Pelletron Accelerator Research Articles

Synthesis, characterization, and photocatalytic performance of gold ions implanted TiO2/graphene nanocomposites for efficient dye photodegradation

The suggested work provides a hydrothermal technique for the synthesis of TiO2/graphene nanocomposites with different weight percentages of graphene (0.0 %, 5.0 %, 10.0 %, and 15.0 %). These composites were implanted with gold ions at a fluence of 1 × 1013 ions/cm2 by using a pelletron accelerator. The structural and physical properties were investigated by utilizing XRD, FESEM, FTIR, EDX, and UV–Vis spectroscopy. The XRD data verified the existence of TiO2 with a rutile crystal phase. FESEM morphology showed that TiO2 particles had aggregated on graphene layers and had a semi-spherical shape. The functional groups present in the sample were identified using FTIR for TiO2 and TiO2/graphene nanocomposites. The stoichiometric ratios of all the constituent elements and the homogeneous composition were confirmed using EDX analysis. The UV–Vis spectroscopy revealed that the optical bandgap decreased from 3.15 eV to 2.80 eV. Additionally, the photocatalytic activity for the degradation of methylene blue (MB) under UV light was investigated. The photocatalytic performance was improved with increased graphene content. The evaluated data reveals that the sample with 10 % graphene has the maximum photocatalytic activity and rate constant. These findings suggest that gold-implanted TiO2/graphene nanocomposites favor photocatalytic applications and use in dye-sensitized solar cells.

Impact of supporting substrate on the measured neutron yields from natLi (p, n) system: A case study with natC and natTa stopping targets

Abstract The high energy neutron generation facilities worldwide uses the Li(p,n) system for production of the quasi mono-energetic neutrons from epithermal to few hundreds of MeV. Among the facilities either self-standing thick Li target or Li foil supported on a target assembly is used. In case of a supported Li target, either low or high mass supporting substrates like Al, C, Au, Ta etc. can be used. However, the neutron emission from the supporting substrate can interfere with the Li(p,n) reaction neutrons. In the present study neutron yields from a thin natural Li target supported on the thick natural Ta (high Z) and C (low Z) targets were measured at incident proton energies between 8-20 MeV. The proton irradiation of targets were performed at the Pelletron accelerator Facility, Mumbai and the emitted neutrons were measures at both forward (0°) and lateral (90°) directions with respect to the incident beam. The neutron yield was estimated using the CR-39 detectors and dual scintillator based active neutron spectrometer. A neutron dose equivalent (NDE) meter was also used to measure the neutron ambient dose equivalent at the measurement point. Experimentally measured neutron yields and ambient neutron dose equivalent estimates indicated higher Li(p,n) neutron yield with carbon as the supporting substrate. This is due to fewer self-emissions from natC compared to natTa target. Carbon supporting substrate also ensures improved spectral features of the Li(p,n) emission neutrons and lesser neutron fluence around the source location. This ensures efficient implementation of radiation protection practices with carbon target due to lower neutron fluence around the source compared to tantalum target. Carbon is a favorable supporting substrate compared to high Z- metal targets like Ta for emission neutron studies on Li target at proton energies between 8-20 MeV.

A compact accelerator driven neutron source at the Applied Nuclear Physics Laboratory, Lund University

The Applied Nuclear Physics Group at Lund University has constructed a CANS (Compact Accelerator-driven Neutron Source). The CANS is based around a 3 MV, single-ended, Pelletron accelerator, which is used to impinge a 2.8 MeV deuterium beam into a beryllium target. The anticipated neutron production will be on the order of 1010 n/s in 4π sr, with future upgrades expected to increase neutron production to 1011 n/s. Neutron energy will be up to 9 MeV with peak emission at ∼5 MeV. Shielding and moderation will be provided by a large water tank surrounding the target, with exit ports to allow moderated neutrons to be directed to experiments. The thermal-neutron flux at the exit of the extraction ports is anticipated to be up to 106 n/cm2/s. The CANS will be used to forward the activities of the group in the area of neutron-activation analysis, in addition to a broader range of neutron related applications.

