Search

We summarize the evidence for DM-like anomalies in neutron multiplicity spectra collected underground with Pb targets by three independent experiments: NEMESIS (at 210 m.w.e.) NMDS (at 583 m.w.e.), and ZEPLIN-II (at 2850 m.w.e.). A new analysis shows small but persistent anomalies at high neutron multiplicities. Adjusted for differences in detection efficiencies, the positions of the anomalies are consistent between the three systems. Also, the intensities match when corrected for the acquisition time and estimated detection efficiency. While the three measurements are inconclusive when analyzed separately, together, they exclude a statistical fluke to better than one in a million. To prove the existence of the anomalies above the 5-sigma discovery threshold, we propose to upgrade the current NEMESIS setup. The upgrade concept and the critical components of the new experiment are described. The upgraded setup would already acquire the needed data sample during the first year of operation. Additional information, vital for the physics interpretation of the analysis, will be obtained with a Cu target.

A radiation detection system consisting of an array of Cs2LiYCl6:Ce3+ elpasolite cells was studied for simultaneous neutron measurements and gamma-ray spectroscopy. The system allowed directional detection with the localization of radiation sources. Computational modeling of detector array showed that the three-cell detector array is feasible to determine the direction to a neutron source and a gamma-ray source.

The aim of this work is to classify twelve anionic surfactants for endpoint (acute toxicity) by QSAR Toolbox software (different profilers) and to apply baseline models of acute toxicity for rat and mouse and to calculate excess toxicity for these compounds. This study has demonstrated that eleven anionic surfactants were classified as toxic and only, one of them has a narcotic action for baseline model of acute toxicity for rat. Acute toxicity studies with baseline model for mouse (oral) found that three of five anionic surfactants are with toxic action and two surfactants have a narcotic action.

Mobile radiation sensing techniques for surge deployment and wide area search are important for nuclear security applications. Radiation sensors were developed for the use with robotic platforms of unmanned aerial systems (UAS). Ambient temperature neutron and gamma CLYC sensor and high resolution CZT gamma sensor were integrated into the UAS as plug-and-play interchangeable components allowing easy attachment to a robot in field conditions. The time and position data were added via Robot Operating System to measured intensities of photon peaks and neutron rates enabling the input for the UAS flight control. The contour mapping of a radiation area by multiple UAS was simulated.

There are many applications which require high yield radiation sources with mixed fluxes of photons and neutrons. In particular, such sources are necessary to test radiation detectors and materials. This study was concerned with the determination of photon and neutron fluxes generated by the interaction of a 6 MeV linear electron accelerator driven photon beam with a beryllium photoneutron converter. The double step procedure of an (e,γ) reaction followed by an (γ,n) emission results in a mixed radiation environment. The optimal converter geometry was determined by comparison of the computed neutron fluxes for each converter position. Computational results have shown that photon fluxes up to 10 11 photons/cm 2 /s and neutron fluxes up to 10 7 neutrons/cm 2 /s are achievable with the optimal setup. This paper is focused on the results of the MCNPX modeling and experiments and discussion of the converter orientation which leads to the largest radiation fluxes.

Remote sensing technologies are important for radiation safety and environmental security applications. A dual-mode Cs2LiYCl6:Ce3+ (CLYC) sensor was developed for simultaneous neutron measurements and gamma-ray spectroscopy. To keep users away from hazardous areas, an unmanned aerial system was used as a mobile sensor platform. The sensor was integrated into a multicopter platform as a ‘plug and fly’ component allowing deployment in the field conditions. The photon energy resolution of the CLYC sensor was measured as less than 5% at 662 keV. The detection of neutrons was achieved via 6Li(n,α)t reaction. The sensor’s signal communication and data fusion were programmed using robot operating system framework, as well as on-board signal analysis functions including the neutron-photon pulse shape discrimination and the identification of photo peaks in the gamma spectrum. These data with added real-time kinematic GPS and time stamps were reported to the user enabling real time awareness of the monitored area, further analysis in temporal and spatial domains, and radiation mapping and source search tasks.

