用于漂移室中宇宙线径迹重建的Cellmap的研究

以L3宇宙线实验的径迹重建为例，讨论了一个在磁谱仪漂移室中对大斜率宇宙线径迹着火点进行重建的Cellmap，并与L3宇宙线实验中已采用的Cellmap进行了比较. 对大斜率径迹，用新的Cellmap可以重建出更多的着火点，并且径迹重建χ2量的分布有所改善.     

Application of Emulsion Cloud Chamber to cosmic-ray muon radiography

Muon radiography (muography) is a powerful technique for probing the internal density profiles of volcanoes. A nuclear emulsion is a desirable detector for this purpose because of its light weight and because it does not require electricity for operation. One technical problem, however, is an existence of background noise signals caused by low energy charged particles. The present work proposes the use of Emulsion Cloud Chamber (ECC), which is a repeated structure of emulsion films and passive metal plates, to reject these noise particles. The performance of the background reduction is demonstrated by a test measurement at Showa-Shinzan Lava Dome, Hokkaido, Japan.     

On the Thermal Stability of Tracks in Plastics and some Uses in Radiography

The eradication of alpha and fission tracks and the selective track discrimination by heat treatment have been studied in cellulose nitrate, cellulose acetate, and polycarbonate sheets. Some applications of the phenomena in alphagraphy and fissionography are presented.     

Tracks to therapy

Studies of the structure of particle tracks have led to models of track effects based on radial dose and radiobiological target theory that have been very successful in describing and predicting track effects in physical, chemical, and biological systems. For describing mammalian cellular inactivation two inactivation modes are required, called gamma-kill and ion-kill, the first due to synergistic effects of delta rays from adjacent ion paths thus resembling the effects from gamma rays, and the second to the effects of single ion transits through a cell nucleus. The ion-kill effect is more severe, where the fraction of cells experiencing ion kill is responsible for a decrease in the oxygen enhancement ratio, and an increase in relative biological effectiveness, but these are accompanied by loss of repair, hence to a reduction in the efficiency of fractionation in high LET therapy, as shown by our calculations for radiobiological effects in the “spread out Bragg Peak”.     

两体衰变径迹

在19MeV/u ⁴⁰Ar+²⁰⁹Bi反应中,云母片固体径迹探测器记录了几例连续两次衰变径迹.分析表明,这些事件两次衰变的时间间隔约为10^－13s.根据位垒穿透的WKB理论,这样的裂变是可能的.     

Formation of Charged Particle Tracks in Solids

A criterion for formation of etchable tracks in solids is suggested using the well-known concepts of ionization and thermal spikes, diffusion process with useful and justified assumptions, and present or published experimental and theoretical investigations on the same subject. The suggested criterion is useful for a wide spectrum of researchers including development and applications of track recording materials, ions implantation, sputtering and other areas, which include interactions of charged particles with solids.     

Field statistics in a one-dimensional Reverberation Chamber model

This work focuses on building a fairly simple yet physically appropriate 1D model for a Reverberation Chamber which claims to be able to analytically predict the statistical behavior of such a chamber, without forsaking to the benefits of deterministic models. The statistical properties are introduced by varying the size of a 1D stirrer or the cavity size itself. A validation analysis shows agreement with other theories and measured results on real RCs. Field statistics in undermoded regime is examined. A radiated emission test is defined and shows reliable matching with reality. The field performance near the conducting walls is investigated. To cite this article: R. Serra, F. Canavero, C. R. Physique 10 (2009).     

Unipolar Arc Tracks on Stainless Steel

Craters caused by unipolar arcs on stainless steel depend strongly on surface conditions. There are three diameter distributions: Small craters (～ 0.3 μm) for oxidised surfaces, larger craters (～ 2 μm) for moderately cleaned areas, and very large craters (～ 20 μm) for clean surfaces. These values are compatible with Joule heating models of crater formation. Compared with other metals of interest, stainless steel shows the largest craters.     

Etchability of Latent Fission Fragment Tracks in CR-39

We report the chemical etching behaviour of the CR-39 polymer detector exposed to fission fragments of 252Cf describing etchability of latent tracks, which are like nanocylinders. The fission fragment exposed detectors were etched in 1-7 N NaOH water solutions at temperatures 50-80℃ for 45 min in the case of track length and 180 min in the case of track diameter measurements. The reduced etch rate S （called here etchability） is determined using experimental results for all etching conditions and the etching conditions with the highest reduced etch are obtained. Physics and energetics of bulk and track etching are discussed. Possible effects causing spurious changes in determination of activation energy of etching are investigated.     

