scholarly journals Measurement of radiation energy and its application. V. Measurement of gamma-ray energy and its application. 1. Measurement of gamma-ray energy using Ge and NaI(Tl) detectors.

RADIOISOTOPES ◽  
1990 ◽  
Vol 39 (8) ◽  
pp. 371-379
Author(s):  
Haruo CHISAKA
Keyword(s):  
Gamma Ray ◽  
Radiation Energy

scholarly journals AXPs & SGRs: Magnetar or Quarctar?

2012 ◽  
Vol 8 (S291) ◽  
pp. 474-476
Author(s):  
Guojun Qiao ◽  
Xionwei Liu ◽  
Renxin Xu ◽  
Yuanjie Du ◽  
Jinlin Han ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Loss Rate ◽  
Gamma Ray ◽  
Radiation Energy ◽  
X Ray ◽  
Two Factors ◽  
Normal Method ◽  
The Magnetic Field

AbstractThe concept of a “magnetar” was proposed mainly because of two factors. First, the X-ray luminosity of Anomalous X-ray Pulsars (AXPs) and Soft Gamma-Ray Repeaters (SGRs) is larger than the rotational energy loss rate (Lx > Ėrot), and second, the magnetic field strength calculated from “normal method” is super strong. It is proposed that the radiation energy of magnetar comes from its magnetic fields. Here it is argued that the magnetic field strength calculated through the normal method is incorrect at the situation Lx > Ėrot, because the wind braking is not taken into account. Besides, the “anti-magnetar” and some other X-ray and radio observations are difficult to understand with a magnetar model.Instead of the magnetar, we propose a “quarctar”, which is a crusted quark star in an accretion disk, to explain the observations. In this model, the persistent X-ray emission, burst luminosity, spectrum of AXPs and SGRs can be understood naturally. The radio-emitting AXPs, which are challenging the magnetar, can also be explained by the quarctar model.

scholarly journals The use of radioactive substances in medicine — history and development prospects

2021 ◽  
Vol 67 (6) ◽  
pp. 59-67
Author(s):  
M. S. Sheremeta ◽  
A. A. Trukhin ◽  
M. O. Korchagina
Keyword(s):  
Nuclear Medicine ◽  
Gamma Ray ◽  
Clinical Medicine ◽  
Radiation Energy ◽  
Medical Specialty ◽  
80Th Anniversary ◽  
Genomic Technologies ◽  
Alpha Emission ◽  
Medicine History ◽  
Development Prospects

Nuclear medicine (NM) is a medical specialty that uses radionuclides (radioactive tracers) and ionising radiation for diagnostic and therapeutic (theranostic) purposes. Nuclear medicine arose and developed at the intersection of physics, chemistry and clinical medicine. The radiation emitted by radioisotopes can consist of gamma-, beta- and alpha emission, or it’s combination. Radioisotope of choice for medical purposes should have futher requirements: low radiotoxicity, suitable type of radiation, energy and half-life (several minutes to several hours and days), and also convenient detection of gamma ray radiation. The radionuclide is part of radiopharmaceutical (RP) and acts as its indicator. RP accumulates in morphological structures, becomes a carrier of coordinated information from patient to gamma camera or other equipment and reflects the dynamics of processes occurring in the examined organ. In 2021 NM celebrates its 80th anniversary. The trajectory of NM combines modern methods of radiotheranostics and applied genomic and post-genomic technologies.

scholarly journals Geant4-based comprehensive study of the absorbed fraction for electrons and gamma-photons using various geometrical models and biological tissues

2013 ◽  
Vol 28 (4) ◽  
pp. 341-351
Author(s):  
Ziaur Rahman ◽  
Shakeel Rehman ◽  
Sikander Mirza ◽  
Waheed Arshed ◽  
Nasir Mirza
Keyword(s):  
Gamma Ray ◽  
Absorbed Dose ◽  
Spherical Model ◽  
Radiation Energy ◽  
Biological Tissues ◽  
Target Volume ◽  
Relative Difference ◽  
Comprehensive Model ◽  
Model Predictions ◽  
Low Energies

