DOCSLIB.ORG

Appendix a How Can We Detect Radiation?

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Appendix a How Can We Detect Radiation? Appendix A How Can We Detect Radiation? If our tongues were as sensitive as these radiation detectors, we could easily taste one drop of vermouth in five carloads of gin. Dixy Lee Ray 1914–1994 It is impossible to smell, see, taste, hear or feel ionising radiation. Humans have no senses for α, β and γ rays, so detectors are needed, to play the part of this absent capability – to sense ionising radiation for us. It is necessary to measure radiation exposures so that they can be monitored, controlled and limited. Humans also have to be protected against unexpected exposures. One important duty is to supervise radiation-exposed workers, and to measure external radiation exposures, contami- nations and incorporations, particularly in working areas. Another is to protect the environment against unnecessary exposures. This includes the determination of radi- ation exposures of the general public, the monitoring of the disposal of radioactive waste into the environment, and the examination of the distribution of radioactive material in the biosphere (the atmosphere, soil, water, and eventually food). National radiation-protection authorities have realised that radiation exposures from natural sources also have to be considered. In certain situations, natural radiation can increase the radiation level for particular individuals in the population quite considerably. Therefore, these natural sources cannot be neglected in the framework of radiation protection. The detectors used in the field of radiation protection have to be reliable and robust, and their measurements have to be reproducible. It is important to note that for each of the various types of radiation, an appropriate detector needs to be used. This chapter introduces the various types of radiation detector normally used in industry, academia and elsewhere. A.1 Ionisation Chambers An ionisation chamber is a detector with a gas-filled region, which measures the amount of ionisation produced by a charged particle passing through the gas. Neutral © Springer International Publishing Switzerland 2016 161 C. Grupen and M. Rodgers, Radioactivity and Radiation, DOI 10.1007/978-3-319-42330-2 162 Appendix A: How Can We Detect Radiation? Fig. A.1 Sketch of an ionisation chamber particles can also be detected by this device via secondary charged particles (those that result from the interaction of the initial neutral ones with electrons or nuclei). The charged particles move through the gas, and strike gas molecules, liberating electrons and leaving ions: i.e. they produce more charged particles. The number of charged particles can be measured using an electric field, which attracts the oppositely charged particles in opposite directions onto conducting plates (the electrodes), from which the signals caused by the particles can be recorded. In the simplest case, an ionisation chamber consists of a pair of parallel electrodes mounted in a gas-tight container that is filled with a gas mixture (see Figure A.1). A charged particle produces electron-ion pairs along its track, and the electrons drift through the gas towards the positive electrode, while the ions drift towards the negative electrode. The number of charge carriers created depends on the particle type and energy, and on the gas used. The parallel electrodes of the ionisation chamber are initially charged to a certain voltage, producing a homogeneous electric field, i.e. one which is the same strength and points in the same direction at all positions within the field. The drifting charge carriers induce an electric charge on the electrodes, which leads to certain change of the voltage. This voltage change has contributions from the much lighter, fast-moving electrons and from the much heavier, slowly drifting ions. There is a significant dis- advantage, which is that the output signal depends on where the particles enter the ionisation chamber. This can be solved by introducing a Frisch grid (a third electrode, constructed to reduce the dependence), or by only permitting the particles to enter the chamber from a well-defined region. With either remedy in place, the amount of energy deposited by the particle can be deduced from the signal: and if the incoming particle is totally absorbed in the gas, the detector measures its total energy. Ionisation chambers are mainly used to detect particles with high charges, because in this case the energies deposited tend to be larger than those of singly charged Appendix A: How Can We Detect Radiation? 163 “The detector is that small because it has to detect tiny particles” particles. α particles have a charge of two units, and if coming from a radioactive source, they will typically deposit 5MeV in a 4cm layer of argon, which is easily detected. A singly charged particle, such as a β particle, passing through the same 4cm layer of argon will deposit only about 11keV,which provides about 400 electron- ion pairs. To detect such a small signal is a very difficult task! Figure A.2 shows a parallel-plate ionisation detector. The charged plates, which are on the top and bottom of the large square area, are sufficiently thin that they are transparent. The controls (for setup, reset and test mode) are next to the built-in display. The device can also be connected to a computer, so that readings can be logged. As well as parallel-plate ionisation counters, cylindrical ionisation counters are also in use. These have the positive electrode (anode) as a thin wire along the centre of the cylinder, and the shell of the cylinder as the negative electrode (cathode). Because of this cylindrical arrangement, the electric field in this case is no longer homogeneous, but is stronger closer to the anode wire and weaker towards the edges of the cylinder. The important point with ionisation chambers is that no multiplication of charge carriers occurs in the gas. Only the electrons and ions originally produced by the incoming particle are collected. 164 Appendix A: How Can We Detect Radiation? Fig. A.2 A parallel-plate ionisation chamber. (Model: DIAMENTOR SET CX, from PTW, Freiburg, Germany) A.2 Proportional Counters Proportional counters are in principle similar to ionisation chambers, but they use a higher voltage between the electrodes, giving a stronger signal due to an amplification effect. When a particle enters the container, it will ionise atoms and produce pairs of positive ions and (negative) electrons. These particles are accelerated strongly in the powerful electric field – sufficiently strongly that they themselves produce further electron-ion pairs when they strike other gas molecules. This process can continue with future generations of charged particles. These cascades of particles can eventually be measured when they strike the electrodes. Crucially, as long as ionisation remains the only significant process, the signal measured is proportional to the original amount of ionisation, but multiplied by, typically, 104 or 105. Proportional counters have a natural upper limit to their operation: at yet higher voltages, the accelerated electrons will not only ionise gas molecules, but will some- times excite them (put molecular electrons into higher energy states, without ejecting them from the molecule). De-excitation usually involves the emission of photons, which can interact with the electrodes (by the photoelectric effect), producing further charged particles and amplifying the cascade. The addition of this effect means that the counters are no longer proportional for very high voltages, and so they are not used with voltages over that level (which depends on the device, but is usually about 1000 V). Since the output signal in a proportional counter is proportional to the energy loss of the particle (or to the total energy of the particle, if the particle stops in the counter), these radiation detectors can be used for spectroscopy, i.e. to determine the distribution of energies for a group of many particles (e.g. of X rays or α particles). A multi-wire proportional chamber (MWPC) is a more advanced device, operating much like a proportional counter, but with multiple charged wires across a planar chamber. In additon to signals proportional to the energy, MWPCs provide accurate track information if the wires are stretched with relatively small separations. Their Appendix A: How Can We Detect Radiation? 165 major use as regards radiation protection is as contamination monitors: measuring the extent of contaminations over large areas. A.3 Geiger-Müller Counters For many circumstances, a strong detector response, even to low levels of signal, is important, even if the cost is that the energy deposited by the particles cannot be measured. In a Geiger-Müller counter (also called a Geiger counter or a GM counter), a still stronger electric field is used, so that the output is no longer proportional to the energy left in the chamber by the passing particle. Like some ionisation chambers, the shape of a GM counter is a cylinder, with the wall negatively charged and a central wire positively charged. Each ionising particle passing through the chamber causes a single brief discharge, and the count of these discharges gives an indication of the radiation level. In order to turn that indication into a measurement of dose, a different calibration is required for each radiation type and energy. Increasing the field strength in a proportional counter, beyond the limit where it ceases to be proportional, leads to copious production of photons during the forma- tion of the particle cascade. These photons, often in the ultraviolet range, may knock electrons out of the electrodes if they strike them (the photoelectric effect). The pho- ton may have travelled some distance (typically several millimetres) before striking the electrodes, and the electrons liberated can cause further cascades, distant from the original interaction point. Another effect with a similar consequence is the strong acceleration of the gas ions: at these energies, they can strike the walls of the cylinder (negative electrode) hard enough to cause ionisation there, also far from the initial interaction point.