On The Motion of Ions in The Self-sustaining Magnetically Confined Electron Cloud

The motion of ions generated from the electron-atom ionization collisions in the self-sustaining magnetically confined electron cloud is studied.It is shown that the motion is chaotic.The method to determine the electric potential idstribution in the electron cloud by measurements of the ion current is discussed.     

Self-Organizing Transport Model of a Spark Discharge in a Thunderstorm Cloud

Radiophysics and Quantum Electronics - We propose a small-scale transport model of the electric-discharge tree formation and analyze its implementation for a characteristic case of the thundercloud...     

Influence of UV-Irradiation on Latent Tracks in Polyethylene Terephthalate Films

Polyethylene terephthalate(PET) films in thickness of 12/μm are irradiated by Xe and Au ions at the energies of9.5 and 11.4MeV/u and with the ion fluence from 5 × 10~9 cm~(-2) to 1 × 10~(11) cm~(-2).After irradiation,ultra-violet lights are used to illuminate the samples with latent trades at the wavelength of 365 nm with flux density of4.2mW/cm~(-2).UV-irradiation effects on tracked PET are investigated by the UV-vis spectrum and positron annihilation lifetime spectroscopy(PALS).It is found that carbonaceous clusters in PET films are generated by ion irradiation and decomposed with UV illumination by calculating the optical energy band gap E_g in the UV-vis spectrum.The free volumes behave differently in track and bulk after UV illumination.In our experiment,the PALS results show an increase in radius and density of free volume in tracked PET films after UV treatment,which indicates an expansion in radius of latent tracks.     

Kinetic Instability of Charged-Particle Flow in a Thunderstorm Cloud

We consider the linear stage of an instability of charged-particle flow in a thunderstorm cloud. A dispersion relation characterizing the temporal evolution of a spectral component of the quasistatic electric field is obtained with account of the size spread of large particles. This dispersion relation is studied for the cases of a monodispersed particle ensemble and a model distribution function. The dependences of the instability parameters on the large-particle size spread and the air-flow conductivity are obtained. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 6, pp. 488–501, June 2005.     

Experimental Study of a Borehole Acoustic Radiator with a Ring in a Long Cylindrical Chamber

We have carried out an experimental study on the generation of pressure oscillations in a model of a borehole ring acoustic radiator that moved within a cylindrical chamber. The possibility of preserving a short jet with increasing resonator chamber length has been studied. The influence of the jet length, which is determined by the interval between the nozzle and the ring, on the frequency and intensity of generation has been considered. The constancy of the chamber resonance at the natural frequency, regardless of the length and velocity of the jet, has been noted. Recommendations for choosing the length of the chamber and the generation frequency associated with it are given.     

Numerical simulation of a Reverberation Chamber with a stochastic collocation method

An original numerical modelling of Mode Stirred Reverberation Chamber used in Electromagnetic Compatibility is proposed. This method relies on an analogy between a reverberation chamber and an enclosure whose walls' conductivity is randomly characterised. The distribution law of this parameter is obtained by measurements. Applying a stochastic collocation method enables one to numerically assess electromagnetic field from a low number of empty cavity (without stirrer) simulations. Thus this approach notably reduces CPU time allowing more complex simulations. To cite this article: P. Bonnet et al., C. R. Physique 10 (2009).     

Transient Response of Particle Distribution in a Chamber to Transient Particle Injection

We inject a large number of newly created nano‐particle aggregates into a chamber for the purpose of removing harmful contents in an indoor environment. This study is to experimentally and numerically investigate transient response of particle distributions to particle injections. A room‐sized chamber of 4 m × 2.1 m × 2.4 m is connected to a specially designed particle‐injection system, with two Optical Particle Counters used to simultaneously measure particle‐number densities with the size range from 0.3 μm to 10 μm at the inlet and in the chamber. A velocity probe measures the flow that is up to 1 m/s. An Euler‐type particulate‐phase‐transport model is developed and validated by comparing with experimental data. The study shows that the transient behavior of particle distributions is determined by many factors, including particle size, particle settling speed, sampling location, and velocity distribution. Particle number densities decrease in time more quickly for large particles than for small particles, and locations farther downstream in the chamber correlate more weakly with the inlet injection.