Gamma rays in the MeV region at balloon altitude

1968 ◽  
Vol 46 (10) ◽  
pp. S494-S497 ◽  
Author(s):  
K. Okudaira ◽  
Y. Hirasima
Keyword(s):  
Gamma Rays ◽  
Main Part ◽  
Counting Rate ◽  
Gamma Ray ◽  
Plastic Scintillator ◽  
Scintillation Counter ◽  
Lower Atmosphere ◽  
Upper Limit ◽  
Extraterrestrial Origin ◽  
The Difference

Gamma rays in the MeV region were observed from balloons at λ = 26 °N on September 29, 1966. A scintillation counter constructed with two NaI ⅓ in. × 2 in. [Formula: see text] crystals separated by 1 cm × 2 in. [Formula: see text] lead was used to measure the directional distribution of the gamma-ray flux. This counter was flown at an atmospheric depth of 14.2 g cm−2. As the response of each crystal of this counter depends on the direction of incidence of the gamma rays, an anisotropic distribution of gamma rays gives rise to a difference between the counting rates of two crystals. It was ascertained from the observation that albedo gamma rays from the lower atmosphere are predominant at this high altitude. The deviation from the calculated values of the difference in counting rate assuming only atmospheric gamma rays may be due to an extraterrestrial origin of part of the gamma-ray flux. For the measurement of the gamma-ray spectrum, a phoswich counter (1 in. × 1 in. [Formula: see text] NaI crystal surrounded by ¼-in.-thick plastic scintillator) was flown to 10 g cm−2. Though the main part of the gamma-ray flux is probably due to atmospheric gamma rays, an upper limit for the isotropic cosmic gamma-ray flux is deduced to be (1.25 ± 0.05) × 10−2 counts cm−2 s−1 sr−1 MeV−1 in the energy range 1.2–3.1 MeV.

Gamma rays and high-energy neutrons in the atmosphere

1968 ◽  
Vol 46 (10) ◽  
pp. S1030-S1033 ◽  
Author(s):  
M. V. K. Apparao ◽  
R. R. Daniel ◽  
George Joseph ◽  
G. S. Gokhale ◽  
P. J. Lavakare ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Counting Rate ◽  
Plastic Scintillator ◽  
Pulse Height ◽  
Growth Curves ◽  
High Energy ◽  
Cutoff Rigidity ◽  
Energy Formula ◽  
Γ Rays ◽  
Γ Ray

In continuation of our earlier experiments studying the emission of solar neutrons, we have now developed detector systems which respond to γ rays of energy 1–5 MeV and neutrons of energy [Formula: see text]. The two detectors are almost identical. Each consists of a CsI (Na) crystal (B) of diameter 3.8 cm, completely enclosed in a tapered cylinder of plastic scintillator (A) operated in anticoincidence; the crystals have thicknesses of 2.4 and 1.2 cm respectively. A balloon carrying these detectors was flown on March 16, 1967 over Hyderabad, India (vertical cutoff rigidity 16.9 GV) and floated at a ceiling altitude of 6.0 mb for 1 hour. In addition to γ-ray and neutron events (AB), events A and AB were also continuously monitored throughout the flight. Pulses corresponding to 1–5 MeV in the 2.4-cm crystal (γ rays) and 6–40 MeV in the 1.2-cm crystal (high-energy neutrons) were analyzed by a 64-channel pulse-height analyzer. On the basis of the pulse-height distributions and γ-ray efficiencies in the two crystals, we attribute events of 1–5 MeV energy from the thicker crystal to γ rays and those > 10 MeV in energy from the thinner one to stars produced by high-energy neutrons [Formula: see text] in the crystal. Atmospheric growth curves for γ rays and neutrons have been obtained; these growth curves as well as those for events A and AB show the normal features of the Pfotzer maximum, steady decreases up to the ceiling altitude, and a constant counting rate at ceiling. The atmospheric counting rates at ceiling altitude give for γ rays of energy 1–5 MeV a flux of ~1 photon per cm2 s and for neutrons of energy [Formula: see text] a flux of ~0.1 neutron per cm2 s. No evidence for a solar component in either channel was found.

