There are three main types of radiation detectors: gas-filled detectors which use a gas between electrodes, scintillation detectors which use materials that produce light when irradiated, and semiconductor detectors made of purified crystalline materials. Detectors can also be classified by the type of information they provide, such as counting interactions, measuring energy, or indicating dose. The main challenges for detectors are dead time at high interaction rates and maintaining good energy resolution and detection efficiency.
This document provides an overview of active methods for neutron detection, including gas filled detectors like ionization chambers and proportional counters, scintillation detectors using materials like lithium iodide and organic scintillators, and semiconductor detectors. It describes the basic detection mechanisms, advantages and disadvantages of different methods, and their typical applications in neutron dosimetry and spectrometry.
The experiment tested two boron trifluoride proportional gas tube neutron detectors and a REM sphere dose meter. The gas tubes detected slow neutrons below 0.5 eV using the 10B(n,α)7Li reaction, while the REM sphere could detect fast neutrons above 0.5 eV after they were slowed. Count rate and pulse height data were taken for the gas tubes at varying voltages to determine optimal operating voltages. Spectral measurements found that gamma rays were effectively blocked. Neutron fluxes were significantly attenuated outside shielding containing boron and cadmium. REM sphere measurements from 1-16 feet from a californium source yielded experimental dose rates from 1.07-77.2 μSv/hr
This document discusses different types of radiation detectors, including scintillation detectors, Geiger-Muller (GM) counters, and proportional counters. Scintillation detectors detect radiation via scintillation light produced in luminescent materials coupled to photomultiplier tubes. GM counters use gas multiplication in Geiger-Muller tubes to detect ionizing radiation via voltage pulses. Proportional counters operate at lower voltages to provide energy information, while GM counters only indicate detection.
This document provides an overview of radiation detectors. It discusses why radiation detection is important, how radiation interacts with matter, common types of detectors like ionization chambers, proportional counters, and GM counters, and how detectors work to detect different types of radiation. Specific examples are given around using an ion chamber survey meter to detect x-rays. Key factors around detector selection, specifications, and operating principles are summarized.
Radiation detectors work by exploiting how radiation interacts with matter to produce measurable signals. The document discusses several types of radiation detectors, including gas-filled detectors like Geiger-Muller counters, scintillation detectors, and semiconductor detectors. It explains how each detector works and its applications, advantages, and limitations. The document also covers topics like pulse processing, resolving time, and quenching in Geiger counters to restore the detector to a quiescent state between detections.
This document discusses various types of particle detectors used in high energy physics experiments. It describes semiconductor detectors, solid state detectors, ionization chambers, Geiger-Muller detectors, and photoconductive detectors. It also discusses applications of these detectors at particle physics labs like LHC, CMS, ATLAS, and SLAC. Specific detectors at the BESIII experiment are described, including the drift chamber, electromagnetic calorimeter, and muon counter. In conclusion, the document outlines how these detectors are important for solving physics problems and their applications in high energy physics.
There are three main types of radiation detectors: gas-filled detectors which use a gas between electrodes, scintillation detectors which use materials that produce light when irradiated, and semiconductor detectors made of purified crystalline materials. Detectors can also be classified by the type of information they provide, such as counting interactions, measuring energy, or indicating dose. The main challenges for detectors are dead time at high interaction rates and maintaining good energy resolution and detection efficiency.
This document provides an overview of active methods for neutron detection, including gas filled detectors like ionization chambers and proportional counters, scintillation detectors using materials like lithium iodide and organic scintillators, and semiconductor detectors. It describes the basic detection mechanisms, advantages and disadvantages of different methods, and their typical applications in neutron dosimetry and spectrometry.
The experiment tested two boron trifluoride proportional gas tube neutron detectors and a REM sphere dose meter. The gas tubes detected slow neutrons below 0.5 eV using the 10B(n,α)7Li reaction, while the REM sphere could detect fast neutrons above 0.5 eV after they were slowed. Count rate and pulse height data were taken for the gas tubes at varying voltages to determine optimal operating voltages. Spectral measurements found that gamma rays were effectively blocked. Neutron fluxes were significantly attenuated outside shielding containing boron and cadmium. REM sphere measurements from 1-16 feet from a californium source yielded experimental dose rates from 1.07-77.2 μSv/hr
This document discusses different types of radiation detectors, including scintillation detectors, Geiger-Muller (GM) counters, and proportional counters. Scintillation detectors detect radiation via scintillation light produced in luminescent materials coupled to photomultiplier tubes. GM counters use gas multiplication in Geiger-Muller tubes to detect ionizing radiation via voltage pulses. Proportional counters operate at lower voltages to provide energy information, while GM counters only indicate detection.
This document provides an overview of radiation detectors. It discusses why radiation detection is important, how radiation interacts with matter, common types of detectors like ionization chambers, proportional counters, and GM counters, and how detectors work to detect different types of radiation. Specific examples are given around using an ion chamber survey meter to detect x-rays. Key factors around detector selection, specifications, and operating principles are summarized.
Radiation detectors work by exploiting how radiation interacts with matter to produce measurable signals. The document discusses several types of radiation detectors, including gas-filled detectors like Geiger-Muller counters, scintillation detectors, and semiconductor detectors. It explains how each detector works and its applications, advantages, and limitations. The document also covers topics like pulse processing, resolving time, and quenching in Geiger counters to restore the detector to a quiescent state between detections.
This document discusses various types of particle detectors used in high energy physics experiments. It describes semiconductor detectors, solid state detectors, ionization chambers, Geiger-Muller detectors, and photoconductive detectors. It also discusses applications of these detectors at particle physics labs like LHC, CMS, ATLAS, and SLAC. Specific detectors at the BESIII experiment are described, including the drift chamber, electromagnetic calorimeter, and muon counter. In conclusion, the document outlines how these detectors are important for solving physics problems and their applications in high energy physics.
The document discusses different types of radiation detection, focusing on gas-filled detectors and ionization chambers. There are two main effects of radiation: ionization and excitation. Gas-filled detectors measure ionization produced in gas. Ionization chambers are the simplest gas-filled detectors and work by collecting ion pairs created through gas ionization using an electric field to measure radiation. Ionization chambers are useful for radiation measurement and medical applications like dose calibration.
