摘要:

Magnetic after-effect measurements have been made in the temperature range 4.2–300 K on both polycrystalline and single-crystal cobalt samples following irradiation with 3 MeV electrons. The temperature of irradiation was 30 K and the dose 1023m−2. All stable relaxation peaks have been analysed quantitatively and their correlated annealing behaviour investigated. The results are discussed in terms of both intrinsic interstitial clusters and also the interaction of intrinsic interstitials with interstitial carbon and substitutional impurity atoms.

ISSN:1042-0150    

DOI:10.1080/10420159008213035

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

An AlMgSi alloy prepared in two different conditions of age-hardening was neutron irradiated to fast fluences up to 2.5 × 1018n cm−2at 50°C. Postirradiation tensile and hardness tests were performed in the range from room temperature up to 350°C. The results show that the alloy in its soft and hard conditions exhibits a pronounced degree of irradiation-induced softening. The degree of softening is found to be dependent upon the ageing treatment given to the alloy before irradiation. The observed softening is suggested to be brought about by irradiation-induced dissolution of the age-hardening precipitates present before irradiation.

ISSN:1042-0150    

DOI:10.1080/10420159008213036

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Deuteron-irradiated and deformed stainless steel specimens were investigated by positron lifetime and Doppler broadening measurements. The evolution of the defect structures was studied as a function of the isochronal annealing temperature and for various degrees of deformation. A different behaviour was observed for deformed and irradiated stainless steel specimens. Evidence for vacancy clusters was found in the deuteron-irradiated steel. These clusters disappear after annealing around 900 K.

ISSN:1042-0150    

DOI:10.1080/10420159008213037

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

This article reviews the panorama of phenomena involved in low energy (1–1000 eV) ion beam-surface interactions. The fundamental chemical and physical processes governing these low energy collisions are delineated and discussed. Interactions of both noble gas ions and chemically active atomic and molecular ions are described. Processes considered include ion-surface charge exchange, dissociation of molecular ions, scattering, recoiling, sputtering, atom capture, excited state formation, and film deposition. References are provided which lead into the original literature describing the electronic, kinematic, thermodynamic, and kinetic aspects of the interactions.

ISSN:1042-0150    

DOI:10.1080/10420159008213038

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Positron lifetime and Doppler broadening measurements have been done to study theα-induced defects in stainless steel SS 302 and polycrystalline cobalt. For stainless steel the samples have been thin and the effect of the presence of helium on defect kinetics has been avoided by allowing the 30 MeV alpha particles to pass through the samples. The presence of impurity (carbon) atoms in steel is found to play an important role in the trapping and detrapping of vacancies in the temperature range 200°C to 450°C. Formation of vacancy-impurity complexes and their dissociation around 500°C have been observed. A steady decrease of the positron parameters has been seen beyond 700°C and they attain those of the reference sample around 1000°C. While annealing alpha irradiated cobalt we find migration of vacancies and rearrangement of dislocation loops below 650 K and then dissolution around 900 K. Helium-vacancy complexes form in the region 600 to 1000 K, leading to the growth of the He-bubble above 1000 K. The trapping model analysis shows strong interaction between He and vacancy clusters in the temperature region 600 to 1000 K.

ISSN:1042-0150    

DOI:10.1080/10420159008213039

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The range and energy-loss of 16.34 MeV/u238U in Kapton-polyamide plastic have been measured by the nuclear track technique. The experimental ranges are compared with two sets of theoretical values. It has been observed that ranges obtained from the computer code ‘DEDXT’ are found to be 5–8% lower as compared to measured ones whereas those from Northcliffe and Schilling are about 10–15% overestimated above 8 MeV/u.

ISSN:1042-0150    

DOI:10.1080/10420159008213040

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Solid State Nuclear Track Detectors which are extensively applied for the detection of charged particles can also be very useful for the detection of thermal and fast neutrons. In this connection the detectors can be used either in internal or external irradiator mode. In the present work we have used several solid state Nuclear Track Detectors for measuring the fast neutron fluence, both in the case of a bare plastic or a plastic coated with a thin layer of uranium. The fast neutrons (∼ 14 MeV) were produced with the help of an AN-400 Model Van de Graaff accelerator at our laboratory using3H(2H, n)4He reaction and were used to irradiate the plastic detectors. After chemical etching of the plastics the tracks were counted under an optical microscope. The variation of the track density for various neutron fluences in different plastic track detectors used in the present work has been found to be linear.

ISSN:1042-0150    

DOI:10.1080/10420159008213041

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The stored energy released in Stage I recovery of reactor neutron irradiated copper was measured by differential thermal analysis calorimetry for three fluences up to a maximum of 3.5 × 1018n/cm2(E>0.1 MeV) after irradiation at temperatures of less than 10 K. The stored energy dependence upon fluence, and a tendency toward saturation, were observed. Theoretical reaction rate processes were compared directly to the experimental rates of stored energy release, and the parameters associated with the theory were compared with results from previous resistivity measurements. Good agreement was found in several parameters, but major differences with previous D + E substage results lead to the conclusion that the point defect model may not describe materials experiencing severe neutron damage. Computer studies of warmup rates were made for first and second order and for correlated recovery processes as a function of defect concentration and of external power input. First and second order processes show definite distortion in their recovery rate curves for high defect concentrations; the correlated recovery process shows a much less pronounced effect.

ISSN:1042-0150    

DOI:10.1080/10420159008213042

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The tunneling probability for d+d nuclear fusion reaction is calculated, incorporating the screening on the Coulomb potential and effective electron mass in solids. The possibility of cold (room temperature) nuclear fusion is discussed.

ISSN:1042-0150    

DOI:10.1080/10420159008213043

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Charge and trap generation in thin thermal SiO2layers on silicon under 1.5 keV Ar+ion bombardment has been investigated by internal photoemission techniques. The long-range perturbation of inner Si-SiO2interface separated by 200 nm oxide from ion penetration layer was observed. Positive charge and Coulombic electron trap formation near the semiconductor surface have been associated with hole transport through oxide layer and their interaction with Si-SiO2interfacial defects. A new neutral-type electron trap generation in oxide bulk has been registered under ion bombardment or hole injection. This effect was attributed to hole-induced break of strained Si-O bonds produced during Si-SiO2system formation or by oxide radiation damage.

ISSN:1042-0150    

DOI:10.1080/10420159008213044

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor