DOCSLIB.ORG

Detectors for the Measurement of Ionizing Radiation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Detectors for the Measurement of Ionizing Radiation Detectors for the measurement of ionizing radiation For the measurement of radiation, the following reactions during the irradiation of matter are predominantly utilized: Ionization in gases (Ionization chamber, proportional flow counter, release counter) Scintillation in solids and liquids (- and - scintillation counters) Ionization in solids (semiconductor-detectors) 1 Detectors for the measurement of ionizing radiation Ionization of gases (gas-filled detectors) Ionization chamber: 50 – 300 V, air, no secondary ionization 2 Detectors for the measurement of ionizing radiation Geiger-Müller Counter GM counter: ≥ 800 V, Argon, electron cascade is generated (1010 electron pairs) Quench gas is needed (Cl2) Only count information can be recorded, no energy Dead time: time interval after a pulse during which the counter is insensitive to further ionizing events Higher count rates mean more counts will be missed Geiger-Müller counters are most suitable for measuring high-energy radiation (Emax >1MeV) 3 Detectors for the measurement of ionizing radiation Proportional Flow Counter Count rate and energy information on the incident radiation can be obtained Proportional counter: 300 – 800 V, argon or xenon, electron cascade is Discerning of alpha from beta generated (106 electron pairs) radiation Total charge is proportional to the Especially suited for measuring energy deposited - and -emitters 4 Detectors for the measurement of ionizing radiation Scintillation Conduction Band Band Scintillation gap photon Valence Band Scintillation is the property of Inorganic scintillators contain luminescence when exited by dense high Z materials ionizing radiation They are very efficient at detecting X- and -rays The energy of the original signal is preserved through the PMT, but precision is lost poor energy resolution 5 Detectors for the measurement of ionizing radiation Solid Scintillation Detectors In order to absorb the largest possible amount of the -radiation, thick crystals with large densities are used; e.g. sodium iodide crystals doped with thallium (ρ =3,67g·cm-3). By using organic crystals like anthracene, trans-stilbene or p-terphenyl, radiation can be detected. 6 Detectors for the measurement of ionizing radiation Scintillation / -scintillation counter (COBRA 5002) Analytical Method: Quantitative Detector: Thallium-activated sodium iodide crystal (through-hole design) Manual Region: 15 – 2000 keV (e.g. Tc-99m 140 keV) Efficiency: >72% for I-125 (others have to be distinguished) 7 Detectors for the measurement of ionizing radiation Liquid Scintillation Detectors Primary Secondary Scintillators: Scintillators: 320 – 360 nm 410 – 470 nm O N N PM Tube Counter O N Aromatic solvent in the scintillation cocktail: Absorbs the kinetic energy from a charged particle and transfers the energy to the primary scintillator molecules. 8 Detectors for the measurement of ionizing radiation Liquid Scintillation Detectors Quenching is the loss of counts due to sample or cocktail characteristics Chemical Quenching Color Quenching Chemical quenchers absorb Color quenchers absorb light in radioactive energy before it is the range of the wavelength converted to light. emitted by the scintillator. Chemical quenchers reduce The number of photons emitted is the number of photons not changed, but the number generated by each β-particle. reaching the photomultiplier tube is reduced. 9 Detectors for the measurement of ionizing radiation Liquid Scintillation Detectors Analytical Method: Quantitative / “Qualitative” Scintillation Cocktail: ULTIMA Gold XR Compatible with alkaline samples High holding capacity (up to 50%) High quench resistance High counting efficiency (up to 50% for H-3) -Spectra are recorded 10 Detectors for the measurement of ionizing radiation Semiconductor Detector Ionizing radiation produces electron-hole pairs as it passes through a semiconductor detector The number of electron-hole pairs is proportional to the energy transmitted by the radiation to the semiconductor http://nsspi.tamu.edu/NSEP Measuring the number of electron-hole pairs (pulse height) allows the energy of the incident radiation to be found Excellent energy resolution 11 Detectors for the measurement of ionizing radiation Semiconductor Detector Measurement of natural probes (Elemental