Laser Isotope Separation Research Articles

Laser enrichment of the 62Ni isotope for betavoltaic devices

We have studied the laser isotope separation of the 62Ni isotope using a three-step ladder type photoionization scheme. Using density matrix formalism, optimum conditions for the efficient separation of the 62Ni isotope have been derived. The optimum bandwidth of the excitation lasers has been found to be 200 MHz, 1200 MHz, and 1200 MHz for the enrichment of the 62Ni isotope. It has also been shown that it is possible to produce 75 mg/day of 90% enriched 62Ni using the optimized experimental operating parameters derived in this work. Upon irradiation of this enriched 62Ni isotopic mixture, it is possible to produce ∼19mg/day of the 63Ni isotope, which is sufficient to manufacture a 100 µW betavoltaic device each day.

Theoretical investigations on the laser isotope separation of 175Yb for medical applications

The possibility of laser isotope separation of 175Yb from irradiated natural Yb has been investigated. The optimum process parameters such as powers and bandwidths of the lasers, Doppler broadening and the number density of the atoms have been derived through density matrix calculations. It has been shown that it is possible to produce 175Yb (>42% enriched) at a production rate of 62 μg/hour (or 1.5 mg/day). This corresponds to the production rate of 1350 patient doses (of 7.4 GBq each) per day. The radionuclidic purity of the isotopic mixture is expected to be 99.9999%. The method is highly suitable for the countries having only low-flux nuclear reactors.

Numerical study of the laser isotope separation of optically pumped 102Pd

The feasibility of laser isotope separation of 102Pd through pulsed laser optical pumping followed by isotope selective photoionization has been studied through density matrix formalism. The effect of various parameters such as bandwidth of the excitation lasers, intensity of the lasers and Doppler broadening of the atomic ensemble on the efficiency of optical pumping and isotope selective photoionization have been evaluated. The optimum number density in the laser-atom interaction region has been derived from the studies of the effect of charge exchange collisions on the degree of enrichment. It has been shown that it is possible to enrich 102Pd up to ~ 23.7% at a production rate of 1.1 mg /h. The achievable degree of enrichment through this photoionization scheme is higher than the previously reported laser isotope separation process. The radionuclidic purity of the irradiated enriched mixture has been found to be suitable for medical applications.

Laser isotope separation of 203Tl through pulsed laser optical pumping

Isotope separation of 203Tl through pulsed laser optical pumping into the 6s26p2P3/2∘ meta-stable state, followed by pulsed laser ionization, has been theoretically studied through density matrix formalism. The efficiency of the isotope separation process has been compared with the cw laser optical pumping followed by pulsed laser photoionization reported earlier. The effect of peak power density, bandwidth and number density of atoms on the degree of enrichment and the production rate has been systematically studied. The optimum parameters for the efficient laser isotope separation 203Tl have been derived. It has been shown that using this method, it is possible to produce about 1.5 kg/y of 203Tl isotope enriched to 90%.

Ion-collection characteristics of photoplasma for atomic vapor laser isotope separator module in electrostatic fields

The laser-based isotope separation process is currently pursued to enrich precursor medical isotopes like lutetium-176 and ytterbium-176. India has successfully produced radionuclide lutetium-177 for clinical use by neutron activation. Atomic vapor laser isotope separation (AVLIS) is used as the enrichment technology. Understanding the physics and technology of processes, like atomic-beam generation, photoplasma production, and ion collection, is essential to designing any AVLIS module. So, a stand-alone research facility was developed before the production plant. This article describes the facility and the experimental and theoretical studies of ion collection in electrostatic fields using barium as the working element. Two types of ion extractors, plate–photoplasma–plate and plate–photoplasma–grid–plate, were designed and fabricated. A model of photo-ion collection in these electrostatic ion extractors was arrived at. Scaling of the initial photo-ion densities and the electric fields is crucial to photoplasma evolution spanning single-particle to collective regimes. Estimates of ion-collection rates of the Indian AVLIS modules for lutetium-176 and ytterbium-176 were carried out. By invoking plasma physics, the technological aspect of producing enriched isotopes was solved by judiciously integrating the atom source, laser system, photoplasma, and ion-extractor geometries. Limitations of the electrostatic ion extractors were also flagged.