Characterization of indigenous OSL phosphors LiCaAlF6:Eu,Y and α-Al2O3:C for space dosimetry

The possibility of using indigenously synthesized Optically Stimulated Luminescence (OSL) phosphors, α-Al2O3:C and LiCaAlF6:Eu,Y is explored for application in space dosimetry. The dosimeters prepared using these phosphors were irradiated in BARC-TIFR Pelletron Accelerator facility with proton beam (8–20 MeV). The OSL properties with proton beam irradiation were compared with beta irradiation corresponding to 90Sr/90Y. No change in the OSL emission was found for both the phosphors when exposed to with low LET 90Sr/90Y beta (0.2 keV/μm) and high LET proton (2 keV/μm, 20 MeV). It was observed that Continuous Wave (CW) OSL signal decays faster with increasing LET of the proton beam for both types of dosimeters α-Al2O3:C and LCAF. The OSL dose response is linear for the high LET proton beam which is similar to the response obtained using low LET beta and gamma irradiation. The variation of OSL efficiency per unit fluence matches reasonably well with the theoretically calculated values of absorbed dose in water.

Revisiting band structures in 118Xe nucleus via in-beam γ-ray spectroscopy* *The authors are grateful for the pelletron and support staff of IUAC, New Delhi. We would also like to acknowledge the contribution of the INGA collaboration, which is partially funded by the Department of Science and Technology (DST, GoI; project no. IR/S2/PF-03/2003-I) and University Grants Commission (UGC). This work was

The neutron deficient Xe nuclei with A 120 are predicted to have strong octupole correlation at low spins. In the present study, an attempt was made to improve upon the level scheme and also to examine the signatures of octupole correlation in Xe via high spin γ-ray spectroscopy. High spin states in Xe have been populated via the Nb(Si, p2n)Xe fusion-evaporation reaction at a beam energy of 115 MeV provided by the 15 UD pelletron accelerator facility at IUAC, New Delhi. In the experiment, seven new γ-transitions have been found and placed appropriately in the level scheme. A theoretical study using the triaxial projected shell model (TPSM) approach suggests that the first bandcrossing is due to the alignment of two neutrons, and a parallel band tracking the yrast configuration is the γ-band built on the two-quasiparticle state. Enhanced E1 transition rates measured between opposite parity bands involving νh and ν d orbitals having Δj = Δl = 3 indicate the presence of octupole correlation in this nucleus.

Effect of low energy cesium ion irradiation on vanadium oxide: Structural and spectroscopic study

Vanadium di-oxide (VO2) and vanadium tetra oxide (V2O4) powders are exposed to cesium (Cs) ion irradiation using Pelletron accelerator. The energy of the Cs ions ranges from 0.2 keV to 5 keV. Mass spectroscopic data from the accelerator is plotted for various energy ranges. Un-irradiated samples and Cs ion irradiated samples are characterized by using x-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectroscopy and four-point probe method. XRD analysis showed improved VO2 crystallinity after ion irradiation. The V2O4 sample shows amorphous behavior after ion irradiation. Dislocation density and tolerance are calculated to explore structure distortion after ion irradiation. Raman spectroscopy reveals vibrational and rotational modes of bonding with oxygen and vanadium. SEM results explain the reduction in agglomeration after Cs ion irradiation. The resistivity of un-irradiated and irradiated (VO2 and V2O4) samples is calculated by four-point probe method. The resistivity of vanadium oxide is decreased after Cs ion irradiation to make it a potential candidate for optoelectrical applications.

Coulomb explosion of BeO− molecular ions – Revisited

Accelerator mass spectrometry (AMS) measurements of 10Be almost invariably utilize the BeO- molecular negative ion. Molecular ions experience the process of ‘Coulomb explosion’ when dissociated by a stripper in the high-voltage terminal of a tandem accelerator, resulting in energy and angular spread of the subsequently-accelerated positive ions. In this paper, the phenomenon is studied in detail for both foil and gas stripping of BeO, using the 14UD pelletron accelerator at the Australian National University operating at 8.5 MV. In a companion paper by Suter et al. [1], a model is developed to interpret, inter alia, these results.