Load more

Recommended publications
  • Dead Time and Count Loss Determination for Radiation Detection Systems in High Count Rate Applications
    Scholars' Mine Doctoral Dissertations Student Theses and Dissertations Spring 2010 Dead time and count loss determination for radiation detection systems in high count rate applications Amol Patil Follow this and additional works at: https://scholarsmine.mst.edu/doctoral_dissertations Part of the Nuclear Engineering Commons Department: Nuclear Engineering and Radiation Science Recommended Citation Patil, Amol, "Dead time and count loss determination for radiation detection systems in high count rate applications" (2010). Doctoral Dissertations. 2148. https://scholarsmine.mst.edu/doctoral_dissertations/2148 This thesis is brought to you by Scholars' Mine, a service of the Missouri S&T Library and Learning Resources. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact [email protected]. DEAD TIME AND COUNT LOSS DETERMINATION FOR RADIATION DETECTION SYSTEMS IN HIGH COUNT RATE APPLICATIONS by AMOL PATIL A DISSERTATION Presented to the Faculty of the Graduate School of the MISSOURI UNIVERSITY OF SCIENCE AND TECHNOLOGY In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY in NUCLEAR ENGINEERING 2010 Approved by Shoaib Usman, Advisor Arvind Kumar Gary E. Mueller Carlos H. Castano Bijaya J. Shrestha © 2010 AMOL PATIL All Rights Reserved iii PUBLICATION DISSERTATION OPTION This dissertation consists of the following two articles that have been, or will be submitted for publication as follows: Pages 4-40 are intended for submission to Journal of Radioanalytical and Nuclear Chemistry. Pages 41-62 have been published in Nuclear Technologies journal (February, 2009). iv ABSTRACT This research is focused on dead time and the subsequent count loss estimation in radiation detection systems.
    [Show full text]
  • Cherenkov Radiation
    TheThe CherenkovCherenkov effecteffect A charged particle traveling in a dielectric medium with n>1 radiates Cherenkov radiation B Wave front if its velocity is larger than the C phase velocity of light v>c/n or > 1/n (threshold) A β Charged particle The emission is due to an asymmetric polarization of the medium in front and at the rear of the particle, giving rise to a varying electric dipole momentum. dN Some of the particle energy is convertedγ = 491into light. A coherent wave front is dx generated moving at velocity v at an angle Θc If the media is transparent the Cherenkov light can be detected. If the particle is ultra-relativistic β~1 Θc = const and has max value c t AB n 1 cosθc = = = In water Θc = 43˚, in ice 41AC˚ βct βn 37 TheThe CherenkovCherenkov effecteffect The intensity of the Cherenkov radiation (number of photons per unit length of particle path and per unit of wave length) 2 2 2 2 2 Number of photons/L and radiation d N 4π z e 1 2πz 2 = 2 1 − 2 2 = 2 α sin ΘC Wavelength depends on charge dxdλ hcλ n β λ and velocity of particle 2πe2 α = Since the intensity is proportional to hc 1/λ2 short wavelengths dominate dN Using light detectors (photomultipliers)γ = sensitive491 in 400-700 nm for an ideally 100% efficient detector in the visibledx € 2 dNγ λ2 d Nγ 2 2 λ2 dλ 2 2 11 1 22 2 d 2 z sin 2 z sin 490393 zz sinsinΘc photons / cm = ∫ λ = π α ΘC ∫ 2 = π α ΘC 2 −− 2 = α ΘC λ1 λ1 dx dxdλ λ λλ1 λ2 d 2 N d 2 N dλ λ2 d 2 N = = dxdE dxdλ dE 2πhc dxdλ Energy loss is about 104 less hc 2πhc than 2 MeV/cm in water from €
    [Show full text]
  • Cherenkov Radiation Induced by Megavolt X-Ray Beams in the Second Near-Infrared Window
    Cherenkov Radiation Induced by Megavolt X-Ray Beams in the Second Near-Infrared Window XIANGXI MENG,1,2 YI DU,3 ZIYUAN LI,1 SIHAO ZHU, 1 HAO WU,3,7 CHANGHUI LI, 1,8 WEIQIANG CHEN, 4 SHUMING NIE, 5 QIUSHI REN 1 AND YANYE LU 6,9 1Department of Biomedical Engineering, College of Engineering, Peking University, Beijing 100871, China 2The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Atlanta, GA 30332, USA 3Key laboratory of Carcinogenesis and Translational ResearchÂă(Ministry of Education/Beijing),ÂăDepartmentÂăof Radiation Oncology, Peking University Cancer Hospital & Institute, Beijing 100142, China 4Institute of Modern Physics, Chinese Academy of Sciences, Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Key Laboratory of Basic Research on Heavy Ion Radiation Application in Medicine, Gansu Province, Lanzhou 730000, China 5Department of Biomedical Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA 6Pattern Recognition Lab, Friedrich-Alexander-University