Theoretical investigations of population trapping phenomena in atomic four-color, three-step photoionization scheme

The four-color three-step selective photoionization process of atom is very important in laser isotope separation technology. The population trapping phenomena and their influences are studied theoretically in monochromatic and non-monochromatic laser fields based on the density matrix theory in this work. Time evolutions of the photoionization properties of the four-color, three-step process are given. The population trapping effects occur intensely in monochromatic excitation, while it gradually turns weak as the laser bandwidth increases. The effects of bandwidth, Rabi frequency, time delay, and frequency detuning on the population trapping effect are investigated in monochromatic and non-monochromatic laser fields. The effects of laser process parameters and atomic parameters on the effective selective photoionization are also discussed. The ionization probability and selectivity factors, as evaluation indexes, are difficult to improve synchronously by adjusting systematic parameters. Besides, the existence of metastable state may play a negative role when its population is low enough.

Need for enrichment of lutetium isotope and design of a laser based separator module

Lutetium-177 radio-pharmaceutical has become an important theranostic candidate in cancer treatment. Its availability from bench-to-bed requires strategic implementation of isotope-enrichment, neutron-irradiation and radio-chemical techniques. In this paper, the need for enrichment of lutetium-176 is emphasized by estimating specific activity of lutetium-177 as a function of enrichment percentage for typical neutron flux available at Dhruva reactor, India. A novel Atomic Vapour Laser Isotope Separation (AVLIS) module for lutetium-176 enrichment is designed to meet the above requirement. The paper documents its characteristics and production estimates. The design is carried out after critical assessment and evaluation of available AVLIS-infrastructure in the country. Outline of lutetium-177 enrichment, capable of producing non-carrier-added lutetium is also provided. This work concludes that India has taken a step forward towards self-reliance (Atmanirbhar Bharat) in securing the supply chain of lutetium-177.

Laser isotope separation to study for the neutrino-less double beta decay of 48Ca

The laser isotope separation (LIS) system is being developed for the study of neutrino-less double beta decay of 48Ca. A proof-of-principle experiment has been successfully conducted, and development of a mass production (∼1 mol/year) system is currently underway. For stable and efficient production, we are preparing an atomic beam system capable of producing a well-collimated beam with sufficient flux and a high-power semiconductor laser system with stable frequency over a long period of time.

Laser isotope separation of 223Ra

A three-step photoionization has been theoretically studied for the laser isotope separation of 223Ra through the following photoionization scheme. 7s21S00.0cm-1→714.3185nm7s7p3P1o13999.3569cm-1→784.0270nm7s8s3S126754.02cm-1→558/581nmAutoionization State→Ra+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\begin{aligned}7s^{2} {}^{1}S_{0} \\left( {0.0 \\;{\ ext{cm}}^{ - 1} } \\right)\\xrightarrow{{714.3185\\;{\ ext{nm}}}} 7s7p\\;{}^{3}P_{1}^{o} \\left( {13999.3569\\;{\ ext{cm}}^{ - 1} } \\right) \\xrightarrow{{784.0270\\;{\ ext{nm}}}}\\\\7s8s\\;{}^{3}S_{1} \\left( {26754.02 {\ ext{cm}}^{ - 1} } \\right) \\xrightarrow{{558/581\\;{\ ext{nm}}}} {\ ext{Autoionization State}} \ o {\ ext{Ra}}^{ + }\\end{aligned}$$\\end{document} The effect of bandwidth, peak power density of the excitation and ionization lasers, Doppler broadening of the atomic ensemble, number density of the atoms, and charge exchange collisions on the laser isotope separation process has been studied. The optimum system parameters for the separation of 223Ra through this photoionization scheme have been derived. The effect of unknown parameters on the degree of enrichment has also been discussed. It has been theoretically shown that it is possible to produce 223Ra isotope with 98.5% radio-isotopic purity at a rate of 0.74 μg/h corresponding to the production rate of 435 patient doses per hour. This is the first ever study on the laser isotope separation of Radium isotopes.

Laser isotope separation of 192Ir

The following two-step isotope selective photoionization process has been studied for the separation of 192Ir isotope from natural Iridium irradiated in a medium flux reactor for 28 days.5d76s2F9/240.0cm−1→247.5871nm5d76s6p40389.83cm−1J=9/2→307.9nmIr+Density matrix formalism has been used for the investigation of laser isotope separation process. Optimum system parameters such as peak power densities of the excitation and ionization lasers, bandwidth of the excitation laser, angular divergence limit to the atomic ensemble have been derived. Effects of number density and ion travel distance prior to collection on charge exchange probability have also been studied. It has been shown that it is possible produce ∼98% enriched 192Ir at rate of 82 μg/h (27.9 GBq/h or 0.76 Ci/h) which can provide activity of 334 TBq/g or 9027 Ci/g. The enriched 192Ir can be used in both high-dose brachytherapy and high speed radiography. This is the first ever study on the laser based enrichment of Iridium isotopes.

