Pelletron Accelerator Research Articles

Precise measurements of energy loss straggling for swift heavy ions in polymers

The energy loss straggling measurements for heavy ions with Z=3–22 (∼0.2–2.5MeV/u) in PEN (C7H5O2) and PET (C10H8O4) polymers have been carried out utilizing the swift heavy ion beam facility from 15UD Pelletron accelerator at Inter University Accelerator Centre (IUAC), New Delhi, India. The recorded spectra are analyzed in such a way that the Straggling associated with energy loss process could be measured in a systematic manner at any selected value of energy, in terms of per unit thickness of the absorber, at any desired energy intervals. The measured values have been compared with the calculated values obtained from the most commonly used Bethe-Livingston formulations applicable for collisional straggling. The results are tried to be understood in terms of the effective charge on the impinging ion within the absorber. Some interesting trends are observed.

Refractive index dispersion of swift heavy ion irradiated BFO thin films using Surface Plasmon Resonance technique

Swift heavy ion irradiation (SHI) is an effective technique to induce defects for possible modifications in the material properties. There is growing interest in studying the optical properties of multiferroic BiFeO3 (BFO) thin films for optoelectronic applications. In the present work, BFO thin films were prepared by sol–gel spin coating technique and were irradiated using the 15UD Pelletron accelerator with 100MeV Au9+ ions at a fluence of 1×1012ionscm−2. The as-grown films became rough and porous on ion irradiation. Surface Plasmon Resonance (SPR) technique has been identified as a highly sensitive and powerful technique for studying the optical properties of a dielectric material. Optical properties of BFO thin films, before and after irradiation were studied using SPR technique in Otto configuration. Refractive index is found to be decreasing from 2.27 to 2.14 on ion irradiation at a wavelength of 633nm. Refractive index dispersion of BFO thin film (from 405nm to 633nm) before and after ion radiation was examined.

Analysis of SRAM-Based FPGA SEU Sensitivity to Combined EMI and TID-Imprinted Effects

This work proposes a novel methodology to evaluate SRAM-based FPGA’s susceptibility with respect to Single-Event Upset (SEU) as a function of noise on VDD power pins, Total-Ionizing Dose (TID) and TID-imprinted effect on BlockRAM cells. The proposed procedure is demonstrated for SEU measurements on a Xilinx Spartan 3E FPGA operating in an 8 MV Pelletron accelerator for the SEU test with heavy-ions, whereas TID was deposited by means of a Shimadzu XRD-7000 X-ray diffractometer. In order to observe the TID-induced imprint effect inside the BlockRAM cells, a second SEU test with neutrons was performed with Americium/Beryllium ( $^{241}{\hbox {AmBe}}$ ). The noise was injected into the power supply bus according to the IEC 61.000-4-29 standard and consisted of voltage dips with 16.67% and 25% of the FPGA’s VDD at frequencies of 10 Hz and 5 kHz, respectively. At the end of the experiment, the combined SEU failure rate, given in error/bit.day, is calculated for the FPGA’s BlockRAM cells. The combined failure rate is defined as the average SEU failure rate computed before and after exposition of the FPGA to the TID.

An application of PIXE technique to Proto Crustal Rocks: Geo chemical evaluation of Granulitic Charnockites of Eastern Ghats, Andhrapradesh, India

In this work, PIXE has been used for a variety of Precambrian proto crustal rocks in the form of granulitic charnockites,Eastern Ghats AP,India.In previous study of exterior part of the charnockite hill elemental analysis using electron microprobe analysis, the elements in host charnockites no Na, traces of Mn,Ca and high Ti,Cl,F (Biotite), no Mn, low Na,and high K,Cl (Hastingsite), and Cl, Fe (Apatite) were only detected, but by using PIXE technique in addition to the above twenty two trace elements are identified. PIXE is highly sensitive and non-destructive method for multi elemental analysis in a variety of Precambrian charnockite rocks down to levels of a few parts per million. The samples chosen for analysis from the central portion of a charnockite hill near Visakhapatnam airport. A big reticular mass of relict litho logical body which is compositionally and physically different from host chatnockite was observed in the central portion of the hill. These experiments are carried out using a 3MV pelletron accelerator facility at the Institute of physics, Bhubaneswar. A collimated proton beam of 2mm diameter is made to fall on to the sample, and the beam current is kept at 20na. A high resolution Si(Li) detector(160ev FWHM at 5.9kev energy) is employed in the present experiments and the Guelph PIXE (GUPIX) software package is used to analyze the spectra. The elements identified in this Precambrian charnockite rock are Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Ru, Ag, Pb..From this study these rocks are early crust(proto crust) rocks. These samples are to belong to a very important geological phase and further work on petrography and REE (Rare Earth Elements in Geology)of the rock is indeed to firmly establish its exact parentage.

