Protons In Aluminium Research Articles

A Theoretical Study of Stopping Power and Range For Low Energy (<3.0mev) Protons In Aluminium, Germanium, Lead, Gold and Copper Solid Materials

A new empirical relation was obtained by modifying an empirical relation deduced by Chaubey (1977) based on Bohr’s classical mechanics by using least squared fitting method for stopping powers from 0.20MeV to 2.90MeV protons in Aluminium (Al), Germanium (Ge), Lead (Pb), Gold (Au) and Copper (Cu) solid target materials and the results compared with some available experimental values and earlier investigations as well as PSTAR and SRIM (2013) results. The proton range relation was obtained by directly integrating the stopping power formula and the values of the ranges for the elements are calculated and compared with PSTAR and Janni (1982) values. The calculated stopping powers and range values were in excellent agreement with the experimental values of Bichsel since the percentage uncertainty was within 10% and the theoretical values of Janni (1982) and, the PSTAR and SRIM-2013 codes generated values had the percentage difference approximately within 10%. The cross section was also calculated and the results discussed. The practical applications of the stopping power, range and cross section values of the selected materials are discussed.

Electron capture and loss processes for protons in aluminium: Comparison between conduction band electron–hole assisted and plasmon assisted Auger processes

Charge changing processes are known to have a strong influence on ion-induced electron emission characteristics. However, up to now, only a few theoretical models of electron emission incorporate electron capture and loss cross sections. For incident protons with velocities around 1 a.u., a thorough theoretical model of the various charge changing processes undergone by the proton is necessary for a correct description of the electron emission induced by the projectile. Indeed, all the electrons excited in the various processes have to be taken into account. In this work, we consider conduction band Auger capture and loss processes. In particular, we consider plasmon assisted processes, which are not negligible with respect to electron–hole pair assisted Auger processes for electron capture.

Calculation of the first four moments of electronic energy loss of protons in aluminium

We present a novel scheme for calculating electronic energy losses and their higher moments which allows to fully account for the electronic structure of solids. Typical structures in solid materials are found in metals with their half filled conduction bands, and in insulators which exhibit a completely filled valence band, and above this a forbidden band gap. The conduction electrons in a metal resemble most closely a free electron gas which would fill a Fermi sphere in velocity space (or in momentum space) homogeneously from ν = 0 to ν = νF. The core electrons are separated from the freely available phase space by distinct band gaps. For protons slowing-down in metals, this means that conduction electrons can accept small energy transfers which are inacceptable for core electrons or valence electrons in insulators. This leads to a completely different stopping behavior of metals, particularly at low velocities. In metals we expect that all energy loss moments increase strictly proportional to νn starting at zero velocity, i.e., the energy loss proportional to ν1, the energy loss straggling proportional to ν 2 etc. We perform the stopping calculations first for the metal Al, where the theoretical input is well known, and where most measurements have been performed. The comparison of theory and experiments shows agreement within the experimental straggle.

Second-order Born collisional stopping of ions in a free-electron gas

The energy loss of a heavy bare projectile with charge ${Z}_{P}$ moving in a free-electron gas is studied within the framework of the binary collisional formalism. The transition-matrix element is expanded in a perturbative series, and terms up to ${Z}_{P}^{3}$ (second Born approximation) are conserved. The Mermin-Lindhard dielectric response function is employed to describe the cylindric potential induced by the projectile. The formalism is applied to the calculation of energy-loss distributions for fixed charges (protons, neutral hydrogen, and antiprotons) colliding with aluminum. We also investigate how the ${Z}_{P}^{3}$ collisional correction affects the total stopping for antiprotons in aluminum and silicon, and for protons in aluminum. In this latest case, different charge states of the projectile are considered. Results are in good agreement with experimental data in the high-energy region.