Analysis) Measurement of probes after neutron activation 12 Detectors for the measurement of ionizing radiation Semiconductor Detector Measurement of natural probes (Elemental Analysis) Measurement of probes after neutron activation Aeroradiometrics Whole-body counter @ PSI 13 Detectors for the measurement of ionizing radiation Relationship between activity and counting rate? The net counting rate (RN) is proportional to the activity (A) of the sample and the average number of the emitted quanta per decay () RN = f · A · f = fG · fA · fS · fR · fi fG: Geometric factor fA: Absorption factor fS: Self absorption factor fR: Backscattering factor fi: Response probability 14 Nuclear Forensic Science „Analysis of intercepted illicit nuclear or radioactive material and any associated material to provide evidence for nuclear attribution.“ Nuclear Forensics Support, 2006. IAEA Nuclear Security Series No. 2. http://www-pub.iaea.org/MTCD/publications/PDF/Pub1241_web.pdf “Scientific analysis of nuclear or other radioactive material, or of other evidence that is contaminated with radioactive material in the context of legal proceedings, including administrative, civil, criminal or international Law.” Nuclear Forensics in Support of Investigations, IAEA Nuclear Security Series No.2 “Analysis of nuclear material of unknown origin.” K. Mayer, M. Wallenius, and Z. Varga, Chem. Rev. 2013, 113, 884−900 15 Nuclear Forensic Science How to provide evidence for nuclear attribution? What can be analyzed? Isotopic Signatures of Plutonium and Uranium Age Dating Chemical Impurities Morphology of Nuclear Material Powders 16 Nuclear Forensic Science Isotopic Signatures Uranium and plutonium are the materials of primary concern - - 238U (n, ) 239U 239Np 239Pu (n, )(n,240Pu ) 241Pu (n, ) 242Pu - (n,2n) fission 241Am - 237U 237Np (n, ) 238Np 238Pu (n, ) (n, ) 235U 236U The probability of the different neutron reactions (capture and fission) is a function of the neutron energy Different types of reactor show different neutron energy distributions The isotopic profile of plutonium can serve as signature of the type of reactor it was produced from 17 Nuclear Forensic Science Isotopic Signatures Uranium and plutonium are the materials of primary concern - - 238U (n, ) 239U 239Np 239Pu (n, )(n,240Pu ) 241Pu (n, ) 242Pu - (n,2n) fission 241Am - 237U 237Np (n, ) 238Np 238Pu (n, ) (n, ) 235U 236U Determination of the reactor class (242Pu compared to 240Pu) Date of discharge (241Pu relationship to 240Pu and 242Pu) Time since the last chemical processing (241Am compared to 241Pu) 18 Nuclear Forensic Science Production date or age Time elapsed since the last chemical processing of the material Can be distinguished by daughter/ parent ratio measurements (s. radio chemical equilibrium) sample type chronometer highly enriched 214Bi/234U uranium 230Th/234U 231Pa/235U uranium oxides 230Th/234U uranium ore 228Th/232Th concentrates 19 Synthesis of Elements Heaviest stable element is Bismuth Holes in the periodic Table: Technetium, Promethium 20 Synthesis of Elements Artificial elements 96 2 97 1 42Mo 1H 43Tc0 n Molybdenum Technetium 209 4 211 1 83Bi 2 He 85 At 20 n Bismuth Astatinium 230 1 223 4 Thorium Francium 90Th1H 87 Fr 22 He 21 Synthesis of Elements Synthesis of Trans-Uranium Elements n, - 238 239 239 McMillan 1940 U U Np (fission product) n,2n - 238U 237U 237Np - 235U n, n, 237U 237Np d,2n - 238U 238Np 238Pu Seaborg 1940 - 239Pu n, n, 241Pu 241Am Seaborg 1944 n, - 241Am 242Am 242Cm Seaborg 1944 n 242Cm 245Cf Thompson 1950 22 Synthesis of Elements Synthesis of Trans-Uranium Elements 26Mg 248Cm 274Hs 270Hs 1·1017 1·1016 5·106 1 projectiles on target compound nuclei atom 23 Synthesis of Elements Synthesis of Trans-Uranium Elements 24 Synthesis of Elements Synthesis of Trans-Uranium Elements atomic no. element name symbol 101 mendelevium Md 102 nobelium No 103 lawrencium Lr 104 rutherfordium Rf 105 dubnium Db 106 seaborgium Sg 107 bohrium Bh 108 hassium Hs 109 meitnerium Mt Current Periodic Table of the Elements with IUPAC approved 110 darmstadtium Ds numbering of groups and element symbols. The names for 111 roentgenium Rg elements 114 (Flerovium, Fl) and 116 (Livermorium, Lv) suggested by the team of discoverers have recently been 112 copernicium Cn officially accepted by IUPAC. 113 ununtrium Uut 114 flerovium Fl 115 ununpentium Uup 116 livermorium Lv 117 ununseptium Uus 118 ununoctium Uuo Andreas Türler; Valeria Pershina; Chem. Rev. 2013, 113, 1237-1312. 25.
