Gamma-ray bursts (GRBs) are extremely bright bursts of gamma rays associated with catastrophic events in distant galaxies. Observations over decades have shown that GRBs originate from relativistic jets outside our galaxy and emit radiation across the electromagnetic spectrum. However, key questions remain about their emission mechanisms and how energy is transferred to accelerate particles to such high energies over short timescales. Future large gamma-ray detectors with improved sensitivity and time resolution are needed to better characterize GRB spectra and search for polarization that could reveal the role of magnetic fields in the emission process.
This document discusses different types of optical fibers. It begins by outlining the evolution of optical fiber technology from 1880 to 1980. It then defines an optical fiber as a thin cylindrical fiber of glass that transmits light via total internal reflection. The structure of an optical fiber is described as having a core that carries light, a cladding with a lower refractive index than the core, and a buffer coating. Optical fibers are classified based on the number of propagation modes as either single-mode or multi-mode fibers, and based on refractive index profile as either step-index or graded-index fibers.
-Neutrino-
It's believed that modern physics nothing can travel faster than the speed of light. The astonishing results of the experiment seem to show that elementary particle Neutrinos, Can. It’s the most spread particles and the lightest. Neutrino is a hardly reacting with matter, It can travel right through the earth without interacting, As an example 70 billion Neutrinos per square second continue coming from the sun. These Neutrino parts traveled through the Earth Crust to the detection point and they synchronized between the 2 points to the nearest Nanno second (A billion of a second) in this distance, they discovered that the neutrino were 60 seconds ahead of what light takes to cover this distance. It's the first time we have an experimental evidence something faster than light and that will make a major change in physics as we know it now.
The gamma camera produces images of organs that have taken up injected radioactive sources known as radioisotopes. It was invented in the 1960s by H. Anger and is sometimes called the Anger camera. The gamma camera uses radioisotopes injected into the bloodstream to create images of organs that have absorbed the radioactive material.
02-Fundamentals of Optical Fiber Waveguides-I.pptxAkliluAyele3
This document discusses fundamentals of optical fiber waveguides. It covers topics such as total internal reflection, acceptance angle, numerical aperture, fiber structures, and propagation of light in fibers. A typical optical fiber consists of a core made of glass or plastic, a cladding, and a protective coating. Total internal reflection guides light through the core due to the refractive index difference between the core and cladding. The acceptance angle and numerical aperture characterize a fiber's ability to accept and transmit light.
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 provides an introduction to nuclear physics. It discusses the history and development of the field, from the discovery of radioactivity and the electron in the early 20th century to the proposal of the liquid drop model and development of the semi-empirical mass formula to describe nuclear structure. Key events discussed include Rutherford's discovery of the nuclear model of the atom, the discovery of the neutron by Chadwick, and Yukawa's proposal of the meson to explain nuclear forces. The introduction concludes by outlining the chapters to follow on topics like nuclear decay, fusion, fission, and reactor physics.
Thermionic emission is the process where heated electrons gain enough thermal energy to overcome the work function of a material, allowing them to flow from its surface. This occurs because the thermal energy given to charge carriers, such as electrons, overcomes the binding potential, or work function, of the material.
Space wave propagation involves radio waves that travel directly or after reflecting off the Earth's surface within the lower 20 km of the atmosphere. These waves can propagate line-of-sight between transmitter and receiver antennas in the VHF and UHF bands. Space waves follow two paths - direct or ground reflected - and may arrive in or out of phase, causing signal fluctuations. The maximum transmission distance is limited by the Earth's curvature and obstructions that can cause shadowing effects. Refractive phenomena like super-refraction can sometimes extend the radio horizon.
This document discusses different types of optical fibers. It begins by outlining the evolution of optical fiber technology from 1880 to 1980. It then defines an optical fiber as a thin cylindrical fiber of glass that transmits light via total internal reflection. The structure of an optical fiber is described as having a core that carries light, a cladding with a lower refractive index than the core, and a buffer coating. Optical fibers are classified based on the number of propagation modes as either single-mode or multi-mode fibers, and based on refractive index profile as either step-index or graded-index fibers.
-Neutrino-
It's believed that modern physics nothing can travel faster than the speed of light. The astonishing results of the experiment seem to show that elementary particle Neutrinos, Can. It’s the most spread particles and the lightest. Neutrino is a hardly reacting with matter, It can travel right through the earth without interacting, As an example 70 billion Neutrinos per square second continue coming from the sun. These Neutrino parts traveled through the Earth Crust to the detection point and they synchronized between the 2 points to the nearest Nanno second (A billion of a second) in this distance, they discovered that the neutrino were 60 seconds ahead of what light takes to cover this distance. It's the first time we have an experimental evidence something faster than light and that will make a major change in physics as we know it now.
The gamma camera produces images of organs that have taken up injected radioactive sources known as radioisotopes. It was invented in the 1960s by H. Anger and is sometimes called the Anger camera. The gamma camera uses radioisotopes injected into the bloodstream to create images of organs that have absorbed the radioactive material.
02-Fundamentals of Optical Fiber Waveguides-I.pptxAkliluAyele3
This document discusses fundamentals of optical fiber waveguides. It covers topics such as total internal reflection, acceptance angle, numerical aperture, fiber structures, and propagation of light in fibers. A typical optical fiber consists of a core made of glass or plastic, a cladding, and a protective coating. Total internal reflection guides light through the core due to the refractive index difference between the core and cladding. The acceptance angle and numerical aperture characterize a fiber's ability to accept and transmit light.