The Geant4-based comprehensive model has been developed to predict absorbed fraction values for both electrons and gamma photons in spherical, ellipsoidal, and cylindrical geometries. Simulations have been carried out for water, ICRP soft-, brain-, lung-, and ICRU bone tissue for electrons in 0.1 MeV-4 MeV and g-photons in the 0.02 MeV-2.75 MeV energy range. Consistent with experimental observations, the Geant4-simulated values of absorbed fractions show a decreasing trend with an increase in radiation energy. Compared with NIST XCOM and ICRU data, the Geant4-based simulated values of the absorbed fraction remain within a 4.2% and 1.6% deviation, respectively. For electrons and g-photons, the relative difference between the Geant4-based comprehensive model predictions and those of Stabin and Konijnenberg's re-evaluation remains within a 6.8% and 7.4% range, respectively. Ellipsoidal and cylindrical models show 4.9% and 10.1% higher respective values of absorbed dose fractions relative to the spherical model. Target volume dependence of the absorbed fraction values has been found to follow a logical behavior for electrons and Belehradek's equation for g-photons. Gamma-ray absorbed fraction values have been found to be sensitive to the material composition of targets, especially at low energies, while for elections, they remain insensitive to them.

Electrons generated from machine sources operated at or below an energy level of 10 MeV The eV (electronvolt) is the unit of energy used to measure and describe the energy of electrons and of other types of radiation. The energy of 1 eV is equivalent to the kinetic energy acquired by an electron on being accelerated through a potential difference of 1 V. The eV is a very small unit of energy. It is therefore more common to speak of keV (kiloelectronvolt = 1000 eV) or MeV (megaelectronvolt = 1 million eV). To convert eV to units of energy one can use the conversion 1 MeV = 1.602 X 10“ J (joule). Gamma rays and x-rays are part of the electromagnetic spectrum (Fig. 1), which reaches from the low-energy, long-wavelength radiowaves to the high-energy, short-wavelength cosmic rays. Radiowaves, infrared (IR) waves, and visible light are nonionizing radiations. Ultraviolet (UV) light can ionize only certain types of molecule under specific conditions and is generally not consid­ ered as ionizing radiation. X-rays and gamma rays are identical in their physical properties and in their effect on matter; they differ in their origin. X-rays are produced by machines and exhibit a wide continuous spectrum of radiation, whereas gamma rays come from radioactive isotopes (radionuclides) in a discon­ tinuous spectrum of radiation intensities. When ionizing radiation penetrates into a medium (e.g., the irradiated food) all or part of the radiation energy is absorbed by the medium. This is called the absorbed dose. The unit in which the absorbed dose is measured is the gray (Gy); it is equal to the absorption of 1 J (joule)/kg. One kGy (kilogray) = 1000 Gy. Formerly the dose unit rad was used. It was defined as 100 erg/g. The conversion of old to new units is based on the relationship 1000 rad = 1 Gy, or 1 krad = 10 Gy, or 1 Mrad = 10 kGy. The dose accumulated per unit of time is called the dose rate. Gamma ray sources provide a relatively low dose rate (typically 100-10,000 Gy/h, whereas

1995 ◽  
pp. 28-28
Keyword(s):  
Ionizing Radiation ◽  
Dose Rate ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Uv Light ◽  
Absorbed Dose ◽  
Radiation Energy ◽  
Radioactive Isotopes ◽  
X Rays ◽  
Small Unit

On the possible gamma-ray source in Cygnus

1967 ◽  
Vol 31 ◽  
pp. 469-471
Author(s):  
J. G. Duthie ◽  
M. P. Savedoff ◽  
R. Cobb
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Right Ascension

A source of gamma rays has been found at right ascension 20h15m, declination +35°, with an uncertainty of 6° in each coordinate. Its flux is (1·5 ± 0·8) x 10-4photons cm-2sec-1at 100 MeV. Possible identifications are reviewed, but no conclusion is reached. The mechanism producing the radiation is also uncertain.

Solar Flare Energetic Neutral Emission Measurements in the Project Coronas-I

1994 ◽  
Vol 144 ◽  
pp. 635-639
Author(s):  
J. Baláž ◽  
A. V. Dmitriev ◽  
M. A. Kovalevskaya ◽  
K. Kudela ◽  
S. N. Kuznetsov ◽  
...  
Keyword(s):  
Solar Flare ◽  
Energy Range ◽  
Gamma Rays ◽  
Pulse Shape ◽  
Gamma Ray ◽  
Pulse Shape Discrimination ◽  
Shape Discrimination ◽  
Solar Neutron ◽  
Low Altitude

AbstractThe experiment SONG (SOlar Neutron and Gamma rays) for the low altitude satellite CORONAS-I is described. The instrument is capable to provide gamma-ray line and continuum detection in the energy range 0.1 – 100 MeV as well as detection of neutrons with energies above 30 MeV. As a by-product, the electrons in the range 11 – 108 MeV will be measured too. The pulse shape discrimination technique (PSD) is used.

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