Electric Monopole Transition Strengths in62Ni

Excited states in 62 Ni were populated with a (p, p') reaction using the 14UD Pelletron accelerator at the Australian National University. Electric monopole transition strengths, ρ 2 (E0), were measured through simultaneous detection of the internal conversion electrons and γ rays emitted from the de-excitation of popu- lated states, using the Super-e spectrometer coupled with a germanium detector. The strength of the 0 + to 0 + transition has been measured to be 77 +23 −34 × 10 −3 and agrees with previously reported values. Upper limits have been placed on the 0 + to 0 + and 0 + to 0 + transitions. The measured ρ 2 (E0) value of the 2 + to 2 + transition in 62 Ni has been measured for the first time and found to be one of the largest ρ 2 (E0) values measured to date in nuclei heavier than Ca. The low-lying states of 62 Ni have previously been classified as one- and two-phonon vibrational states based on level energies. The measured electric quadrupole transition strengths are consistent with this interpretation. However as electric monopole transitions are forbidden between states which differ by one phonon number, the simple harmonic quadrupole vibrational picture is not sufficient to explain the large ρ 2 (E0) value for the 2 + to 2 + transition.

Using a Tandem Pelletron accelerator to produce a thermal neutron beam for detector testing purposes

Active thermal neutron detectors are used in a wide range of measuring devices in medicine, industry and research. For many applications, the long-term stability of these devices is crucial, so that very well controlled neutron fields are needed to perform calibrations and repeatability tests. A way to achieve such reference neutron fields, relying on a 3MV Tandem Pelletron accelerator available at the CNA (Seville, Spain), is reported here. This paper shows thermal neutron field production and reproducibility characteristics over few days.

Verification of the sputter-generated 32SFn− (n = 1–6) anions by accelerator mass spectrometry

Recently, we have performed systematic Secondary Ion Mass Spectrometry (SIMS) measurements at our ion source test set up and have demonstrated that gas phase 32SFn− (n=1–6) anions for all size ‘n’ can be readily generated from a variety of surfaces undergoing Cs+ ion sputtering in the presence of high purity SF6 gas by employing the gas spray-cesium sputter technique. In our SIMS measurements, the isotopic yield ratio 34SFn−/32SFn− (n=1–6) was found to be close to its natural abundance but not for all size ‘n’. In order to gain further insight into the constituents of these molecular anions, ultra sensitive Accelerator Mass Spectrometry (AMS) measurements were conducted with the most abundant 32SFn− (n=1–6) anions, at BARC-TIFR 14 UD Pelletron accelerator. The results from these measurements are discussed in this paper.

Energy loss straggling in Aluminium foils for Li and C ions in fractional energy loss limits (ΔE/E) ∼10–60%

The energy loss straggling of Li and C ions in Al foils of various thicknesses has been measured, within the fractional energy loss limit (∆E/E) ∼ 10–60%. These measurements have been performed using the 15UD Pelletron accelerator facility available at Inter University Accelerator Centre (IUAC), New Delhi, India. The measured straggling values have been compared with the corresponding predicted values adopting popularly used collisional straggling formulations viz Bohr, Lindhard and Scharff, Bethe–Livingston, Titeica. In addition, the experimental data has been compared to the Yang et al. empirical formula and Close Form Model, recently proposed by Montanari et al. The straggling values derived by Titeica theory were found to be in better agreement with the measured values as compared to other straggling formulations. The charge-exchange straggling component has been estimated from the measured data based on Titeica’s theory. Finally, a function of the ion effective charge and the energy loss fraction within the target has been fitted to the latter straggling component.

Recent results from the AMS/IBA laboratory at the Comenius University in Bratislava: preparation of targets and optimization of ion sources

Developments of solid targets and optimizations of ion sources were carried out with the aim to produce high ion yields for applications of tandem accelerators as mass spectrometers. A comparison of Al− yields from different aluminum targets showed that the best results were obtained with AlN targets. Transmission studies of 9Be and 12C ions through the Pelletron accelerator showed highest efficiencies for 9Be2+ and 12C2+. First results obtained with a simplified version of the AMS line are presented as well.