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 provides an introduction to nuclear physics. It discusses the history and development of the field, from the discovery of radioactivity and the electron in the early 20th century to the proposal of the liquid drop model and development of the semi-empirical mass formula to describe nuclear structure. Key events discussed include Rutherford's discovery of the nuclear model of the atom, the discovery of the neutron by Chadwick, and Yukawa's proposal of the meson to explain nuclear forces. The introduction concludes by outlining the chapters to follow on topics like nuclear decay, fusion, fission, and reactor physics.
Thermionic emission is the process where heated electrons gain enough thermal energy to overcome the work function of a material, allowing them to flow from its surface. This occurs because the thermal energy given to charge carriers, such as electrons, overcomes the binding potential, or work function, of the material.
Space wave propagation involves radio waves that travel directly or after reflecting off the Earth's surface within the lower 20 km of the atmosphere. These waves can propagate line-of-sight between transmitter and receiver antennas in the VHF and UHF bands. Space waves follow two paths - direct or ground reflected - and may arrive in or out of phase, causing signal fluctuations. The maximum transmission distance is limited by the Earth's curvature and obstructions that can cause shadowing effects. Refractive phenomena like super-refraction can sometimes extend the radio horizon.
Fiber Bragg gratings are filters built into the core of optical fibers that reflect specific wavelengths of light and transmit others. They can be used as inline filters or wavelength-specific reflectors to improve optical signal quality. The document discusses several types of FBGs: uniform FBGs with consistent grating periods; chirped FBGs with varying periods that act as dispersion compensators; blazed FBGs with tilted grating planes that reflect light out of the fiber; phase-shifted FBGs with periodic index changes that create narrow transmission windows; and long-period FBGs that couple light into cladding modes, removing resonant wavelengths from the system. Each FBG type has distinct features and applications in optical communications, sensing, and laser
This document discusses the design of shielding for X-ray rooms. It covers topics such as equipment design standards, using dose constraints in design, barriers and protective devices. The key aspects of shielding design are the type of X-ray equipment, its usage, positioning, number of tubes, and the occupancy of surrounding areas. Design involves calculating the dose at specific points and factors such as use, occupancy, and workload. Continuous integrity of shielding materials is important to prevent radiation leakage. Records of shielding design and inspections should be maintained.
Nuclear physics studies the building blocks and interactions of atomic nuclei. The field is the basis for applications like nuclear power, nuclear bombs, nuclear medicine, and radiocarbon dating. Atoms consist of a nucleus containing protons and neutrons, surrounded by orbiting electrons. Radioactivity occurs when unstable atomic nuclei decay by emitting particles like alpha and beta particles or gamma rays. Nuclear fission and fusion can release energy as nuclei split or combine.
This document discusses optoelectronic devices and provides examples. It introduces optoelectronics as the study of electronic devices that interact with light. Major optoelectronic devices directly convert between electrons and photons, including light-emitting diodes (LEDs), laser diodes, and photodiodes. LEDs emit light when electrically biased and the color depends on the semiconductor material. Laser diodes use stimulated emission to produce coherent light. Photodiodes are photodetectors that generate a current when struck by photons. The document also discusses solar cells and trends in optoelectronic devices.
This document discusses scintillation detectors and their properties. Scintillation detectors work by emitting light when exposed to radiation, and this light output can be used to measure incident radiation. The key properties of scintillation detectors are that they must have high scintillation efficiency, light yield proportional to deposited energy, short decay time, transparency to emitted wavelengths, and be able to be made in large sizes and desired shapes. Common inorganic scintillators discussed are NaI(Tl), which is widely used due to its availability and high detection efficiency, and BGO, which has high intrinsic efficiency for high gamma energies.
1) OFDM uses multiple carriers to transmit data in parallel. It can be described mathematically using the Fourier transform which relates events in the time and frequency domains.
2) At the transmitter, the signal is defined in the frequency domain using a discrete Fourier transform and generated using the inverse discrete Fourier transform. This allows the carriers to be orthogonal.
3) A guard interval is added between symbols to prevent intersymbol interference from multipath distortion. This increases the symbol duration and provides timing tolerance at the receiver.
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.
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.
The document discusses the photoacoustic effect and its applications. It was discovered in 1880 by Alexander Graham Bell and Charles Sumner Tainter who developed the photophone, which transmitted speech using modulated light. The photoacoustic effect occurs when a material is exposed to pulsed or modulated light, causing the absorption of photons which leads to transient thermoelastic expansion and the generation of ultrasonic stress waves. These waves can be detected externally using piezoelectric transducers and used to form photoacoustic images which provide optical absorption contrast with ultrasonic resolution. Present applications of photoacoustic imaging include biomedical imaging to visualize physiology and molecular markers.
This document discusses different types of radiation detectors used for dosimetry. It begins by defining radiation and the different types. It then discusses dosimetry, including common dosimetric quantities like activity, exposure, and absorbed dose. The main types of radiation detectors covered are gas-filled detectors like ionization chambers and Geiger-Müller counters, as well as scintillation counters. Ionization chambers detect radiation by ionizing gas molecules, while GM counters amplify this signal. Scintillation counters use a scintillator to convert radiation into light, which is then converted to an electrical signal.
