scholarly journals Gamma Ray Intensity and Angular Correlation Measurements in 160Dy

1976 ◽  
Vol 29 (5) ◽  
pp. 405 ◽  
Author(s):  
SS Bhati ◽  
Nirmal Singh ◽  
PD Bajaj ◽  
PN Trehan
Keyword(s):  
Angular Correlation ◽  
Gamma Ray ◽  
Intensity Measurements ◽  
First Time ◽  
Coincidence Arrangement

Gamma-ray intensity measurements in 160Dy have been carried out using a Ge(Li) detector. In addition, 1'-1' angular correlation measurements have been made on 10 cascades in 160Dy using a Ge(Li)-NaI(TI) fast coincidence arrangement. These cascades are 299 ..... 966, 299 ..... 879, 879 ..... 87, 197 ..... 87, 962 ..... 87, 21S ..... 962, 299 ..... (879) ..... 87, 299 ..... (682) ..... 197, 21S ..... (962) ..... 87 and 21S ..... (76S) ..... 197 keY. Of these, the 21S ..... (962) ..... 87 and 21S ..... (76S) ..... 197 keY cascades have been measured for the first time. The multipolarities of the 197, 21S, 299, 879 and 962 keY transitions were found to be E2+(0'2�0'2)%M3, El +(2'S~~:g)%M2, El +(2~~)%M2, Ml +(99�1)%E2 and Ml + (98 � 1) % E2 respectively.

One-step synthesis of well-dispersed polypyrrole copolymers under gamma-ray irradiation

2021 ◽  
Vol 12 (5) ◽  
pp. 645-649
Author(s):  
Yu Gu ◽  
Yuqing Qiao ◽  
Yusen Meng ◽  
Ming Yu ◽  
Bowu Zhang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Gamma Ray ◽  
Gamma Ray Irradiation ◽  
One Step ◽  
First Time

Herein, we report for the first time the synthesis of polypyrrole copolymers with good solvent-dispersibility under gamma-ray irradiation at room temperature in air.

scholarly journals SDSS J211852.96−073227.5: The first non-local, interacting, late-type intermediate Seyfert galaxy with relativistic jets

2020 ◽  
Vol 636 ◽  
pp. L12 ◽  
Author(s):  
E. Järvelä ◽  
M. Berton ◽  
S. Ciroi ◽  
E. Congiu ◽  
A. Lähteenmäki ◽  
...  
Keyword(s):  
Near Infrared ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
Seyfert Galaxy ◽  
Late Type ◽  
Host Galaxies ◽  
Relativistic Jets ◽  
Galaxy Interactions ◽  
Non Local ◽  
First Time

It has been often suggested that a tangible relation exists between relativistic jets in active galactic nuclei (AGN) and the morphology of their host galaxies. In particular, relativistic jets may commonly be related to merging events. Here we present for the first time a detailed spectroscopic and morphological analysis of a Seyfert galaxy, SDSS J211852.96−073227.5, at z = 0.26. This source has previously been classified as a gamma-ray emitting narrow-line Seyfert 1 galaxy. We re-observed it with the 6.5 m Clay Telescope and these new, high-quality spectroscopic data have revealed that it is actually an intermediate-type Seyfert galaxy. Furthermore, the results of modelling the Ks-band near-infrared images obtained with the 6.5 m Baade Telescope indicate that the AGN is hosted by a late-type galaxy in an interacting system, strengthening the suggested connection between galaxy interactions and relativistic jets.

scholarly journals Precision measurements on oxygen formation in stellar helium burning with gamma-ray beams and a Time Projection Chamber

2021 ◽  
Author(s):  
Robin Smith ◽  
Moshe Gai ◽  
Sarah Stern ◽  
Deran Schweitzer ◽  
Mohammad Ahmed
Keyword(s):  
Time Projection Chamber ◽  
Gamma Ray ◽  
Nuclear Reactions ◽  
Angular Distributions ◽  
Helium Burning ◽  
Low Energies ◽  
Important Input ◽  
Novel Method ◽  
Time Projection ◽  
First Time

Abstract Stellar Evolution theory relies on our knowledge of nuclear reactions, with the carbon/oxygen (C/O) ratio, at the end of helium burning, being the single most important input. However, the C/O ratio is still not known with sufficient accuracy, due to large uncertainties in the cross section for the fusion of helium with 12C to form 16O, denoted as the 12C(α,γ)16O reaction. We present initial results at moderately low energies using a novel method, which is significantly different from the experimental efforts of the past four decades. Precise angular distributions of the 12C(α,γ)16O reaction were obtained by measuring the inverse 16O(γ,α)12C reaction with gamma-beams and a Time Projection Chamber detector. These allowed us to measure, for the first time, the interference angle of the l = 1 and 2 partial waves contributing to this reaction (φ12), which agrees with predictions based on the unitarity of the scattering matrix.

scholarly journals Detection of the Geminga pulsar with MAGIC hints at a power-law tail emission beyond 15 GeV

2020 ◽  
Vol 643 ◽  
pp. L14
Author(s):  
◽  
V. A. Acciari ◽  
S. Ansoldi ◽  
L. A. Antonelli ◽  
A. Arbet Engels ◽  
...  
Keyword(s):  
Energy Range ◽  
Power Law ◽  
Gamma Ray ◽  
Low Energy ◽  
Significance Level ◽  
Inverse Compton Scattering ◽  
Curvature Radiation ◽  
Sensitivity Range ◽  
Inverse Compton ◽  
First Time

