Excitation functions of proton-induced nuclear reactions on124Xe: Production of123I

Highy enriched gaseous¹²⁴Xe /99.9%/ is used to perform instrumental measurements of excitation functions of the¹²⁴Xe/p, 2n/¹²³Cs and¹²⁴Xe/p, pn/¹²³Xe reactions up to the proton energy of 33 MeV. Differential and integral yields of¹²³I have also been determined /6.6 h after irradiation/.     

Neutron diffraction using an electron linear accelerator

The Harwell electron linear acceleratorhelios has been used for studying the crystal structures of polycrystalline materials by neutron diffraction. Atomic positions and atomic vibrational amplitudes can be determined equally well with the pulsed method as with the more conventional method employing a high-flux nuclear reactor as source. The powder pattern can be indexed more easily with pulsed neutrons.     

Development of a process for routine production of123I using the127I(p, 5n)123Xe→123I reaction

The object of this paper is to give details of a production method for¹²³I, now in routine use at Harwell. We employ the (p, 5n) reaction, irradiating a liquid target of di-iodomethane (CH₂I₂) spiked with additional iodine, with 58 MeV protons. A yield of ∼9 mCi/μAh is obtained; the only detectable radionuclidic impurity is¹²⁵I, present to the extent of ∼0.15% by activity at the time of separation of Xe from I.     

Ultra-low intensity electron beams of a linear accelerator for irradiation

Ultra-low intensity electron pulsed beams for irradiation have been developed by the use of the electron linear accelerator at Radiation Research Center of Osaka Prefecture University. The energy and the pulse width of the beams are about 4–12 MeV and 0.5–4 μs, respectively. The minimum beam charge has been estimated to be about several aC/pulse. These electrons are basically mono energetic, controllable, collimated and synchronized with the master oscillator of the accelerator, which are favorable features for various uses compared with β-ray sources. Especially, the system is suitable for evaluation of response of radiation detectors. In this study, the response of the TLD for high energetic electron irradiation was also evaluated by the use of these electrons.     

Production of123I using the CV-28 cyclotron at IPEN-CNEN/SP

These studies had the purpose of establishing the optimal conditions for the production of¹²³I through the¹²⁴Te (p, 2n)¹²³I reaction, using the CV-28 Cyclotron (E_max=24 MeV for protons) at IPEN-CNEN/SP. Two different targets (TeO₂ and TeO₂+2% Al₂O₃) were irradiated in order to check their physical resistance against beam current (up to 12 A) and length of irradiation (10 min — 2h), and to evaluate the recovery of the radioiodine produced, by a dry distillation process with a high frequency induction furnace. Later on, enriched¹²⁴TeO₂ (96.2%) targets were irradiated, and¹²³I was produced routinely with a production yield of (3. 31±0.07) mCi/Ah, 1.7% of¹²⁴I at EOB and radiochemically pure.     

Photon activation analysis of NIST SRM sediment sample using the electron linear accelerator at Pohang Accelerator Laboratory

Journal of Radioanalytical and Nuclear Chemistry - Photon activation analysis (PAA) of a sample of standard reference material 1646a (SRM 1646a) sediment sample was carried out using the...     

New irradiation system for photon activation analysis by electron linear accelerator

A more exact and reliable irradiation system for the photon activation analysis by the use of high power electron linear accelerator was originally designed and tested. Applications of a simple beam position monitor and a thin beryllium oxide ceramic disk in this system made possible to control the beam position on the center axis of sample during irradiation, and also permitted the reproducible irradiations in situ.     

Production of 99Mo and 64Cu in a mixed field of photons and neutrons in a clinical electron linear accelerator

Journal of Radioanalytical and Nuclear Chemistry - The medical isotopes 99Mo and 64Cu were produced via the dual routes of 100Mo(γ,n)99Mo + 98Mo(n,γ)99Mo and 65Cu(γ,n)...     

Experiences in the routine production of123I via the124Te(p, 2n)123I reaction with a low energy cyclotron

This paper deals with the results and experimental observations obtained in routine production of¹²³I via¹²⁴Te(p, 2n)¹²³I reaction, using the low energy cyclotron (protons, E_max=22 MeV) at the German Cancer Research Center in Heidelberg. The reaction was studied during the past 4 years using¹²⁴TeO₂ targets with various levels of enrichment. The purpose of the study was to determine which target material provided the highest quality and most economical production of¹²³I. A viable routine production was defined as one in which¹²³I could be conveniently and reproducably prepared in reasonable purity while maintaining a low cost for the entire process. Different methods of sublimation of¹²³I activity from the¹²⁴TeO₂ target were examined to determine the optimal conditions for recovery of radioactivity and recycling of target material. A rapid method is described which permits quantitative separation of¹²³I while allowing only a negligible loss of¹²⁴TeO₂.     

Production of iodine-124

Iodine-124 is produced in high yield by the¹²⁴Te/d, 2n/¹²⁴I reaction and >99.5% radionuclidic purity at 48 h post irradiation. The production yield was 0.55±0.06 mCi/Ah. Radiochemical separation and targetry methodology are described.For earlier papers in this series see: R.M. Lambrecht and M. Sajjad, Radiochimica Acta /in press/.     

