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in creator/contributor: "Kirk, M."

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Comparison of fission neutron and pulsed spallation neutron sources for radiation effects experiments on Cu/sub 3/Au

Through our recent experimental work on the neutron irradiation effects in Cu/sub 3/Au, we will compare fission and pulsed spallation neutron sources. Neutron characteristics of irradiation facilities at the Intense Pulsed Neutron Source (IPNS) and the CP-5 reactor (now closed down), are briefly described. Defect cascade size distributions from irradiations of Cu/sub 3/Au at both neutron sources illustrated by transmission electron micrographs of disordered zones. Radiation-enhanced diffusion e… more

Date: October 1, 1983

Creator: Kirk, M.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Studies of neutron irradiation effects at IPNS-REF

Neutron irradiation effects studies at the Radiation Effects Facility (REF) at the Intense Pulsed Neutron Source (IPNS) located at Argonne National Laboratory (ANL) are reviewed. A brief history of the development of this user facility is followed by an overview of the scientific program. Experiments unique to a spallation neutron source are covered in more detail. Future direction of research at this facility is suggested.

Date: September 1, 1983

Creator: Kirk, M.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Cascade defect production and irradiation enhanced diffusion in Cu/sub 3/Au

By using the ordering alloy Cu/sub 3/Au and measuring resistivity changes during and following fast-neutron irradiations at IPNS, we have studied cascade defect production and irradiation enhanced diffusion between 10 and 460/sup 0/K. Ordering and disordering rates were measured as functions of irradiation temperature, neutron dose, neutron dose rate, time following cessation of flux, and step annealing. Free and clustered vacancy production was observed. The temperature dependence of the produ… more

Date: March 1, 1986

Creator: Kirk, M. A. & Funk, L. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Ordered alloys reveal fundamental mechanisms of neutron-damage production. [Ni/sub 3/Mn; Cu/sub 3/Au]

Magnetic saturation measurements performed on Ni/sub 3/Mn during neutron irradiations are briefly reviewed and critically re-examined. Disordering during thermal-neutron bombardment at 5/sup 0/K uniquely revealed the existence,number and average length of replacement collision sequences. Confirmation of our analysis by others is presented; some refinements are introduced; comparisons with recent molecular-dynamic calculations are drawn; and the (n,..gamma..) recoil spectrum in Ni/sub 3/Mn is re… more

Date: April 1, 1982

Creator: Kirk, M.A. & Blewitt, T.H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Production of defects in metals by collision cascades: TEM experiments

This paper reviews experimental TEM data on production of dislocation loops by low energy ion bombardment to low doses, as simulations of similar collision cascades produced by fast neutrons, in various metals and alloys. Dependence of vacancy dislocation loop formation on recoil energy, temperature and metal/alloy is examined. Emphasis is placed on effects on dilute alloy additions. A model for cascade melting is used to understand these effects; this will require an examination of the role of… more

Date: January 1996

Creator: Kirk, M. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Production of defects in metals by collision cascades: TEM experiments

This paper reviews experimental TEM data on production of dislocation loops by low energy ion bombardment to low doses, as simulations of similar collision cascades produced by fast neutron irradiation, in various metals and alloys. The dependence of vacancy dislocation loop formation on recoil energy, sample temperature, and specific metal or alloy will be examined. Special emphasis will be placed on the effects of dilute alloy additions. A model for cascade melting will be employed to underst… more

Date: March 1, 1995

Creator: Kirk, M.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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In situ TEM observations of heavy ion damage in gallium arsenide

Transmission electron microscopy experiments have been performed to investigate the lattice damage created by heavy-ion bombardments in GaAs. These experiments have been performed in situ by using the HVEM - Ion Accelerator Facility at Argonne National Laboratory. The ion bombardments (50 keV Ar/sup +/ and Kr/sup +/) and the microscopy have been carried out at temperatures ranging from 30 to 300/sup 0/K. Ion fluences ranged from 2 x 10/sup 11/ to 5 x 10/sup 13/ ions cm/sup -2/. Direct-impact am… more

Date: January 1, 1988

Creator: Bench, M.W.; Robertson, I.M. & Kirk, M.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Fission neutron disordering of Ni/sub 3/Mn at 5 K. [Fission neutrons]

Preliminary results on the disordering of Ni/sub 3/Mn by fission neutrons at 5/sup 0/K are presented. An upper limit is placed on the contribution of long-ranged (110) replacement collision sequences emanating from the cascade.