This document provides information about nuclear radiation detectors. It discusses three main types of gaseous ionization detectors: ionization chambers, proportional counters, and Geiger-Müller tubes. Ionization chambers detect radiation by collecting all ion pairs created through gas ionization when radiation passes through. Proportional counters can measure radiation energy by producing output proportional to radiation energy through gas amplification of ion pairs. Geiger-Müller tubes operate at very high voltages where any initial ionization causes a self-sustaining discharge and produces a standard pulse height independent of radiation type.
A Geiger-Muller counter consists of a gas-filled tube that detects ionizing radiation such as alpha particles, beta particles, and gamma rays. When radiation enters the tube, it ionizes the gas and produces a pulse of current that is counted by a scaler. To prevent additional pulses from a single radiation event, a small amount of quenching gas is added which absorbs excess energy and prevents further ionization of the main gas. The Geiger-Muller counter has a dead time after each detection where it cannot detect additional radiation as it re-establishes the electric field inside the tube.
This document discusses different types of gas-filled radiation detectors, including their operating principles and applications. It covers ionization chambers, proportional counters, and Geiger-Muller counters. Key points include:
1) Ionization chambers measure current and have a wide operating voltage range where ion pairs are collected. They are commonly used to measure exposure in radiology and nuclear medicine.
2) Proportional counters use a higher electric field to cause ion avalanches, amplifying the signal. Noble gases like argon and xenon are used to enable gas multiplication.
3) Geiger-Muller counters operate at an even higher voltage where each interaction produces the same-sized pulse, regardless of
This document discusses types of radiation, their interaction with matter, and radiation detectors. It covers the following types of radiation: photons (gamma rays and x-rays), neutrons, electrons, ions, protons, and alpha particles. It describes the processes of photoelectric effect, Compton scattering, and pair production for photon interaction, as well as scattering, capture and other interactions for neutrons. The document also discusses why radiation detection is important and gives examples of different types of radiation detectors like gas detectors, scintillation detectors, and semiconductor detectors.
This document discusses different types of gas-filled and scintillation radiation detectors. It provides information on GM counters, proportional counters, scintillators, photomultiplier tubes, and thermoluminescent dosimeters. Key points include: how GM counters differ from proportional counters in their avalanche chain reactions; common scintillator materials like NaI(Tl) and BGO; how photomultiplier tubes convert light photons to electrical signals and amplify signals through dynode multiplication; and applications of different detector types in nuclear medicine imaging. The document is in a question-answer format where various concepts are explained in response to questions.
This document discusses various types of radiation detection devices, including film badges, ionization chambers, Geiger-Muller counters, proportional counters, scintillation counters, photographic plates, electroscopes, bubble chambers, solid-state detectors, cloud chambers, and spark counters. Each detection method works by using different processes like ionization, fluorescence, or track visualization to detect and sometimes quantify radiation levels or particle energy. Regular monitoring of radiation is important for safety when working with radioactive materials.
This document discusses using atom trap trace analysis (ATTA) to measure krypton contamination in rare gases like neon and xenon. ATTA can trap and detect individual krypton atoms, allowing measurement of krypton abundance down to levels of 10-14 in only 3 hours. This high sensitivity and fast measurement makes ATTA a useful technique for evaluating krypton backgrounds in rare gas detectors for neutrinos and complementing gas purification efforts for next-generation neutrino experiments.
The document describes the proportional counter, which is a gaseous state particle detector used to detect nuclear particles and radiation. It consists of a cylindrical metal tube filled with argon and methane gas and a thin metal wire running down the center as an anode. When radiation enters the tube, it ionizes the gas, producing electron-ion pairs. An applied voltage between the wire and tube causes gas amplification through avalanching, resulting in a pulse signal. The proportional counter can be used for particle counting and energy determination, and has advantages like low-energy detection but requires stable applied voltages.
Ionization chamber - INAYA MEDICAL COLLEGEAnas Yess
Radiation detection uses two main methods: ionization and excitation. There are two types of radiation detection in nuclear medicine: gas-filled detectors used for non-imaging and scintillator detectors used for imaging. Gas-filled detectors like ionization chambers function by measuring the ionization produced in the gas when radiation passes through. Ionization chambers are the simplest gas-filled detectors and are widely used to detect x-rays, gamma rays, and beta particles by collecting the ion pairs created through ionization in the gas using an electric field.
This document discusses various methods for detecting radiation. It outlines passive detectors like photographic film, electroscopes, dosimeters, and thermoluminescent dosimeters (TLDs) which do not require a power source. Active detectors mentioned include Geiger-Muller tubes and scintillation detectors, which need a constant energy supply. Both types detect radiation indirectly by ionizing matter and detecting the ions produced, though active detectors provide more information about the radiation type and energy.
This document discusses semi-conductor detectors and their use in radiation detection. It describes the basic structure of atoms and different types of bonds between atoms. It explains that in crystalline materials like semiconductors, electrons exist in energy bands separated by gaps. In semiconductors and insulators, the valence band is full while the conduction band is empty, allowing electrons to move if given enough energy to cross the band gap. Semiconductors can be "doped" with impurities to create p-type or n-type materials and function as radiation detectors by generating electron-hole pairs when ionizing radiation transfers electrons to the conduction band.
1) The document discusses various types of neutron detectors, their detection principles, energy response characteristics, and challenges in accurately measuring neutron dose equivalent rates. It focuses on REM balls but also covers other technologies like TEPC, mixed gas detectors, and CLYC.
2) Key points covered include how detector response varies with neutron energy spectrum, factors of over or under response depending on energy, and importance of characterizing the neutron field energy spectrum. It also highlights challenges in accounting for directionality and mixed gamma/neutron exposures.
3) Newer portable neutron detectors like mixed gas, Domino, and CLYC provide alternatives to REM balls and aim to improve gamma rejection, energy response, and form factor for radiological
Measurement of Radiation (Thimble Ionization Chamber, Free air Ionization Cha...Upakar Paudel
The document discusses different methods for measuring ionizing radiation, including early methods based on chemical or biological effects and later adoption of the roentgen unit based on ionization in air. It focuses on the free-air ionization chamber, which measures exposure (roentgens) by collecting ions produced in a known mass of air. Limitations led to the development of thimble chambers, which mimic free-air chambers using solid, air-equivalent walls of appropriate thickness to achieve electronic equilibrium within the chamber.