Radioactive decay occurs through three main types: alpha decay, beta decay, and gamma decay. Alpha decay involves emitting an alpha particle, which is identical to a helium nucleus containing two protons and two neutrons. Beta decay results in one less neutron but one extra proton. Gamma decay occurs when atoms are still energetic after alpha or beta decay and emit gamma rays to become stable. These decays are important applications in areas like nuclear medicine, nuclear reactors, and sterilization.
This document provides an overview of optical fibers, including their definition, main components, types, parameters, transmission properties, attenuation factors, dispersion effects, and applications. Optical fibers are thin strands of glass that transmit light signals over long distances using total internal reflection. They have a higher glass core surrounded by a lower index cladding. Key fiber types are single-mode and multimode (step-index and graded-index), which differ in core size and number of propagation modes. Parameters like acceptance angle, numerical aperture, and normalized frequency determine fiber properties and performance.
Los neutrinos y los rayos gamma son partículas subatómicas. Los neutrinos viajan cerca de la velocidad de la luz, no tienen carga eléctrica y son difíciles de detectar debido a su poca interacción con la materia. Existen tres tipos de neutrinos que pueden oscilar entre sí. Los rayos gamma son fotones de alta energía producidos por procesos nucleares y cósmicos, y son absorbidos por la atmósfera terrestre. Ambos son estudiados para comprender procesos físicos fundamentales.
Optical detectors details and technologies with formulasSyed Kamran Haider
This document presents information on optical detectors. It begins with an overview of optical communication systems and fiber optic architecture. It then discusses the key components of optical receivers including light sources, detectors, and fiber-optic cables. Common types of optical detectors are photo diodes (PIN and APD). PIN diodes have good linearity and speed but lower sensitivity, while APDs provide internal gain but more noise. Characteristics like responsivity, bandwidth, capacitance, and noise are examined. Factors influencing detector performance and tradeoffs between bandwidth and efficiency are also summarized.
Broadside Array vs end-fire array
Higher directivity.
Provide increased directivity in
elevation and azimuth planes.
Generally used for reception.
Impedance match difficulty in
high power transmissions.
Variants are:
Horizontal Array of Dipoles
RCA Fishborne Antenna
Series Phase Array
There are two main types of multimode fibers: step index and graded index. Step index fibers have a core with a uniform refractive index, while graded index fibers have a refractive index that gradually changes from the center to the edge of the core. Light rays travel in a controlled manner in graded index fibers, reaching the end at the same time, while they travel uncontrolled distances in step index fibers and arrive at different times. Graded index fibers are better for communication due to this controlled light ray behavior. While graded index fibers have advantages for longer distances and communication applications, step index fibers are lower cost and sufficient for shorter distances.
Artificial intelligence in the design of microstrip antennaRaj Kumar Thenua
This work presents a Neural Network model for the design of Microstrip Antenna for a desired frequency between 3.5 GHz to 5.5 GHz. The results obtained from the proposed method are compared with the results of IE3D and are found to be in good agreement. The advantage of the proposed method lies with the fact that the various parameters required for the design of specific Microstrip antenna at a particular frequency of interest can be easily extracted without going into the rigorous time consuming, iterative design procedures using a costly software package. In this work, a general design procedure is suggested for the Microstrip antennas using artificial neural networks and this is demonstrated using the rectangular patch geometry.
This document provides an overview of a presentation on semiconductor lasers. The presentation aims to understand the principle of semiconductor lasers, discuss their applications, and distinguish them from other laser types. It first introduces lasers in general, defining them, describing their properties and components. It then focuses on semiconductor lasers, classifying them, explaining their emission process and features, disadvantages, materials used, and main applications.
Airborne and underground matter-wave interferometers: geodesy, navigation and...Philippe Bouyer
The remarkable success of atom coherent manipulation techniques has motivated competitive research and development in precision metrology. Matter-wave inertial sensors – accelerometers, gyrometers, gravimeters – based on these techniques are all at the forefront of their respective measurement classes. Atom inertial sensors provide nowadays about the best accelerometers and gravimeters and allow, for instance, to make the most precise monitoring of gravity or to device precise tests of the weak equivalence principle (WEP). I present here some recent advances in these fields
Fiber Bragg gratings are filters built into the core of optical fibers that reflect specific wavelengths of light and transmit others. They can be used as inline filters or wavelength-specific reflectors to improve optical signal quality. The document discusses several types of FBGs: uniform FBGs with consistent grating periods; chirped FBGs with varying periods that act as dispersion compensators; blazed FBGs with tilted grating planes that reflect light out of the fiber; phase-shifted FBGs with periodic index changes that create narrow transmission windows; and long-period FBGs that couple light into cladding modes, removing resonant wavelengths from the system. Each FBG type has distinct features and applications in optical communications, sensing, and laser
This document discusses the design of shielding for X-ray rooms. It covers topics such as equipment design standards, using dose constraints in design, barriers and protective devices. The key aspects of shielding design are the type of X-ray equipment, its usage, positioning, number of tubes, and the occupancy of surrounding areas. Design involves calculating the dose at specific points and factors such as use, occupancy, and workload. Continuous integrity of shielding materials is important to prevent radiation leakage. Records of shielding design and inspections should be maintained.
