Proton Bombarded Research Articles

Mechanical properties of proton bombarded SS316L thin foils using the small punch technique

The mechanical properties of thin foils (∼25 μm), to be used as a target’s window in a high intensity accelerator, require non-standard characterization techniques. In the current research, the innovative small punch test technique (SPT) had been used to map and determine the mechanical properties of SS 316L foil irradiated by high intensity of proton beams. The SPT results and the energy to fracture are presented and the fracture modes were determined by scanning electron microscopy (SEM) observations and electron backscatter diffraction (EBSD) analysis. The irradiated samples were exposed to 3.6 MeV proton bombardment at 250 μA and 290 μA, for 42 and 5 h, respectively. The major damage, as was reflected by significant ductility and energy to fracture losses, was associated with the irradiated zones which experienced the highest temperature and protons flux. Based on the observed evidence of deformation twins and dense dislocation bands, as well as the EBSD analysis, it was revealed that the limited deformation in the irradiated samples is related mainly to radiation damage and probably a minor effect of hydrogen embrittlement phenomenon. The limited ductility was explained by the accumulation of radiation damage that most probably hinder dislocations mobility through crystallographic glide. Nevertheless, these alternative deformation mechanisms involve nucleation and propagation of dislocation slip bands (DSBs) and intra-grain fragmentation. The DSBs intersections were proposed as the source for stress localization, which initiates crack formation which was followed by crack propagation through slip bands. This cracking mechanism was exhibited by a unique “saw tooth” fracture mode.

Qualitative Analysis of Long-Lived Residual Radioisotopes in 18 MeV Proton Bombarded Enriched Water Target

Residual radioisotope analysis as a result of cyclotron-based 18F production is of paramount importance since it relates to the radiation safety of patients as well as radiation workers. In this investigation, 18-MeV proton beams were employed to irradiate enriched water (H2 18O) target for 18F production while Talys Evaluated Nuclear Data Library (TENDL) 2017 were used to study the origins of the radionuclide impurities. Gamma rays emmitted by the residual radionuclides were detected using a gamma ray spectroscopic system following a month of decay while their origins were analyzed from the TENDL 2017 nuclear cross-section calculations. Experimental results indicated that several long-lived radionuclides such as 109Cd, 57Co, 57Ni, 58Co and 56Co were recorded by the gamma ray spectroscopic system. The long-lived residual radionuclides were presumably due to proton interactions with Havar window and Silver body. Using the TENDL 2017-calculated nuclear cross-sections, it was discovered that several nuclear reactions responsible for the residual radioisotopes include 109Ag(p,n)109Cd which corresponded to the generation of 109Cd radioisotope, 60Ni(p,α)57Co and 58Ni(p,2p)57Co reactions for the formation of 57Co, 58Ni(p,d)57Ni reaction for the production of 57Ni radioisotope, 58Fe(p,n)58Co reaction for the generation of 58Co, and 56Fe(p,n)56Co reaction for the formation of 56Co. This experimental result can be used as a reference for future production of 18F and other radioisotopes should Havar window and silver body are used in the target system.

Incorporation of chlorine in polymer films due to MeV proton bombardment

Adsorption of Cl on polymer films and enhanced uptake due to bombardment with 1.1 MeV protons has been studied after an occasional contamination of an analysis chamber for external proton-induced X-ray analysis (PIXE). The contamination occurred as a result of cleaning the Be window of the Si(Li) detector with CCl4. Changes in areal density of Cl on and in polymer films were measured by PIXE, at Cl partial pressures between about 10−4 and 10−5 mbar in the He backfilling gas. The partial pressure of gases with atomic numbers Z⩾10 (Ne) was measured by gas phase PIXE. After a few hours of exposure to CCl4 at 5×10−4 mbar, areal densities of 1 μg/cm2 of Cl were observed on cellulose acetate, cellulose nitrate and polycarbonate films. Detailed studies at about 2×10−5 mbar showed that uptake of Cl in proton bombarded cellulose acetate is enhanced by several orders of magnitude compared to the non-bombarded film. After exposure to low bombardment fluences, ∼1014 p/cm2, approximately two Cl atoms per incident proton were incorporated in 2 min. This rate increased by a factor of 3.3 after bombardment to 2×1015 p/cm2. Long-term exposure (45 min) in He after low-fluence bombardment showed that the rate of uptake decreases with increasing time. The results suggest that proton-induced damage produces active sites in the polymer film that can bond Cl atoms or Cl containing molecules.