Nuclear radiation detectors detect nuclear particles and radiation. They work by exciting or ionizing the atoms in the material they pass through. There are different types of radiation including charged particles like alpha and beta particles, uncharged neutrons, and electromagnetic gamma rays and x-rays. Detection methods are based on the radiation interacting with the detector's base material, often ionizing or exciting its atoms. Detectors are classified as gas filled, ionization chambers, Geiger-Muller counters, semiconductors, Wilson cloud chambers or bubble chambers. Their workings exploit the properties of ionization, fluorescence, or exposing photographic plates.
SRIM Calculations Applied to Ionization Chambers Tyler BaileyTyler Bailey
1) SRIM simulations were used to model the interaction of alpha particles in different gases to determine the ideal gas for an ionization chamber. Argon gas was found to be optimal as it produced the largest voltage signal for a given alpha energy due to its high atomic number and low ionization potential.
2) The simulations calculated ion pairs produced and voltage pulses for various alpha energies in different gases. Argon had the highest ion pair production and voltage pulses, making it suitable for compact ionization chamber designs.
3) The voltage pulses could be used to determine the alpha energy interacting in the chamber, allowing identification of radioactive sources. However, more sophisticated processing is needed to account for other radiation types.
The document summarizes the Geiger-Müller counter, an instrument used to detect ionizing radiation such as alpha particles, beta particles, and gamma rays. It describes the history and development of the counter, from its original detection principle discovered in 1908 to its modern form using a Geiger-Müller tube. The operating principle is explained, where ionization events in an inert gas-filled tube produce electrical pulses that are counted and displayed. Different readout types including counts per second and absorbed dose are discussed. Applications include detection of radioactive materials and environmental monitoring for radiation levels.
The document discusses the measurement of ionizing radiation using ionization chambers. It describes how ionization chambers work by collecting ions produced when radiation interacts with air. Exposure is defined as the charge produced in air divided by the mass of air. The roentgen is the special unit of exposure. Types of ionization chambers discussed include thimble chambers, parallel plate chambers, and extrapolation chambers. Factors that affect ion collection such as voltage, recombination, temperature, and pressure are also summarized.
JEE Physics/ Lakshmikanta Satapathy/ Beta decay of a nucleus and the subsequent emission of a Gamma ray photon with the related concepts of mass defect and excitation energy
The document discusses different types of radiation detection, focusing on gas-filled detectors and ionization chambers. There are two main effects of radiation: ionization and excitation. Gas-filled detectors measure ionization produced in gas. Ionization chambers are the simplest gas-filled detectors and work by collecting ion pairs created through gas ionization using an electric field to measure radiation. Ionization chambers are useful for radiation measurement and medical applications like dose calibration.
This document provides information about nuclear radiation detectors. It discusses three main types of gaseous ionization detectors: ionization chambers, proportional counters, and Geiger-Müller tubes. Ionization chambers detect radiation by collecting all ion pairs created through gas ionization when radiation passes through. Proportional counters can measure radiation energy by producing output proportional to radiation energy through gas amplification of ion pairs. Geiger-Müller tubes operate at very high voltages where any initial ionization causes a self-sustaining discharge and produces a standard pulse height independent of radiation type.
A Geiger-Muller counter consists of a gas-filled tube that detects ionizing radiation such as alpha particles, beta particles, and gamma rays. When radiation enters the tube, it ionizes the gas and produces a pulse of current that is counted by a scaler. To prevent additional pulses from a single radiation event, a small amount of quenching gas is added which absorbs excess energy and prevents further ionization of the main gas. The Geiger-Muller counter has a dead time after each detection where it cannot detect additional radiation as it re-establishes the electric field inside the tube.
This document discusses different types of gas-filled radiation detectors, including their operating principles and applications. It covers ionization chambers, proportional counters, and Geiger-Muller counters. Key points include:
1) Ionization chambers measure current and have a wide operating voltage range where ion pairs are collected. They are commonly used to measure exposure in radiology and nuclear medicine.
2) Proportional counters use a higher electric field to cause ion avalanches, amplifying the signal. Noble gases like argon and xenon are used to enable gas multiplication.
3) Geiger-Muller counters operate at an even higher voltage where each interaction produces the same-sized pulse, regardless of
This document discusses types of radiation, their interaction with matter, and radiation detectors. It covers the following types of radiation: photons (gamma rays and x-rays), neutrons, electrons, ions, protons, and alpha particles. It describes the processes of photoelectric effect, Compton scattering, and pair production for photon interaction, as well as scattering, capture and other interactions for neutrons. The document also discusses why radiation detection is important and gives examples of different types of radiation detectors like gas detectors, scintillation detectors, and semiconductor detectors.
This document discusses different types of gas-filled and scintillation radiation detectors. It provides information on GM counters, proportional counters, scintillators, photomultiplier tubes, and thermoluminescent dosimeters. Key points include: how GM counters differ from proportional counters in their avalanche chain reactions; common scintillator materials like NaI(Tl) and BGO; how photomultiplier tubes convert light photons to electrical signals and amplify signals through dynode multiplication; and applications of different detector types in nuclear medicine imaging. The document is in a question-answer format where various concepts are explained in response to questions.
This document discusses various types of radiation detection devices, including film badges, ionization chambers, Geiger-Muller counters, proportional counters, scintillation counters, photographic plates, electroscopes, bubble chambers, solid-state detectors, cloud chambers, and spark counters. Each detection method works by using different processes like ionization, fluorescence, or track visualization to detect and sometimes quantify radiation levels or particle energy. Regular monitoring of radiation is important for safety when working with radioactive materials.
This document discusses using atom trap trace analysis (ATTA) to measure krypton contamination in rare gases like neon and xenon. ATTA can trap and detect individual krypton atoms, allowing measurement of krypton abundance down to levels of 10-14 in only 3 hours. This high sensitivity and fast measurement makes ATTA a useful technique for evaluating krypton backgrounds in rare gas detectors for neutrinos and complementing gas purification efforts for next-generation neutrino experiments.