Load more

Recommended publications
  • 3 Gamma-Ray Detectors
    3 Gamma-Ray Detectors Hastings A Smith,Jr., and Marcia Lucas S.1 INTRODUCTION In order for a gamma ray to be detected, it must interact with matteu that interaction must be recorded. Fortunately, the electromagnetic nature of gamma-ray photons allows them to interact strongly with the charged electrons in the atoms of all matter. The key process by which a gamma ray is detected is ionization, where it gives up part or all of its energy to an electron. The ionized electrons collide with other atoms and liberate many more electrons. The liberated charge is collected, either directly (as with a proportional counter or a solid-state semiconductor detector) or indirectly (as with a scintillation detector), in order to register the presence of the gamma ray and measure its energy. The final result is an electrical pulse whose voltage is proportional to the energy deposited in the detecting medhtm. In this chapter, we will present some general information on types of’ gamma-ray detectors that are used in nondestructive assay (NDA) of nuclear materials. The elec- tronic instrumentation associated with gamma-ray detection is discussed in Chapter 4. More in-depth treatments of the design and operation of gamma-ray detectors can be found in Refs. 1 and 2. 3.2 TYPES OF DETECTORS Many different detectors have been used to register the gamma ray and its eneqgy. In NDA, it is usually necessary to measure not only the amount of radiation emanating from a sample but also its energy spectrum. Thus, the detectors of most use in NDA applications are those whose signal outputs are proportional to the energy deposited by the gamma ray in the sensitive volume of the detector.
    [Show full text]
  • 1. Gamma-Ray Detectors for Nondestructive Analysis P
    1. GAMMA-RAY DETECTORS FOR NONDESTRUCTIVE ANALYSIS P. A. Russo and D. T. Vo I. INTRODUCTION AND OVERVIEW Gamma rays are used for nondestructive quantitative analysis of nuclear material. Knowledge of both the energy of the gamma ray and its rate of emission from the unknown mass of nuclear material is required to interpret most measurements of nuclear material quantities. Therefore, detection of gamma rays for nondestructive analysis of nuclear materials requires both spectroscopy capability and knowledge of absolute specific detector response. Some techniques nondestructively quantify attributes other than nuclear material mass, but all rely on the ability to distinguish elements or isotopes and measure the relative or absolute yields of their corresponding radiation signatures. All require spectroscopy and most require high resolution. Therefore, detection of gamma rays for quantitative nondestructive analysis (NDA) of the mass or of other attributes of nuclear materials requires spectroscopy. A previous book on gamma-ray detectors for NDA1 provided generic descriptions of three detector categories: inorganic scintillation detectors, semiconductor detectors, and gas-filled detectors. This report described relevant detector properties, corresponding spectral characteristics, and guidelines for choosing detectors for NDA. The current report focuses on significant new advances in detector technology in these categories. Emphasis here is given to those detectors that have been developed at least to the stage of commercial prototypes. The type of NDA application – fixed installation in a count room, portable measurements, or fixed installation in a processing line or other active facility (storage, shipping/receiving, etc.) – influences the choice of an appropriate detector. Some prototype gamma-ray detection techniques applied to new NDA approaches may revolutionize how nuclear materials are quantified in the future.