Standardization of proton-induced x-ray emission technique for analysis of thick samples

This paper describes the standardization of the proton-induced x-ray emission (PIXE) technique for finding the elemental composition of thick samples. For the standardization, three different samples of standard reference materials (SRMs) were analyzed using this technique and the data were compared with the already known data of these certified SRMs. These samples were selected in order to cover the maximum range of elements in the periodic table. Each sample was irradiated for three different values of collected beam charges at three different times. A proton beam of 2.57 MeV obtained using 5UDH-II Pelletron accelerator was used for excitation of x-rays from the sample. The acquired experimental data were analyzed using the GUPIXWIN software. The results show that the SRM data and the data obtained using the PIXE technique are in good agreement.

Application of Pelletron Accelerator to Study High Total Dose Radiation Effects on Semiconductor Devices

Silicon bipolar junction transistors (BJTs), Silicon-germanium heterojunction bipolar transistors (SiGe HBTs) and metal oxide semiconductor (MOS) devices are the key components of BiCMOS integrated circuits. The semiconductor devices need to withstand very high total doses (100’s of Mrad) for reliable operation of electronic circuits for 8-10 years of LHC operation. The study of radiation tolerance of semiconductor devices up to 100 Mrad of total dose takes longer time with conventional60Co gamma, proton and electron irradiation facilities and the effects due to these radiations are well understood. Hence it is important to study the effects of heavy ion irradiation on various semiconductor devices. The irradiation time decreases with increasing linear energy transfer (LET) of incident radiation and LET increases with atomic number of the impinging ions. But it is essential to understand the mechanism of energy transfer by different heavy ions in semiconductor devices. Therefore, here we give an overview of different heavy ion interactions with Si BJTs, MOSFETs and SiGe HBTs by primarily focusing on the electrical characteristics of these devices before and after ion irradiation. We show that the irradiation time needed to reach very high total dose can be reduced by using Pelletron accelerator facilities instead of conventional irradiation facilities.

The compact AMS facility at Guangzhou Institute of Geochemistry, Chinese Academy of Sciences

A compact 14C AMS facility manufactured by the National Electrostatics Corporation (NEC) has been installed at Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (GIGCAS). The system is based on a Model 1.5SDH-1 Pelletron accelerator with a maximum terminal volt 0.6MV. This paper reports the performance and the operation of this machine in the first several months after installation.

Water fragmentation by Liq+ and Cq+ projectiles with MeV energies

SynopsisWe report on fragment distributions from water targets by impact of Liq+ and Cq+ projectiles with MeV energies. We identify fragment species as function of emission energy by using an electrostatic spectrometer and as function of velocity by a time of flight mass spectrometer (pulsing the beam at the injector of the Pelletron accelerator). An improved Coulomb explosion model married to CTMC simulations allows us to calculate the energy of each fragment for different fragmentation channels.

Improvement in the pitting resistance of Inconel-600 by nitrogen ions implantation

The surface of Ni-Cr-Fe (Inconel-600) alloy was modified by implanting 500 keV nitrogen ions at room temperature using pelletron accelerator to dose of 1.87 × 1014 ions/cm2. X-ray diffraction analysis of the ions implanted samples indicated the formation of Cr2N phase. Electrochemical testing of Inconel-600 alloy before and after the ions implantation was conducted using potentiodynamic tafel scan, potentiodynamic anodic polarization and electrochemical impedance spectroscopy techniques in an acidic saline solution. The higher anodic polarization slope (βa), low cathodic polarization slope (βc) and decrease in corrosion current density after ions implantation were attributed to the modification of passive film by the nitrogen ions. The scanning electron microscopy and electrochemical analyses of the ions implanted samples revealed an improvement in the pitting resistance of the alloy.

A new AMS facility at Inter University Accelerator Centre, New Delhi

Inter University Accelerator Centre (IUAC), a national facility of government of India, is having a 15UD Pelletron accelerator for multidisciplinary ion beam based research programs. Recently, a new accelerator mass spectrometry (AMS) facility has been developed after incorporating many changes in the existing 15UD Pelletron accelerator. A clean chemistry laboratory for 10Be and 26Al with all the modern facilities has also been developed for the chemical processing of samples. 10Be measurements on sediment samples, inter laboratory comparison results and 26Al measurements on standard samples are presented in this paper. In addition to the 10Be and 26Al AMS facilities, a new 14C AMS facility based on a dedicated 500kV tandem ion accelerator with two cesium sputter ion sources, is also being setup at IUAC.