The document describes the proportional counter, which is a gaseous state particle detector used to detect nuclear particles and radiation. It consists of a cylindrical metal tube filled with argon and methane gas and a thin metal wire running down the center as an anode. When radiation enters the tube, it ionizes the gas, producing electron-ion pairs. An applied voltage between the wire and tube causes gas amplification through avalanching, resulting in a pulse signal. The proportional counter can be used for particle counting and energy determination, and has advantages like low-energy detection but requires stable applied voltages.
Ionization chamber - INAYA MEDICAL COLLEGEAnas Yess
Radiation detection uses two main methods: ionization and excitation. There are two types of radiation detection in nuclear medicine: gas-filled detectors used for non-imaging and scintillator detectors used for imaging. Gas-filled detectors like ionization chambers function by measuring the ionization produced in the gas when radiation passes through. Ionization chambers are the simplest gas-filled detectors and are widely used to detect x-rays, gamma rays, and beta particles by collecting the ion pairs created through ionization in the gas using an electric field.
This document discusses various methods for detecting radiation. It outlines passive detectors like photographic film, electroscopes, dosimeters, and thermoluminescent dosimeters (TLDs) which do not require a power source. Active detectors mentioned include Geiger-Muller tubes and scintillation detectors, which need a constant energy supply. Both types detect radiation indirectly by ionizing matter and detecting the ions produced, though active detectors provide more information about the radiation type and energy.
This document discusses semi-conductor detectors and their use in radiation detection. It describes the basic structure of atoms and different types of bonds between atoms. It explains that in crystalline materials like semiconductors, electrons exist in energy bands separated by gaps. In semiconductors and insulators, the valence band is full while the conduction band is empty, allowing electrons to move if given enough energy to cross the band gap. Semiconductors can be "doped" with impurities to create p-type or n-type materials and function as radiation detectors by generating electron-hole pairs when ionizing radiation transfers electrons to the conduction band.
1) The document discusses various types of neutron detectors, their detection principles, energy response characteristics, and challenges in accurately measuring neutron dose equivalent rates. It focuses on REM balls but also covers other technologies like TEPC, mixed gas detectors, and CLYC.
2) Key points covered include how detector response varies with neutron energy spectrum, factors of over or under response depending on energy, and importance of characterizing the neutron field energy spectrum. It also highlights challenges in accounting for directionality and mixed gamma/neutron exposures.
3) Newer portable neutron detectors like mixed gas, Domino, and CLYC provide alternatives to REM balls and aim to improve gamma rejection, energy response, and form factor for radiological
Measurement of Radiation (Thimble Ionization Chamber, Free air Ionization Cha...Upakar Paudel
The document discusses different methods for measuring ionizing radiation, including early methods based on chemical or biological effects and later adoption of the roentgen unit based on ionization in air. It focuses on the free-air ionization chamber, which measures exposure (roentgens) by collecting ions produced in a known mass of air. Limitations led to the development of thimble chambers, which mimic free-air chambers using solid, air-equivalent walls of appropriate thickness to achieve electronic equilibrium within the chamber.
Nuclear radiation detectors detect nuclear particles and radiation. They work by exciting or ionizing the atoms in the material they pass through. There are different types of radiation including charged particles like alpha and beta particles, uncharged neutrons, and electromagnetic gamma rays and x-rays. Detection methods are based on the radiation interacting with the detector's base material, often ionizing or exciting its atoms. Detectors are classified as gas filled, ionization chambers, Geiger-Muller counters, semiconductors, Wilson cloud chambers or bubble chambers. Their workings exploit the properties of ionization, fluorescence, or exposing photographic plates.
SRIM Calculations Applied to Ionization Chambers Tyler BaileyTyler Bailey
1) SRIM simulations were used to model the interaction of alpha particles in different gases to determine the ideal gas for an ionization chamber. Argon gas was found to be optimal as it produced the largest voltage signal for a given alpha energy due to its high atomic number and low ionization potential.
2) The simulations calculated ion pairs produced and voltage pulses for various alpha energies in different gases. Argon had the highest ion pair production and voltage pulses, making it suitable for compact ionization chamber designs.
3) The voltage pulses could be used to determine the alpha energy interacting in the chamber, allowing identification of radioactive sources. However, more sophisticated processing is needed to account for other radiation types.
The document summarizes the Geiger-Müller counter, an instrument used to detect ionizing radiation such as alpha particles, beta particles, and gamma rays. It describes the history and development of the counter, from its original detection principle discovered in 1908 to its modern form using a Geiger-Müller tube. The operating principle is explained, where ionization events in an inert gas-filled tube produce electrical pulses that are counted and displayed. Different readout types including counts per second and absorbed dose are discussed. Applications include detection of radioactive materials and environmental monitoring for radiation levels.
The document discusses the measurement of ionizing radiation using ionization chambers. It describes how ionization chambers work by collecting ions produced when radiation interacts with air. Exposure is defined as the charge produced in air divided by the mass of air. The roentgen is the special unit of exposure. Types of ionization chambers discussed include thimble chambers, parallel plate chambers, and extrapolation chambers. Factors that affect ion collection such as voltage, recombination, temperature, and pressure are also summarized.
JEE Physics/ Lakshmikanta Satapathy/ Beta decay of a nucleus and the subsequent emission of a Gamma ray photon with the related concepts of mass defect and excitation energy
The characterization of_the_gamma_ray_signal_from_the_central_milk_way_a_comp...Sérgio Sacani
This document analyzes the gamma-ray signal from the central Milky Way that is consistent with emission from annihilating dark matter particles. The authors re-examine Fermi data using cuts on an event parameter to improve gamma-ray maps and more easily separate components. They find the GeV excess is robust and well-fit by a 36-51 GeV dark matter particle annihilating to bottom quarks with a cross section of 1-3×10−26 cm3/s. The signal extends over 10 degrees from the Galactic Center and is spherically symmetric, disfavoring explanations from millisecond pulsars or gas interactions.
Final year project: To Design and Test a low cost Gamma Ray detectorChristopher Mitchell
The document describes designing and testing a low-cost gamma radiation detector using a smartphone camera. The author tests various parameters of the smartphone detector such as calibration with radiation sources, thermal noise, distance effects, shielding effects, timing resolution, and efficiency compared to semiconductor detectors. Although not as efficient as professional detectors, the smartphone detector provides a low-cost option for estimating radiation dose that is more accessible than specialized equipment.