Erlangen-Nuremberg, 91058 Erlangen, Germany [email protected] [email protected] [email protected] Abstract: Although the Cherenkov light contains mostly short-wavelength components, it is beneficial in the aspect of imaging to visualize it in the second near-infrared (NIR-II) window. In this study, Cherenkov imaging was performed within the NIR-II range on megavolt X-ray beams delivered by a medical linear accelerator. A shielding system was used to reduce the noises of the NIR-II image, enabling high quality signal acquisition. It was demonstrated that the NIR-II Cherenkov imaging is potentially a tool for radiotherapy dosimetry, and correlates well with different parameters.
    [Show full text]
  • Polarized Light from Black Hole Can Be a Symbol of Cherenkov Radiation Generated by Faster Than Light Movement in Vacuum Under Gravity
    Polarized light from black hole can be a symbol of Cherenkov radiation generated by Faster Than Light movement in vacuum under gravity Sterling-Jilin Liu, An independent researcher, Email: [email protected], Cell phone: +86 18621356287, Profile: https://www.linkedin.com/in/sterling-liu-9016096b/ Abstract Light speed is assumed as a constant in Einstein’s general relativity theory. In this paper, the polarized light from blacK hole Cygnus X-1 is found fit well with CherenKov radiation generated by Faster Than Light movement in vacuum under gravity. Thus, proved the gravitational lens is a real existence, the refractive index of space did increase with the gravity field, and light speed is changeable with gravitational potential energy. Possible experiments to double verify the theory on the earth is discussed. A new way to find more advanced alien civilizations in lower gravitational potential energy area is proposed. Introduction In Einstein’s general relativity theory, Mercury precession, gravitational lens and gravitational red shift, etc. can be considered as geodetic effect while assuming light speed is a constant, hence get time goes slower in gravitational field. However, in another view, all these phenomena can be also explained as space curved in gravitational field, refractive index of vacuum is larger, and light speed become smaller, but time keep no change. These two views are both acceptable based on previous experimental verification of general relativity theory, whether light or time speed changed is indistinguishable. In this paper, the author found polarized light from black hole Cygnus X-1 can be well explained by CherenKov radiation generated by Faster Than Light movement in vacuum under gravity.
    [Show full text]
  • Chapter 2 – General Background Information Chapter 2 General Background Information
    16 European Atlas of Natural Radiation | Chapter 2 – General background information Chapter 2 General background information This chapter provides the background information geology of Europe, one can already form a general necessary to understand how ionising radiation works, and large-scale idea of the level of natural radioactiv- why it is present in our environment, and how it can be ity that can be expected. For instance, young and mo- represented on a map. bile unconsolidated sediments (like clay or sand) that are found in many regions in northern and northwest- The ionising radiation discussed in this chapter consists ern Europe contain generally fewer radionuclides than of alpha, beta and neutron particles as well as gamma certain magmatic or metamorphic rocks found in for rays. Each interacts with matter in a specific way, caus- example Scandinavia (Fennoscandian Shield), Central ing biological effects that can be hazardous. Health risk Europe (Bohemian Massif), France (Bretagne and Cen- from radiation is described by the absorbed dose, tral Massif) and in Spain (Iberian Massif). The more equivalent dose and effective dose, calculated using recent alpine mountain belts are composed of many specific weighting factors. The effects of ionising radia- different types of rocks, leading to strong spatial vari- tion on humans can be deterministic and stochastic. All ations in radiological signature and radiological back- this information leads to the general principles of radi- ground. Some types of volcanic rocks have a higher ation protection. Natural ionising radiation is emitted by radionuclide content and can lead to increased indoor a variety of sources, both cosmogenic and terrigenous, gamma dose rates and radon or thoron concentra- and can be primordial (existing since the origin of the tions.
