Experimental set-up for the measurement of prompt gamma rays resulting from interactions of 14.5 MeV neutrons

The gamma ray spectrum resolution from a 241Am-Be source-based prompt gamma ray activation analysis set-up has been observed to increase in the energy region of interest with enclosing the NaI detector in a proper neutron and gamma ray shield. We have investigated the tact that the peak resolution of prompt gamma rays in the region of interest from the set-up depends on the source activity to the great extent, size and kind of the detector and the geometry of the detector shield. In order to see the role of a detector shield, five kinds of the detector shield were used and finally the proper kind was introduced. Since the detector shield has an important contribution in the reduction of the undesirable and high rate gamma rays coming to the gamma ray detector, a good design of a proper shield enables the elimination of the unwanted events, such as a pulse pile-up. By improving the shielding design, discrete and distinguishable photoelectric peaks in the energy region of interest have been observed in the spectrum of prompt gamma rays.

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Detection capability of Migdal effect for argon and xenon nuclei with position sensitive gaseous detectors

Progress of Theoretical and Experimental Physics ◽

10.1093/ptep/ptaa162 ◽

2020 ◽

Author(s):

Kiseki D Nakamura ◽

Kentaro Miuchi ◽

Shingo Kazama ◽

Yutaro Shoji ◽

Masahiro Ibe ◽

...

Keyword(s):

Gamma Rays ◽

Experimental Approach ◽

Isotope Separation ◽

Mass Region ◽

Background Rate ◽

Argon Gas ◽

Low Mass ◽

Position Sensitive ◽

Set Up ◽

Direct Dark Matter

Abstract Migdal effect is attracting interests because of the potential to enhance the sensitivities of direct dark matter searches to the low mass region. In spite of its great importance, the Migdal effect has not been experimentally observed yet. A realistic experimental approach towards the first observation of the Migdal effect in the neutron scattering was studied with Monte Carlo simulations. In this study, potential background rate was studied together with the event rate of the Migdal effect by a neutron source. It was found that a table-top sized ~ (30cm)3 position-sensitive gaseous detector filled with argon or xenon target gas can detect characteristic signatures of the Migdal effect with sufficient rates (O(102 ~ 103) events/day). A simulation result of a simple experimental set-up showed two significant background sources, namely the intrinsic neutrons and the neutron induced gamma-rays. It is found that the intrinsic neutron background rate for the argon gas is acceptable level and some future study for the reduction of the gamma-rays from the laboratory would make the observation of the Migdal effect possible. The background for the xenon gas, on the other hand, is found to be much more serious than for the argon gas. Future works on the isotope separation as well as the reduction of the gamma-rays from the detector and laboratory will be needed before the Migdal effect observation for xenon gas case.

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Optical Afterglows as Probes for the Central Engine and Fireball of Gamma-Ray Bursts

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312019928 ◽

2012 ◽

Vol 8 (S290) ◽

pp. 263-264

Author(s):

Liang Li ◽

En-Wei Liang ◽

He Gao ◽

Bing Zhang

Keyword(s):

Statistical Analysis ◽

Gamma Rays ◽

Density Profile ◽

Gamma Ray ◽

Ambient Medium ◽

Gamma Ray Bursts ◽

Prompt Gamma ◽

Medium Density ◽

Central Engine ◽

Prompt Emission

AbstractWell-sampled optical lightcurves of 146 gamma-ray bursts (GRBs) are compiled from literature. We identify possible emission components based on our empirical fits and present statistical analysis for these components. We find that the flares are related to prompt emission, suggesting that they could have the same origin in different episodes. The shallow decay segment is not correlated with prompt gamma-rays. It likely signals a long-lasting injected wind from GRB central engines. Early after onset peak is closely related with prompt emission. The ambient medium density profile is likely n ∝ r−1. No correlation between the late re-brightening bump and prompt gamma-rays or the onset bump is found. They may be from another jet component.

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