Alles wat U nodig hebt in verband met "Gezonde Voeding", Gezond Bewegen, Gezond handelen.
Alles in een handig Werkboek.
Druk een af als handleiding en een dat U dagelijks kunt invullen als Werkboek.
Succes
#Theo Herbots
PS. vindt alles terug op https://theoherbotstv2.com/
High Sensitivity Gamma Ray Spectroscopy FYPDavid Holland
This document summarizes an investigation into potential impurities in the radiopharmaceutical isotopes samarium-153 and radium-223, which are used to treat bone pain in cancer patients. Samples were analyzed using sodium iodide and germanium detectors. The germanium detector results showed several impurities like actinium-227, thorium-227, protactinium-231 and uranium-235 present in both isotopes. However, further investigation is needed as the detector was not properly calibrated. The presence of impurities could potentially harm patients or cause issues with waste disposal. Samarium-153 and its uses in bone pain treatment are also discussed.
A Low Power & Low Noise Multi-Channel ASIC for X-Ray and Gamma-Ray SpectroscopyGunnar Maehlum
The document describes a family of multi-channel detector readout integrated circuits (ROICs) developed for X-ray and gamma-ray spectroscopy in space applications. The ROICs, called VATAs, integrate analog-to-digital converters for fully digital readout of radiation detectors. VATAs are being used on several space missions including ASTRO-H, BepiColombo, and FOXSI. They have low power dissipation, low noise, and provide digital pulse heights and pixel addresses upon detection of radiation. Test results show the VATAs achieve good energy resolution and meet requirements for noise, power, and temperature range for different space missions.
The document summarizes a gamma ray spectroscopy lab experiment. Key findings include:
- Gamma rays from various radioactive samples were measured using a sodium iodide detector and spectrometer interface.
- A linear relationship was found between the gamma ray energies and their channel numbers on the spectrometer.
- All major gamma ray interactions (photoelectric effect, Compton scattering) were observed except pair production which requires higher energies.
- The unknown isotope was identified as Cesium-137 based on its measured energy of 655.5 keV, though the author initially disagreed with this assessment.
This document discusses several key concepts in radiobiology including:
1. The interaction of radiation with cells is probabilistic, with damage occurring through direct and indirect action. Indirect action involves free radicals produced by radiation interacting with water molecules within cells.
2. Different phases of the cell cycle have differing radiosensitivities, with G2/M being most sensitive. Fractionated radiation can exploit this through redistribution effects.
3. The linear quadratic model describes cell survival curves and accounts for both single-hit and double-hit damage from radiation. It is used to calculate biologically equivalent doses.
4. Mechanisms like reoxygenation between fractions can improve the therapeutic ratio by making tumor cells
Gamma rays are a form of electromagnetic radiation emitted from radioactive substances. They have the shortest wavelengths and highest frequencies of any type of electromagnetic wave. Gamma rays are produced during radioactive decay, electron-positron annihilation, and other nuclear processes. Some key applications of gamma rays include use in radiography, cancer treatment, food sterilization, and nuclear weapons.
This is the presentation I gave when defending my Ph.D thesis at SLAC. The title of my defense was "Neutron Star Powered Nebulae: a New View on Pulsar Wind Nebulae with the Fermi Gamma-ray Space Telescope".
1) Radiation is naturally present and comes from space, ground, and within our bodies. Biological effects depend on factors like radiation type, dose, and exposed tissues.
2) Acute radiation exposure can cause acute radiation syndrome with prodromal, latent, and manifest illness stages depending on dose. Bone marrow, gastrointestinal, and cardiovascular syndromes can occur.
3) Radiation damages DNA directly or indirectly through water radiolysis. Cells may be delayed, die, mutate, or develop genomic instability and cancer. Bystander effects can also occur.
Radioactive isotopes emit radiation through radioactive decay as their unstable nuclei break down. There are three main types of radiation emitted: alpha particles, beta particles, and gamma rays. Radioactive isotopes are used in scientific research, analytical applications like radioimmunoassays, and medical diagnostic procedures and therapies. Some key radioactive isotopes used include iodine-131 for thyroid imaging and cancer treatment, technetium-99m for thyroid scans, and strontium-89 or samarium-153 to treat bone metastases.
This document summarizes key concepts in radiobiology. It discusses how radiation can directly or indirectly damage biological molecules through ionization. Both deterministic and stochastic effects are covered, with deterministic referring to cell killing and stochastic to long-term effects like cancer. Specific radiation effects are outlined for DNA, chromosomes, tissues, and organs. The document also examines radiation effects on oral tissues, whole body irradiation, and heritable/stochastic effects like cancer formation.
This document provides an overview of planning systems in radiotherapy and discusses various topics related to clinical treatment planning using computerized treatment planning systems. It begins with an introduction to the author and their experience with different treatment planning systems. It then covers definitions and concepts important for clinical treatment planning such as volumes, dose specifications, patient data acquisition, beam combinations, and dose statistics. The document also discusses virtual simulation, image fusion, treatment aids, oblique incidence corrections, and portal imaging. It provides details on the hardware, calculations algorithms, and commissioning of computerized treatment planning systems. In summary, the document offers a comprehensive review of clinical treatment planning processes and considerations for computerized treatment planning systems.
Ionizing radiation can damage biological molecules and tissues by removing electrons from atoms, breaking molecular bonds. This radiation damage occurs through direct interaction with radiation or indirectly via reactive oxygen species produced by radiolysis of water. DNA is particularly susceptible to radiation damage which can lead to mutations if not repaired. The type and severity of health effects from radiation exposure depends on dose and can include hematopoietic, gastrointestinal and central nervous system syndromes causing acute illness.
This document provides an overview of radiation biology. It discusses radiation measurements, injury mechanisms, and various effects of radiation exposure. Regarding measurements, it defines units like the gray (Gy), sievert (Sv), and becquerel (Bq). It describes radiation injury occurring via ionization and free radical formation. Effects are categorized as stochastic, deterministic, acute, chronic, somatic, and genetic. Sensitive tissues include skin, bone marrow, and developing fetuses. Factors influencing biological effects include the irradiated tissue type, area, and dose rate.
From my class on nuclear physics for nuclear medicine technologists. This class covers alpha, beta, and gamma decay, plus conversion electrons, Auger electrons, and k-alpha and other X-rays
Dielectrics are materials that have permanent electric dipole moments. All dielectrics are electrical insulators and are mainly used to store electrical energy by utilizing bound electric charges and dipoles within their molecular structure. Important properties of dielectrics include their electric intensity or field strength, electric flux density, dielectric parameters such as dielectric constant and electric dipole moment, and polarization processes including electronic, ionic, and orientation polarization. Dielectrics are characterized by their complex permittivity, which relates to their ability to transmit electric fields and is dependent on factors like frequency, temperature, and humidity that can influence dielectric losses.
Dielectrics are materials that contain permanently aligned electric dipoles. When an electric field is applied, the dipoles in dielectric materials can undergo several types of polarization, including electronic, ionic, orientational, and space charge polarization. This polarization leads to an increase in the electric flux density and dielectric constant within the material. The dielectric constant is the ratio of the material's permeability to the permeability of free space and determines the material's behavior in electric fields.
Dielectrics are materials that contain permanent or induced electric dipoles. They can be polarized by an external electric field, resulting in dipole orientation or charge displacement within the material. There are several types of polarization that can occur in dielectrics, including electronic, ionic, orientation, and space charge polarization. Dielectrics have a wide variety of applications including use in capacitors, transformers, cables, and other electrical equipment due to their insulating properties.
Semiconductor theory describes how small amounts of impurities can be added to intrinsic semiconductors to create n-type and p-type materials. N-type semiconductors are created by adding elements with extra electrons, while p-type are created by adding elements with electron deficiencies. The junction between a p-type and n-type material allows current to flow in only one direction, forming the basis for important semiconductor devices such as diodes, transistors, and solar cells.
This document discusses electrical conductivity in various materials. It begins by explaining that metals are good conductors due to their large number of free electrons. Semiconductors have lower conductivity than metals due to their lower concentration of free charge carriers. Conductivity in nonmetals like ionic crystals and glasses depends on mobile charges like electrons and ions. The document then discusses how conductivity varies with temperature in nonmetals. It also covers the skin effect in conductors at high frequencies and conductivity considerations in thin metal films. The document concludes by discussing copper interconnects in microelectronics.
This document discusses polarography, which is a technique for analyzing solutions using two electrodes - a dropping mercury working electrode and a reference electrode. It provides details on:
1. How polarography works by applying a voltage to induce a redox reaction and measuring the resulting current.
2. The components needed, including the dropping mercury electrode, reference electrode, and a supporting electrolyte.
3. How polarograms are generated by plotting current vs. applied voltage and the different regions that can be seen on a polarogram.
4. Factors that influence the diffusion current measured, such as concentration of the analyte, diffusion coefficient, and drop lifetime. Equations for calculating diffusion current are also presented.
Solid State Electronics.
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Rad.det.munich 07252011
1. SEMICONDUCTOR RADIATION DETECTORS Eugene E. Haller University of California and LBNL, Berkeley, CA 94720 Fourth Summer School in Radiation Detection and Measurements, July 24-30, 2011 Munich, Germany
2.
3. "Nuclear Radiation Detector Materials," eds. E.E. Haller, H.W. Kraner and W.A. Higginbotham, Mat. Res. Soc. Proc. Vol. 16 (North Holland, 1983).
16. 7/19/11 E. E. Haller 7 The Ionization Chamber:Operating Principle The field lines of a charge in volume V end on the electrodes and "influence" an electric charge. The relative quantities of charge influenced on each electrode depends only on the geometry. When the charge moves (in an externally applied field), the relative quantities of influenced charge change, forming a displacement current. When the charge stops moving, the displacement current stops flowing. Charge may stop flowing because it gets "trapped" at a defect center or gets "collected" at a contact. In a typical p-n junction, charge ideally flows to one of the electrodes. In a resistive detector, charge arriving at one electrode may lead to the injection of a new charge at the opposite electrode. We define the "photoconductive" gain: Note: For a high resolution detector, a fixed, constant gain is required (for p-n junctions: G = 1.00; though there are ways to compensate incomplete charge collection) = average distance traveled by a free charge L = inter electrode distance
17. 7/19/11 E. E. Haller 8 SEMICONDUCTOR PROPERTIES Diamond Crystal Lattice: [100] Direction
20. 7/19/11 E. E. Haller 11 Silicon Real space structure, [100] projection (The sign = represents the two electrons in each bond.) Electronic band structure (CB = conduction band, VB = valence band)
21. 7/19/11 E. E. Haller 12 Doped Silicon Donor doping (e.g., phosphorus on Si sites) provides extra electrons which can move into the conduction band or compensate an acceptor; Acceptor doping (e.g., aluminum on Si sites) creates holes which can move into the valence band or compensate a donor
22. 7/19/11 E. E. Haller 13 Radiation detector performance is affected by temperature in several ways. Two important ones are: A. Generation of free electrons and holes by thermal ionization across the bandgap. This affects the bias current I (also called "leakage" or "dark" current) through the detector. This current is a source of electrical noise, in its simplest form "shot" noise ( df= 2eIdf; e = charge of the electron, f = frequency) B. Trapping and de-trapping of the free charge carriers at defect or doping related energy levels in the bandgap. Temperature Effects
23. 7/19/11 E. E. Haller 14 A. Free Carrier Concentration At finite temperatures a very small number of bonds in a crystal is broken. For each broken bond there exists a mobile electron and a mobile hole. The concentration of these electrons (n) and holes (p) is called intrinsic carrier concentration ni: ni2= NcNv exp (-Egap/kBT)= np (Law of mass action) Nc = conduction band effective density of states Nv = valence band effective density of states kB = Boltzmann's constant = 8.65 × 10-5eV/K Egap = energy gap (Si: 1.1 eV, Ge: 0.7 eV, GaAs = 1.42 eV, CdTe: 1.47 eV, Hgl2: 2.13 eV, AlSb: 1.58 eV) ni (Si, 300K) = 2 x 1010 cm-3 ni (Ge, 300K) = 3 x 1013 cm-3 ni (GaAs, 300K) = 107 cm-3
24. 7/19/11 E. E. Haller 15 Thermal Carrier Generation The thermal generation of electrons and holes gives rise to the reverse (also called "leakage" or "dark") current. This current constitutes a source of electronic noise. Consequences • Because of the small bandgap (Eg=0.7 eV), Ge diodes must be cooled in order to achieve sufficiently low reverse currents. • Si diodes (Eg=1.2 eV) have to be cooled only for high resolution applications. • CdTe, CdZnTe, GaAs, AlSb, ThBr, PbOand Hgl2 should not require cooling.
25. 7/19/11 E. E. Haller 16 Arrhenius plot (log conc. versus 1/T) of the intrinsic carrier concentration of the major semiconductors
26. 7/19/11 E. E. Haller 17 B. Charge Trapping Electrons and holes are also created in ionization events caused by radiation. In order to be detected they have to traverse the detector crystal all the way to their respective electrodes. On the way they encounter shallow and deep impurities, some of which may be charged. Trapping and release of charge from deep impurities is described as follows: emission rate e (per level) of a carrier to the nearest band: e = <v> Nband exp (-E/kBT) with = carrier capture cross-section (cm2) <v> = average thermal velocity = (3kT/m*)1/2 Nband= effective density of states = 2 (2πm*kT/h2)3/2 kB = 8.65 × 10-5eV/K E = binding energy (depth!) of a particular level
27. 7/19/11 E. E. Haller 18 B. Charge Trapping (cont.) Shallow dopant levels in Si (E ~ 45 meV) or Ge (E ~ 10 meV) do not trap charge for any significant length of time at temperatures above 77 K (liquid nitrogen). Their binding energy is too small for trapping. However, already very small concentrations of deep levels (E > 100 meV) trap charge effectively and do not release it within the collection time. The fluctuations in this charge loss lead to asymmetric peaks in the energy spectrum.
28. 7/19/11 E. E. Haller 19 Deep Levels <—> Trapping 1: trapping of an electron by a deep level: 2: recombination of the trapped electron with a free hole or 3: detrapping after a time t.
29. 7/19/11 E. E. Haller 20 Electric Charge Transport At low electric fields the carrier velocity is proportional to the electric field: The mobility µ rises with decreasing temperature because the phonon density drops: At high electric fields velocity saturationoccurs. The carriers emit phonons* at a rapidly increasing rate and the velocity becomes almost constant. (See figures 11-2 on pages 341 and 342 in G. Knoll’s textbook). It is interesting to note that the saturation velocity for most semiconductors lies around 107cm/s. _______________________________ * Lattice vibrations (quantized E = hw)
30. 7/19/11 E. E. Haller 21 The Asymmetric Planar N+-P-Junction (parallel plate capacitor) Ionized positively charged donors Ionized negatively charged acceptors
31. 7/19/11 E. E. Haller 22 The ionized shallow impurity levels constitute a space charge e |NA - ND|. Poisson's equation relates the potential to the charge: 2 = -e |NA - ND| /o = dielectric constant, o = permittivity of vacuum In one dimension: ∂2/∂x2 = -e |NA - ND| /o integrating twice leads to: = d2 |NA - ND| =d2|NA - ND| C CSi = 7.72 10-8Vcm CGe = 5.64 10-8Vcm with: d = width of the depletion layer Planar N+-P-Junction
32. 7/19/11 E. E. Haller 23 Planar N+-P-Junction For Ge junctions we find: V = d2 | NA - ND | x 5.64 x 10-8 (Vcm) and for Si: V = d2 | NA - ND | x 7.72 x 10-8 (Vcm) with V = applied voltage (V) d = depletion depth (cm) | NA - ND | = net-impurity concentration (cm-3) EXAMPLE: Planar P-I-N Detector d = 2 cm, V = 3000V What is | NA - ND | for full depletion? Ge: 1.33 x 1010 cm-3 Si: 9.7 x 109 cm-3 } These are extremely small concentrations compared to ~ 4 x 1022 Ge or Si per cm3!
33. 7/19/11 E. E. Haller 24 Ultra-pure Ge Crystal Growth Ultra-purity (~ 1 residual impurity in 1012 cm-3 Ge atoms!) requires highly specialized materials: e.g. Ultra pure silica for the crucible, ultra pure graphite for RF coupling, Ultra pure H2 atmosphere and ultrapure chemicals.
34. 7/19/11 E. E. Haller 25 Ge seed An ultra-pure Germanium single crystal is being “pulled” from a melt contained in a silica crucible at 936oC. The atmosphere is pure Hydrogen. Heat is supplied by the water cooled radiofrequency (RF) coil surrounding the silica envelope. This bulk crystal growth technique carries the name of it’s inventor, “Jan Czochralski.” Ge single crystal Ge melt Silica crucible RF coil
35. 7/19/11 E. E. Haller 26 The Floating Zone (FZ) crystal growth process is used for ultra pure silicon up to 6” in diameter. No crucible is used. The ambient is typically nitrogen but vacuum and argon have been used.
36. 7/19/11 E. E. Haller 27 Poly Si feed rod One turn RF coil Si single crystal Silicon Floating Zone (FZ) crystal with 10 cm diameter is being pulled. The single turn RF heating coil creates the liquid “floating zone” between the lower part (single crystal) and the upper polycrystalline section.
37. 7/19/11 E. E. Haller 28 Determining Ultra-Purity Electrical conductivity is an accurate measure of the net-impurity concentration. The intrinsic conduction can be “turned-off” through cooling to liquid nitrogen temperature (77K).
38. 7/19/11 E. E. Haller 29 Dopant Impurity Profiles Typical impurity profile of an ultra-pure Ge crystal. The acceptor aluminum (Al, dashed line) does not segregate in silica grown Ge, leading to a constant concentration. The donor phosphorus segregates (P, dotted line). In our particular example, the phosphorus concentration equals the aluminum concentration at 80% of the melt frozen and exceeds it beyond. In the Al dominated part, the crystal is p-type, in the P dominated type, the crystal is n-type. All ultra-pure Ge single crystals contain about 1014cm-3 H, O and C, inert impurities. Special thermal treatment can lead to the formation of shallow acceptors [A(Si,H) and A(C,H)], and donors (D(O,H). These trigonaldopants are not thermally stable and disappear at ~160oC.