Present status of the YU-AMS system and its operation over the past 10 years

In 2009, Yamagata University installed a compact 14C accelerator mass spectrometry (YU-AMS) system and an automated graphitization line. The YU-AMS system is based on a 0.5 MV pelletron accelerator (1.5SDH-1) developed by National Electrostatics Corporation (NEC). A second automated graphitization line and an additional ion source of the YU-AMS system were installed in 2014. Approximately 2,000 samples have been measured per year using the system since 2010. The long-term stability of the system from 2010 to 2021 was assessed by measuring the IAEA-C6 and IAEA-C7 standard samples graphitized by the automated graphitization line.

Status report: A decade of traditional radiocarbon dating applications by DirectAMS

DirectAMS debuted as an affordable, high-throughput radiocarbon dating service at AMS-12 in 2011. A dedicated pretreatment laboratory has been in operation since 2012 in conjunction with an NEC 1.5SDH-1 Compact Pelletron Accelerator Mass Spectrometer installed in 2006. Over 60,000 14C radiocarbon dating targets have been measured over the last decade. The status of the laboratory and performance from routinely measured standard, reference, and blank materials are presented.

Development of a Pelletron-based compact neutron source

The Applied Nuclear Physics Group at Lund University is constructing a prototype CANS (Compact Accelerator-driven Neutron Source). The CANS is based around a 3 MV, single-ended, Pelletron accelerator, which is used to impinge a 2.8 MeV deuterium beam into a beryllium target. The anticipated neutron production will be on the order of 1010 n/s in 4π sr. A further upgrade to the ion source of the Pelletron is expected to increase neutron production to 1011 n/s. Neutron energies will be up to 9 MeV with peak emission at ∼5 MeV. Shielding and moderation will be provided by a large water tank surrounding the target, with three exit ports to allow neutrons of different energies to be directed to experiments. The design is supported by simulation results which predict fast-neutron fluxes of 9×104 to 5×106 n/cm2/s, and thermal-neutron fluxes of 1×104 to 5×104 n/cm2/s to be readily obtainable with a 10 µA deuteron beam.

Ion Implantation in the Form of Layers: A Novel Method to Surface Properties

In this study, a novel method was adopted to tailor the surface properties of iron. We attempted to increase the degradation rate of iron by H-induced damaging. Equal number of H ions were implanted in four samples using a 2MV Pelletron accelerator. But the ion distribution was varied in the iron matrix by adding H ion layers in successively increasing depths. Interesting outcomes, contrary to our assumption were observed. The open-circuit potential was observed to shift toward a stable side. The Tefal plot also revealed improved corrosion potential and decreased corrosion current by adding H layers. Crystallographic studies revealed improved crystallinity and a small shift in preferred orientation of crystal growth.

Investigation of 500 keV Si ion induced surface structuring of Ni and Ti for enhancement of field emission properties

The present paper reports the investigation of surface morphology, elemental composition, phase changes and field emission properties of Si ion irradiated nickel (Ni) and titanium (Ti). The Ni and Ti targets have been irradiated with 500 keV Si ions generated by Pelletron accelerator at various fluences ranging from 6.9 × 1013 to 77.1 × 1013 ions/cm2. Stopping range of ions in matter analysis revealed higher values of electronic stopping and sputtering yield for Ni as compared with Ti. For both irradiated metals, electronic energy loss dominant over the nuclear stopping. The growth of induced surface structures have been analysed by using field emission scanning electron microscopy (FESEM) analysis. In case of Ni, as the ion fluence increases from 6.9 × 1013 to 65.8 × 1013 ions/cm2, the formation of spherical particulates, agglomers and sputtering is observed. Although in the case of Ti, with the increase of Si ion fluence from 11.6 × 1013 to 77.1 × 1013 ions/cm2, the formation of irregular‐shaped particulates along with crater and sputtered channels is observed. X‐ray diffraction (XRD) analysis shows that no new phase is identified. However, a significant increase in peak intensity is observed with increasing ion fluence. The variation in crystallite size and dislocation line density is also observed as a function of Si ion fluence. Fourier transform infrared spectroscopy analysis shows that no bands are formed after the Si ion irradiation. Field emission properties of ion‐structured Ni and Ti are well correlated with the growth of surface structures observed by SEM and dislocation line density evaluated by XRD analysis.