scholarly journals Recent Results on the Search for 1011 eV Gamma Rays from the Crab Nebula

1971 ◽  
Vol 46 ◽  
pp. 65-67
Author(s):  
G. G. Fazio ◽  
H. F. Helmken ◽  
G. H. Rieke ◽  
T. C. Weekes
Keyword(s):  
Magnetic Field ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Crab Nebula ◽  
Cosmic Ray ◽  
Air Showers ◽  
Upper Limit ◽  
The Crab Nebula ◽  
Cerenkov Light ◽  
Significant Flux

The detection of Čerenkov light emitted by cosmic-ray air showers was used to search for cosmic gamma rays from the Crab Nebula. By use of the 10-m optical reflector at Mt. Hopkins, Arizona, the Crab Nebula was observed during the winter of 1969–1970 for approximately 112 hours, which was a significant increase in exposure time over previous experiments. Above a gamma-ray energy of 2.2 × 1011 eV, no significant flux was detected, resulting in an upper limit to the flux of 8.1 × 10-11 photon/cm2 sec. In the synchrotron-Compton-scattering model of gamma-ray production in the Crab Nebula, this limit on the flux indicates the average magnetic field in the nebula must be greater than 3 × 10-4 G.

The isotope effect in the electronic structure factors of liquid NH3 and ND3

1995 ◽  
Vol 73 (11-12) ◽  
pp. 735-740 ◽  
Author(s):  
S. Takeda ◽  
P. A. Egelstaff
Keyword(s):  
Electronic Structure ◽  
Gamma Rays ◽  
Correlation Functions ◽  
Gamma Ray ◽  
Liquid Structure ◽  
Density Correlation ◽  
Structure Factors ◽  
Radioisotope Source ◽  
The Difference ◽  
Absorption Technique

Gamma rays from a radioisotope source, 241Am, were scattered from samples of liquid light ammonia (NH3) and heavy ammonia (ND3) at temperatures of 294.5 and 284.5 K under their normal vapour pressures to determine the electronic liquid structure factors. In addition the densities of these samples were checked by the gamma ray absorption technique. From the difference between the total electronic structure factors of liquid NH3 and ND3, the difference of the r-space electronic correlation functions of the two liquids (at the same temperature) was evaluated. The observable difference is due (mainly) to quantum effects in the intermolecular electron-density correlation functions of liquid ammonia, which will be discussed.

scholarly journals Optimization of Plastic Scintillator for Detection of Gamma-Rays: Simulation and Experimental Study

Chemosensors ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 239
Author(s):  
Sujung Min ◽  
Youngsu Kim ◽  
Kwang-Hoon Ko ◽  
Bumkyung Seo ◽  
JaeHak Cheong ◽  
...  
Keyword(s):  
Atomic Number ◽  
High Performance ◽  
High Efficiency ◽  
Gamma Ray ◽  
Plastic Scintillator ◽  
Computational Simulation ◽  
Radiation Detection ◽  
High Atomic Number ◽  
Plastic Scintillators ◽  
The Difference

Plastic scintillators are widely used in various radiation measurement applications, and the use of plastic scintillators for nuclear applications including decommissioning, such as gamma-ray detection and measurement, is an important concern. With regard to efficient and effective gamma-ray detection, the optimization for thickness of plastic scintillator is strongly needed. Here, we elucidate optimization of the thickness of high-performance plastic scintillator using high atomic number material. Moreover, the EJ-200 of commercial plastic scintillators with the same thickness was compared. Two computational simulation codes (MCNP, GEANT4) were used for thickness optimization and were compared with experimental results to verify data obtained by computational simulation. From the obtained results, it was confirmed that the difference in total counts was less than 10% in the thickness of the scintillator of 50 mm or more, which means optimized thickness for high efficiency gamma-ray detection such as radioactive 137Cs and 60CO. Finally, simulated results, along with experimental data, were discussed in this study. The results of this study can be used as basic data for optimizing the thickness of plastic scintillators using high atomic number elements for radiation detection and monitoring.

