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Scintillators: Gamma Radiation Detectors

Scintillators: Gamma Radiation Detectors. Bryant Jerome. Scintillators. Scintillators emit light when exposed to ionizing radiation [1] . Can react alpha, beta, and gamma radiation, muons, etc., depending on material and build [2,3] .

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Scintillators: Gamma Radiation Detectors

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  1. Scintillators: Gamma Radiation Detectors Bryant Jerome

  2. Scintillators • Scintillators emit light when exposed to ionizing radiation[1]. • Can react alpha, beta, and gamma radiation, muons, etc., depending on material and build[2,3]. • Widely used due to long durations of signal, ease of use, and time and energy resolutions. 1) An example of several different organic scintillators. Adapted from Azimuth Photonics. Retrieved February 9th, 2019, from http://www.azimp.ru/en/products/scintillation-detectors/

  3. History • Notable early scientific use was in Rutherford’s gold foil experiments, and similar scattering experiments[4]. • ZnS screen devolved by William Crookes that lit up when alpha particles struck it. • Modern-day Scintillation counters were developed for the Manhattan project to obtain accurate readings of U radioactivity[5]. • Developed by Samuel Curran and Nicholas Baker • Combed the newly-developed photomultiplier tube with existing scintillation crystals 2) A visual representation of Rutherford’s alpha particle scattering.. Retrieved February 9th, 2019, from https://www.simply.science/images/content/physics/modern_physics/early_model_atom/ Concept_map/Rutherford_Atomic_Model.html 3) The alpha 1 racetrack at Y-12, a electromagnetic separation plant used to sort U isotopes for the Manhattan project. Adapted from Ed Wescott. Taken from https://www.nashvillepublicradio.org/post/how-us-created-secret-city-oak-ridge-build-atomic-bomb-75-years-ago#stream/0

  4. Applications • Scintillators are one of the oldest and widest used methods for measuring particle and electromagnetic radiation. • Employed in reactors, particle detectors, oil exploration[6], SPECT scanners[7], etc. • Can also be used to preform spectroscopy, giving us greater insight into our incoming radiation. 4) A SPECT Scanner, one of the many uses for scintillators. Adapted from Credit Valley Hospital. Taken on February 9th, 2019 from https://commons.wikimedia.org/wiki/File:SPECT_CT.JPG 5) A stereo detector built for studying light sterile neutrinos, with liquid scintillators used to measure particles. Adapated from Max-Plank-Institute for Particle and Astroparticle Physics. Taken on 9th February, 2019 from https://www.mpi-hd.mpg.de/lin/research_st.en.html

  5. Scintillation • Scintillators work by re-emitting light at lower wavelengths[1]. • Crystal takes in ionizing radiation (i.e., gamma radiation) • Some energy is lost in absorption (i.e., electronic dissociation, increasing vibration, etc.). • Remaining energy forces electron to a higher energy state. • Electron releases light quantum when it relaxes from; energy of emitted photon has significantly lower frequency, and is easier to use in a photomultiplier. • Emitted light is typically near blue wavelengths in the visible spectrum. 6) A simplified image of the mechanical structure of a scintillator counter. Adapted from Wikipedia on February 9th, 2019, from https://commons.wikimedia.org/wiki/File:PhotoMultiplierTubeAndScintillator.svg

  6. Spectroscopy • Intensity of light is proportional to energy lost by particle[1] • By comparing intensity of incoming light (pulse height), and the number of signals with that energy a photomultiplier reads, we can get a general sense of the energy spectrum of the incoming radiation. • Some peaks not directly due to intensity of incoming radiation • Compton-scattered gamma rays. • Escaped photons from positron-electron production and consequential annihilation. 7) The pulse-height spectrum of 60Co gammay rays obtained with a NaI scintillator. Adapated from “Experiments in Modern Physics, 2nd Edition”, pg. 338.