Mathematical Modeling and Optimization of Low Energy Beam Line in 2MV Pelletron Accelerator

The 2 MV 6SDH-2 tandem pelletron accelerator installed at CASP, GC University Lahore has evolved over the past years from acceptance tests to an extremely reliable and convenient research tool in the field of particle accelerator physics, hav-ing capability of providing variety of ion beams from few keV to several MeV in energy. Many electrostatic and magnetic devices are employed to steer an ion beam in an accelerator system all the way from ion source to experimental setup. Mathematical modeling and optimization of low energy beamline has been done for this accelerator. Several ion optics and steering devices are provided in the pre-acceleration beamline for ion beam manipulation and in order to optimize the overall beam transmission. As the quality of the beam from the accelerator depends upon the design of these electrostatic and magnetic devices, optimum settings are derived by manually adjusting voltages and currents provided to low energy beam-line components. From these calibrations and optimization measurements, calculations has been done for mass analysis magnets, steering and focusing components and the results has been represented. From the results, it has been found that there exists a complex relationship between the effects of different voltages and currents in order to tune the desired output current and beam profile at the end-stations. Details of experiments and data analysis are presented.

The prototyping of a high-resolution neutron activation analysis system – based on a Pelletron accelerator and fast pneumatic sample-transport

A new neutron activation analysis system is currently being designed at Lund University. The design incorporates a compact accelerator driven neutron source, based on a 3 MV Pelletron accelerator and a pneumatic sample conveyor to transport samples from the neutron source to a measurement station consisting of an array of high-purity Ge γ-ray detectors. A prototype for this new station is currently in operation, with a Genie 16 SODERN neutron generator used in place of the compact accelerator driven neutron source. Preliminary results from the prototype system are presented, alongside qualitative analysis supported by simulations performed in FISPACT-II. The system has been tested with the measurements of Al and In foils, using a PLA sample holder. The results demonstrate that activation products with half-lives of as little as 2 s can be measured. γ-rays from the 2 s isomer, 116n In are clearly observed providing the irradiation and measurement times are appropriately chosen.

Structural, surface and optical investigations of Cu+ implanted NiO film prepared by reactive sputtering

Nickel oxide (NiO) films were deposited on silicon substrate using a DC magnetron sputtering system. The deposited films were annealed at 400 °C for 2 h and then irradiated by 500 keV copper ions (Cu+) in the dose range of 1 × 1011 to 1 × 1014 ions-cm−2 using Pelletron Accelerator. X-ray diffraction study revealed NiO and Ni phases in the films corresponding to (111) and (200) planes. The lattice parameter was increased with the increase of ion dose to 1 × 1012 ions-cm−2 and then decreased at the higher doses. Ion irradiation at 1 × 1011 ions-cm−2 improved the crystallinity of the film while at the higher doses, the crystallinity was decreased. The surface morphology of the films showed a decrease in the compactness of the granular structure with increasing the ion dose. Fourier Transform Infrared spectroscopy showed Cu–O and Ni–O stretching vibration peaks in the irradiated films. X-ray photoelectron spectroscopy (XPS) results revealed a decrease in NiO and increase in the Ni+3Ni+2 ratio with an increase of the ion dose to 1 × 1012 ions-cm−2, demonstrating an increase in the Ni vacancies in the film at lower doses. The depth-resolved XPS analysis displayed a change in the Ni and O atomic percentages in the film with the increase of the etching time from 50 to 250 s and validated the existence of metallic Ni in the NiO film. The photoluminescence (PL) spectra analysis showed a decreasing trend in the band gap of the NiO film irradiated up to 1 × 1012 ions-cm−2, then an increasing trend at the higher doses.

Isomeric state in the odd-odd 68Ga nucleus

The half life of the 7− isomeric state of the odd-odd 68Ga nucleus was measured using a particle-γ delayed coincidence technique. The 68Ga nuclei were produced using the fusion-evaporation reaction 55Mn(16O,2pn)68Ga at 55 MeV incident beam energy. The beam was produced by the 8 MV Pelletron accelerator of the Nuclear Physics Open Laboratory of the University of São Paulo. The half life was measured using the Isomeric State Measurement System (SISMEI). The obtained value was 60.83(25) ns, compatible with previous measurements. The 68Ga excited states were well described with the Large Scale Shell Model using the JUN45 residual interaction.