scholarly journals Gamma-Ray Spectrometry in the Energy Range 0.5–5 MeV

1971 ◽  
Vol 41 ◽  
pp. 58-62 ◽  
Author(s):  
F. Albernhe ◽  
C. Doulade ◽  
I. M. Martin ◽  
R. Talon ◽  
G. Vedrenne
Keyword(s):  
Gamma Rays ◽  
Pulse Shape ◽  
Gamma Ray ◽  
Plastic Scintillator ◽  
Pulse Shape Discrimination ◽  
Field Of View ◽  
Gamma Ray Spectrometry ◽  
Shape Discrimination ◽  
Equatorial Latitude ◽  
Compton Electron

A stilbene scintillator detector allowing gamma-ray spectrometry in the range 0.5–5 MeV is presented. A complete elimination of charged particles is obtained by a plastic scintillator anticoïncidence jacket. Separation of gamma rays from neutrons is made by pulse shape discrimination technique with over 99% efficiency. This detector which has a 4 π field of view has been made as light as possible to avoid perturbation due to secondary production in the apparatus. The correction of the edge effects and the method of conversion from experimental Compton electron spectrum to gamma-ray spectrum are explained.Results from balloon launchings at three latitudes (Kourou Guyana: 10 N, Aire sur l'Adour: 46°N and Oboziersky U.S.S.R.: 62 °N) are briefly presented. The detection possibility with balloons of galactic gamma rays at equatorial latitude is shown. The atmospheric part of the flux at the equator is deduced from the measurements at higher latitudes, (46 °N and 62 °N) where the galactic component is of negligible importance. Assuming a power law spectrum and after correction of the atmospheric absorption we obtain for the galactic spectrum the expression dN/dE = 1.1 × 10−5E−1, 2 photons/cm2 s sr keV. This spectrum agrees with the results of ERS 18 satellite given by Vette et al. showing an excess of flux for energies higher than 1 MeV.

scholarly journals Techniques for Gamma Rays

1971 ◽  
Vol 41 ◽  
pp. 14-36 ◽  
Author(s):  
Carl E. Fichtel
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Scintillation Counter ◽  
High Energy ◽  
Detector System ◽  
Detector Arrays ◽  
High Particle ◽  
Electron Positron ◽  
Energy Gamma ◽  
Counter Telescope

The detecting systems used in high energy astrophysics are generally more similar to particle detectors than to optical devices. The basic design of the gamma ray instrument depends on whether the energy range is below about 10 MeV and therefore in the region where the Compton effect predominates in the absorption of the gamma-rays, or above that energy where electron-positron pair production is most important. The most usual approach to the detector system in the lower of the two energy intervals is to use a scintillation counter in the center of the detector system to absorb the photons and permit a measure of their energy, and to surround it by another detector which is employed as an active anticoincidence shield to discriminate against charged particles. In the gamma-ray interval above about 10 MeV, the very low flux of gamma rays and the high particle background has directed the development of high energy gamma-ray telescopes towards complicated techniques and large detector arrays. As a result, several investigators have now turned to the spark chamber as the heart of a detector system. Generally, it is surrounded by an anticoincidence system and is triggered by a counter telescope.