Date: January 1, 1976

Creator: Kirk, M. A.; Blewitt, T. H. & Scott, T. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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In-situ observations of point-defect precipitation at dislocations in electron-irradiated silver

In-situ weak-beam observations of the development of electron irradiation damage at dislocations in silver are described. Dislocations constrict and promote in their vicinity the formation of stacking-fault tetrahedra. The possibility that these are of interstitial nature is discussed.

Date: September 1, 1986

Creator: Jenkins, M. L.; Hardy, G. J. & Kirk, M. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Replacement collision sequences in metals

The concept of radiation-induced defects traveling large distances by focussed collision sequences (focusons) without thermal activation has important consequences in radiation effect studies. The focussed collision sequences are of two types: (1) ''Silsbee focussing'' or momentum focussing which can cause defect pairs to form large distances from the primary knock-on and (2) focussed replacement collisions also called ''dynamic crowdions'' where mass transport causes a large separation between… more

Date: October 1, 1975

Creator: Blewitt, T. H.; Kirk, M. A. & Scott, T. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Neutron and. gamma. -ray irradiation effects in composite organic insulators

Neutron irradiations with low ..gamma..-ray flux in the Intense Pulsed Neutron Source were carried out on four kinds of cloth-filled organic composites (filler: E-glass or carbon fiber; matrix: epoxy or polyimide resin) and a unidirectional alumina fiber/epoxy composite. The mechanical test was performed at room temperature. Following irradiation at room temperature, the glass/epoxy and glass/polyimide composites degrade significantly at a total neutron fluence of 5.0 x 10/sup 18/ n/cm/sup 2/ (… more

Date: 1984

Creator: Egusa, S.; Kirk, M. A.; Birtcher, R. C. & Hagiwara, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Irradiation defect structures in YBa sub 2 Cu sub 3 O sub 7 minus x and their correlation with superconducting properties

We review our work on irradiation effects in single crystal YBa{sub 2}CU{sub 3}O{sub 7-x}. Transmission electron microscopy has been employed to study the defect microstructures produced by irradiations with fast neutrons, MeV ions (Kr, Ne and p), and electrons. The atomic structure within defect cascades was investigated using 50 keV Kr and Xe ion irradiations to low doses. Evidence is shown for an amorphous structure with some incoherent recrystallization within individual cascades. Correlati… more

Date: November 1, 1990

Creator: Kirk, M.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Collapse of Defect Cascades to Dislocation Loops in Cu3Au

TEM and ordered Cu/sub 3/Au were employed to measure the probability of dislocation loop formation as functions of irradiating ion mass (Ar/sup +/, Cu/sup +/ and Kr/sup +/), energy (50 and 100 keV), and irradiation temperature (30 and 300/sup 0/K). Disordered zones were produced at every defect cascade site and imaged in dark-field superlattice reflections. Dislocation loops were imaged in fundamental reflections in the same sample areas to produce an accurate measurement of the probability of … more

Date: February 1, 1986

Creator: Black, T. J.; Jenkins, M. L.; English, C. A. & Kirk, M. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Irradiation effects on the mechanical properties of composite organic insulators

Four kinds of cloth-filled organic composites (filler: glass or carbon fiber; matrix: epoxy or polymide resin) were irradiated with 2-MeV electrons at room temperature, and were examined with regard to the mechanical properties. Following irradiation, the Young's (tensile) modulus of these composites remains practically unchanged even after irradiation up to 15,000 Mrad. The shear modulus and the ultimate strength, on the other hand, begin to decrease after the absorbed dose reaches about 2000 … more

Date: 1983~

Creator: Egusa, S.; Kirk, M. A.; Birtcher, R. C.; Hagiwara, M. & Kawanishi, S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Fusion neutron irradiation induced ordering and defect production in Cu/sub 3/Au at high temperatures

We irradiate three Cu/sub 3/Au alloys different degrees of initial long-range order at temperatures between 300K and 434K. The resistivity of samples is monitored during irradiation and related to the long-term order parameter by the Muto relation. The results show that the ordering rate, which is proportional to the concentration of freely migrating vacancies, increases at the beginning and then decreases later with fluence. The decrease is a result of the continuous production of sinks in the… more