Study of the influence of the electron capture and loss process on the secondary electron emission induced by protons in aluminium

Experiments on the secondary emission of electrons from thin carbon foils bombarded with protons have shown that the forward-backward yield ratio increases with energy below 200 keV. Theoretical calculations for an aluminium target, on the contrary, show that this ratio decreases with energy. To explain this discrepancy, we have included in our Monte Carlo simulation model the electron capture and loss process, assuming that a proton-captured electron system does not excite electrons in the solid. We have also taken into account the partial yield due to the lost electrons. This simple model, applied to aluminium, gives results consistent with the carbon experiments. We have also studied the statistics of the number of secondary electrons accompanying an outgoing proton or hydrogen atom.

Measurement of cross sections for aluminum-26 and sodium-24 induced by protons in aluminum

We have measured cross sections for the reactions (p, pn) and (p, 3pn) in high purity aluminum targets, leading to the products 26Al and 24Na. Proton bombardments were made at eight energies from 40 to 160 MeV. The proton fluences were calibrated with a Faraday cup at each energy. The 24Na (15 h half-life) cross section was determined by counting the 1.369 MeV gamma rays in a 90 cm 3 Ge(Li) spectrometer. The 26Al (703000 yr half-life) cross section was determined by direct atom counting with accelerator mass spectrometry.

Production cross section of radionuclides in (p, x) reactions at copper and nickel nuclei

The authors measured the cross sections of the production of radionuclides by 10-100-MeV protons in copper and nickel targets of the natural isotope composition. The currently available data on these target nuclei are basically limited to a proton energy of approx. 50 MeV and some of the information is even inconsistent. The experiment was made on the linear injector of the Institute of High-Energy Physics. The targets were irradiated with the extracted proton beam of the linear injector with a beam current of 97 mA, a current-pulse duration of 57 ..mu..sec, and a pulse-repetition frequency of 0.25 Hz. In order to calculate the proton energy after the passage through a stack of foils, data on the stopping power and the ranges of protons in aluminium were used. The proton flux was monitored via the nuclear reactions /sup 65/Cu(p,n)/sup 65/Zn in the proton energy range 10-40 MeV and /sup 27/Al(p,x)/sup 24/Na in the proton energy range 40-100 MeV.

Plasma dynamics of the interaction of intense ion beams with ‘‘sub’’ and ‘‘super’’ range plane targets

Analytic and numerical solutions for the problem of the interaction of intense ion beams with matter in the form of plane targets are considered in this paper. The theory of the interaction of protons with matter at low energies is discussed and calculations are presented for the energy loss of protons in aluminum and gold. Zero- and one-dimensional models are developed and the results are compared to numerical simulations carried out with the one-dimensional Lagrangian hydrodynamic code medusa [Comp. Phys. Comm. 1, 271 (1974)], which has been extended to include the various physical effects needed to carry out realistic simulations of the interaction of ion beams with matter. The theory and simulation of the acceleration of foils by intense ion beams is also considered and representative results are given. The theoretical results are used to investigate the optimum conditions in which to carry out stopping power experiments for ions in hot, dense plasmas, so that the theory can be tested. These results are needed in order to perform more realistic pellet calculations for inertial fusion.

Cross sections for reactions with 593 and 540 MeV protons in aluminium, arsenic, bromine, rubidium and yttrium

Spallation cross sections for γ-ray-emitting products have been measured in Al, As, Br, Rb and Y with 593 MeV and, in some cases, 540 MeV protons. The experimental results are compared to predictions. The influence of secondary particles on cross sections in As and Y was also investigated.

The energy straggling of protons in aluminium

The energy straggling of protons in aluminium has been measured as a function of the foil thickness in the range from 40 to 120 μm at incident energies between 8 and 19 MeV. The residual energy spectra were measured with surface barrier silicon semiconductor detectors. The experimental results show good agreement with the theory of Bohr.

A PRECISE MEASUREMENT OF THE RANGE OF 100-MEV PROTONS IN ALUMINIUM

The range of 100-MeV protons in aluminium has been determined using the external beam of the McGill synchrocyclotron. The energy and range were determined for a finely collimated pencil beam with an energy spread of 0.12 MeV. Beam energy was measured by the floating-wire technique. Two range determinations yielded values of 9 840 ± 9 mg/cm2 at 99.88 ± 0.08 MeV and 9 768 ± 10 mg/cm2 at 99.58 ± 0.08 MeV. Range straggling was found to be in agreement with theory. The mean excitation potential in aluminium has been estimated from these results to be 156 ± 2 eV.

