence of photon registration efficiency on LaBr3(Ce) detector orientation for in situ radionuclide monitoring

Knowledge of a radiation detector's numerical characteristics allows its energy efficiency to be calibrated theoretically for any measurement geometry. Here, energy efficiency calibration is discussed for oriented LaBr3(Ce) detectors used for in situ radiation monitoring. Vertical and horizontal detector orientations relative to the ground surface are compared using efficiency calibrations based on the detector's numerical characteristics and are equally effective. Quantitative assessment of the different measurement geometries was performed using a new analytical approach: integrated absolute full energy peak efficiency.

MCNP/Lab SOCS Model for Calculating the Absolute Full-Energy Peak Efficiency of HPGe Detector for Different Volume Sources

MCNP/Lab SOCS Model for Calculating the Absolute Full-Energy Peak Efficiency of HPGe Detector for Different Volume Sources

Investigation hybrid MCNP/Angle model for calculating the absolute full-energy peak efficiency of HPGe detector

The absolute full energy peak efficiency values have been obtained by Monte Carlo MCNP5 code and semi-empirical ANGLE3 calibration software for a coaxial HPGe detector. The two calibration methods were combined to build a hybrid MCNP5/ANGLE3 model. The hybrid model can give efficiency calibrations values for various gamma-ray source shapes and geometries and then generate efficiency calibrations for new geometries instantly without needing new standards. The model has been checked experimentally and theoretically and then approved to cover the various gamma detection measurements.

Determination of gamma ray spectrometry efficiency for the attenuation coefficients of some bismuth borate glasses by MCNP and (ISOCS) techniques

Radiation detection has been a main interest for researchers as all kind of produced particles in atomic and subatomic physics based on the measurement systems so-called detector. Detection efficiency is one of the main parameters in detection system besides many other different parameters of the detector. The detector in experimental physics is an instrument that converts radiation energy into an electrical signal, and this is achieved basically by either ionization or excitation. The choice for any type of a detector (gas-filled, scintillation or semiconductor) for any application depends upon the X-ray of gamma energy range of interest. A working model is therefore developed which is capable of describing the overall NaI(Tl) detection efficiency as a function of several known parameters. The attenuation coefficients for the bismuth borate glasses with different concentrations were measured using gamma spectroscopy technique. The numerical absolute efficiency calibration of a detector can be determined by In-Situ Object Calibration Software (ISOCS) and Monte Carlo Neutral Particle version 5 (MCNP5) techniques which does not require any calibration standards or reference materials. By using the ISOCS and MCNP5 methodologies, the full energy peak efficiency of a scintillator detector (3“X3” NaI (Tl)) exposed to Co-60 and Cs-137 gamma ray sources with average accuracy range 0.126–1.224% for the used samples can be detected. The used materials are ternary and are located between the detector and the source to determine the attenuation coefficients for these samples by using the calculated full energy peak efficiencies of a detector. The average accuracy ranged from − 1.808 to 1.960% for linear attenuation coefficient ( $$\mu $$ ), while it ranged from − 1.999 to 1.888% and from − 1.924 to 1.960% for half value layer (HVL) and mass linear attenuation coefficient ( $$\mu _m$$ ), respectively. The calculated values of the absolute full energy peak efficiency have been used to determine the attenuation coefficients of materials with different concentrations and different densities. The results proved the validation of ISOCS and MCNP to determine the absolute full energy peak efficiency of the detector which can be used to determine the attenuation coefficients for the simulated samples and it is a good tool to be used when experimental methods are not available.

Full-energy peak efficiency of asymmetrical polyhedron germanium detector

To understand the nuclear structure for most elements, it is essential to investigate the nuclear excitations by using high precision gamma-ray spectroscopy in which intensive measurements should be carried out. This is becoming a new challenge for the radiation scientific community nowadays, where the instrumentations and technical advances must be developed to be used in a wide range of applications. To discover the weakest nuclear reaction, the maximum probability of the detection system of the total energy of any released individual photon must be determined. In this work, a new mathematical method to calculate the absolute full-energy peak efficiency of asymmetrical polyhedron germanium detector is presented. This type of detector can be arranged in array, forming ?complex detectors of encapsulated germanium crystals?, with the solid angle reaching 82 % of total solid angle coverage, i. e., with the highest possible efficiency and with a good quality of spectral response. In addition, the photon path length was enclosed in the mathematical method to determine its attenuation through different materials such as, the detector active medium and any other material in-between source-detector system during the measuring process. The comparison between the efficiency calculated in this work and that of the published Monte Carlo simulation showed a good agreement and a small variation. However, the method discussed in the current work can be useful in nuclear safeguards, in overcoming the huge difficulties in identification of the energy range of radioactive isotopes and their quantities in nuclear waste.