Proton bombardment for enhanced four-wave mixing in InGaAsP-InP waveguides

A model for the transmission and four-wave mixing (FWM) conversion efficiency of InGaAsP-InP passive quantum-well (QW) waveguides which includes the effect of an additional nonlinear loss due to the accumulation of photogenerated free carriers is introduced and compared to experimental measurements. The model accurately describes the observed loss at high average powers and predicts that a reduction in the carrier lifetime of 10-100 times should effectively eliminate free carrier effects. Proton bombardment was investigated as a means of reducing the carrier lifetime, and both the conversion efficiency and relative transmission of proton bombarded single QW and multiple QW devices were significantly improved compared to unbombarded devices.

Transition time and turn-on jitter of optically triggered bistable lasers incorporating a proton bombarded absorber

Recently, we have demonstrated 1 Gbit/s error free operation of an optically triggered bistable laser, which is the highest bit-rate operation ever reported without electrical reset. This is achieved by using proton bombardment of the absorber section which induces a reduction of the carrier lifetime in this section. This letter presents the first experimental results on the transition time and the turn-on jitter of an optically triggered bistable laser incorporating a proton bombarded absorber section. Current injection conditions that minimize the overall transition time have been derived. It has been found that for a constant current in one active section, the rise time decreases, but the fall time increases with injection current in the other section. An optimal current value can then be found to minimize the overall transition time. The measured turn-on jitter and relaxation oscillation period decrease with increasing injection current, in good agreement with theoretical predictions.

Comparison of Fast Electron and Thermal Annealing of Proton Bombarded Silicon - X-Ray and IR Spectroscopy Study

physica status solidi (a)Volume 79, Issue 1 p. K13-K15 Short Note Comparison of Fast Electron and Thermal Annealing of Proton Bombarded Silicon - X-Ray and IR Spectroscopy Study K. Biskupska, K. Biskupska Institute of Nuclear Research, Swierk Search for more papers by this authorJ. Tatarkiewicz, J. Tatarkiewicz Institute of Nuclear Research, Swierk Search for more papers by this authorK. Wieteska, K. Wieteska Institute of Nuclear Research, Swierk Search for more papers by this author K. Biskupska, K. Biskupska Institute of Nuclear Research, Swierk Search for more papers by this authorJ. Tatarkiewicz, J. Tatarkiewicz Institute of Nuclear Research, Swierk Search for more papers by this authorK. Wieteska, K. Wieteska Institute of Nuclear Research, Swierk Search for more papers by this author First published: 16 September 1983 https://doi.org/10.1002/pssa.2210790142 05-400 ŚAvierk/Otwock, Poland. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Volume79, Issue116 September 1983Pages K13-K15 RelatedInformation

The nature of dislocation sources in proton bombarded GaAs

Abstract The technique of transmission electron microscopy (TEM) has been applied to study the nature of damage rafts, which act as dislocation sources, in proton bombarded (5×1015, 1016 protons cm2) GaAs. The results show that the rafts consist of a planar array of voids lying on the {110} planes. The dislocations generated at these rafts are glissile, of the (a/2) <110> type and glide on the {111} planes intersecting the rafts.

Optical properties of proton bombarded InP and GaInAsP

The spectral dependence of the optical absorption introduced in InP and GaInAsP by proton bombardment has been measured as a function of dose. A multienergy bombardment schedule was used in order to produce a uniformly bombarded layer 3 μm thick. The induced absorption, which increases nearly linearly with dose, extends well beyond the band edge and decreases nearly exponentially with wavelength over a broad range. A short 420°C anneal reduces this bombardment-induced absorption by more than a factor of ten.

Nonradiative recombination in GaAlAs proton-bombarded stripe-geometry lasers

Nonradiative recombination processes in GaAlAs double-heterostructure lasers are examined using luminescence time-response measurements. Photoluminescence time-decay data for proton-bombarded (PB) isotype (p-type) heterostructures give an effective recombination velocity for the PB region of (7±1) ×105 cm/sec. Electroluminescence decay times of laser devices indicate that the interfacial recombination velocity of the anisotype interface (p-GaAs/N-GaAlAs) is 1500±500 cm/sec compared with 400±100 cm/sec for isotype (p-type) interfaces. The contribution of each important recombination process to the laser threshold current is calculated. For devices in which the PB region penetrates into the active layer, recombination in the PB region and interfacial recombination are the major nonradiative paths.

Spatially resolved emission in stripe geometry GaAlAs DH lasers

Double-peak spatially resolved side emission spectra are observed in GaAlAs DH lasers with proton bombarded stripe contact. Results are explained in terms of internal stress as a result of proton bombardment of the p + region and absorption shift.

Negative Electrolytic Breakdown in Proton Bombarded LiF Crystal

The dielectric breakdown under proton bombardment of LiF was studied. Negative electrolytic breakdown figure was observed which was similar to that obtained by the conventional point-to-plate discharge. It is suggested that the breakdown is due to the potential difference between the range plane of the bombarding protons and the earthing point on the opposite surface. The breakdown figure consists of random and paths with layers of precipitated Li metal.