Date: August 1, 1987

Creator: Huang, J.S.; Guinan, M.W.; Kirk, M.A. & Hahn, P.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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In-situ observations of the development of heavy-ion damage in semiconductors

In-situ observations on ion-beam induced amorphisation of GaAs, GaP and Si are reported. Direct-impact amorphisation was found to occur in GaAs irradiated with 100-keV Xe/sup +/ ions to low doses at low temperature (approx. 40K) in contrast to previous room temperature irradiations. In GaP and in silicon, where heavy projectiles do cause direct impact amorphisation at room temperature, the evolution of the damage structure with ion-dose was studied. The defect yield both in GaP irradiated with … more

Date: January 1, 1985

Creator: Jenkins, M.L.; Chandler, T.J.; Robertson, I.M. & Kirk, M.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The Effects of Hydroxylamine on the C14O2 Fixation Pattern During Photosynthesis

No Description Available.

Date: March 21, 1958

Creator: Bassham, J. A.; Kirk, M. & Calvin, M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Approximate techniques for predicting size effects on cleavage fracture toughness (J{sub c})

This investigation examines the ability of an elastic T-stress analysis coupled with modified boundary layer (MBL) solution to predict stresses ahead of a crack tip in a variety of planar geometries. The approximate stresses are used as input to estimate the effective driving force for cleavage fracture (J{sub 0}) using the micromechanically based approach introduced by Dodds and Anderson. Finite element analyses for a wide variety of planar cracked geometries are conducted which have elastic b… more

Date: July 1, 1993

Creator: Kirk, M. T. & Dodds, R. H., Jr.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Influence of dilute impurities on the evolution of defect cascades in nickel

We have employed transmission electron microscopy to study the formation of vacancy dislocation loops from defect cascades produced by a 50 key Kr{sup +} ion irradiation of Ni and its dilute alloys with Si and Al. An unusual and reproducible dependence of the loop collapse probabilities and loop size distributions on solute content was found. The results are explained by impurity caused changes in both the collisional and thermal spike (molten zone) phase of the defect cascade. Specific mechani… more

Date: April 1, 1992

Creator: Vetrano, J. S.; Robertson, I. M. & Kirk, M. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Experimental studies of cascade phenomena in metals

We review recent ion-irradiation experiments which have been performed to investigate the collapse of displacement cascades to dislocation loops in a range of metals and alloys. Many of the results including the dependencies of the collapse probabilities on irradiation temperature, and ion dose, energy and mass, can be explained within the framework of a thermal spike/cascade melting model which has been suggested by computer molecular dynamics simulations. Other aspects, such as the dependence… more

Date: June 1, 1992

Creator: Jenkins, M. L.; Kirk, M. A. & Phythian, W. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Influence of dilute impurities on the evolution of defect cascades in nickel

Date: April 1, 1992

Creator: Vetrano, J. S.; Robertson, I. M. & Kirk, M. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Experimental studies of cascade phenomena in metals

Date: June 1, 1992

Creator: Jenkins, M. L.; Kirk, M. A. & Phythian, W. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Transmission electron microscopy study of cascade collapse in copper during in-situ ion-irradiation at elevated temperatures.

The basic mechanisms driving the collapse of point defects produced in collision cascades are investigated by transmission electron microscope (TEM) characterization of defect microstructure produced in fcc-Cu irradiated with low-fluences of heavy (100 keV Kr) ions at elevated temperature (23--600 C). Areal defect yields are determined from direct TEM observation of the total defect production integrated over the duration of the in-situ ion-irradiation. They are unequivocally demonstrated to de… more

Date: January 29, 1998

Creator: Daulton, T. L.; Kirk, M. A. & Rehn, L. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Neutron sputtering of gold

From surface effects in controlled thermonuclear fusion devices and reactors meeting; Argonne, Illinois, USA (10 Jan 1974). The sputtering yield of gold bombarded with fission neutrons was studied in the CP-5 reactor. Bulk single crystals were used at near liquid helium temperature. Overall sputtering yields ranged from 1 x 10/sup -3/ to 6 x 10/sup -3/ sputtered gold atoms per incident neutron for doses ranging from 2.1 x 10/sup 17/ to 5.5 x 10/sup 17/ (nvt > 0.1 MeV). Results are roughly an or… more

Date: February 1, 1974

Creator: Kirk, M. A.; Blewitt, T. H.; Klank, A. C.; Malewicki, R. & Scott, T. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department