China
Africa
Explore chapters and articles related to this topic
Scintillation Detectors
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
In the mid-1940s several groups [3–7] proved the possibility of converting the weak scintillation light, usually from ZnS-screens, to readable electric pulses by coupling the scintillator to a photomultiplier tube, thus enabling a revival for scintillators as radiation detectors. Kallmann in 1947 [8] and Deutsch in 1948 [9] showed that scintillations from gamma-irradiated naphthalene-blocks could be detected using photomultipliers, naphthalene thus being the first organic scintillator and the first large-volume scintillator. Eventually Hofstadter [10] discovered the (nowadays standard) thallium-doped sodium iodide crystal following numerous studies of the luminescent properties of the thallium ion in alkali halides. Although much focus on scintillation radiation detectors traditionally is on the properties of the scintillator material, it is important to remember that the development of the light-amplification techniques (PM tubes and photodiodes) also have played a crucial part in enabling today’s radiation detection systems. Figure 6.1 shows two examples of modern scintillation detector designs (NaI(Tl)).
Detection Technology
Published in Rick Houghton, William Bennett, Emergency Characterization of Unknown Materials, 2020
Rick Houghton, William Bennett
A scintillator is a material that fluoresces briefly in response to absorbing ionizing radiation. Scintillator characteristics include the amount and specific wavelength of light emitted and the duration of the fluorescence. Scintillator material will be chosen by the designer to maximize the intended function of the detector based on these and other factors (Figure 3.38).
Slow Neutron Detectors
Published in Douglas S. McGregor, J. Kenneth Shultis, Radiation Detection, 2020
Douglas S. McGregor, J. Kenneth Shultis
Because liquid scintillators are often employed in large containers, the solvents are chosen to have high flash points to reduce the risk of combustion.16 Also, liquid scintillators can be contaminated with water moisture, a condition that compromises performance. Hence, the user must take care to keep exposure to air at a minimum. Typically these liquid scintillators are packaged under an inert environment (gas).
Study of crystalline scintillator response with development of single-electron beam of 2–6 MeV at KU-FEL
Published in Journal of Nuclear Science and Technology, 2023
Yusuke Uozumi, Toshimasa Furuta, Yuji Yamaguchi, Heishun Zen, Toshiteru Kii, Hideaki Ohgaki, Elena Velicheva, Vladimir Kalinnikov, Zviadi Tsamalaidze, Petr Evtoukhovitch
Crystalline scintillators are frequently used to detect energetic ions and electrons as well as photons. The corresponding data analysis requires knowledge about the scintillation response, namely, the proportionality of the scintillation light yield of the crystal over a wide energy range. To date, there have been many experimental studies of the nonproportionality of the response to heavy ions [e.g [1–5], and much data have been accumulated through experimental studies of the electron responses of certain scintillation crystals. However, because scintillators show remarkable nonproportionality at relatively low energies, most of the data are concentrated at electron energies below 1 MeV [6–14]. There are only a few reports at high energies of around 1 GeV [15,16], in which prototype calorimeters were examined for photon-detection purposes at energies of gigaelectronvolts.
Performance Testing of Dysprosium-Based Scintillation Screens and Demonstration of Digital Transfer Method Neutron Radiography of Highly Radioactive Samples
Published in Nuclear Technology, 2022
William Chuirazzi, Aaron Craft, Burkhard Schillinger, Nicholas Boulton, Glen Papaioannou, Amanda Smolinski, Kyrone Riley, Andrew Smolinski, Michael Ruddell
Figure 1 describes the digital transfer method radiography process in which a scintillator screen is first placed in the neutron beam and becomes activated in the pattern of the beam after passing through the imaging object. The converter material becomes activated when it absorbs neutrons and subsequently releases ionizing radiation as it decays. The ionizing radiation then excites scintillator material in the screen, which releases visible light photons upon relaxation. After activation in the neutron beam, the screen is then physically removed from the beamline and positioned in a light-tight environment where a digital camera measures the photons released from the activated scintillator screen to make a digital image. The scintillator screen’s ability to produce an image for the duration of the converter’s activation, and not just when it is directly in the beamline, allows for latent images to be recorded as activation that indirectly produces a digital image. Physically removing the activated screen from the sample and neutron beam during image readout makes the resulting image completely insensitive to gamma radiation from the neutron beam and the sample. The physical removal of the screen and digital camera from the radioactive object could also help protect sensitive electronics from radiation damage. This approach enables examination of highly radioactive samples, such as irradiated nuclear fuel, to be imaged using the digital transfer method.
Radiation effects on luminescent and structural properties of YPO4: Pr3+ nanophosphors
Published in Radiation Effects and Defects in Solids, 2018
Ivica Vujčić, Tamara Gavrilović, Milica Sekulić, Slobodan Mašić, Bojana Milićević, Miroslav D. Dramićanin, Vesna Đorđević
Scintillators are luminescent materials that absorb high energy photons and then emit visible light. They are mainly used for the production of radiation detectors in medical diagnostics, dosimetry, high-energy physics, and nuclear medicine. Yttrium orthophosphate YPO4 doped with Ce3+ and Pr3+ ions is widely used as a scintillation detector, used in medical imaging and display device (1, 2). Important characteristics of these materials are high chemical and high temperature stability (3, 4). YPO4 crystallizes with the zircon structure with tetragonal symmetry. The YPO4 matrix has excellent optical and physical properties: large indirect band gap (∼8.6 eV), high dielectric constant (∼7–10), refractive index (∼1.72), high melting point (∼1600°C) and phonon energy (∼1080 cm−1), and can be easily doped with trivalent rare-earth ions (5–7). Important fluorescent properties of the trivalent Pr3+ ion are upconversion and UV emission (8). The properties of YPO4 doped with trivalent Pr3+ were studied by several authors (9, 10). However, the impact of high doses of radiation on this material has not been studied so far.