摘要:

Influence of irradiation dose, 0.1–1.0 MGY of60Coγ-ray on the isothermal decomposition of doped (Ba2+) caesium bromate has been investigated. The α-tplots at 673.0 K explore that the process occurs through initial gas evolution, acceleratory and decay stages. Though irradiation reduces the value of “α”, the fraction decomposed in the initial period, it enhances the latter at higher time intervals. The data are well fitted to various kinetic equations like Prout-Tompkins, Avrami-Evofeev, and contracting square and indicate that the rate constant of the acceleratory stage is decreased by irradiation and is increased with increasing radiation dose, whereas that of the decay period is enhanced by irradiation.

ISSN:1042-0150    

DOI:10.1080/10420159008220559

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

1 to 2 MeV nitrogen (N+and N2+) ions were implanted at high fluences in stainless steel, and their depth distributions were measured subsequently by Rutherford backscattering and thermal neutron depth profiling. The range profiles were broader than theoretically expected. With increasing fluence, deviations from ballistic computer codes increase. These deviations can well be described by the assumption of radiation enhanced diffusion for which a simple analytical model is presented. The thermal mobility shows a different behavior for low, and for high implanted fluences.

ISSN:1042-0150    

DOI:10.1080/10420159008220560

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The scintillation response of liquid scintillator NE 213 has been studied as function of temperature in the range 225 to 300 K. It has been found that the light output under gamma excitation increases with decrease in temperature. The data is well encompassed by the relation:Ilow−I=I0exp(−E/kT), whereIis the count rate at temperatureT, Ilowis a constant equal to 750 counts/minute, the pre-exponential factorI0is 15 × 105counts/minute,kis the Boltzmann constant andEis the activation energy equal to 0.21 eV, which is typical for a diffusion controlled process in the temperature range studied.

ISSN:1042-0150    

DOI:10.1080/10420159008220561

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Blisters have been observed in evaporated alumina thin films after xenon irradiation. The aim of this study is to further understand the mechanisms responsible of such process. Surface blistering dependence on thickness of the alumina films as well as irradiation fluence, temperature and post-irradiation thermal annealing have been investigated. From our experimental results, it has been proved that the substrate-alumina interface is not responsible for blistering. Also, according to the gas pressure model and the lateral compressive stress model the latter seems to be more adequate to explain blister formation.

ISSN:1042-0150    

DOI:10.1080/10420159008220562

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

In proton bombarded InP single crystals the incorporation behaviour of different hydrogen isotopes is studied in relation to implantation induced radiation defects. Investigations of the fluence dependence (D= 1016-1018cm−2), of the depth profile and of the annealing behaviour (Tan= 300–1000 K) of hydrogen incorporation and of damage density indicate that only a small fraction of the implanted hydrogen is chemically bonded to host lattice atoms. These bonded hydrogen atoms saturate dangling bonds at defect sites.

ISSN:1042-0150    

DOI:10.1080/10420159008220563

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The aims of this study are to investigate (i) the influence of substrate temperature during the implant on the crystal quality of the overlying silicon layer and (ii) the synthesis of thin (less than 2000 Å) buried layers of SiO2from lower dose (∼ 1017cm−2) oxygen implants at various medium (80–150 keV) energies after a 30 min anneal at 1400°C in order to reveal the energy dependence of the minimum substoichiometric dose necessary to produce a continuous oxide layer. The main diagnostic technique used is Rutherford backscattering and channelling (RBS) of 1.5 MeV He+ions. A dynamic computer simulation of the evolution of implanted oxygen profiles is performed as a useful adjunct to experimental methods. Experimental results are compared with computer modelling of the oxygen distributions.

ISSN:1042-0150    

DOI:10.1080/10420159008220564

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Radiation damage produced by short ranged (ranges 20–30 μm) charged particles (alpha particles and fission fragments) in thick plastic track detectors (thickness ≈ 150 μm) has been enlarged to produce “through” holes by using a combination of electrochemical and chemical etching processes. A series of experiments were conducted with a view to optimize the operating conditions required to produce through holes with most suitable profiles for a particular application at hand. This novel technique has been employed in producing thick nuclear track filters using fission fragments from U-235 fission and alpha particles from radon and its daughters.

ISSN:1042-0150    

DOI:10.1080/10420159008220565

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Damaging effect of diatomic phosphorus ions implanted into silicon was compared with that of atomic ions in the range between 25 and 300 keV/atom. Dose was around 1014ions/cm2. Target temperature varied between 77 and 533 K. Below and at 300 K the “damage enhancement factor” defined as ratio of damage produced by equivalnet molecular and atomic ion implantation varied from 1 to 1.6 depending on incident energy. At elevated implantation temperature this factor increased by almost an order of magnitude. In interpretation of experimental results, fluctuations in damage structure inside the volume of collision cascades was proposed. Conclusions are believed to be relevant for other molecular implantation, e.g. for the BF2+.

ISSN:1042-0150    

DOI:10.1080/10420159008220566

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The apparent substitutional fraction,fs, of Rh and Ir implanted into Al single crystals at 293 K with peak concentrations of 0.17±0.01 at.% is 0.57 ± 0.02 and 0.47±0.02, respectively. Upon annealing to 593 Kfsdecreases and the critical angles of the impurities narrow due to partially coherent precipitate formation. Irradiation with 300 keV Ar ions at 77 K with deposited energy densities up to 20 dpa leads to precipitate dissolution accompanied by an increase offsup to 0.70±0.02 for Al(Rh) and 0.82±0.02 for Al(Ir). The relatively highfsvalues do not decrease during annealing from 77 K to 293 K, indicating that vacancy trapping is not a dominant process. Precipitate formation seems therefore to limit the maximum obtainablefsvalues during implantation at 293 K for these systems.

ISSN:1042-0150    

DOI:10.1080/10420159008220567

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A field ion microscopy (FIM) and transmission electron microscopy (TEM) investigation of radiation damage in tungsten after heavy ion bombardment has been carried out. Field ion specimens of tungsten were irradiated with 180–230 keV Xe+ions. The irradiation doses were varied between 4 × 1011and 4 × 1012ions/cm2. The irradiated specimens were examined in FIM. Experiments combining both TEM and FIM were performed in order to compare the results obtainable by these two methods. The distribution of defects visible by TEM was inhomogeneous. The influence of the imaging field in FIM on the defects visible in TEM is discussed.

ISSN:1042-0150    

DOI:10.1080/10420159008220568

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor