Physics 441: Gamma-Ray Spectroscopy (original) (raw)
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This research investigates the basic properties of γ-rays using a high-resolution Germanium (Ge) detector, a Sodium Iodide (NaI(Tl)) Scintillation detector and Multi-Channel Analyser (MCA). These detectors are kept cold in operation and once the detector is switched on neither power supply nor the electronics setup are altered. In this experiment, we also determine linear attenuation coefficient for two different materials (Aluminium and Steel) by taking spectra and recording the count rate with varying thicknesses of these materials between the source and detector. Starting with five plates of our chosen materials, we took a spectrum until the 511.0 keV and 1274.6 keV photopeaks were clearly identified for a set time interval. We recorded the net number of counts (including the error) in each of these two peaks using the software which takes account of the large background under the peak. Also, recorded are the live time, real time and dead time. Dead time is the amount of time spent by the detector in a state where it could be missing events. Any detection system has a limit to the rate at which events can be registered and processed. In the case of a scintillation detector, if pulses from different photon interactions overlap significantly, only one light pulse will be measured by the photomultiplier tubes (pulse pileup). The electronics also have a maximum rate at which they can process data, typically around 1 MHz. __________________________________________________________________________________________ I. Introduction Gamma rays interact with matter by three main processes, the photo-electric effect, Compton scattering and pair production[6]. For the range of γ-ray sources used, Compton scattering is the most dominant process, since this process involves γ-rays scattering from electrons, the amount of scattering or attenuation strongly depend on the number of electrons in the material. Heavier materials, such as lead, are often used to shield γ-rays because they have a large atomic number and therefore, a greater density of electrons. II. Aim & Objective This work looks at the manner at which γ-rays interact with matter. The setup uses a high-resolution Germanium (Ge) detector, a Sodium Iodide (NaI(Tl)) Scintillation detector and a Multi-Channel Analyser (MCA). This research is an important tool in health physics and is effectively used to shield oneself from a radiation source. The work also investigates the attenuation of γ-rays in matter. The first part of this work focus on the radiation emitted from a 137 Cs source. The understanding of this work was made easy by studying the schematic nuclear decay charts to help understand the decays of the radioactive sources used. III. Methodology & Result A. The 137 Cs source Place the 137 Cs source on the holder a few centimetres above the detector face and take a γ-ray decay spectrum of this source for approximately five minutes.
COMPARISON OF METHODS FOR NOISE REDUCTION OF GAMMA ENERGY SPECTRA
The article presents a comparison of three methods of noise reduction in the gamma spectrum evaluation. The distortions' elimination in this way can lead to increasing accuracy of elements content and identification of radionuclides. The proposed methods were applied for data obtained from the scintillation spectrometer for standards and samples of ash from coal power plants. For presented methods, the measurement system calibration and determination of the content of radioactive elements are described.
Spectrum catalogue of gamma spectra taken with CdTe and CdZnTe detectors
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2001
The project of compiling a catalogue of gamma spectra for room-temperature semiconductor detectors is described. The catalogue is intended to help with the planning of measurements in various gamma spectrometric applications where these detectors are used such as the veri"cation of nuclear material, waste characterization and nuclear medicine. Gamma spectra are measured with CdZnTe and CdTe detectors under well-de"ned conditions. The spectra are archived and plotted to allow the assessment and comparison of the detector performance for various sources and detector types. The format of collecting and presenting the data is described and sample spectra are given.
Radiopurity assessment of the energy readout for the NEXT double beta decay experiment
Journal of Instrumentation, 2017
The "Neutrino Experiment with a Xenon Time-Projection Chamber" (NEXT) experiment intends to investigate the neutrinoless double beta decay of 136 Xe, and therefore requires a severe suppression of potential backgrounds. An extensive material screening and selection process was undertaken to quantify the radioactivity of the materials used in the experiment. Separate energy and tracking readout planes using different sensors allow us to combine the measurement of the topological signature of the event for background discrimination with the energy resolution optimization. The design of radiopure readout planes, in direct contact with the gas detector medium, was especially challenging since the required components typically have activities too large for experiments demanding ultra-low background conditions. After studying the tracking plane, here the radiopurity control of the energy plane is presented, mainly based on gamma-ray spectroscopy using ultra-low background germanium detectors at the Laboratorio Subterráneo de Canfranc (Spain). All the available units of the selected model of photomultiplier have been screened together with most of the components for the bases, enclosures and windows. According to these results for the activity of the relevant radioisotopes, the selected components of the energy plane would give a contribution to the overall background level in the region of interest of at most 2.4 × 10 −4 counts keV −1 kg −1 y −1 , satisfying the sensitivity requirements of the NEXT experiment.
Scintillation detector for gamma spectroscopy
2018
This project is documentation of a scintillator radiation detector for gamma spectroscopy. Gamma radiation causes a scintillator crystal to illuminate, which is captured and converted to an electrical signal. The detector works by measuring electrical pulses from the output of a photomultiplier tube (PMT). The amplitude of these pulses is proportional to the energy of the radiation. By creating a histogram with x-axis of energy and y axis of “# of counts”, the energy spectrum of the radiation can be identified and analyzed
STATISTICAL DATA ANALYSIS OF GAMMA-RAY BACKGROUND SPECTRA FOR QUALITY ASSURANCE PURPOSES
2010
Twenty five gamma-ray spectra were accumulated in the gamma-ray spectrometry laboratory located at the Chemistry Division, PINSTECH, Islamabad over a period of three years. Different background components along with their variation with time have been discussed in this paper. It was found that natural component of the background radiations can be reduced with a better design of shielding around the detector. However, the component from the fission products cannot be reduced by increased shielding but with a better shielding material containing less or no fission products.