English

In this study, dumpsite soils and vegetables were analyzed for total elemental composition using a 5SDH Tandem Pelletron accelerator available at Centre for Energy Research and Development, Obafemi Awolowo University Ile-Ife. The results at a 2.5 MeV energy revealed the presence of elements: Cu, Cr, Ni,Al, Si, P, S,Cl, K, Ca, Ti, Mn, Fe, Zn, Rb, Sr, Y, Zr and Pb in the dump site soil, with the exception of Cu, Cr,Ni, Zr and Y; other elements with Mg in addition were found in the vegetables around the dump site soil, majority of the elements were at lesser concentrations. However, there was a sharp difference in the concentrations of Mg, Ca and K being present at higher concentrations in the vegetables than in the soil. The result showed no significant difference in the concentration of elements analyzed on each site with the control site, both in the vegetable and the soil samples at 95 and 99% confidence interval. The analysis of variance (ANOVA) for the soil and vegetable samples also confirmed no significant differences. The relationship among the sites was determined in either direction (positive and negative, 2-tailed analysis) using correlation coefficient, the R2 values among sites were all above 0.5 in vegetable and > 0.9 in the dumpsite soil, showing that all sites were well related depicting common components. Fe, Zn and Pb were within the range of concentration of metals in plant but were higher than the permissible limit of International Organization (WHO/FAO, 2007; EU, 2006). High concentrations coupled with high standard deviation values of some elements suggest influence of anthropogenic activities. Key words: Dumpsite soil, vegetable, elemental composition, PIXE.

A New Test Environment Approach to SEE Detection in MOSFETs

This paper shows a comparison between two different MOSFET structures: a conventional layout (CM) and Diamond (DM - enclosed layout transistor), as tolerance to the Single Event effect - SEE. Both CMOS 0.35μm technology devices types have the same geometric factor (W/L) and during irradiation were monitored continuously to detect and acquire the SEEs applying a new approach with a PXI test system. For this work was used heavy ion beams produced at the São Paulo 8 UD Pelletron accelerator.

Final Commissioning of the Superconducting Heavy Ion Linear Accelerator at IUAC, Delhi

The superconducting linac as a booster of the 15UD Pelletron accelerator was partly commissioned with one linac module housing eight quarter wave bulk niobium cavities along with the superbuncher and rebuncher cryomodules. Subsequently two more linac cryomodules were added to have in total 24 cavities for acceleration. In addition, a new Linde helium refrigerator of capacity 750W @ 4.2K was installed in parallel to the earlier CCI refrigerator. The new refrigerator was integrated with the earlier cryogenics network system through a specially designed liquid helium distribution line without any valve box. The cooling philosophy with this new system is modified to have a faster cool down rate in the critical zone (150 - 70K) to avoid Q disease. The helium gas pressure fluctuation in the cavities is reduced significantly to have stable RF locking. The full linac is being operated and beams with higher energy are being delivered to the users. The present paper will highlight the performance of the new cryogenic system with respect to cool down rate, and helium pressure fluctuation.

Electrochemical behavior and biological response of Mesenchymal Stem Cells on cp-Ti after N-ions implantation

Titanium and its alloys are most widely used as implant materials due to their excellent biocompatibility, mechanical properties and chemical stability. In this study Nitrogen ions of known dosage were implanted over cp-Ti by Pelletron accelerator with beam energy of 0.25MeV.The atomic force microscopy of bare and nitrogen implanted specimens confirmed increase in surface roughness with increase in nitrogen ions concentration. X-ray diffraction patterns of ions implanted surfaces validated the formation of TiN0.3 and Ti3N2-xnitride phases. The tendency to form passive film and electrochemical behavior of these surfaces in ringer lactate (RL) solution was evaluated by Potentiodynamic polarization and electrochemical impedance spectroscopy respectively. It is proved that nitrogen ions implantation was beneficial to reduce corrosion rate and stabilizing passive film by increasing charge transfer resistance in RL. It was concluded that morphology and proliferation of Mesenchymal Stem Cells on nitrogen ions implanted surfaces strongly depends on surface roughness and nitride phases.

Track etch membranes (TEMs) for separation sciences from BARC-TIFR Pelletron accelerator

Track etch membranes (TEMs) program at 14 UD Pelletron accelerator at TIFR, Mumbai, India using 25 micron thick polyethylene terepthalate film is described. Large scale preparation of TEMs by scanning heavy ion beams using a electromagnetic scanner and rolling mechanism using a geared D.C. motor and vacuum rotary feed through are presented. The selection of ions of suitable energy and etching parameters for making various pore sizes were investigated using Rutherford scattered beam from Pelletron accelerator. Pore size and pore density were measured using scanning electron microscope. Scanning width up to 35 cm and irradiation up to 22 m were successfully carried out using this facility. Some applications carried out using these membranes are also mentioned.