Transport of electrons induced by highly charged Ni (74 MeV/u) and Cu (9.6 MeV/u) ions in carbon: A study of target-thickness-dependent electron yields

Jung, Matthias; Rothard, H.; Gervais, B.; Grandin, J. P.; Clouvas, A.; Wünsch, R.

doi:10.1103/physreva.54.4153

Cited by 41 publications

(26 citation statements)

References 38 publications

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“…The value of L δ is found to increase strongly with increasing projectile velocity and can be described by a simple power law reported in equation 5.1 [Jung et al, 1996].…”

Section: The Emission Of Secondary Electrons From a Thin Foil Bombardmentioning

confidence: 90%

“…A fraction β of the energy lost by the incident proton is supposed to be lost in close collisions (β = 0.5 [Sternglass, 1957]), the rest of the lost energy being lost in distant collisions. The low-energy secondaryelectron transport is represented by an exponential decreasing function with a characteristic length L SE , which is supposed to be small (L SE = 65Å [Jung et al, 1996]). The δ-electrons transport energy according to a diffusion function…”

Section: The Emission Of Secondary Electrons From a Thin Foil Bombardmentioning

confidence: 99%

“…where Λ is a constant depending on the target material (for carbon Λ ≈ 10 µg/(keV · cm 2 ) [Jung et al, 1996]) and dE/dx denotes the electronic stopping power for the incident ions in the target material.…”

Section: The Emission Of Secondary Electrons From a Thin Foil Bombardmentioning

confidence: 99%

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Development of a PET cyclotron based irradiation setup for proton radiobiology

et al. 2015

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An out-of-yoke irradiation setup using the proton beam from a cyclotron that ordinary produces radioisotopes for positron emission tomography (PET) has been developed, characterized, calibrated and validated. The current from a 20 µm thick aluminum transmission foil is readout by home-made transimpedance electronics, providing online dose information. The main monitoring variables, delivered in real-time, include beam current, integrated charge and dose rate. Hence the dose and integrated current delivered at a given instant to an experimental setup can be computercontrolled with a shutter. In this work, we report on experimental results and Geant4 simulations of a setup which exploits for the first time the 18 MeV proton beam from a PET cyclotron to irradiate a selected region of a target using the developed irradiation system. By using this system, we are able to deliver a homogeneous beam on targets with 18 mm diameter, allowing to achieve the controlled irradiation of cell cultures located in biological multi-well dishes of 16 mm diameter. We found that the magnetic field applied inside the cyclotron plays a major role for achieving the referred to homogeneity. The quasi-Gaussian curve obtained by scanning the magnet current and measuring the corresponding dose rate must be measured before any irradiation procedure, with the shutter closed. At the optimum magnet current, which corresponds to the center of the Gaussian, a homogenous dose is observed over the whole target area. Making use of a rotating disk with a slit of 0.5 mm at a radius of 150 mm, we could measure dose rates on target ranging from 500 mGy/s down to 5 mGy/s. For validating the developed irradiation setup, several Gafchromic R EBT2 films were exposed to different values of dose. The absolute dose in the irradiated films were assessed in the 2D film dosimetry system of the Department of Radiotherapy of Coimbra University Hospital Center with a precision better than 2%. In the future, we plan to irradiate small animals, cell cultures, or other materials or samples.

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“…The value of L δ is found to increase strongly with increasing projectile velocity and can be described by a simple power law reported in equation 5.1 [Jung et al, 1996].…”

Section: The Emission Of Secondary Electrons From a Thin Foil Bombardmentioning

confidence: 90%

Section: The Emission Of Secondary Electrons From a Thin Foil Bombardmentioning

confidence: 99%

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Development of a PET cyclotron based irradiation setup for proton radiobiology

et al. 2015

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“…Thus the electronic sputtering strongly depends on the electron phonon coupling strength (g), which is inversally proportional to the square of the electron mean free path (λ). The electrons liberated in different directions from the ion track have different diffusion length depending on their energies [11]. As the grain size become smaller, scattering of electrons from grain boundaries influences the mean free path, and since the grains in the films have all the possible orientations, these grain boundaries effectively become electron scatterers and start behaving like a film interface.…”

