Radiation Damage of Diamond by Electron and Gamma Irradiation

Campbell, B.; Mainwood, Alison

doi:10.1002/1521-396x(200009)181:1<99::aid-pssa99>3.0.co;2-5

Cited by 96 publications

(96 citation statements)

References 16 publications

(6 reference statements)

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“…This offers the possibility for applying diamond for signal amplification, e. g. in scanning electron microscopy. The high radiation resistivity of diamond makes it an ideal candidate to work as a semiconductor in high-radiation environments [30], as, for instance, in particle detectors. …”

Section: -Implicationsmentioning

confidence: 99%

Space-time evolution of electron cascades in diamond

et al. 2002

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Abstract:The impact of a primary electron initiates a cascade of secondary electrons in solids, and these cascades play a significant role in the dynamics of ionization. Here we describe model calculations to follow the spatiotemporal evolution of secondary electron cascades in diamond. The band structure of the insulator has been explicitly incorporated into the calculations as it affects ionizations from the valence band. A Monte-Carlo model was constructed to describe the path of electrons following the impact of a single electron of energy E ∼ 250 eV. This energy is similar to the energy of an Auger electron from carbon. Two limiting cases were considered: the case in which electrons transmit energy to the lattice, and the case where no such energy transfer is permitted. The results show the evolution of the secondary electron cascades in terms of the number of electrons liberated, the spatial distribution of these electrons, and the energy distribution among the electrons as a function of time. The predicted ionization rates (∼ 5-13 electrons in 100 fs) lie within the limits given by experiments and phenomenological models. Calculation of the local electron density and the correspond-1 e-mail:ziaja@tsl.uu.se, szoke1@llnl.gov, spoel@xray.bmc.uu.se, hajdu@xray.bmc.uu.se ing Debye length shows that the latter is systematically larger than the radius of the electron cloud, and it increases exponentially with the radial size of the cascade. This means that the long-range Coulomb field is not shielded within this cloud, and the electron gas generated does not represent a plasma in a single impact cascade triggered by an electron of E ∼ 250 eV energy. This is important as it justifies the independent-electron approximation used in the model. At 1 fs, the (average) spatial distribution of secondary electrons is anisotropic with the electron cloud elongated in the direction of the primary impact. The maximal radius of the cascade is about 50Å at this time. At 10 fs the cascade has a maximal radius of ∼ 70Å, and is already dominated by low energy electrons (> 50%, E < 10 eV). These electrons do not contribute to ionization but exchange energies with the lattice. As the system cools, energy is distributed more equally, and the spatial distribution of the electron cloud becomes isotropic. At 90 fs, the maximal radius is about 150Å. An analysis of the ionization fraction shows that ionization level needed to create an Auger electron plasma in diamond will be reached with a dose of ∼ 2 × 10 5 impact X-ray photons perÅ 2 if these photons arrive before the cascade electrons recombine. The Monte-Carlo model described here could be adopted for the investigation of radiation damage in other insulators and has implications for planned experiments with intense femtosecond X-ray sources.The treatment of electron cascades in this paper is restricted to low energy electrons (E impact = 250 eV) and weakly ionized samples where only a few interatomic bonds are perturbed. We chose diamond as a model compound because of its significan...

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Section: -Implicationsmentioning

confidence: 99%

Space-time evolution of electron cascades in diamond

et al. 2002

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“…[159] and ∼ 1.5 vacancies/e -/cm in Ref. [169] and theoretically to be ∼ 2.2 vacancies/e -/cm [174]. Since the electrons are relativistic, the dierence in vacancy production between 2-and 3-MeV electrons is small [174], so we assume a vacancy production for the 3-MeV electrons used in this work of ∼ 2 vacancies/e -/cm.…”

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Optical magnetometry with nitrogen-vacancy centers in diamond

Acosta¹

2013

Optical Magnetometry

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Precision measurement of magnetic elds is at the heart of many important analytic techniques in materials, geology, biology, medicine, security, space, and the physical sciences. These applications require operation under a wide range of specications regarding sensitivity, spatial resolution, bandwidth, scalability, and temperature. In this work we have developed the enabling technology for magnetometers based on nitrogen-vacancy (NV) defects in diamond which promise to cover a wider portion of this parameter space than existing sensors. We have studied how to prepare diamond material optimized for magnetometry, and we observed the basic optical and spin properties of the NV centers. Using a novel scheme inspired by new information about NV centers gathered from these studies, we constructed a sensor which improved on the state-of-the-art in a number of areas. Finally, we outline a plan for improving these sensors to study micro-and nano-scale magnetic phenomena currently inaccessible using existing technology.

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“…We noticed that samples irradiated with electron beams had far higher peak intensities than did the non-irradiated samples. If electron energy of 10 MeV is used to irradiate samples, the penetration depth will increase linearly up to 15 mm [11]. However, to penetrate 10 mm into the sample, over 45 MeV of proton energy must be used for irradiation [12].…”

Section: Resultsmentioning

confidence: 99%