    [Show full text]
  • Optimization of a Gas Flow Proportional Counter for Alpha Decay
    Optimization of a gas flow proportional counter for alpha decay measurements Elena Ceballos Romero Master Thesis Institut f¨urKernphysik Mathematisch-Naturwissenschaftliche Fakult¨at Westf¨alische Wilhelms-Universit¨atM¨unster Prof. Dr. Alfons Khoukaz October 2012 III I am among those who think that science has great beauty. A scientist in his laboratory is not only a technician: he is also a child placed before natural phenomena which impress him like a fairy tale. We should not allow it to be believed that all scientific progress can be reduced to mechanisms, machines, gearings, even though such machinery has its own beauty. -Marie Curie A magdalena, por ponerme en este camino. A mis padres, por siempre acompa~narmeen ´el. IV V I certify that I have independently written this thesis and no other sources than the mentioned ones have been used. Referent: Prof. Dr. Alfons Khoukaz Correferent: Dr. Mar´ıaVilla Alfageme VI Contents 1. Introduction 1 2. Introduction to natural radiations 5 2.1. Radioactivity . .5 2.1.1. Decay laws . .5 2.1.2. Activity . .7 2.2. Decays . .7 2.2.1. Alpha decay . .7 2.2.2. Beta decay . .9 2.2.3. Gamma decay . 11 3. Theoretical background: Gas-filled detectors 13 3.1. General properties . 13 3.1.1. Number of ion pairs formed . 14 3.1.2. Behaviour of charged particles in gases . 14 3.1.3. Operational modes of gas detectors . 15 3.2. Proportional counters: gas multiplication effect . 17 3.3. Gas flow detectors . 18 4. Experimental set-up 21 4.1. Detector . 21 4.1.1.
    [Show full text]
  • Cherenkov Light Imaging in Astroparticle Physics
    Cherenkov light imaging in astroparticle physics U. F. Katz Erlangen Centre for Astroparticle Physics, Friedrich-Alexander University Erlangen-N¨urnberg, Erwin-Rommel-Str. 1, 91058 Erlangen, Germany Abstract Cherenkov light induced by fast charged particles in transparent dielectric media such as air or water is exploited by a variety of experimental techniques to detect and measure extraterrestrial particles impinging on Earth. A selection of detection principles is discussed and corresponding experiments are presented together with breakthrough-results they achieved. Some future develop- ments are highlighted. Keywords: Astroparticle physics, Cherenkov detectors, neutrino telescopes, gamma-ray telescopes, cosmic-ray detectors 1. Introduction Photomultiplier tubes (PMTs) and, more recently, silicon pho- tomultipliers (SiPMs) [3,4] are the standard sensor types. They In 2018, we commemorate the 60th anniversary of the award are provided by specialised companies who cooperate with the of the Nobel Prize to Pavel Alexeyewich Cherenkov, Ilya experiments in developing and optimising sensors according to Mikhailovich Frank and Igor Yevgenyevich Tamm for the dis- the respective specific needs (see e.g. [5,6]). covery and the interpretation of the Cherenkov effect [1,2]. In the following, the detection principles of different types of The impact of this discovery on astroparticle physics is enor- Cherenkov experiments in astroparticle physics are presented mous and persistent. Cherenkov detection techniques were ins- together with selected technical details and outstanding results. tumental for the dicovery of neutrino oscillations; the detection of high-energy cosmic neutrinos; the establishment of ground- based gamma-ray astronomy; and important for the progress in 2. Ground-based gamma-ray detectors cosmic-ray physics.