  7. Types of Scintillators 8) An inorganic scintillation crystal surrounded by various other producets. Adapted from Saint-Gobain Crystals. Taken at February 9th, 2019, from https://www.revolvy.com/page/Scintillator 9) Saint-Gobain’s BC 412 plastic scintillator. Adapted from Johann Meskal-. Taken at February 9th, 2019, from https://www.oeaw.ac.at/fileadmin/subsites/etc/Institute/SMI/PDF/Detectors_WS2014-15_A2.pdf

  8. Inorganic Scintillators • Typically constructed from crystals such as NaI, or CsI[1]. • Heavy element are then doped into the lattice • Typically, 1 part in 10,000. • Thallium and Cerium are popular choices for dopant • Ionization of impurity sites, and migration of electrons to those sights, cause longer light pulses.[1] • High density and heavier materials make it easier for gamma rays to excite inorganic scintillators.[1] 8) An inorganic scintillation crystal surrounded by various other producets. Adapted from Saint-Gobain Crystals. Taken at February 9th, 2019, from https://www.revolvy.com/page/Scintillator

  9. Plastic Scintillators • Transparent plastic encompasses organic material that emits for the desired wavelength[10]. • Active materials like PPO, 2-6-napithalate, etc. • Because of low density in the active material, hard for gamma radiation to lose energy. • Process for emitting electrons is more direct, meaning faster response times. 9) Saint-Gobain’s BC 412 plastic scintillator. Adapted from Johann Meskal-. Taken at February 9th, 2019, from https://www.oeaw.ac.at/fileadmin/subsites/etc/Institute/SMI/PDF/Detectors_WS2014-15_A2.pdf

  10. Photomultipliers • Light emitted from the Scintillator is then transferred to a photomultiplier, either directly or using a light pipe. • Photomultipliers amplify scintillation light into a large electronic signal[11] • Cutting edge precision can detect individual photons[12] 6) A simplified image of the mechanical structure of a scintillator counter. Adapted from Wikipedia on February 9th, 2019, from https://commons.wikimedia.org/wiki/File:PhotoMultiplierTubeAndScintillator.svg / 10) A disassembled photomultiplier tube. Adapted from Hamamatsu Photonics. Taken on February 9th, 2019, from https://www.hamamatsu.com/us/en/product/optical-sensors/pmt/pmt_tube-alone/index.html

  11. Lab Use • For our purposes in lab, scintillators will allow us to take note of alpha, beta, and gamma radiation, and to note in what quantity and in with what frequency the radiation is being omitted. • Scintillators, combined with photomultipliers, are one of the cornerstone detectors for particle and nuclear physics. • Allow measurements too small for conventional devices • Can commit complex analysis on incoming signal, to determine energy, time period, etc. 11) An example of some of the phenomenon scintillators can be used to detect. Adapted from Alexander V. Nesterenko. Taken on February 9th, 2019, from “Strong Interactions in Spacelike and Timelike Domains: Dispersive Approach.”