    [Show full text]
  • Appendix B: Recommended Procedures
    Recommended Procedures Appendix B Appendix B: Recommended Procedures Appendix B provides recommended procedures for tasks frequently performed in the laboratory. These procedures outline acceptable methods for meeting radiation safety requirements. The procedures are generic in nature, allowing for the diversity of research facilities, on campus. Contamination Survey Procedures Surveys are performed to monitor for the presence of contamination. Minimum survey frequencies are specified on the radiation permit. The surveys should be sufficiently extensive to allow confidence that there is no contamination. Common places to check for contamination are: bench tops, tools and equipment, floors, telephones, floors, door handles and drawer pulls, and computer keyboards. Types of Contamination Removable contamination can be readily transferred from one surface to another. Removable contamination may present an internal and external hazard because it can be picked up on the skin and ingested. Fixed contamination cannot be readily removed and generally does not present a significant hazard unless the material comes loose or is present large enough amounts to be an external hazard. Types of Surveys There are two types of survey methods used: 1) a direct (or meter) survey, and 2) a wipe (or smear) survey. Direct surveys, using a Geiger-Mueller (GM) detector or scintillation probe, can identify gross contamination (total contamination consisting of both fixed and removable contamination) but will detect only certain isotopes. Wipe surveys, using “wipes” such as cotton swabs or filter papers counted on a liquid scintillation counter or gamma counter can identify removable contamination only but will detect most isotopes used at the U of I. Wipe surveys are the most versatile and sensitive method of detecting low-level removable contamination in the laboratory.
    [Show full text]
  • DRC-2016-012921.Pdf
    CLN-SRT-011 R1.0 Page 2 of 33 Introduction ................................................................................................................................ 3 Sources of Radiation .................................................................................................................. 3 Radiation: Particle vs Electromagnetic ....................................................................................... 5 Ionizing and non- ionizing radiation ............................................................................................ 8 Radioactive Decay ....................................................................................................................10 Interaction of Radiation with Matter ...........................................................................................15 Radiation Detection and Measurement .....................................................................................17 Biological Effects of Radiation ...................................................................................................18 Radiation quantities and units ...................................................................................................18 Biological effects .......................................................................................................................20 Effects of Radiation by Biological Organization .........................................................................20 Mechanisms of biological damage ............................................................................................21
    [Show full text]
  • Portable Front-End Readout System for Radiation Detection
    Portable Front-End Readout System for Radiation Detection by Maris Tali THESIS for the degree of MASTER OF SCIENCE (Master in Electronics) Faculty of Mathematics and Natural Sciences University of Oslo June 2015 Det matematisk- naturvitenskapelige fakultet Universitetet i Oslo Portable Front-End Readout System for Radiation Detection Maris Tali Portable Front-End Readout System for Radiation Detection Maris Tali Portable Front-End Readout System for Radiation Detection Acknowledgements First of all, I would like to thank my advisor, Ketil Røed, for giving me the opportunity to write my master thesis on such an interesting and challenging subject as radiation instrumentation and measurement. I would also like to thank him for his insight and guidance during my master thesis and for the exciting opportunities during my studies to work in a real experimental environment. I would also like to thank the Electronic Laboratory of the University of Oslo, specif- ically Halvor Strøm, David Bang and Stein Nielsen who all gave me valuable advice and assistance and without whom this master thesis could not have been finished. Lastly, I would like to thank the co-designer of the system whom I worked together with during my master thesis, Eino J. Oltedal. It is customary to write that half of ones master thesis belongs to ones partner. However, this is actually the case in this instance so I guess 2/3 of my master thesis is yours and I definitely could not have done this without you. So, thank you very much! Oslo, June 2015 Maris Tali I Maris Tali Portable Front-End Readout System for Radiation Detection Contents Acknowledgments I Glossary VI List of Figures X List of Tables X Abstract XI 1 Introduction 1 1.1 Background and motivation .