Nuclear physics studies the building blocks and interactions of atomic nuclei. The field is the basis for applications like nuclear power, nuclear bombs, nuclear medicine, and radiocarbon dating. Atoms consist of a nucleus containing protons and neutrons, surrounded by orbiting electrons. Radioactivity occurs when unstable atomic nuclei decay by emitting particles like alpha and beta particles or gamma rays. Nuclear fission and fusion can release energy as nuclei split or combine.
This document discusses optoelectronic devices and provides examples. It introduces optoelectronics as the study of electronic devices that interact with light. Major optoelectronic devices directly convert between electrons and photons, including light-emitting diodes (LEDs), laser diodes, and photodiodes. LEDs emit light when electrically biased and the color depends on the semiconductor material. Laser diodes use stimulated emission to produce coherent light. Photodiodes are photodetectors that generate a current when struck by photons. The document also discusses solar cells and trends in optoelectronic devices.
This document discusses scintillation detectors and their properties. Scintillation detectors work by emitting light when exposed to radiation, and this light output can be used to measure incident radiation. The key properties of scintillation detectors are that they must have high scintillation efficiency, light yield proportional to deposited energy, short decay time, transparency to emitted wavelengths, and be able to be made in large sizes and desired shapes. Common inorganic scintillators discussed are NaI(Tl), which is widely used due to its availability and high detection efficiency, and BGO, which has high intrinsic efficiency for high gamma energies.
1) OFDM uses multiple carriers to transmit data in parallel. It can be described mathematically using the Fourier transform which relates events in the time and frequency domains.
2) At the transmitter, the signal is defined in the frequency domain using a discrete Fourier transform and generated using the inverse discrete Fourier transform. This allows the carriers to be orthogonal.
3) A guard interval is added between symbols to prevent intersymbol interference from multipath distortion. This increases the symbol duration and provides timing tolerance at the receiver.
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.
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.
The document discusses the photoacoustic effect and its applications. It was discovered in 1880 by Alexander Graham Bell and Charles Sumner Tainter who developed the photophone, which transmitted speech using modulated light. The photoacoustic effect occurs when a material is exposed to pulsed or modulated light, causing the absorption of photons which leads to transient thermoelastic expansion and the generation of ultrasonic stress waves. These waves can be detected externally using piezoelectric transducers and used to form photoacoustic images which provide optical absorption contrast with ultrasonic resolution. Present applications of photoacoustic imaging include biomedical imaging to visualize physiology and molecular markers.
This document discusses different types of radiation detectors used for dosimetry. It begins by defining radiation and the different types. It then discusses dosimetry, including common dosimetric quantities like activity, exposure, and absorbed dose. The main types of radiation detectors covered are gas-filled detectors like ionization chambers and Geiger-Müller counters, as well as scintillation counters. Ionization chambers detect radiation by ionizing gas molecules, while GM counters amplify this signal. Scintillation counters use a scintillator to convert radiation into light, which is then converted to an electrical signal.
Radioactive decay occurs through three main types: alpha decay, beta decay, and gamma decay. Alpha decay involves emitting an alpha particle, which is identical to a helium nucleus containing two protons and two neutrons. Beta decay results in one less neutron but one extra proton. Gamma decay occurs when atoms are still energetic after alpha or beta decay and emit gamma rays to become stable. These decays are important applications in areas like nuclear medicine, nuclear reactors, and sterilization.
This document provides an overview of optical fibers, including their definition, main components, types, parameters, transmission properties, attenuation factors, dispersion effects, and applications. Optical fibers are thin strands of glass that transmit light signals over long distances using total internal reflection. They have a higher glass core surrounded by a lower index cladding. Key fiber types are single-mode and multimode (step-index and graded-index), which differ in core size and number of propagation modes. Parameters like acceptance angle, numerical aperture, and normalized frequency determine fiber properties and performance.
Los neutrinos y los rayos gamma son partículas subatómicas. Los neutrinos viajan cerca de la velocidad de la luz, no tienen carga eléctrica y son difíciles de detectar debido a su poca interacción con la materia. Existen tres tipos de neutrinos que pueden oscilar entre sí. Los rayos gamma son fotones de alta energía producidos por procesos nucleares y cósmicos, y son absorbidos por la atmósfera terrestre. Ambos son estudiados para comprender procesos físicos fundamentales.
Optical detectors details and technologies with formulasSyed Kamran Haider
This document presents information on optical detectors. It begins with an overview of optical communication systems and fiber optic architecture. It then discusses the key components of optical receivers including light sources, detectors, and fiber-optic cables. Common types of optical detectors are photo diodes (PIN and APD). PIN diodes have good linearity and speed but lower sensitivity, while APDs provide internal gain but more noise. Characteristics like responsivity, bandwidth, capacitance, and noise are examined. Factors influencing detector performance and tradeoffs between bandwidth and efficiency are also summarized.
Broadside Array vs end-fire array
Higher directivity.
Provide increased directivity in
elevation and azimuth planes.
Generally used for reception.
Impedance match difficulty in
high power transmissions.