  12. Works Cited [1] Melissinos, A. C., & Napolitano, J. (2011). Experiments in modern physics. pg. 333-340. San Diego: AcademicPress [2] Yamamoto, S., & Hatazawa, J. (2011). Development of an alpha/beta/gamma detector for radiation monitoring. Review of Scientific Instruments,82(11), 113503. doi:10.1063/1.3658821 [3]Coan, T., Liu, T., & Ye, J. (2006). A compact apparatus for muon lifetime measurement and time dilation demonstration in the undergraduate laboratory. American Journal of Physics,74(2), pg. 161, doi:10.1119/1.2135319 [4] Rutherford, Ernest (1911). "The Scattering of α and β Particles by Matter and the Structure of the Atom". Philosophical Magazine. Series 6. 21: 669– 688. doi:10.1080/14786440508637080 [5] Curran, Samuel C (1949). Counting tubes, theory and applications. Academic Press (New York). [6] Saint-Gobain Crystals Extreme Environment (Ruggedized) Retrieved from https://www.crystals.saint-gobain.com/products/rugged-extreme- environment [7] Lecoq, P. (2016). Development of new scintillators for medical applications. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 809, 130. [8]Moser, S. W., Harder, W. F., Hurlbut, C. R., & Kusner, M. R. (1993). Principles and practice of plastic scintillator design. Radiation Physics and Chemistry, 41(1-2), 31-36. [9] Hayes, F. N. (1956). Liquid scintillators: attributes and applications. The International Journal of Applied Radiation and Isotopes, 1(1-2), 46. [10]Guo, Jimei; Bücherl, Thomas; Zou, Yubin; Guo, Zhiyu; Tang, Guoyou (2009). "Comparison of the performance of different converters for neutron radiography and tomography using fission neutrons". Nuclear Instruments and Methods in Physics Research. 605 (1–2): 69–72. Bibcode:2009NIMPA.605...69G. doi:10.1016/j.nima.2009.01.129. [11]Allen, J. S., & Engelder, T. C. (1951). Scintillation Counting with an EMI 5311 Photomultiplier Tube. Review of Scientific Instruments,22(6), pg. 401- 402. doi:10.1063/1.1745950 [12] Križan, P. (2014). Overview of photon detectors for fast single photon detection. Journal of Instrumentation, 9(10), C10010. pg. 1-5. [13]Kleinknecht, K. (1998). Detectors for particle radiation. New York: Cambridge University Press.

  13. Works Cited (Pictures) [1] Azimuth Photonics (2017). Retrieved February 9th, 2019, from http://www.azimp.ru/en/products/scintillation-detectors/ [2] Retrieved February 9th, 2019, from https://www.simply.science/images/content/physics/modern_physics/early_model_atom/ Concept_map/Rutherford_Atomic_Model.html [3] Wescott, Ed (1945). “Alpha 1 racetrack”. Taken on February 9th, 2019 from https://www.nashvillepublicradio.org/post/how-us-created-secret-city-oak- ridge-build-atomic-bomb-75-years-ago#stream/0, pg. 276. [4] Ytrottier (2012). “Siemens single-photon emission computed tomography machine in operation, doing a total body bone scan at the Credit Valley Hospital.” Taken on February 9th, 2019 from https://commons.wikimedia.org/wiki/File:SPECT_CT.JPG [5] Max-Plank-Institute for Particle and Astroparticle Physics (2019). “Schematic of the design of the Stereo detector.” Taken on February 9th, 2019 from https://www.mpi-hd.mpg.de/lin/research_st.en.html. [6] Qwerty123uiop (2013). “Schematic view of a photomultiplier coupled to a scintillator, illustrating detection of gamma rays.” Taken on February 9th, 2019 from https://commons.wikimedia.org/wiki/File:PhotoMultiplierTubeAndScintillator.svg. [7] Melissinos, A. C., & Napolitano, J. (2011). ”Pulse-height spectrum of 60Co gamma rays obtained with a NaI crystal, along with the decay scheme of 60Co. Taken on February 9th, 2019 , from Experiments in modern physics. pg. 338. [8] Saint-Gobain Crystals (1990) “A scintillation crystal surrounded by various scintillation detector assemblies.” Taken at February 9th, 2019, from https://commons.wikimedia.org/wiki/File:SGCat24454-scint-gris.noirEtBlanc.jpg [9] Meskal, Johann Z (2015). “Staint-Gobain’s BC412 Plastic Scintillator.” Taken on February 9th, 2019, from https://www.oeaw.ac.at/fileadmin/subsites/etc/Institute/SMI/PDF/Detectors_WS2014-15_A2.pdf, pg. 3. [10] Hamamatsu Photonics. Taken on February 9th, 2019, from https://www.hamamatsu.com/us/en/product/optical-sensors/pmt/pmt_tube-alone/index.html. [11] Nesterenko, Alexander V. (2017). Cover. Taken on February 9th, 2019, from “Strong Interactions in Spacelike and Timelike Domains: Dispersive Approach.”

  14. Questions

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