THE SIMULATION OF AN IMAGING GAMMA-RAY COMPTON BACKSCATTERING DEVICE USING GEANT4

2014 ◽  
Vol 27 ◽  
pp. 1460152
Author(s):  
D. FLECHAS ◽  
L.G. SARMIENTO ◽  
F. CRISTANCHO ◽  
E. FAJARDO
Keyword(s):  
Gamma Rays ◽  
Nuclear Physics ◽  
Gamma Ray ◽  
Structural Defects ◽  
Compton Camera ◽  
Experimental Conditions ◽  
Imaging Device ◽  
Compton Backscattering ◽  
National University ◽  
Simulated Images

A gamma-backscattering imaging device dubbed Compton Camera, developed at GSI (Darmstadt, Germany) and modified and studied at the Nuclear Physics Group of the National University of Colombia in Bogotá, uses the back-to-back emission of two gamma rays in the positron annihilation to construct a bidimensional image that represents the distribution of matter in the field-of-view of the camera. This imaging capability can be used in a host of different situations, for example, to identify and study deposition and structural defects, and to help locating concealed objects, to name just two cases. In order to increase the understanding of the response of the Compton Camera and, in particular, its image formation process, and to assist in the data analysis, a simulation of the camera was developed using the GEANT4 simulation toolkit. In this work, the images resulting from different experimental conditions are shown. The simulated images and their comparison with the experimental ones already suggest methods to improve the present experimental device

Using a clinical linac to determine the energies of gamma-ray transitions and half-lives of barium nuclei

2020 ◽  
Vol 35 (10) ◽  
pp. 2050062
Author(s):  
Abdullah Engin Çalık ◽  
Kaan Manisa ◽  
Ahmet Biçer ◽  
Mehmet Erdoğan ◽  
Mürsel Şen ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Linear Accelerator ◽  
Nuclear Physics ◽  
Hpge Detector ◽  
Gamma Ray ◽  
Energy Levels ◽  
Photonuclear Reactions ◽  
High Purity Germanium ◽  
Physics Experiment ◽  
First Time

Photonuclear reactions have great importance in understanding the structure of the nuclei. These reactions, performed using the gamma rays obtained by way of bremsstrahlung, are a standard nuclear physics experiment. In this study, a non-enriched barium sample was activated for the first time by using a clinical linear accelerator (cLINACs). The spectrum of barium radioisotopes was obtained by using a gamma spectrometry with a high purity germanium (HPGe) detector. The obtained spectroscopic data were analyzed and energy levels and half-life values together with their uncertainties were obtained. Some energy levels and half-lives of [Formula: see text]Ba were determined with more precision than those of literature values.

scholarly journals Development and performance verification of a 3-D position-sensitive Compton camera for imaging MeV gamma rays

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hiroki Hosokoshi ◽  
Jun Kataoka ◽  
Saku Mochizuki ◽  
Masaki Yoneyama ◽  
Soichiro Ito ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Angular Resolution ◽  
Astronomical Observation ◽  
Large Field ◽  
Energy Bands ◽  
Compton Camera ◽  
Satellite Mission ◽  
Performance Verification ◽  
Position Sensitive

AbstractIn gamma-ray astronomy, the 1–10 MeV range is one of the most challenging energy bands to observe owing to low photon signals and a considerable amount of background contamination. This energy band, however, comprises a substantial number of nuclear gamma-ray lines that may hold the key to understanding the nucleosynthesis at the core of stars, spatial distribution of cosmic rays, and interstellar medium. Although several studies have attempted to improve observation of this energy window, development of a detector for astronomy has not progressed since NASA launched the Compton Gamma Ray Observatory (CGRO) in 1991. In this work, we first developed a prototype 3-D position-sensitive Compton camera (3D-PSCC), and then conducted a performance verification at NewSUBARU, Hyogo in Japan. To mimic the situation of astronomical observation, we used a MeV gamma-ray beam produced by laser inverse Compton scattering. As a result, we obtained sharp peak images of incident gamma rays irradiating from incident angles of 0° and 20°. The angular resolution of the prototype 3D-PSCC was measured by the Angular Resolution Measure and estimated to be 3.4° ± 0.1° (full width at half maximum (FWHM)) at 1.7 MeV and 4.0° ± 0.5° (FWHM) at 3.9 MeV. Subsequently, we conceived a new geometry of the 3D-PSCC optimized for future astronomical observations, assuming a 50-kg class small satellite mission. The SΩ of the 3D-PSCC is 11 cm2sr, anticipated at 1 MeV, which is small but provides an interesting possibility to observe bright gamma-ray sources owing to the high intrinsic efficiency and large field of view (FoV).