Variants are:
Horizontal Array of Dipoles
RCA Fishborne Antenna
Series Phase Array
There are two main types of multimode fibers: step index and graded index. Step index fibers have a core with a uniform refractive index, while graded index fibers have a refractive index that gradually changes from the center to the edge of the core. Light rays travel in a controlled manner in graded index fibers, reaching the end at the same time, while they travel uncontrolled distances in step index fibers and arrive at different times. Graded index fibers are better for communication due to this controlled light ray behavior. While graded index fibers have advantages for longer distances and communication applications, step index fibers are lower cost and sufficient for shorter distances.
Artificial intelligence in the design of microstrip antennaRaj Kumar Thenua
This work presents a Neural Network model for the design of Microstrip Antenna for a desired frequency between 3.5 GHz to 5.5 GHz. The results obtained from the proposed method are compared with the results of IE3D and are found to be in good agreement. The advantage of the proposed method lies with the fact that the various parameters required for the design of specific Microstrip antenna at a particular frequency of interest can be easily extracted without going into the rigorous time consuming, iterative design procedures using a costly software package. In this work, a general design procedure is suggested for the Microstrip antennas using artificial neural networks and this is demonstrated using the rectangular patch geometry.
This document provides an overview of a presentation on semiconductor lasers. The presentation aims to understand the principle of semiconductor lasers, discuss their applications, and distinguish them from other laser types. It first introduces lasers in general, defining them, describing their properties and components. It then focuses on semiconductor lasers, classifying them, explaining their emission process and features, disadvantages, materials used, and main applications.
Airborne and underground matter-wave interferometers: geodesy, navigation and...Philippe Bouyer
The remarkable success of atom coherent manipulation techniques has motivated competitive research and development in precision metrology. Matter-wave inertial sensors – accelerometers, gyrometers, gravimeters – based on these techniques are all at the forefront of their respective measurement classes. Atom inertial sensors provide nowadays about the best accelerometers and gravimeters and allow, for instance, to make the most precise monitoring of gravity or to device precise tests of the weak equivalence principle (WEP). I present here some recent advances in these fields
This document discusses the scientific opportunity of measuring prompt optical emission from gamma-ray bursts (GRBs) in order to better understand GRB emission mechanisms. It proposes a new instrument capable of simultaneous multi-color optical and infrared observations of GRBs with high time resolution. Such an instrument could measure prompt optical light curves and spectra, test models of GRB emission, and probe properties of dust around GRBs.
- The document discusses cosmological horizons in physics and cosmology.
- It describes the particle horizon, which separates what we can observe from what came before the light had time to reach us.
- It also describes the physical horizon, which is closer due to details of light propagation in an expanding universe. This physical horizon corresponds to the surface of last scattering from 380,000 years after the Big Bang.
- Observing the cosmic microwave background radiation provides evidence of homogeneity across regions larger than the particle horizon, suggesting they were in causal contact earlier when the expansion rate was higher.
Anisotropic Kondo effect
Wael Chibani (email: chibani@fhi-berlin.mpg.de)
Using the numerical renormalization group (NRG), we study the STM tunneling current through a Co atom embedded on an anisotropic lattice and experiencing a magnetic field in both directions, parallel and perpendicular to the anisotropy, as was measured by Otte et al. [1]. We introduce the Kondo-Anderson hybrid model (KAHM) Hamiltonian, by which we describe the system, where we take the spin of the Co atom as being S=3/2, and present the mapping of the self energy representation [2] onto our model. After discussing the easy-axis and easy-plan anisotropy, we demonstrate, that our problem is best described by an easy-axis anisotropy. Moreover, the experimental spectra show a dependence of the splitting of the Kondo resonance at finite magnetic fields on the direction of the magnetic field with respect to the anisotropy, which we will also discuss.
Finally, when comparing our NRG calculated current with the experimentally measured one, we found, that, the Kondo temperature as given in the experiment is too small and thus, we choose an effective temperature to describe the system.
[1] Otte A. F., Ternes. M., von Bergmann K., Loth S., Brune H. Lutz C. P., Hirjibehedin C. F. and Heinrich A. J., Nature Physics, Vol 4, November 2008.
[2] Bulla R., Hewson A. C. and Pruschke T., J.Phys. : Condens. Matter 10, 8365- 8380 (1998).
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.
1) The document discusses multi-messenger astronomy and the detection of electromagnetic counterparts to gravitational waves, neutrinos, and cosmic rays.
2) It provides background on neutrino astronomy, gravitational wave detections from binary neutron star mergers, and kilonova emissions from such mergers.
3) The merger of GW170817 and its association with GRB170817A and kilonova AT2017gfo provided the first direct evidence that neutron star mergers are the origin of short gamma-ray bursts and produce r-process nucleosynthesis.
1. The document discusses potential low frequency gravitational wave sources that could be detected by LISA, including galactic white dwarf binaries, massive black hole binaries, and extreme mass ratio inspirals.
2. LISA could detect thousands of massive black hole binaries and provide precise measurements of their parameters like mass and spin, enabling tests of general relativity and learning about black hole formation mechanisms.
3. Extreme mass ratio inspirals where a compact object spirals into a massive black hole could occur at a rate of 10-7 per year in our galaxy, allowing precision cosmology and tests of the no-hair theorem.