A method for establishing absolute full-energy peak efficiency and its confidence interval for HPGe detectors

A method is proposed for establishing the absolute efficiency calibration of a HPGe detector including the confidence interval in the energy range of 79.6–3451.2keV. The calibrations were accomplished with the 133Ba, 60Co, 56Co and 152Eu point-like radioactive sources with only the 60Co source being activity calibrated to an accuracy of 2% at the 90% confidence level. All data sets measured from activity calibrated and uncalibrated sources were fit simultaneously using the linearized least squares method. The proposed fit function accounts for scaling of the data taken with activity uncalibrated sources to the data taken with the high accuracy activity calibrated source. The confidence interval for the fit was found analytically using the covariance matrix. Accuracy of the fit was below 3.5% at the 90% confidence level in the 79.6–3451.2keV energy range.

VERIFICATION OF 235U, 238U BY MATHEMATICAL CALIBRATION CURVE FOR POINT SOURCES BY USING MONTE CARLO

The calibration of -ray spectrometer was performed by means of a set of certified standard point sources of energies thatcover the energy range of interest. The value of the absolute full energy peak efficiency ab “ could be found by measuring“CR” experimentally and the use of the known value of “ A “. Also, it is possible to calculate “ab” for a certain source todetector distances (D) by using Monte Carlo [MC] simulation method.The obtained results indicated that the fitting is identical to the experimental curve and MCNP calculations, that is boththese two methods (experimental and MCNP) can be used to extend the curve to cover the high energy range. It is possible todrop any line energy inside the used energy range to estimate the absolute full energy peak efficiency, (for example, the energies185.7, 1001 and 1275 keV corresponding to the sources 235U, 238U and 22Na). However, it can be estimated by usingany method from the previous methods (experimental or MCNP in addition to the fitting equation).

Characterization of HPGe gamma spectrometers by geant4 Monte Carlo simulations

Two coaxial and a low-energy HPGe detector were characterized with Monte Carlo simulations, using the geant4 toolkit. The geometry of the detectors, including the dimensions of the crystal and the internal structural parts, were initially taken from the factory specifications and from X-ray radiographies, and were later fine-tuned. The detector response functions, with special emphasis on the absolute full-energy peak efficiencies and peak-to-total ratios, were calculated and compared to experimental data taken at different measurement geometries. Between 150 keV and 11 MeV an agreement within 1–2 standard deviation has been achieved, whereas systematic deviations were experienced at lower energies.

Evaluation of efficiency for in situ gamma spectrometer based upon cerium-doped lanthanum bromide detector dedicated for environmental radiation monitoring

Nuclear power plants that are planned to be constructed in various countries, including Poland, require to setup an environmental radiation monitoring system. Localization of the installation has to be preceded by the studies determining the level of natural background radiation. Presently the in situ gamma spectrometry is widely used for monitoring the natural as well as artificial radionuclides. An analysis and evaluation of parameters of the spectrometric system equipped with scintillation detector made of cerium-doped lanthanum bromide crystal are both the subject of the paper. The main question of the application of any gamma spectrometry system for the radiation monitoring purpose is how its efficiency looks like. Based on the numerical characteristics of the detector the absolute full energy peak efficiency was calculated. The three dimensions characteristics of gamma ray registration efficiency as the function of its energy and considered contaminated area diameter has been also performed. The study of numerical modeling based on MCNP code was performed by the ISOCS/LabSOCS software tool.

Efficiency Inter-Comparison Measurements of Medium and Large Volume HPGe Detectors in Far and Close Geometries

Inter-comparisons of the absolute full-energy peak efficiencies of two high-purity-germanium (HPGe-50 and HPGe-20) Ortec-model photon detectors were carried out with efficiencies previously measured from a HPGe-20 Tennelec detector in the energy range from 40 to 1,500 keV. The functional parameters are fitted to calibration points from 11 long-lived standard sources (129I, 241Am, 109Cd, 57Co, 137Cs, 60Co,22Na, 133Ba, 152Eu, 154Eu and 166Ho) to an accuracy better than the quoted uncertainties of the calibration sources. The efficiencies in far and close geometries for both detectors are compared.

A software package using a mesh-grid method for simulating HPGe detector efficiencies

Traditional ways of determining the absolute full-energy peak efficiencies of high-purity germanium (HPGe) detectors are often time consuming, cost prohibitive, or not feasible. A software package, KMESS (Kevin’s Mesh Efficiency Simulator Software), was developed to assist in predicting these efficiencies. It uses a semi-empirical mesh-grid method and works for arbitrary source shapes and counting geometries. The model assumes that any gamma-ray source shape can be treated as a large enough collection of point sources. The code is readily adaptable, has a web-based graphical front-end, and could easily be coupled to a 3D scanner. As will be shown, this software can estimate absolute full-energy peak efficiencies with good accuracy in reasonable computation times. It has applications to the field of gamma-ray spectroscopy because it is a quick and accurate way to assist in performing quantitative analyses using HPGe detectors.

Methods and software for predicting germanium detector absolute full-energy peak efficiencies

High-purity germanium (HPGe) and lithium drifted germanium (Ge(Li)) detectors have been the detector of choice for high resolution gamma-ray spectroscopy for many years. This is primarily due to the superior energy resolution that germanium detectors present over other gamma-ray detectors. In order to perform quantitative analyses with germanium detectors, such as activity determination or nuclide identification, one must know the absolute full-energy peak efficiency at the desired gamma-ray energy. Many different methods and computer codes have been developed throughout history in an effort to predict these efficiencies using minimal or no experimental observations. A review of these methods and the computer codes that utilize them is presented.

Calibration of closed-end HPGe detectors using bar (Parallelepiped) sources

The National Institute of Standards and Technology (NIST, Gaithersburg, MD 20878, USA) uses different extended sources, such as bar (parallelepiped) sources of high activity to calibrate the hyper pure germanium (HPGe) cylindrical detectors. The absolute full-energy peak efficiency and the source self-absorption have been investigated in this work by the use of compact analytical expressions for closed-end HPGe detectors and bar sources. The validity of these expressions is tested through extensive comparisons with the experimental values carried out in the NIST. The comparisons indicate that the direct mathematical method used in the present work is useful in the efficiency calibration of HPGe detectors with bar sources.

Wide energy range efficiency calibration for a lanthanum bromide scintillation detector

In recent years a new type of scintillation detector based on the LaBr 3 :Ce crystal has been developed. This detector offers a substantial advantage over the standard NaI(Tl) detector. In comparison the energy resolution (about 3% at 662 keV) is better and the efficiency for high-energy gamma rays is higher. The detector crystal has other advantages such as a high scintillation light output with a fast decay time. Due to the favorable characteristics and ease of use, the lanthanum bromide detector is likely to gain acceptance quickly in a variety of applications. We use the detector for activation analysis in conjunction with a 14-MeV neutron generator. This includes the detection of prompt gamma rays from neutron inelastic scattering and neutron capture. The elements of our interest include oxygen, hydrogen, nitrogen, carbon, fluorine and chlorine which emit characteristic gamma energies in the range of 1–10 MeV. The paper presents the absolute full-energy peak efficiency calibration of a 38.1 mm × 38.1 mm ( 1.5 in × 1.5 in ) LaBr 3:Ce crystal for gamma-ray energies up to 5 MeV. For the present calibration the detector/source distance was set to 250 mm.