    [Show full text]
  • THESIS VERIFICATION of BACKGROUND REDUCTION in a LIQUID SCINTILLATION COUNTER Submitted by Marilyn Alice Magenis Department of E
    THESIS VERIFICATION OF BACKGROUND REDUCTION IN A LIQUID SCINTILLATION COUNTER Submitted by Marilyn Alice Magenis Department of Environmental and Radiological Health Sciences In partial fulfillment of the requirements For the Degree of Master of Science Colorado State University Fort Collins, Colorado Summer 2013 Master’s Committee: Advisor: Alexander Brandl Thomas E. Johnson John Volckens John Harton ABSTRACT VERIFICATION OF BACKGROUND REDUCTION IN A LIQUID SCINTILLATION COUNTER A new method for subtraction of extraneous cosmic ray background counts from liquid scintillation detection has been developed by HidexTM. The method uses a background counter located beneath the liquid scintillation detector, the guard, to account for background signals. A double to triple coincidence counting methodology is used to reduce photomultiplier noise and to quantify quench. It is important to characterize the interactions from background in any new system. Characterizing interactions in the instrument will help to verify the accuracy and efficiency of the guard by determining the noise cancellation capabilities of the liquid scintillation counter. The liquid scintillation counter and guard detector responses were modeled using MCNP for the expected cosmic ray interactions at the instrument location and altitude in Fort Collins, CO. Cosmic ray interactions in the detector are most relevant to examine because of their predominance due to the higher elevation in Fort Collins. The cosmic ray interactions that are most important come from electron, positron, and gamma interactions. The expected cosmic ray interactions from these particles were modeled by using a cosmic ray library that determines the cosmic rays that are most likely to occur at an altitude of 2100 meters.
    [Show full text]
  • Semiconductor Detectors Silvia Masciocchi GSI Darmstadt and University of Heidelberg
    Semiconductor detectors Silvia Masciocchi GSI Darmstadt and University of Heidelberg 39th Heidelberg Physics Graduate Days, HGSFP Heidelberg October 10, 2017 Semiconductor detector: basics IONIZATION as in gas detectors → Now in semiconductors = solid materials with crystalline structure (Si, Ge, GaAs) → electron-hole pairs (instead of electron-ion) + use microchip technology: structures with few micrometer precision can be produced at low cost. Read-out electronics can be directly bonded to the detectors + only a few eV per electron-hole pair → 10 times more charge produced (wrt gas) → better energy resolution + high density compared to gases → need only thin layers (greater stopping power) – apart from silicon, the detectors need to be cooled (cryogenics) – crystal lattices → radiation damage [email protected] Semiconductor detectors, October 11, 2017 2 Applications Main applications: ● γ spectroscopy with high energy resolution ● Energy measurement of charged particles (few MeV) and particle identification (PID) via dE/dx (multiple layers needed) ● Very high spatial resolution for tracking and vertexing A few dates: 1930s – very first crystal detectors 1950s – first serious developments of particle detectors 1960s – energy measurement devices in commerce [email protected] Semiconductor detectors, October 11, 2017 3 Semiconductor detectors: outline ● Principle of operation of semiconductor detectors ● Properties of semiconductors (band structure) ● Intrinsic material ● Extrinsic (doped) semiconductors ● p-n junction ● Signal generation ● Energy measurement with semiconductor detectors ● Position measurement with semiconductor detectors ● Radiation damage [email protected] Semiconductor detectors, October 11, 2017 4 Principle of operation ● Detector operates as a solid state ionization chamber ● Charged particles create electron-hole pairs ● Place the crystal between two electrodes that set up an electric field → charge carriers drift and induce a signal ● Less than 1/3 of energy deposited goes into ionization.