Apartes de la Conferencia de la SJG del 14 y 21 de Enero de 2012: Neutrino ma...SOCIEDAD JULIO GARAVITO
This document discusses a novel method for determining neutrino mass spectra using gravitational waves and neutrinos from supernovae. It proposes that two bursts of gravitational waves could be generated during neutrino oscillations in supernovae: one from neutrinos converting from left-handed to right-handed states via interaction with the magnetic field of the expanding plasma, and another when some of these right-handed neutrinos flip back to left-handed flavors later due to a different interaction. Measuring the time delay between the arrival of neutrinos and gravitational waves could directly measure neutrino masses, since massive neutrinos would be delayed relative to massless gravitational waves. This could provide a new way to determine absolute neutrino masses that does not depend on mass-squared differences
The 21cm line from neutral hydrogen can be used to study cosmology during the first billion years of the universe. This includes the Dark Ages when no structures formed, the Cosmic Dawn when the first luminous objects formed, and the Epoch of Reionization when these objects reionized the intergalactic medium. Current and future 21cm experiments like LOFAR, MWA, PAPER, and HERA aim to detect the signal from these eras but face challenges in calibrating the instruments and subtracting bright foreground sources. Some progress has been made in placing upper limits on the signal and constraining the heating of the intergalactic medium by X-rays, but a clear detection of the signal is still needed
Introduction to Scanning Tunneling Microscopynirupam12
This document provides an overview of scanning tunneling microscopy (STM) principles and applications. It begins with a general introduction and outlines the basic theoretical framework of STM operation. Specifically, it discusses how STM works by bringing a tip within atomic reach of a surface and measuring tunneling current. The document then covers various STM capabilities such as surface characterization, probing oxides and high-temperature superconductors, and atomic resolution imaging. It concludes by discussing advanced STM techniques including spectroscopy, momentum-space imaging, spin-polarized measurements, and time-resolved applications with picosecond resolution.
Nuclear magnetic resonance spectroscopy is a powerful technique for chemical analysis that involves the absorption of radiofrequency radiation by atomic nuclei in a magnetic field. It is useful for determining molecular structures and understanding how molecules function. The technique works by exciting atomic nuclei to higher energy states using radiofrequency pulses in a strong magnetic field. As the nuclei relax back to lower energy states, they emit radiofrequency signals that can be analyzed to provide information about molecular structure. NMR spectroscopy is widely used across many fields due to its applicability to a variety of sample sizes.
1) Stars in the central parsec of the Galaxy supply mass to the galactic center black hole at a rate of around 10-3 solar masses per year, but only about 10-5 solar masses per year is captured by the black hole's gravitational influence.
2) The captured gas accretes onto the black hole via a radiatively inefficient accretion flow at a very low rate of around 10-8 solar masses per year, resulting in an accretion efficiency over 1000 times lower than typical black holes.
3) Variable infrared and x-ray emission is believed to originate from nonthermal synchrotron radiation of accelerated electrons very close to the black hole, providing a unique probe of gas dynamics and particle acceleration in
The bright optical_flash_and_afterglow_from_the_gamma_ray_burst_grb_130427aSérgio Sacani
1) Researchers observed an optical flash and fading afterglow from the powerful gamma-ray burst GRB 130427A. 2) The optical and gamma-ray (>100 MeV) light curves were closely correlated during the first 7,000 seconds, best explained by reverse shock emission generated in the relativistic ejecta. 3) At later times, the optical light showed evidence of forward shock emission as it interacted with the surrounding environment.
Neutron reflectometry can be used to study oxide interfaces. It provides a non-destructive technique to determine the structure and magnetism of surfaces and buried interfaces with angstrom-level resolution. Examples of systems studied include ferromagnet-superconductor heterostructures where competing interactions at the interface can be observed, and cuprate-manganite interfaces where charge transfer and magnetic reconstruction occur within a few nanometers of the boundary. Neutron reflectometry is a powerful "interface toolbox" for understanding complex oxide materials.
The document provides an overview of the history and development of spectroscopy, from Newton's discovery of the rainbow spectrum to modern applications across the electromagnetic spectrum. Key events and figures discussed include Kirchoff and Bunsen's establishment of spectroscopy and the development of new techniques in the 20th century that enabled analysis of different wavelength regions.
Observations of Gamma-Ray Bursts with the Fermi-Large Area TelescopeVlasios Vasileiou
Brief introduction to the history and science of Gamma Ray Bursts and a report of the latest observational results of the Fermi-Large Area Telescope on GRBs.
The document summarizes research on finding electromagnetic counterparts to gravitational wave sources detected by LIGO and Virgo. It discusses that neutron star mergers are a promising source of both gravitational waves and short gamma-ray bursts. Numerical simulations show neutron star mergers produce neutron-rich debris ejected at high velocities, which could power a luminous "kilonova" lasting several days. Future wide-field optical surveys like LSST could detect such kilonova emissions from neutron star mergers within the gravitational wave detection range of advanced LIGO and Virgo, helping associate gravitational wave sources with electromagnetic events.
2. Outline
● What do we know about GRBs?
● What there is more to learn about GRBs?
● How are the GRBs useful?
3. GRBs are bright
Fluence reaching 10-3 erg/cm2 hugely dominating the gamma-ray sky
Numerous detectors may serve unintentionally as GRB detectors: as long as they
are out of atmosphere
In fact the first one to observe them was military satellite searching for the nuclear
explosions in 1967.
4. Early theories
First decades after the
discovery, a number of
theories were suggested
Most of them appeared to
be applicable in other
objects
Essential to keep in mind nowadays!
