Efficiency calibration and self-attenuation correction in radioxenon measurement using β-γ coincidence method.

Measurement of the four radioxenon isotopes, namely Xe, Xe, Xe, and Xe, play a key role in underground nuclear test monitoring for ensuring compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). To improve detection sensitivity, a β-γ coincidence technique is commonly used. Due to the presence of the gas matrix, such as stable xenon, nitrogen, helium, the self-attenuation effects should be taken into account when measuring different types of sample.

Radioactivity measurement of Kr by using anti-cosmic HPGe γ spectrometer.

In order to improve the detection sensitivity of Kr, an anti-cosmic HPGe γ spectrometer was established and a specific Marinelli beaker was designed for Kr measurement. Comparing to the non-anticoincidence γ spectrum, the integral background counts rate range from 20 to 2400 keV was reduced by a factor of 5.17 using anticoincidence shielding.

Assessment of a compton-suppressed spectrometer for measurement of radioactive xenon isotopes.

Airborne radionuclide monitoring is considered to be the most certain way to detect a clandestine nuclear weapon test. The activity concentration of radioxenon samples collected by the radionuclide stations of the International Monitoring System (IMS) for the Comprehensive Nuclear-Test-Ban Treaty (CTBT) is generally performed at the low-level, hence it is necessary to improve the detection sensitivity of the radioactivity measuring apparatus for radionuclide monitoring. The Compton-suppressed spectrometer (CSS) has the advantage of reducing the background and improving the sensitivity in the environmental level measurement.

Blind Frequency Estimation and Symbol Recovery for the Analytically Solvable Chaotic System.

The analytically solvable chaotic system (ASCS) is a promising chaotic system in chaos communication and radar fields. In this paper, we propose a maximum likelihood estimator (MLE) to estimate the frequency of ASCS, then a difference-integral (DI) detector is designed with the estimated frequency, and the symbols encoded in the signal are recovered. In the proposed method, the frequency parameter is estimated by an MLE based on the square power of the received signal.

Measurement of the gamma-ray emission probability of Xe.

Xe has been standardized by means of an internal gas proportional counting system, employing a length-compensated method. The activity concentration of Xe was measured with a relative standard uncertainty of 0.6%.

Aspect-Aware Target Detection and Localization by Wireless Sensor Networks.

This paper considers the active detection of a stealth target with aspect dependent reflection (e.g., submarine, aircraft, etc.

An Energy Balanced and Lifetime Extended Routing Protocol for Underwater Sensor Networks.

Energy limitation is an adverse problem in designing routing protocols for underwater sensor networks (UWSNs). To prolong the network lifetime with limited battery power, an energy balanced and efficient routing protocol, called energy balanced and lifetime extended routing protocol (EBLE), is proposed in this paper. The proposed EBLE not only balances traffic loads according to the residual energy, but also optimizes data transmissions by selecting low-cost paths.

Security weaknesses of underwater wireless optical communication.

In this work, for the first time, we uncover that the level of security we have traditionally taken for granted on underwater wireless optical communication (UWOC) may not always be there. We first numerically investigate the security weaknesses of UWOC via Monte Carlo simulation. With the link distance increasing or the water becoming more turbid, the simulation results indicate that the possibility of information leakage increases, which may pose a great threat to the security of UWOC.

A Novel Cross-Layer Routing Protocol Based on Network Coding for Underwater Sensor Networks.

Underwater wireless sensor networks (UWSNs) have attracted increasing attention in recent years because of their numerous applications in ocean monitoring, resource discovery and tactical surveillance. However, the design of reliable and efficient transmission and routing protocols is a challenge due to the low acoustic propagation speed and complex channel environment in UWSNs. In this paper, we propose a novel cross-layer routing protocol based on network coding (NCRP) for UWSNs, which utilizes network coding and cross-layer design to greedily forward data packets to sink nodes efficiently.

A Network Coding Based Hybrid ARQ Protocol for Underwater Acoustic Sensor Networks.

Underwater Acoustic Sensor Networks (UASNs) have attracted increasing interest in recent years due to their extensive commercial and military applications. However, the harsh underwater channel causes many challenges for the design of reliable underwater data transport protocol. In this paper, we propose an energy efficient data transport protocol based on network coding and hybrid automatic repeat request (NCHARQ) to ensure reliability, efficiency and availability in UASNs.

Determination of 226Ra Activity Using Gamma Spectrometry with 226Ra-222Rn Disequilibrium.

Radium-226 (Ra) activity is normally determined indirectly by gamma spectrometry, in particular by measuring the characteristic γ-ray emitted from its progeny (Pb and Bi) when Ra-Rn secular equilibrium is reached. This article describes a measurement method involving the measurement of Pb ingrowth. The activity of Ra determined by this method agrees with that measured after Ra-Rn equilibrium.

Fitting formula for the injection volume of a gas chromatograph for radio-xenon sampling in the lower troposphere.

GC is usually used for xenon concentration and radon removal in the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty. In a gas chromatograph, the injection volume is defined to calculate the column capacity. In this paper, the injection volume was investigated and a fitting formula for the injection volume was derived and discussed subsequently.

Inference and analysis of xenon outflow curves under multi-pulse injection in two-dimensional chromatography.

Multidimensional gas chromatography is widely applied to atmospheric xenon monitoring for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). To improve the capability for xenon sampling from the atmosphere, sampling techniques have been investigated in detail. The sampling techniques are designed by xenon outflow curves which are influenced by many factors, and the injecting condition is one of the key factors that could influence the xenon outflow curves.

Measurement of absolute gamma-ray emission probabilities from decay of 138Xe.

The fission gaseous (138)Xe products play an important role in the research of nuclear-reaction products and radioisotope applications. Therefore, precise data for emission probabilities of gamma-ray from decay of (138)Xe are highly desired. However, a high precision is not achievable with a sufficient accuracy due to the limitations of the usual experimental techniques.

Radioxenon monitoring in Beijing following the Fukushima Daiichi NPP accident.

This paper reports the brief process and results of radioxenon monitoring and analysis in Beijing following the Fukushima Daiichi nuclear power plant accident. The accident and release of volatile radionuclides were caused by 9.0 magnitude earthquake and tsunami on March 11, 2011.

The performance determination of a Compton-suppression spectrometer and the measurement of the low level radioactive samples.

The performance of a new Compton-suppression spectrometer consisting of one HPGe detector and three NaI(Tl) detectors was studied. The peak-to-Compton ratio for a (137)Cs source is 1150 and the integral background count rate is 0.3 5s(-1) over the energy interval 20-3000 keV.

Half-life determination of 88Kr and 138Xe.

The half-lives of (88)Kr and (138)Xe have been determined with two high purity germanium (HPGe) detectors by the position relay method. Data have been recorded at regular time intervals during measurements covering more than nine times the respective half-lives. This article describes in detail the principle and process of the position relay method with two HPGe detectors.

The coincidence-summing correction of the Compton-suppression spectrometer.

The compton-suppression Spectrometer can suppress the Compton baseline and make weak full energy peaks prominent in low-level activity gamma spectra, so it is used to measure environmental radioactive samples. In order to quantify the activities of the radionuclides in the sample coincidence-summing corrections should be applied. In this article the expressions of coincidence-summing correction of Compton-Suppression Spectrometer were deduced and the validity of the expressions was verified.