Section: Electronic Sputteringmentioning

confidence: 99%

Swift heavy ion induced effects in LiF thin films

Kumar

Singh

Khan

et al. 2007

Phys. Status Solidi (c)

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Swift heavy ions induced effects on optical (color centers), structural and surface (electronic sputtering and morphology) modifications, in nano-grains LiF thin films were studied by glancing angle X-ray diffraction, optical absorption, photoluminescence and elastic recoil detection analysis techniques. Our results show that grain size and irradiation temperature play a crucial role in materials modifications as a function of fluence for the selected ion beam parameters. Also for the first time, lamellae formation was observed in LiF thin films after a high fluence irradiation of 5×10 13 ions/cm 2 at liquid nitrogen temperature with 120 MeV Ag ions irradiation under grazing incidence (~10°).1 Introduction The bombardment of solid surfaces by ionizing radiation has great deal of attraction due to many interesting fundamental and technical aspects of ion beam induced effects. Ionizing irradiation is known for synthesis, modifications and characterization of materials. The ions having kinetic energy in the range of few MeV/u, known as swift heavy ions (SHI), interact with the target materials mainly via electronic excitation resulting in interesting effects on physical and chemical properties of the materials. Lithium Fluoride (LiF) has lots of applications in the fields of tunable color center lasers, radiation dosimeters, optical isolators and in other wide range of opto-electronic devices. Ion induced effects in LiF has been studied, mostly in the form of bulk [1][2][3][4][5][6]. Aim of the present work is to study the effect of SHI irradiation on nanometer sized LiF thin films. In case of thin films, the structural and optical properties are strongly influenced by growth and irradiation parameters. Therefore, it would be interesting to study the SHI induced effects like color centers (CCs), electronic sputtering (i.e. the removal of target materials) and surface restructuring in nanometer sized thin films of LiF.

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“…For a carbon foil, with protons as projectiles, less than 10 electrons per incoming projectile are emitted even around the maximum of the electronic stopping power, the yield dropping below one electron per projectile for 10 MeV protons [5]. In contrast, for a heavy Kr ion at 64 MeV u −1 , it can be estimated from known scaling relations [6,7] that about 130 electrons are emitted per incoming projectile: about 100 in the forward direction (beam exit side) and about 30 in the backward direction (beam entrance side) with a carbon foil of ≈130 μg cm −2 thickness.…”

Section: Introductionmentioning

confidence: 97%

Bombarding insulating foils with highly energetic ions

Lanzanó¹,

Filippo²,

Hagmann³

et al. 2007

Radiation Effects and Defects in Solids

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Insulating (MYLAR), semi-insulating (MYLAR-Au) and conducting foils have been bombarded by very energetic 64 MeV u −1 78 Kr 32+ ions. The velocity spectra of fast electrons emitted in the backward and forward directions have been measured and analyzed as a function of the elapsed time in the run. A shift of binary encounter and convoy electrons emitted in the forward direction toward lower velocities has been observed with insulating targets. No such shift occurs with metallic targets. The surface potential evolves with time (i.e. ion fluence) both at forward and backward emission angle. It is shown that strong bulk charging of insulating targets leads to a positive potential as high as 9 kV before charge breakdown.

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Transport of electrons induced by highly charged Ni (74 MeV/u) and Cu (9.6 MeV/u) ions in carbon: A study of target-thickness-dependent electron yields

Cited by 41 publications

References 38 publications

Development of a PET cyclotron based irradiation setup for proton radiobiology

Development of a PET cyclotron based irradiation setup for proton radiobiology

Swift heavy ion induced effects in LiF thin films

Bombarding insulating foils with highly energetic ions

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