Efficiency calibration of an HPGe detector in the 0.1–2.5 MeV energy range for Am-Be neutron source-based PGAA applications

A 740 GBq 241Am-Be neutron source based prompt gamma-ray activation analysis (PGAA) setup in combination with a typical coaxial n-type HPGe detector (REGe) system was used to analyze light elements like H, B, C, N, etc. The absolute full energy peak (FEP) efficiencies of the shielded REGe detector for irradiation and counting geometries and for sources with different sizes (point, ampoule and cylindrical) were measured in the 0.1–2.5 MeV energy range by utilizing calibrated sources (point, liquid and solid). 4th order polynomials were fitted to the experimental data. Efficiencies in far irradiation and counting geometries are compared.

The 4.438 MeV gamma to neutron ratio for the Am–Be neutron source

An accurate measurement of the 4.438 MeV γ -ray to total neutron ratio, namely R = S γ / S n , for a Chinese-made Am–Be neutron source is described. The neutron strength of the source relative to a previously standardized source was determined by the manganese bath technique. The γ -rays spectra of the source were measured using a ∅ 75 × 75 mm NaI(Tl) detector. The background induced by neutrons and the absolute full energy peak efficiency of the detector were calculated using the MCNP code. The experimental ratio so obtained agrees well with the calculated value. A synthetic evaluated and recommended value of R = 0.575 ± 4.8 % was given. We conclude that the experimental R-value appears an important characteristic for an Am–Be source.

HPGe detector absolute full-energy peak efficiency calibration including coincidence correction for circular disc sources

A direct mathematical approach is presented to calculate the absolute full-energy peak (photopeak) efficiency and coincidence correction of hyper pure germanium (HPGe) detectors for extended circular disc sources. The calculation of the full-energy peak efficiency is based on elliptic integration and its validity was checked by comparison with experimental measurements. Extensive experimental readings have been carried out; gamma sources containing several radionuclides covering the energy range from 60 to 1836 keV were used. By comparison, the theoretical and experimental full-energy peak efficiency values are in good agreement; the overall percentage error is less than 3%.

Absolute full-energy peak efficiency calibration of a Clover–BGO detector system

Abstract An absolute full-energy peak efficiency calibration of a Clover-type composite germanium gamma-ray detector system is presented. The efficiency curve was measured in the energy range of 120 keV–12.2 MeV for the first time, using the combination of proton-capture nuclear reactions and radioactive sources, such as 56Co, 60Co, 66Ga and 152Eu. At high energies gamma-ray pairs from proton resonance capture on 27Al, 23Na, 39K and 11B were employed using evaporated Al, Na2WO4, K2SO4 and LiBO2 targets, respectively. The experimental data were fitted with a single polynomial function on log–log scale using a recently developed method. The add-back factor is found to increase quadratically with the energy, in contrast to the previously suggested linear relationship. The efficiency gain with respect to a single detector is about one order of magnitude at 10 MeV energy.

Calibration of the JET neutron activation system for DT operation

The neutron activation system at JET is a pneumatic transfer system capable of positioning activation samples close to the plasma. Its primary purpose is to provide a calibration for the time-dependent neutron yield monitors (fission chambers and solid state detectors). Various activation reactions with different high energy thresholds were used including Fe56(n,p) Mn56, Al27(n,α) 24Na, 93Nb(n,2n) 92mNb, and Si28(n,p) 28Al reactions. The silicon reaction, with its short half life (2.25 min), provides a prompt determination of the 14 MeV DT yield. The neutron induced γ-ray activity of the Si samples was measured using three sodium iodide scintillators, while two high purity germanium detectors were used for other foils. It was necessary to use a range of sample masses and different counting geometries in order to cover the wide range of neutron yields (1015–1019 neutrons) while avoiding excessive count rates in the detectors. The absolute full energy peak efficiency calibration of the detectors was measured taking into account the source-detector geometry, the self-attenuation of the samples and cross-talk effects. An error analysis of the neutron yield measurement was performed including uncertainties in efficiency calibration, neutron transport calculations, cross sections, and counting statistics. Cross calibrations between the different irradiation ends were carried out in DD and DT (with 1% and 10% tritium content) discharges. The effect of the plasma vertical displacement was also experimentally studied. An agreement within 10% was found between the 14 MeV neutron yields measured from Si, Fe, Al, Nb samples in DT discharges.