    [Show full text]
  • Radiation Safety Manual University of Massachusetts Amherst
    Radiation Safety Manual University of Massachusetts Amherst Environmental Health and Safety 117 Draper Hall 413-545-2682 January, 2007 This manual must be returned to Radiation Safety Services when the Approved Principal Investigator no longer uses radioisotopes or radiation generating machines and all permits issued by the Radiation Use Committee have been deactivated. Table of Contents The Program & Basic User Requirements How The Program Works Radiation Safety Organization As Low as Reasonably Achievable (ALARA) The Definition of Compliance The Regulatory Agencies Audit of the Radiation Safety Office Audit of the Authorized Principal Investigator (API) & the Authorized Laboratory Radiation Safety Standard Operating Procedures (SOP’s) Radiation Safety Records Responsibilities of Radiation Safety Program Personnel and Users License Conditions and Regulations Radiation Use Committee Radiation Safety Officer Authorized Principal Investigator Authorized Users Visitors Obtaining Approval to Use RM Qualifications for Authorized Users Training Requesting an API Permit from the RUC Approval for Radioisotope Work in Experimental Animals Laboratory Requirements & Access Control To Radioisotopes & Radiation Administrative Controls in the Laboratory Controlled Areas Restricted Areas Surface Contamination Limits Physical Controls in Laboratory Radiation Warnings & Posting Requirements for RM Use Laboratories or Areas Labeling Requirements for Containers Decommissioning Requirements Individual Laboratories Records of Decommissioning
    [Show full text]
  • Radiation Glossary
    Radiation Glossary Activity The rate of disintegration (transformation) or decay of radioactive material. The units of activity are Curie (Ci) and the Becquerel (Bq). Agreement State Any state with which the U.S. Nuclear Regulatory Commission has entered into an effective agreement under subsection 274b. of the Atomic Energy Act of 1954, as amended. Under the agreement, the state regulates the use of by-product, source, and small quantities of special nuclear material within said state. Airborne Radioactive Material Radioactive material dispersed in the air in the form of dusts, fumes, particulates, mists, vapors, or gases. ALARA Acronym for "As Low As Reasonably Achievable". Making every reasonable effort to maintain exposures to ionizing radiation as far below the dose limits as practical, consistent with the purpose for which the licensed activity is undertaken. It takes into account the state of technology, the economics of improvements in relation to state of technology, the economics of improvements in relation to benefits to the public health and safety, societal and socioeconomic considerations, and in relation to utilization of radioactive materials and licensed materials in the public interest. Alpha Particle A positively charged particle ejected spontaneously from the nuclei of some radioactive elements. It is identical to a helium nucleus, with a mass number of 4 and a charge of +2. Annual Limit on Intake (ALI) Annual intake of a given radionuclide by "Reference Man" which would result in either a committed effective dose equivalent of 5 rems or a committed dose equivalent of 50 rems to an organ or tissue. Attenuation The process by which radiation is reduced in intensity when passing through some material.
    [Show full text]
  • Radiation Fields Using a Tepc*
    XA00XC014 EUROPEAN LABORATORY FOR PARTICLE PHYSICS CERN/TIS-RP/95-14/CF A STUDY OF BUILD-UP EFFECTS IN HIGH-ENERGY RADIATION FIELDS USING A TEPC* M. Hofert1), A. Aroua2), A. V. Sannikov3) and G. R. Stevenson1) !) CERN, European Laboratory for Particle Physics, CH 1211 Geneva 23, Switzerland 2) IAR, Institute for Applied Radiophysics, CH 1015 Lausanne, Switzerland 3) IHEP, Institute for High-Energy Physics, RU 142284 Protvino, Russia * Supported by EU Research Contract FI3P-CT92-0026 Abstract A dose of 2 mSv close to the body surface of a pregnant woman is considered by ICRP to assure a dose limit of 1 mSv to the foetus. Such an assumption depends on the energy spectrum and composition of the external radiation field and it was tested in radiation fields containing high-energy particles similar to those found around high-energy particle accelerators and in air-craft. Measurements of dose and dose equivalent were performed as a function of wall thickness using a tissue-equivalent proportional counter (TEPC) in radiation fields at the CERN-EU Reference Radiation Facility. Results are presented both with respect to integral quantities and event size spectra. The decrease in dose and dose equivalent at a depth equivalent to that of the foetus was typically 10% in a high-energy stray radiation field and in the case of Pu- Be source neutrons amounted to only 30%. It is concluded that it would be prudent under such exposure conditions to limit the dose of a pregnant woman to 1 mSv in order to assure that the dose to the foetus remains below the same limit.