39. E. E. Haller 30 Charge Collection in Real Time in a 1 mm thick Si p-n-Diode Courtesy J. Fink et al., NIM A 560, 435-443 (2006) n+ P+ α α n-Si + − min E-field max 7/19/11
40. E. E. Haller 31 Charge Collection in Real Time in a 1 mm thick Si p-n-Diode Courtesy J. Fink et al., NIM A 560, 435-443 (2006) α α n-Si + − (b) min E-field max 7/19/11
41. 7/19/11 E. E. Haller 32 The n+-i-p+ Diode Detector or
42. 7/19/11 E. E. Haller 33 Free Carrier Velocity as a Function of the Electric Field
43. 7/19/11 E. E. Haller 34 High-Purity Ge Detector Structures Planar high-purity germanium (hpGe) radiation detector After G. S. Hubbard, MRS Proc. Vol. 16, 161 (1983) Coaxial structure hpGe radiation detectors. Device (a) has standard electrode geometry (SEGe); detector (b) has been fabricated with reverse electrode geometry (REGe)
44. 7/19/11 E. E. Haller 35 Position sensitive orthogonal-strip hp Ge detector with 64 strip electrodes on each side fabricated using amorphous-Ge contacts. Strip pitch is 1.25 mm. The active volume of the detector is 9 cm X 9 cm X 2 cm. (Courtesy P.N. Luke, LBNL)
45. Is this the end of the story ? No, because ultra-pure Ge detectors offer the highest resolution gamma ray spectroscopy only when they are cooled. This requirement causes serious problems in certain applications especially in security surveying situations. There is a need for room temperature medium resolution detectors. Many groups have tested many materials but only a very small number look promising. What do we need: - High Z material which can stop gamma rays efficiently - A bandgap larger than ~1.7 eV so no cooling is required - A bandgap < 2.5 eV to keep the number of electron-hole pairs large for good resolution - High purity to minimize the trap concentration - large µτ (mu-tau) products for electron and holes (µ = mobility, τ = free carrier lifetime) 7/19/11 36 E. E. Haller
46. 7/19/11 E. E. Haller 37 Properties of Compound Semiconductors [Courtesy M.R. Squillanteet al., MRS Proc. Vol. 302, 326 (1993)]
47. Lattice Const. and Bandgapsof Important Semiconductors 7/19/11 38 E. E. Haller
48. What do we find: - there is no material matching all the above conditions - there are a few materials with at least one free carrier exhibiting good µτ (mu-tau) products The challenge: - Obtain good energy resolution with single carrier collection - Form a High Resistivity Detector instead of a p-n junction 7/19/11 39 E. E. Haller
49. E. E. Haller 40 Why do we want high resistivity? No Radiation, No Signal: I=0 - + High Bias In presence of radiation, strong signal: I + - High Bias 7/19/11 - +
50. 41 The “Right Kind” of Resistivity These should be high! These should be low! Three options for realizing low free carrier concentration: Achieve extremely high purity Materials: Only FZ- Si and high purity Ge 2) Deep level compensation Materials: GaAs,CZT and most other resistive material candidates 3) Shallow level compensation Materials:Ge:Ga,Li; TlBr(?) 7/19/11 E. E. Haller
51. 42 The “Right Kind” of Resistivity The Fermi level must be in the middle of the band gap for the highest resistivity possible at room temperature. The 3 ways to do this: 3. Shallow Level Compensation* 2. Deep Level Compensation 1. Ultra Purity CB EF VB 7/19/11 E. E. Haller * The idea of shallow level compensation or passivation is attractive because deep levels frequently negatively affect carrier mobilities. This mechanism provides a way to achieve low carrier concentrations without affecting mobilities. However, its realization with Li drifting of p-type Ge or Si is thermally unstable. This lead to the development of ultra-pure Ge
60. Transport Properties comparable to CZTElectronic transport properties dramatically improved in last decade by RMD! TlBr detector, courtesy of RMD E. E. Haller 7/19/11
61. 7/19/11 E. E. Haller 45 The “Frisch Grid”: An Old Idea with Great Relevance and Promise • Gas ionization chambers suffer from the same problem as many semiconductor detectors: of one charge species (ions) is significantly lower than of the other charge species (electrons). • Solution: the "Frisch Grid" (FG)
62. 7/19/11 E. E. Haller 46 Reincarnation of the Frisch Grid as two Sets of Interdigitated Contacts A and B P.N. Luke, Appl. Phys. Lett. 65(22) 2884 (1994)
63. 7/19/11 E. E. Haller 47 Cd0.8Zn0.2Te (5 x 5 x 5 mm3) Courtesy P.N. Luke, LBNL
65. 7/19/11 E. E. Haller 49 Sub 1% Resolution CZT Detector
66. 7/19/11 E. E. Haller 50 CZT CPG vs Ge CZT coplanar-grid detector – 1 cm3 (cooled to -30 °C) Peak/Compton=16.2 Ge detector – 3 cm3 Peak/Compton=11.4 Courtesy P.N. Luke, LBNL
67. 7/19/11 E. E. Haller 51 Conclusions • The ideal semiconductor material for all radiation detection applications does not exist but it can be approached closely. • Certain material property requirements and application requirements are incompatible (e.g. bandgap: large for low leakage current but small for small energy per e/h pair). • Si & Ge are the high resolution spectrometer materials. Detectors exhibit excellent stability, good efficiency, timing, etc. • Thin epitaxial films (100-150 µm) of high-purity GaAs (|NA-ND|< 1012 cm-3) have been grown by the LPE technique and early spectrometer results look promising. In contrast, semi-insulating (SI) GaAs contains very large concentrations of deep traps which make the material highly resistive and lead to extreme charge trapping.
68. 7/19/11 E. E. Haller 52 Conclusions, cont. • CdTe, CdZnTe, ThBr& HgI2 are room temperature materials. Low energy X rays can be detected with good resolution. Medium and high energy photons ( rays) still pose problems. Trapping and poor hole transport seem to be fundamental and/or related to material inhomogeneitiesand defects. • Single-polarity charge sensing using coplanar electrodes (an analog of the Frisch grid in gas proportional counters) looks very promising for semiconductors with good collection of at least one type of charge carrier (typically electrons; see: P.N. Luke, Appl. Phys. Lett. 65, 2884 (1994) and more recent publications).