5. First indication of the luminosity scale
● CGRO/BATSE: big dedicated detector (1991-2000)
~2500 GRBs: No correlation with the galactic plane or any local structures, suggesting
extragalactic origin for the bulk of the events
6. Afterglows: the breakthrough
Dedicated instrument had to be build to react to the prompt emission
by rotating the X-ray instrument.
First implemented in Beppo-SAX immediately led to discovery of X-
ray emission following GRB (Costa et al 1997), opening the whole
new field.
Redshifted lines were
observed in the afterglow,
firmly establishing
cosmological nature of the
GRBs
Lasting sometimes for
months
7. Afterglows: the breakthrough
Dedicated instrument had to be build to react to the prompt emission
by rotating the X-ray instrument.
First implemented in Beppo-SAX immediately led to discovery of X-
ray emission following GRB (Costa et al 1997), opening the whole
new field.
Redshifted lines were
The luminosity of the order of 1054 erg
observed in the afterglow,
on the time scale of about some seconds
firmly establishing
would suggest underlying
cosmological nature of the
gravitational source of energy
GRBs
for the bulk of the events
Lasting sometimes for
months
8. Early spectra
Peaks at ~1MeV
Powerlaw (i.e. certainly non-
thermal) both above and
below the peak
Phenomenological “Band model”
is used to describe:
Spectra of the bulk of the GRBs still contain roughly same amount of information
9. Compatness problem
Fast variability suggests small region - ~<10ms
High luminosity in small emission region would cause pair production and
thermalize the particles
Very large optical depth
But the observed spectrum is non-thermal!
10. Compatness problem
The situation can be saved assuming the emission region is moving relativistically
Gamma-factor at least 100 is required
The most relativistic outflow known.
11. Beaming
●
The isotropic equivalent of 1054 erg solely in gamma-rays would
be hard to explain: probably the emission is beamed.
Characteristic achromatic break in the
afterglow light curve is a signature of
beaming
Another confirmation comes from the observation of late time radio scintilations
Beaming of the order of 1-10 degrees is usually inferred
It is possible that there are two components, differently beamed
12. Emission mechanism
● Thermal: expected, but observed non-thermal,
can be a contribution
● Electron synchrotron: requires non-thermal
population of electrons
● Electron Inverse Compton: requires target field
● Proton synchrotron, pion decay: requires proton-
loaded outflow
13. The fireball model
The most radiatively efficient process is the electron synchrotron
Non-thermal population would have to be re-accelerated in the shocks
Rapid and violent “internal” shocks are responsible for the prompt
emission
More regular external shock accounts for the afterglow
14. Challenge to the fireball model
● Prediction of the “synchrotron deathline”
BATSE
Preece at al 2000
Low-energy asymptote can not be
harder than that of a single electron
But it is.
Swift/BAT Savchenko et al 2008
15. Challenge to the fireball model
● Prediction of the “synchrotron deathline”
Preece at al 2000
A set of models were proposed to
address the problem (modified synchrotron,
inverse compton, thermal contribution), all with
considerable issues
The measurement itself was not
considered quite reliable due to lack
of systematically high precision at the most
Low-energy asymptote can not be
important low energy part of the spectrum
harder than that of a single electron
But it is.
Savchenko et al 2008
16. Not the true spectrum
Another complication is that the spectrum is highly variable
Evolution of spectral parameters of GRB 090902B Evolution of spectral parameters of GRB 080319B
low-energy slope
peak energy
seconds
The measured spectra are averaged on the time scale larger then variability
17. The true spectrum
Another complication is that the spectrum is highly variable
Evolution of spectral parameters of GRB 090902B Evolution of spectral parameters of GRB 080319B
low-energy slope
peak energy
Big detector is required to measure
spectra below the variability scale.
To access 1 ms one needs
10 m2 at 1 MeV
10.000 kg
seconds
The measured spectra are averaged on the time scale larger then variability
18. Polarization of the MeV emission
Polarization of sub-MeV photons can be measured by measuring direction of
Compton-scattered electron
Requires dedicated instrument or very careful analysis
IKAROS: Solar sail with a GRB detector
Strong and variable
polarization?
INTEGRAL
IBIS
Yonetoku 2012
Gotz 2004
Would indicate ordered magnetic field in the emission region and non-thermal
emission process. But further measurements are required.
19. Polarization of the MeV emission
Polarization of sub-MeV photons can be measured by measuring direction of
Compton-scattered electron
Requires dedicated instrument or very careful analysis
IKAROS: Solar sail with a GRB detector
Strong and variable
polarization?
INTEGRAL
IBIS
only 3-4 sigma results
Would indicate ordered magnetic field in the emission region and non-thermal
emission process. But further measurements are required.
20. Polarization of the MeV emission
Polarization of sub-MeV photons can be measured by measuring direction of
Compton-scattered electron
Requires dedicated instrument or very careful analysis
IKAROS: Solar sail with a GRB detector
Strong and variable
Dedicated instrument: POLAR
polarization?
INTEGRAL
IBIS
In space soon
Would indicate ordered magnetic field in the emission region and non-thermal
emission process. But further measurements are required.