Tsinghua Center for Astrophysics and the Dark Universe

2014 ◽  
Vol 03 (02) ◽  
pp. 63-70
Author(s):  
Charling Tao
Keyword(s):  
Gamma Rays ◽  
Nuclear Physics ◽  
Gamma Ray ◽  
High Energy ◽  
X Rays ◽  
High Energy Astrophysics ◽  
Research Directions ◽  
X Ray ◽  
Main Research ◽  
Optical Wavelengths

The Tsinghua Center for Astrophysics (THCA) was founded in 2001 by Prof. Li Tipei and Shang Rencheng. A distinguishing characteristic of THCA's astrophysics program is its emphasis on space X-ray and gamma-ray instrumentation, by taking advantage of Tsinghua's strong programs on nuclear physics, nuclear engineering, space and aeronautics engineering, as well as electronics and information technology. The main research directions in THCA include high energy astrophysics and cosmology with space and ground observations in X-rays and gamma-rays, and more recently in optical wavelengths, radio-astronomy, gravitational waves, dark matter and dark energy analyses and projects.

scholarly journals New methods to reconstruct $$X_{\mathrm{max}}$$ and the energy of gamma-ray air showers with high accuracy in large wide-field observatories

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
R. Conceição ◽  
L. Peres ◽  
M. Pimenta ◽  
B. Tomé
Keyword(s):  
Gamma Rays ◽  
Arrival Time ◽  
Gamma Ray ◽  
High Energy ◽  
New Physics ◽  
Wide Field ◽  
Air Showers ◽  
Experimental Conditions ◽  
New Methods ◽  
Wide Field Of View

AbstractNovel methods to reconstruct the slant depth of the maximum of the longitudinal profile ($$X_{\mathrm{max}}$$ X max ) of high-energy showers initiated by gamma-rays as well as their energy ($$E_0$$ E 0 ) are presented. The methods were developed for gamma rays with energies ranging from a few hundred GeV to $$\sim 10$$ ∼ 10 TeV. An estimator of $$X_{\mathrm{max}}$$ X max is obtained, event-by-event, from its correlation with the distribution of the arrival time of the particles at the ground, or the signal at the ground for lower energies. An estimator of $$E_0$$ E 0 is obtained, event-by-event, using a parametrization that has as inputs the total measured energy at the ground, the amount of energy contained in a region near to the shower core and the estimated $$X_{\mathrm{max}}$$ X max . Resolutions about $$40 \, (20)\,\mathrm{g/cm^2}$$ 40 ( 20 ) g / cm 2 and about $$30 \, (20)\%$$ 30 ( 20 ) % for, respectively, $$X_{\mathrm{max}}$$ X max and $$E_0$$ E 0 at $$1 \, (10) \ \mathrm {TeV}$$ 1 ( 10 ) TeV energies are obtained, considering vertical showers. The obtained results are auspicious and can lead to the opening of new physics avenues for large wide field-of-view gamma-ray observatories. The dependence of the resolutions with experimental conditions is discussed.

scholarly journals Multiple-Collision Free-Electron Laser Compton Backscattering for a High-Yield Gamma-Ray Source

2020 ◽  
Vol 10 (4) ◽  
pp. 1418
Author(s):  
Norihiro Sei ◽  
Hiroshi Ogawa ◽  
QiKa Jia
Keyword(s):  
Gamma Rays ◽  
Free Electron ◽  
Free Electron Laser ◽  
Gamma Ray ◽  
Optical Cavity ◽  
High Yield ◽  
Multiple Collision ◽  
Collision Point ◽  
Compton Backscattering ◽  
Multiple Collisions

We observed multiple-collision free-electron laser (FEL)-Compton backscattering in which a multi-bunch electron beam makes head-on collisions with multi-pulse FELs in an optical cavity, using an infrared FEL system in the storage ring NIJI-IV. It was demonstrated that the measured spectrum of the multiple-collision FEL-Compton backscattering gamma rays was the summation of the spectra of the gamma rays generated at each collision point. Moreover, it was demonstrated that the spatial distribution of the multiple-collision FEL-Compton backscattering gamma rays was the summation of those of the gamma rays generated at each collision point. Our experimental results proved quantitatively that the multiple collisions in the FEL-Compton backscattering process are effective in increasing the yield of the gamma rays. By applying the multiple-collision FEL-Compton backscattering to high-repetition FEL devices such as energy recovery linac FELs, an unprecedented high-yield gamma-ray source with quasi-monochromaticity and wavelength tunability will be realized.