Separation and purification of 99mTc from 99Mo produced by electron linear accelerator

The medical radionuclide ⁹⁹Mo was produced by the ¹⁰⁰Mo(γ,n) reaction using bremsstrahlung photons generated by an electron linear accelerator. The amount of ⁹⁹Mo produced was compared to that predicted by calculation using the particles and heavy ion transport code system. From the ⁹⁹Mo produced, highly pure ^99mTc was separated using the so-called technetium master milker, and the chemical yield of ^99mTc was 83–99 %. The installation of a new complex using this method and the electron linear accelerator with the preferable specification was suggested, and a possibility to supply the demand of ^99mTc was discussed and shown.

     

Decomposition of PCBs in transformer oil using an electron beam accelerator

Decomposition of PCBs in commercially used transformer oil used for more than 30 years has been carried out at normal temperature and pressure without any additives using an electron beam accelerator. The experiments were carried out in two ways: batch and continuous pilot plant with 1.5 MeV of energy, a 50 mA current, and 75 kW of power in a commercial scale accelerator.The electron beam irradiation seemed to transform large molecular weight compounds into lower ones, but the impact was considered too small on the physical properties of oil. Residual concentrations of PCBs after irradiation depend on the absorption dose of the electron beam energy, but aliphatic chloride compounds were produced at higher doses of irradiation. As the results from FT-NMR, chloride ions decomposed from the PCBs are likely to react with aliphatic hydro carbon compounds rather than existing as free radical ions in the transformer oil. Since this is a dry process, treated oil can be used as cutting oil or machine oil for heavy equipment without any additional treatments.     

Analysis of low-level 129I in brine using accelerator mass spectrometry

An improved solvent extraction procedure for iodine separation from brine samples has been applied at Xi’an Accelerator Mass Spectrometry (AMS) center. Oil in the brine sample has to be removed to avoid appearance of the third phase during solvent extraction and to improve the chemical yield of iodine. The small amount of oil remained in the water phase was first removed by phase separation through settling down sufficiently based on their immiscibility, and then by filtration through a cellulose filter, on which oil was absorbed and removed. After oil removed, extraction recovery of iodine could achieve more than 90 %. The sodium bisulfite as an effective reductant should be added before acidification to avoid loss of iodine by formation of I₂ in sample via reaction of iodate and iodide at pH 1–2, and then pH was adjusted to 1–2 to reduce the iodate to iodide followed by oxidation of iodide to I₂ and solvent extraction to separate all inorganic iodine. As a pre-nuclear era sample, ¹²⁹I/¹²⁷I ratio in brine is normally more than two orders of magnitude lower than that in present surface environmental samples, so prevention of cross-contamination and memory effect in apparatus during processing procedure are very critical for obtaining reliable results, and monitoring the procedure blank is very important for analytical quality of ¹²⁹I. The ¹²⁹I/¹²⁷I isotopic ratio in the brine samples and procedure blank of iodine reagents were measured to be (1.9–2.7) × 10^?13 and 2.08 × 10^?13, respectively, 3–4 orders of magnitudes lower than that in environmental samples in Xi’an, and the result of procedure blank is in the same level as the previous experiments in past 3 years, indicating contamination is not observed in our method.     

Hyperfine structure of some near-infrared Xe I and Xe II lines

This work reports on the experimental determination of the hyperfine splitting of the Xe I lines at 828.01 nm and 834.68 nm and the Xe II line at 834.72 nm. Measurements were performed by means of Doppler-free saturation spectroscopy in a low-pressure radio-frequency discharge. The absolute wavelength of all hyperfine components is obtained by way of a high-precision wavemeter backed-up with the absorption spectrum of the NO₂ molecule. We provide an accurate estimate of hyperfine constants for the lower level of the Xe II transition at 834.72 nm. The two Xe I transition outcomes of our experimental study are compared with data available in the literature.     

Cell inactivation studies on yeast cells under euoxic and hypoxic condition using electron beam from microtron accelerator

In the case of sparsely ionizing radiation such as electron, the dose rate and the pattern of energy deposition of the radiation are the important physical factors which can affect the amount of damage in living cells. In the present study, the differences in the cell survival efficiency and dose rate effect in diploid yeast strains Saccharomyces cerevisiae X2180 and Saccharomyces cerevisiae D7 under euoxic and hypoxic condition have been quantified. Irradiation was carried out using 8 MeV pulsed electron beam from Microtron accelerator. The dose per pulse and pulse width of the beam used was 0.6 Gy and 2.3 μs, respectively, which correspond to an instantaneous dose rate of 2.6 × 10⁵ Gy s⁻¹. For survival studies doses were delivered at a rate of 50 pulses per second (an average dose rate of 1,800 Gy s⁻¹). Fricke and alanine dosimeters were used to measure the dose delivered to the sample. A significant difference in the dose response has been observed under euoxic and hypoxic condition. Dose rate effect has been studied by changing the pulse repetition rate of the Microtron and the dose rate used was from 180 to 1800 Gy min⁻¹. A significant dose rate effect was observed under euoxic condition for Saccharomyces cerevisiae X2180 but the same was absent under hypoxic condition. The dose rate effect was absent for Saccharomyces cerevisiae D7 under both irradiation condition. The survival curves are found to be sigmoidal in shape under both condition but with a wider shoulder under hypoxic condition. The D₀ value and the Oxygen Enhancement Ratio (OER) at that point have been derived.