21. Extension of the energy range: GeV
● First observed only in a handful of cases by CGRO/EGRET
● Fermi/LAT since 2008 has dramatically improved the quality of the measurements
The emission correlates with the prompt at first but then extends for decades
longer
22. Extension of the energy range: GeV
● First observed only in a handful of cases by CGRO/EGRET
● Fermi/LAT detected 30 GeV-loud bursts in 4 years
It's not yet clear what fraction of the bursts have GeV emission. The number of the bursts in LAT
is less then expected, but no HE cut off was so far observed, putting extreme limit of
>1000 on the Lorentz factor.
23. Extension of the energy range: GeV to TeV
Current generation Cherenkov telescopes are barely able to perform GRB observations
MAGIC specificity was designed light – rapid – to follow GRBs. But no bright enough burst
was in the FoV.
CTA will be major improvement. Might measure the cutoff due to pair production,
study the decay of the emission in greater detail
24. Extension of the energy range: keV
The additional component extends also below the peak
It modifies measurements of the low-energy slopes during the prompt phase
In one case instead an inexplicable suppression is measured
Very few quality measurements are available – X-ray instrument is hard to point
promptly
25. Extension of the energy range: keV
The additional component extends also below the peak
It modifies measurements of the low-energy slopes during the prompt phase
In one case instead an inexplicable emission down measured
Will measure prompt suppression is to 1 KeV
(instead of 10 keV)!
Very few quality measurements are available – X-ray instrument is hard to point
promptly
26. Extension of the energy range
GeV-to-X-ray emission long after the prompt phase: INTEGRAL/ISGRI is very useful,
but only if lucky
2012, in preparation
27. Extension of the energy range
GeV-to-X-ray emission long after the prompt phase: INTEGRAL/ISGRI is very useful,
but only if lucky
Missing instrument
2012, in preparation
28. Extension of the energy range: optical
Optical emission during the prompt phase of the GRB has been detected in few
cases.
The challenge is to start observation of a narrow-field optical instrument in time.
It can be in fact extremely bright: reaching magnitude 5.3: stellar size object visible to a
naked eye from redshift of 0.97!
29. Extension of the energy range: optical
Optical emission during the prompt phase of the GRB has been detected in few
cases.
The challenge is to start observation of a narrow-field optical instrument in time.
Although no burst was seen simultaneously in GeV and optical
energetics and MeV spectrum comparative evolution suggest that
They might be of common origin
A single powerlaw from 1 eV to 10 GeV probably carrying
bulk of the GRB energy
It can be in fact extremely bright: reaching magnitude 5.3: stellar size object visible to a
naked eye from redshift of 0.97!
30. Extension of the energy range: optical
To study the prompt GRB optical emission the telescope has to be
extremely fast: react at <1 second.
Currently available cases are due to extreme GRB duration, presence
of a precursor or to pure luck
UFFO
The slewing mirror telescope(SMT), can slew to Field of view of SVOM will be constantly
target within 10 msec using MEMS (Micro-Electro-
monitored by a group of optical telescopes
Mechanical Systems)
31. Classification
Two components?
Large sample is required –
large instrument
Kouveliotou 1999
32. Classification
Using more then only the duration
Three components?..
34. Progenitors
Two major classes: two kind of progenitors
Collapsar: hypernova – massive supernova Merging compact objects
Supported by localization in the host galaxies
35. Collapsar: direct confirmation
In some cases supernova was directly observed after a GRB – always long
But in two cases upper limit excluded supernova...
36. Neutron star merger: direct
Close compact binary must emit gravitational waves, especially before merging
LIGO: interferometer
Bulk of the short GRBs, if related to NS mergers, will be soon detectable
For local events the limit already is reached. No detection indicates that the origin
was most likely not a merger.
37. Tidal disruptions
Tidal disruptions of small objects by stellar BH or stars by
supermassive black holes lead to similar phenomena.
The difference can be seen in the afterglow.
In several cases were directly identified, but contribution to the bulk of
the events is not really known
It may be seen as a reminder that a single event should may not represent
a population (although it is often tempting in the case of GRBs)
38. Magnetar flares
Reorganization of magnetic field in extremely magnetized neutron stars also
leads to short strong bursts, sometimes confused with the GRBs.
40. GRBs to probe history of the universe
GRBs are distant: have a potential
The most distant single event is at redshift of 9.4
Population studies suggest that there may be till ~20
41. GRBs as standard candles
The idea is to deduce luminosity from the spectral parameters
Most notably correlation between energy of the peak of the spectrum and
the luminosity is observed
The correlation is probably driven by the Lorentz
factor of the outflow
43. GRBs as probes star formation
GRBs carry unique direct information about high-redshift stars
Counting number of GRBs with
redshift one can deduce the star
formation history to
unprecedented redshift
Unbiased large sample is
required
44. GRBs line of sight
Absorption lines by different structures along the line of sight are observed
and can be used to study the structure, similarly to Lyman-alpha forest
Different elements can be probed, to higher redshift
Absorption in X-ray probes ionized medium
45. GRB as probes for vacuum dispersion
Dependency of speed of light on photon energy and polarization can be tested.
Strong upper limits are set, especially if the polarization is measured.
46. Conclusions
● Mechanism of the MeV prompt emission is still not clear but
major advances were made recently
● Classification is gradually shaping out
● Connections of the GRBs with cosmology are strengthening
● New results are expected in the coming years