    [Show full text]
  • Internal and External Exposure Exposure Routes 2.1
    Exposure Routes Internal and External Exposure Exposure Routes 2.1 External exposure Internal exposure Body surface From outer space contamination and the sun Inhalation Suspended matters Food and drink consumption From a radiation Lungs generator Radio‐ pharmaceuticals Wound Buildings Ground Radiation coming from outside the body Radiation emitted within the body Radioactive The body is equally exposed to radiation in both cases. materials "Radiation exposure" refers to the situation where the body is in the presence of radiation. There are two types of radiation exposure, "internal exposure" and "external exposure." External exposure means to receive radiation that comes from radioactive materials existing on the ground, suspended in the air, or attached to clothes or the surface of the body (p.25 of Vol. 1, "External Exposure and Skin"). Conversely, internal exposure is caused (i) when a person has a meal and takes in radioactive materials in the food or drink (ingestion); (ii) when a person breathes in radioactive materials in the air (inhalation); (iii) when radioactive materials are absorbed through the skin (percutaneous absorption); (iv) when radioactive materials enter the body from a wound (wound contamination); and (v) when radiopharmaceuticals containing radioactive materials are administered for the purpose of medical treatment. Once radioactive materials enter the body, the body will continue to be exposed to radiation until the radioactive materials are excreted in the urine or feces (biological half-life) or as the radioactivity weakens over time (p.26 of Vol. 1, "Internal Exposure"). The difference between internal exposure and external exposure lies in whether the source that emits radiation is inside or outside the body.
    [Show full text]
  • Liquid Scintillation Counting
    Institutionen för medicin och vård Avdelningen för radiofysik Hälsouniversitetet Liquid Scintillation Counting Sten Carlsson Department of Medicine and Care Radio Physics Faculty of Health Sciences Series: Report / Institutionen för radiologi, Universitetet i Linköping; 78 ISSN: 1102-1799 ISRN: LIU-RAD-R-078 Publishing year: 1993 © The Author(s) Report 78 lSSN 1102-1799 Nov 1993 lSRN ULI-RAD-R--78--SE Liquid Scintillation Counting Sten Carlsson Dept of Radiation Physlcs Dept Medical Physlcs Linköping Unlverslly , Sweden: UddevalIa,Svveden i 1. INTRODUCTIQN In liquid scintillation counting (LSC) we use the process ofluminescense to detect ionising radiation emit$ed from a radionuclide. Luminescense is emission of visible light ofnon­ thermal origin. 1t was early found that certain organic molecules have luminescent properties and such molecules are used in LSC. Today LSC is the mostwidespread method to detect pure beta-ernitters like tritium and carbon-14. 1t has unique properties in its efficient counting geometry, deteetability and the lack of any window which the beta­ particles have to penetrate. These properties are achieved by solving the sample to measure in a scintillation cocktail composed of an organic solvent and a solute (scintillator). Even if LSC is a weil established measurement technique, the user can run into problems and abasic knowledge of the deteetor and its different components is offundamental importance in a correct use of the technique. The alm of this presentation is to provide the user with some of this fundamental knowledge. 2. BAS1C PRINCIPLE LSC is based on the principle oftransformlng some of the kinetic energy of the beta-partic1e into light photons.
    [Show full text]
  • A Direct Search for Dark Matter with the Majorana Demonstrator
    A DIRECT SEARCH FOR DARK MATTER WITH THE MAJORANA DEMONSTRATOR Kristopher Reidar Vorren A dissertation submitted to the faculty at the University of North Carolina at Chapel Hill in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Physics. Chapel Hill 2017 Approved by: Reyco Henning Chris Clemens Jonathan Engel Christian Iliadis John F. Wilkerson c 2017 Kristopher Reidar Vorren ALL RIGHTS RESERVED ii ABSTRACT Kristopher Reidar Vorren: A Direct Search for Dark Matter with the Majorana Demonstrator (Under the direction of Reyco Henning) The Majorana Demonstrator is a neutrinoless double-beta decay experiment cur- rently operating 4850 ft underground in the Sanford Underground Research Facility in Lead, SD. Sub-keV thresholds and excellent low-energy resolution are features of the p-type point- contact high-purity germanium detectors deployed by Majorana, making them ideal for use in direct dark matter searches when combined with Majorana's ultra-low backgrounds. An analysis of data from a 2015 commissioning run of the Demonstrator with 478 kg d of exposure was performed to search for mono-energetic lines in the detectors' energy-spectrum from bosonic dark matter absorption. No dark matter signature was found in the 5-100 keV range, and upper limits were placed on dark bosonic pseudoscalar and vector-electric cou- plings. The same analysis produced null results and upper limits for three additional rare- event searches: Pauli-Exclusion Principle violating decay, solar axions, and electron decay. Improvements made to Majorana since commissioning will result in increased sensitivity to rare-event searches in future analyses.