    [Show full text]
  • Applications of Cherenkov Light Emission for Dosimetry in Radiation Therapy a Thesis Submitted to the Faculty in Partial Fulfill
    Applications of Cherenkov Light Emission for Dosimetry in Radiation Therapy A Thesis Submitted to the Faculty in partial fulfillment of the requirements for the degree of Doctor of Philosophy by Adam Kenneth Glaser Thayer School of Engineering Dartmouth College Hanover, New Hampshire May 2015 Examining Committee: Chairman_______________________ Brian Pogue, Ph.D. Member________________________ Alexander Hartov, Ph.D. Member________________________ Eric Fossum, Ph.D. Member________________________ David Gladstone, Sc.D. Member________________________ Lei Xing, Ph.D. ___________________ F. Jon Kull Dean of Graduate Studies THIS PAGE IS INTENTIONALLY LEFT BLANK, UNCOUNTED AND UNNUMBERED ADDITIONAL ORIGINAL SIGNED COPIES OF THE PREVIOUS SIGNATURE PAGE ARE RECOMMENDED, JUST IN CASE. Abstract Since its discovery during the 1930's, the Cherenkov effect has been paramount in the development of high-energy physics research. It results in light emission from charged particles traveling faster than the local speed of light in a dielectric medium. The ability of this emitted light to describe a charged particle’s trajectory, energy, velocity, and mass has allowed scientists to study subatomic particles, detect neutrinos, and explore the properties of interstellar matter. However, only recently has the phenomenon been considered in the practical context of medical physics and radiation therapy dosimetry, where Cherenkov light is induced by clinical x-ray photon, electron, and proton beams. To investigate the relationship between this phenomenon and dose deposition, a Monte Carlo plug-in was developed within the Geant4 architecture for medically-oriented simulations (GAMOS) to simulate radiation-induced optical emission in biological media. Using this simulation framework, it was determined that Cherenkov light emission may be well suited for radiation dosimetry of clinically used x-ray photon beams.
    [Show full text]
  • Inter/Intramolecular Cherenkov Radiation Energy Transfer (CRET) from a Fluorophore with a Built-In Radionuclide Yann Bernhard, Bertrand Collin, Richard Decréau
    Inter/intramolecular Cherenkov radiation energy transfer (CRET) from a fluorophore with a built-in radionuclide Yann Bernhard, Bertrand Collin, Richard Decréau To cite this version: Yann Bernhard, Bertrand Collin, Richard Decréau. Inter/intramolecular Cherenkov radiation energy transfer (CRET) from a fluorophore with a built-in radionuclide. Chemical Communications, Royal Society of Chemistry, 2014, 50, pp.6711 - 6713. 10.1039/c4cc01690d. hal-03262965 HAL Id: hal-03262965 https://hal.univ-lorraine.fr/hal-03262965 Submitted on 16 Jun 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Showcasing research from Richard A Decréau, Institut de Chimie Moléculaire de l’Université de Bourgogne, France As featured in: Inter/intramolecular Cherenkov radiation energy transfer (CRET) from a fl uorophore with a built-in radionuclide Some radionuclides emit optical light, the Cerenkov Radiation (CR, i.e. the blue glow in nuclear reactors), which can activate fl uorophores. Key parameters were addressed to optimize such processes (energy of the emitted particle, concentrations, Φ λmax, F × ε, η). See Richard A Decréau et al., Chem. Commun., 2014, 50, 6711. www.rsc.org/chemcomm Registered charity number: 207890 ChemComm View Article Online COMMUNICATION View Journal | View Issue Inter/intramolecular Cherenkov radiation energy transfer (CRET) from a fluorophore with a built-in Cite this: Chem.
    [Show full text]