SOME LOW-ENERGY ATOMIC STOPPING CROSS SECTIONS

The electronic stopping cross sections for protons in aluminum are reported in the energy interval 10 < E < 70 keV. Stopping cross sections below 150 keV in carbon targets for projectiles with [Formula: see text], and in aluminum targets for [Formula: see text] are reported also. The results are compared with theory and show reasonable agreement. The previously reported periodic dependence of Se on the atomic number of the projectile is also evident in the present results.

Ranges of 5- to 27-keV Deuterons in Aluminum, Copper, and Gold

A method of measuring ranges is presented which uses the change in optical-reflection coefficient of quartz due to radiation damage by the deuterons as a means of detecting the deuterons. The metal films are deposited on the quartz by vacuum evaporation and their thickness is determined with an accuracy of \ifmmode\pm\else\textpm\fi{}5% by weighing. By bombarding a given metal film on quartz at a fixed flux and a number of different energies, a number of bombarded areas are formed where the deuterons have penetrated to a corresponding number of different depths in the quartz. After chemically removing the metal film, the optical-reflection coefficients of the bombarded areas are measured and compared with theoretical predictions to determine the bombarding energy for which exactly one-half of the incident deuterons have penetrated the metal films. The ranges obtained agree with theoretical estimates and are consistent with known ranges of protons in aluminum.

The range in G5 nuclear emulsion of protons with energies 87, 118 and 146 MeV

A comparison was made between the ranges of artificially accelerated protons in Aluminium and in Ilford G5 photographic emulsion. The ranges in emulsion were obtained by direct measurements along the particle tracks, and those in Aluminium by an attenuation method. The ranges of protons of three different energies were 19.31, 13.23 and 7.82 g/cm2 in Aluminium, and 22.85, 15.58 and 9.50 g/cm2 in emulsion of density 3.791 g/cm3 conditioned to 58% relative humidity. The corresponding energies were 146.5 MeV, 117.9 MeV and 87.4 MeV. Assuming the range-energy relation for protons to be at present better determined for Aluminium than for photographic emulsion, this experiment provides new information concerning the relation between particle range and energy in nuclear emulsion.

Mean Excitation Potentials

Previous experimental results of the present authors on the energy loss of 18-Mev protons in aluminum are corrected to give a value for the mean excitation potential $I=168$ ev. It is pointed out that recent work on the range-energy relationship for protons in aluminum may indicate a variation of $I$ with proton energy which is considerably larger than that to be attributed to the nonparticipation of the $K$ electrons.

The Range of 18-Mev Protons in Aluminum

The circulating beam of protons in the cyclotron was multiply scattered upward by a strip of Th suspended vertically inside the dee. The energy of the scattered beam was defined by the Th strip and two slits in the magnetic field of the cyclotron. From a plot of the magnetic field along the path of the scattered protons, the mean energy was determined to be 18.00\ifmmode\pm\else\textpm\fi{}0.02 Mev. By determining the thickness of Al that stopped half the incident beam, the mean range was found to be 447.0\ifmmode\pm\else\textpm\fi{}0.5 mg/${\mathrm{cm}}^{2}$.

The Range and Straggling of Protons between 35 and 120 Mev

The range of protons in aluminum, copper, and lead has been determined with a photographic method, using the internal beam of the 95-in. synchrocyclotron of Harvard University. The method allows the simultaneous determination of the range, straggling, and the energy distribution of the protons in the internal beam. The latter was shown to have a half-width of 12 Mev. The experimental results for the range show slight, but significant deviations from tabulated values. Results for the straggling agree well with theory, if the effect of multiple scattering in the absorber is taken into account.

The Range of Protons in Aluminum and in Air

The Range of Protons in Aluminum and in Air