GAMMA-RAY TRANSITIONS IN 15O AND 15N

1965 ◽  
Vol 43 (12) ◽  
pp. 2310-2318 ◽  
Author(s):  
T. K. Alexander ◽  
A. E. Litherland ◽  
C. Broude
Keyword(s):  
Excited States ◽  
Gamma Rays ◽  
Doppler Shift ◽  
Gamma Ray ◽  
Measured Energy ◽  
The Mean ◽  
The Difference ◽  
Mean Lifetimes

The gamma rays from the first two excited states of 15O and 15N populated by the 14N + d, T(16O, αγ)15N, and 16O(3He, αγ)15O reactions have been observed with a Ge(Li) spectrometer. The measured energy separations are 50 ± 5 keV for the 15O doublet and 28.5 ± 3 keV for the 15N doublet. The difference between the 5.24-MeV gamma ray from 15O and the 5.27-MeV gamma ray from 15N is 29 ± 1 keV. From Doppler-shift and broadening measurements of the energies of the gamma rays from the T(16O, αγ)15N and 16O(3He, αγ)15O reactions, information on the mean lifetimes of the states was obtained. The mean lifetimes of the 5.30-and 5.27-MeV states of 15N are 4.3 ± 1.8 × 10−14 sec and > 10−12 sec respectively. The mean lifetimes of the 5.19- and 5.24-MeV states of 15O are < 3 × 10−13 sec and > 10−12 sec respectively.

The performances of M4 generation of Mentik Susu rice mutants irradiated with gamma-ray

2020 ◽  
Vol 21 (9) ◽  
Author(s):  
Wafa’ Nur Hanifah ◽  
Parjanto PARJANTO ◽  
Sri Hartati ◽  
Ahmad Yunus
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Design Experiment ◽  
High Productivity ◽  
Central Java ◽  
Gamma Ray Irradiation ◽  
Long Life ◽  
The Difference ◽  
Short Stems ◽  
And Control

Abstract. Hanifah WN, Parjanto, Hartati S, Yunus A. 2020. The performances of m4 generation of Mentik Susu rice mutants irradiated with gamma-ray. Biodiversitas 21: 4041-4046. Mentik Susu is local rice from Magelang, Central Java, Indonesia. It has superiority, in terms of soft texture and white color, but on the other hand, this local rice has the disadvantage of having relatively high stems, low yield, and long life. One way to overcome the weakness of Mentik Susu rice is by mutating plants using gamma-rays. The purpose of this research was to study M4 mutants from Mentik Susu rice irradiated with gamma-ray and to select mutans that have short stem and high productivity. The study was conducted using a simple random design experiment by planting various strains of M4 generation of Mentik Susu rice irradiated with 100 Gy and 200 Gy gamma-rays. T-test was employed to test the difference between strains treated with gamma-ray irradiation and control samples (without gamma-ray irradiation). The results showed that the M4 Mentik Susu rice irradiated with 100 Gy and 200 Gy gamma-rays in overall had lower stems, shorter flowering and harvesting ages, and higher productivity than non-irradiated Mentik Susu rice (control). The strains with the shortest stem and with highest yield productivity was resulted from 200 Gy gamma-ray irradiation with code of M-MS200-G15T3-2. This study also selected 30 individual mutant plants that had short stems and high productivity, suggesting that these plants can be passed to M5 generation.

scholarly journals A new compact neutron/gamma ray scintillation detector

2016 ◽  
Vol 44 ◽  
pp. 1660228 ◽  
Author(s):  
A. Buffler ◽  
A. C. Comrie ◽  
F. D. Smit ◽  
H. J. Wörtche
Keyword(s):  
Gamma Rays ◽  
Pulse Shape ◽  
Gamma Ray ◽  
Plastic Scintillator ◽  
Pulse Shape Discrimination ◽  
Shape Discrimination ◽  
Neutron Energy Range ◽  
Neutron Spectrometer ◽  
Silicon Photomultipliers ◽  
Digital Implementation

Progress towards the realization of a new compact neutron spectrometer is described. The detector is based on EJ299-33 plastic scintillator coupled to silicon photomultipliers, and a digital implementation of pulse shape discrimination is used to separate events associated with neutrons from those associated with gamma rays. The spectrometer will be suitable over the neutron energy range 1–100 MeV, illustrated in this work with measurements made using an AmBe radioisotopic source and quasi-monoenergetic neutron beams produced using a cyclotron.

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.

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