Remote sensing of radiological and nuclear materials is important for safety and security. Gamma-ray and neutron detectors can be deployed in the field using robotic platforms. Unmanned aerial systems (UAS) and ground vehicles (UGV) allow remote radiation sensing operations in hard to reach hazardous areas where the level of contamination is unknown while keeping users away from the risk of exposure. In order to achieve this, radiation sensors must be integrated with robotic platforms. A CZT semiconductor detector and a CLYC scintillation detector were integrated with a multicopter aerial platform and a ground vehicle. The Robot Operating System (ROS) was used for the detector’s data fusion. Functions were developed within ROS to perform automated gamma spectrum analysis and neutron/gamma discrimination. Each measurement was supplied with real-time kinematic GPS data and a timestamp enabling analysis of the radiation flux in temporal and spatial coordinates. Moreover, a plug-and-play interface was designed for both detectors to enable their user-friendly application in field conditions.

Gamma ray and neutron measurements are important at nuclear facilities. To enable remote sensing, robotic platforms are used to carry the radiation detectors. In a radiation environment, robots will be exposed to high doses which limits the platform’s operational time. Electronic components are affected the most and must be shielded. The tradeoff between shielding and capabilities of the robot can be made to achieve specific tasks during a required time period. The PhantomX hexapod was studied as a platform for the use of a CZT detector and a video camera in neutron and gamma fluxes. The stochastic radiation transport code FLUKA was used to calculate damage rates in electronic components of the system. The compact packaging of these components and the shielding design were determined to reduce radiation damage under dose conditions while keeping the optimal payload. Results of the computational study are discussed.Gamma ray and neutron measurements are important at nuclear facilities. To enable remote sensing, robotic platforms are used to carry the radiation detectors. In a radiation environment, robots will be exposed to high doses which limits the platform’s operational time. Electronic components are affected the most and must be shielded. The tradeoff between shielding and capabilities of the robot can be made to achieve specific tasks during a required time period. The PhantomX hexapod was studied as a platform for the use of a CZT detector and a video camera in neutron and gamma fluxes. The stochastic radiation transport code FLUKA was used to calculate damage rates in electronic components of the system. The compact packaging of these components and the shielding design were determined to reduce radiation damage under dose conditions while keeping the optimal payload. Results of the computational study are discussed.

Gamma ray measurements involved in monitoring technologies of field conditions are of vital importance for environmental safety and radiation protection. This chapter addresses the method of cooperative gamma sensing using multiple unmanned aerial systems. Section 1 provides an introduction. The design of semiconductor and scintillation gamma ray sensors integrated into aerial robotic platforms is discussed in Section 2, along with the fusion of time-stamped radiation data with position information using the real-time kinematic positioning technique. Section 3 addresses the multirobot contour mapping of radiation fields. Computer simulation of radiation contour mapping is discussed in Section 4. Experimental verification of the contour mapping and source-seeking algorithm is described in Section 5. Section 6 summarizes results of the project.

A radiation detection system consisting of an array of three Cs2LiYCl6:Ce 3 + elpasolite cells was studied for simultaneous, directional neutron and gamma-ray measurements. Utilizing a neutron source and gamma-ray sources, measurements were carried out while rotating the three-cell array 360°. The measurement data was processed using a maximum likelihood estimation technique to determine the most probable angle pointing to the radioactive source. The detection system enables measuring gamma rays and neutrons simultaneously and estimating locations of radioactive sources within 23°.

We report the first observation of the parity-violating gamma-ray asymmetry A_{γ}^{np} in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. A_{γ}^{np} isolates the ΔI=1, ^{3}S_{1}→^{3}P_{1} component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless effective field theory. We measured A_{γ}^{np}=[-3.0±1.4(stat)±0.2(syst)]×10^{-8}, which implies a DDH weak πNN coupling of h_{π}^{1}=[2.6±1.2(stat)±0.2(syst)]×10^{-7} and a pionless EFT constant of C^{^{3}S_{1}→^{3}P_{1}}/C_{0}=[-7.4±3.5(stat)±0.5(syst)]×10^{-11} MeV^{-1}. We describe the experiment, data analysis, systematic uncertainties, and implications of the result.

We report the first observation of the parity-violating gamma-ray asymmetry A_{γ}^{np} in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. A_{γ}^{np} isolates the ΔI=1, ^{3}S_{1}→^{3}P_{1} component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless effective field theory. We measured A_{γ}^{np}=[-3.0±1.4(stat)±0.2(syst)]×10^{-8}, which implies a DDH weak πNN coupling of h_{π}^{1}=[2.6±1.2(stat)±0.2(syst)]×10^{-7} and a pionless EFT constant of C^{^{3}S_{1}→^{3}P_{1}}/C_{0}=[-7.4±3.5(stat)±0.5(syst)]×10^{-11} MeV^{-1}. We describe the experiment, data analysis, systematic uncertainties, and implications of the result.