We report the detection of pulsed gamma-ray emission from the Geminga pulsar (PSR J0633+1746) between 15 GeV and 75 GeV. This is the first time a middle-aged pulsar has been detected up to these energies. Observations were carried out with the MAGIC telescopes between 2017 and 2019 using the low-energy threshold Sum-Trigger-II system. After quality selection cuts, ∼80 h of observational data were used for this analysis. To compare with the emission at lower energies below the sensitivity range of MAGIC, 11 years of Fermi-LAT data above 100 MeV were also analysed. From the two pulses per rotation seen by Fermi-LAT, only the second one, P2, is detected in the MAGIC energy range, with a significance of 6.3σ. The spectrum measured by MAGIC is well-represented by a simple power law of spectral index Γ = 5.62 ± 0.54, which smoothly extends the Fermi-LAT spectrum. A joint fit to MAGIC and Fermi-LAT data rules out the existence of a sub-exponential cut-off in the combined energy range at the 3.6σ significance level. The power-law tail emission detected by MAGIC is interpreted as the transition from curvature radiation to Inverse Compton Scattering of particles accelerated in the northern outer gap.

scholarly journals A comparison between short GRB afterglows and kilonova AT2017gfo: shedding light on kilonovae properties

2020 ◽  
Vol 493 (3) ◽  
pp. 3379-3397 ◽  
Author(s):  
A Rossi ◽  
G Stratta ◽  
E Maiorano ◽  
D Spighi ◽  
N Masetti ◽  
...  
Keyword(s):  
Gravitational Wave ◽  
Gamma Ray ◽  
Light Curves ◽  
Optical Counterpart ◽  
Wave Source ◽  
Gamma Ray Burst ◽  
Nir Light ◽  
First Time ◽  
Short Grbs

ABSTRACT Multimessenger astronomy received a great boost following the discovery of kilonova (KN) AT2017gfo, the optical counterpart of the gravitational wave source GW170817 associated with the short gamma-ray burst GRB 170817A. AT2017gfo was the first KN that could be extensively monitored in time using both photometry and spectroscopy. Previously, only few candidates have been observed against the glare of short GRB afterglows. In this work, we aim to search the fingerprints of AT2017gfo-like KN emissions in the optical/NIR light curves of 39 short GRBs with known redshift. For the first time, our results allow us to study separately the range of luminosity of the blue and red components of AT2017gfo-like kilonovae in short GRBs. In particular, the red component is similar in luminosity to AT2017gfo, while the blue KN can be more than 10 times brighter. Finally, we exclude a KN as luminous as AT2017gfo in GRBs 050509B and 061201.

scholarly journals Radio counterparts of gamma-ray pulsars

2012 ◽  
Vol 8 (S291) ◽  
pp. 87-92
Author(s):  
L. Guillemot
Keyword(s):  
Gamma Ray ◽  
Population Studies ◽  
Radio Observations ◽  
Large Area ◽  
Millisecond Pulsars ◽  
Follow Up Studies ◽  
First Time

AbstractObservations of pulsars with the Large Area Telescope (LAT) on the Fermi satellite have revolutionized our view of the gamma-ray pulsar population. For the first time, a large number of young gamma-ray pulsars have been discovered in blind searches of the LAT data. More generally, the LAT has discovered many new gamma-ray sources whose properties suggest that they are powered by unknown pulsars. Radio observations of gamma-ray sources have been key to the success of pulsar studies with the LAT. For example, radio observations of LAT-discovered pulsars provide constraints on the relative beaming fractions, which are crucial for pulsar population studies. Also, radio searches of LAT sources with no known counterparts have been very efficient, with the discovery of over forty millisecond pulsars. I review radio follow-up studies of LAT-discovered pulsars and unidentified sources, and discuss some of the implications of the results.

scholarly journals Detection of a flaring blazar coincident with an IceCube high-energy neutrino

2019 ◽  
Vol 207 ◽  
pp. 02001
Author(s):  
Anna Franckowiak
Keyword(s):  
Gamma Ray ◽  
Spectral Energy Distribution ◽  
Neutrino Flux ◽  
High Energy ◽  
Spectral Energy ◽  
Large Area ◽  
High Energy Neutrino ◽  
Energy Neutrino ◽  
Radio Wavelength ◽  
First Time

In September 22, 2017, IceCube released a public alert announcing the detection of a 290 TeV neutrino track event with an angular uncertainty of one square degree (90% containment). A multi-messenger follow-up campaign was initiated resulting in the detection of a GeV gamma-ray flare by the Fermi Large Area Telescope positionally consistent with the location of the known Bl Lac object, TXS 0506+056 , located only 0.1 degrees from the best-fit neutrino position. The probability of finding a GeV gamma-ray flare in coincidence with a high-energy neutrino event assuming a correlation of the neutrino flux with the gamma-ray energy flux in the energy band between 1 and 100 GeV was calculated to be 3σ (after trials correction). Following the detection of the flaring blazar the imaging air Cherenkov telescope MAGIC detected the source for the first time in the > 100 GeV gamma-ray band. The activity of the source was confirmed in X-ray, optical and radio wavelength. Several groups have developed lepto-hadronic models which succeed to explain the multi-messenger spectral energy distribution.

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