scholarly journals A Low Background Gamma Ray Spectrometer with Anticosmic Shielding

2016 ◽  
Vol 26 (1) ◽  
pp. 93
Author(s):  
Nguyen Quoc Hung ◽  
Vo Hong Hai ◽  
Tran Kim Tuyet ◽  
Ho Lai Tuan
Keyword(s):  
Nuclear Physics ◽  
Gamma Ray ◽  
Gamma Line ◽  
Background Suppression ◽  
Background Count ◽  
Background Count Rate ◽  
Low Background ◽  
Lead Shield ◽  
Gamma Ray Spectrometer ◽  
National University

The article describes a gamma ray spectrometer protected by a lead shield (Model 747E Canberra lead shield) and an active shield made of an 80~cm \(\times\) 80~cm \(\times\) 3~cm plastic scintillator plate in anticoincidence on top of the lead shield. The detector used as low background gamma-spectrometer is a high purity Germanium crystal of model GC2018 Canberra. The background count rate currently achieved (30-2400 keV) is 1.27 cps without anticoincidence. The level of background suppression obtained from the active protection is 0.80 overall and about 0.43 for the 511 keV gamma line. The gamma ray spectrometer is installed and operated in the Nuclear Laboratory, Department of Nuclear Physics, University of Science, HCMC-Vietnam National University.

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.

New Particles

2018 ◽  
Author(s):  
Roger H. Stuewer
Keyword(s):  
Gamma Rays ◽  
Atomic Hydrogen ◽  
Nuclear Physics ◽  
Hydrogen Isotope ◽  
Alpha Particles ◽  
Cloud Chamber ◽  
Ernest Rutherford ◽  
James Chadwick ◽  
Theoretical Foundations ◽  
New Particles

In December 1931, Harold Urey discovered deuterium (and its nucleus, the deuteron) by spectroscopically detecting the faint companion lines in the Balmer spectrum of atomic hydrogen that were produced by the heavy hydrogen isotope. In February 1932, James Chadwick, stimulated by the claim of the wife-and-husband team of Irène Curie and Frédéric Joliot that polonium alpha particles cause the emission of energetic gamma rays from beryllium, proved experimentally that not gamma rays but neutrons are emitted, thereby discovering the particle whose existence had been predicted a dozen years earlier by Chadwick’s mentor, Ernest Rutherford. In August 1932, Carl Anderson took a cloud-chamber photograph of a positron traversing a lead plate, unaware that Paul Dirac had predicted the existence of the anti-electron in 1931. These three new particles, the deuteron, neutron, and positron, were immediately incorporated into the experimental and theoretical foundations of nuclear physics.

scholarly journals On a Possible Origin of the Gamma-ray Excess around the Galactic Center

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1432
Author(s):  
Dmitry O. Chernyshov ◽  
Andrei E. Egorov ◽  
Vladimir A. Dogiel ◽  
Alexei V. Ivlev
Keyword(s):  
Dark Matter ◽  
Gamma Rays ◽  
Molecular Clouds ◽  
Alternative Explanation ◽  
Gamma Ray ◽  
Galactic Center ◽  
The Self ◽  
Large Area ◽  
Mhd Turbulence ◽  
The Standard Model

Recent observations of gamma rays with the Fermi Large Area Telescope (LAT) in the direction of the inner galaxy revealed a mysterious excess of GeV. Its intensity is significantly above predictions of the standard model of cosmic rays (CRs) generation and propagation with a peak in the spectrum around a few GeV. Popular interpretations of this excess are that it is due to either spherically distributed annihilating dark matter (DM) or an abnormal population of millisecond pulsars. We suggest an alternative explanation of the excess through the CR interactions with molecular clouds in the Galactic Center (GC) region. We assumed that the excess could be imitated by the emission of molecular clouds with depleted density of CRs with energies below ∼10 GeV inside. A novelty of our work is in detailed elaboration of the depletion mechanism of CRs with the mentioned energies through the “barrier” near the cloud edge formed by the self-excited MHD turbulence. This depletion of CRs inside the clouds may be a reason for the deficit of gamma rays from the Central Molecular Zone (CMZ) at energies below a few GeV. This in turn changes the ratio between various emission components at those energies and may potentially absorb the GeV excess by a simple renormalization of key components.

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