    [Show full text]
  • Radiation Safety Guide Research Use of Radioactive Materials
    Radiation Safety Guide Research Use of Radioactive Materials Table of Contents Page RADIATION AND RADIOACTIVITY 4 A. Decay by Alpha (α)-Particle Emission 4 B. Decay by Beta (β)− Particle Emission 5 C. Decay by Gamma Ray (γ) emission 5 D. Decay by Electron Capture (X-ray) 5 E. Other sources of Radiation 5 F. Neutron particles (n) 6 G. Radiation Quantities 6 H. Half-life, Biological half-life, Effective half-life 7 I. Radiation Detection Instrument 8 1. Gas-filled detectors 8 2. Scintillation Detector 8 J. Background Radiation 9 K. Biological Effect of Radiation 10 PRINCIPLES OF RADIATION SAFETY 11 A. Occupational Dose Limit 11 B. Public Dose 11 D. Dose to an Embryo/Fetus 11 E. Registration of Radiation Workers 12 F. Personnel Monitoring 12 G. Type of Dosimeters 12 H. Dosimeter Placement 12 I. Internal Monitoring 13 J. Exposure Reports 13 K. ALARA 13 L.Posting 14 1 RADIATION SAFETY PROGRAM 16 A. Individuals Responsible For Radiation Safety Program 16 B. Organization Chart 16 C. Radiation Safety Committee 16 D. Radiation Safety Officer 17 E. Authorized Users 18 F. Radiation Workers 19 G. Radioactive Drug Research Committee (RDRC) 19 H. Medical Radiation Subcommittee (MRC) 22 RADIATION SAFETY PROCEDURES 23 A. Training Program 23 1. Initial Radiation Safety Training 24 2. Annual Refresher Training 24 3. Radiation Safety Training for Clinical Staff 24 4. Radiation Safety Training for House Keeping, Physical Plant and Security Staff 24 5. Radiation Safety Training for irradiator workers 24 B. Audit Program 24 C. Survey Program 25 1. Survey for Removable Contamination 27 2.
    [Show full text]
  • Semiconductor Detectors Part 1
    1 Lectures on Detector Techniques Stanford Linear Accelerator Center September 1998 – February, 1999 Semiconductor Detectors Part 1 Helmuth Spieler Physics Division Lawrence Berkeley National Laboratory for more details see UC Berkeley Physics 198 course notes at http://www-physics.lbl.gov/~spieler Semiconductor Detectors Helmuth Spieler SLUO Lectures on Detector Techniques, October 23, 1998 LBNL 2 1. Principles Important excitations when radiation is absorbed in solids 1. atomic electrons ⇒ mobile charge carriers ⇒ lattice excitations (phonons) 2. elastic scattering on nuclei Recoil energy < order 10 eV ⇒ ionization ⇒ lattice excitations (phonons) at higher recoil energies ⇒ radiation damage (displacement of from lattice sites) Semiconductor Detectors Helmuth Spieler SLUO Lectures on Detector Techniques, October 23, 1998 LBNL 3 Most Semiconductor Detectors are Ionization Chambers Detection volume with electric field Energy deposited → positive and negative charge pairs Charges move in field → current in external circuit (continuity equation) Semiconductor Detectors Helmuth Spieler SLUO Lectures on Detector Techniques, October 23, 1998 LBNL 4 Ionization chambers can be made with any medium that allows charge collection to a pair of electrodes. Medium can be gas liquid solid Crude comparison of relevant properties gas liquid solid density low moderate high atomic number Z low moderate moderate ionization energy εi moderate moderate low signal speed moderate moderate fast Desirable properties: low ionization energy ⇒ 1. increased charge
    [Show full text]