Cross-sections for production of [formula omitted] by quasi-monoenergetic neutrons within 7-20 MeV

The measurement of cross-sections producing In115m has been carried out within the energy range of 7–20 MeV. The neutron activation analysis (NAA) followed by off-line γ-ray spectrometry have been used for the purpose. The quasi-monoenergetic neutron beam was produced using the Li(p,n)7 reaction at the 14UD BARC-TIFR Pelletron accelerator facility at Mumbai, India. The ratio technique of covariance analysis has been used to estimate the uncertainty and correlation between the current experimental data which considers the collective uncertainty from all the attributes in the measurement. The measured cross-sections were compared with the experimental data from the previous literatures, different evaluated data libraries such as ENDF/B-VIII.0, JEFF-3.3, JENDL-4.0, CENDL-3.2 and the theoretically predicted results using the TALYS 1.95 and EMPIRE 3.2.3. The experimental results presented in this work are crucial for the measurement of neutron flux in the NAA technique.

Investigations of N+-ion implanted polymethylmethacrylate for flexible electronics

The samples of Polymethylmethacrylate (PMMA) have been implanted with 700 keV N+-ions at different fluences ranging from 3 × 1013 to 5 × 1014 ions/cm2 using Pelletron accelerator. The modifications in structural, electrical, morphological and optical properties of implanted polymer are examined using Raman spectrometer, Four probe technique, scanning electron microscope and UV–visible spectrometer, respectively. Raman spectroscopic analysis confirms the formation of carbonaceous structures at relatively lower fluence ≥2 × 1014 N+/cm2. The formation of carbonaceous network results in enhancement of conductivity of a PMMA sample from 2.14 × 10−10 to semiconducting regime (1.06 × 10−6 S/cm). The microscopic images show surface modifications in terms of ion-induced cracks, pores and wrinkles with increasing ion fluence. The optical bandgap reduces from 3.18 to 2.97 eV after implantation at 5 × 1014 ions/cm2. Moreover, the Urbach energy, photoconductivity and refractive index are found to increase with increasing ion fluence. The combination of increased electrical conductivity and reduced optical band gap energy makes PMMA a promising candidate for flexible electronics.

Ion beam activation of natCu, natTi, natNi and measurement of product formation cross sections at low energy (<10 MeV)

Abstract In this study we investigated the production cross sections of natCu(p, x)63,65Zn, natTi(p, x)48V, natNi(p, x)55Co,61Cu and natCu(α, x)66,67,68Ga, natTi(α, x)49,51Cr, natNi(α, x)63,65Zn reactions in the low energy range using the foil activation technique. The samples were activated in vacuum at 5 MV tandem (Pelletron) accelerator installed at National Centre for Physics (NCP), Islamabad, Pakistan. The reaction products were identified with the help of off-line gamma ray spectroscopy system connected with Genie 2000 software. The data analysis revealed the production of different radioisotopes that have valuable importance in monitoring charged-particle beams and medical applications. The measured results were verified by comparing them with earlier evaluated data as well as with the theoretical values given in the TENDL-library based on TALYS-1.9 code calculations.

Ion Beam Effect on the Structural and Optical Properties of AlN:Er

Erbium (Er)-doped Aluminum Nitride (AlN) thin films were deposited and fabricated on Si (100) and Si (111) substrates in a Nitrogen atmosphere using the plasma magnetron sputtering technique. The deposited and fabricated thin films were thermally annealed at 900 °C in Argon (Ar) atmosphere. The samples were irradiated with protons at a dose of 1 × 1014 ions/cm2 which carried an incident energy of 335 keV, using a tandem pelletron accelerator. Rutherford backscattering spectroscopy (RBS) and X-ray diffraction (XRD) were used for the stoichiometric and structural analysis of the films, while Fourier transforms infrared spectroscopy (FTIR) was performed to track the changes in the optical characteristics of thin films before and after the ions’ irradiation and implantation. The irradiation has affected the optical and structural properties of the films, which could be exploited to use the AlN:Er films for various optoelectronic and solid-state device applications.