Molecular laser isotope separation of 13C isotope by multi-photon dissociation of CF2HCl molecules with CO2 Laser

در این پژوهش، برای نخستین بار در کشور، جداسازی لیزری ایزوتوپ C13 از راه گسست چندفوتونی ایزوتوپ- گزین مولکول‌های گاز HCl2CF در مقیاس آزمایشگاهی به انجام رسید. برای این کار، تپ‌های یک لیزر 2TEA CO کوک‌پذیر که با یک برش­گر پلاسمایی کوتاه‌سازی شده‌اند، با شاریدگی 2J/cm 50 درون اتاقک تابش‌دهی کانونی شدند. اتاقک تابش‌‌دهی نیز با فشار mbar 10-20 از گاز HCl2CF با نسبت‌های HCl: He2CF برابر 1:5 و 1:10 پر شده بود. نشان داده شد که فراوانی ایزوتوپ C13 در فرآورده‌ی گسست 4F2C با کاهش فشار گاز و شمار تپ‌های لیزری فرودی افزایش می‌یابد. در این آزمایش‌ها، بیشینه‌ی فراوانی ایزوتوپ C13 به‌دست آمده در آمیزه‌ی گازی با نسبت HCl: He2CF برابر 1:5 و فشار HCl2CF برابر mbar 10 به‌دست آمد که با 1500 تپ لیزری با شاریدگی 2J/cm 50 تابش‌دهی شده بودند.

Numerical simulation of effect of carrier gas on flow state in laser isotope separation

The gas flow in the Condensation Repression by Isotope Selective Laser Activation (CRISLA) is modeled and computed with computational fluid dynamics method. The temperature and velocity distributions of jet flows formed by different gases through nozzle are obtained. Based on the analysis of simulation results, the carrier gas is selected out from the perspective of flow, beneficial to the improvement of isotope separation effect. Our results pave the way towards the follow-up research.

Isotope selective three-step photoionization of 174Yb

A three-step photoionization scheme has been theoretically studied for the laser isotope separation of 174 Y b from natural Yb using density matrix formalism. The effects of bandwidth and peak power density of lasers, Doppler broadening, and the number density of atoms on the degree of enrichment and production rate have been studied, and the optimum conditions for the efficient separation of 174 Y b have been derived. It has been shown that it is possible to enrich the 174 Y b isotope up to ∼ 90 % using lasers with a bandwidth of 500 MHz with a production rate up to 48 mg/h. On the whole, the system required for the laser isotope separation of 174 Y b is much simpler than that required for the separation of any of the 176 L u , 177 L u , and 176 Y b isotopes. 1 g of the enriched isotope mixture upon irradiation for 21 days in widely available low flux reactors produces 759 doses (7.4 GBq each) of 175 Y b radionuclide for peptide receptor radionuclide therapy (PRRT) with 98.6% radionuclidic purity. It is envisaged that the production of the 175 Y b isotope through this route will be economical and widely available to the public at large as a PRRT drug for cancer therapy.

Forensic signatures from laser isotope separation

This work introduces an analysis of the Atomic Vapor Laser Isotope Separation (AVLIS) process to assist regulatory agencies in detecting and inspecting uranium AVLIS facilities. Operating parameters of a theoretical AVLIS device are calculated based on product and tails assays. Further analysis shows a direct relationship between feed assays of minor isotopes and product assays, allowing inspectors to confirm the method of a sample’s enrichment and identify the feedstock origin due to natural variations in 234U assay. The decay of 234U into 230Th is used to estimate the time of last enrichment and increase the accuracy of feed assay calculations.

Isotope selective three-step photoionization of 177Lu

A 540-535-618 three-step photoionization scheme has been theoretically investigated for the laser isotope separation of 177 L u through density matrix formalism. Equations of motion for the three-step photoionization of odd isotopes have been derived. The effects of Doppler broadening, bandwidth and peak power density of excitation lasers, number density of atoms on the degree of enrichment of 177 L u and production rate have been studied. Optimum conditions for the laser isotope separation of 177 L u for the cases of initial abundances corresponding to the irradiation of natural Lu in low, medium, and high flux reactors have been derived. Under optimum conditions, the production rates of 177 L u in ranges of 0.87, 14.5, and 92.5 mg/h can be achieved with degrees of enrichment of 66%, 97%, and 100%, respectively, for the cases of initial abundances corresponding to the irradiation of natural Lu in low, medium, and high flux reactors. It has also been shown that the content of 177 m L u in the enriched isotope mixture will be in the range of 10 − 2 % to 10 − 4 % . This provides a comprehensive solution to the application of 177 L u for cancer therapy.

Numerical studies of atomic three-step photoionization processes with non-monochromatic laser fields

The atomic selective multi-step photoionization process is a critical step in laser isotope separation. In this work, we study three-step photoionization processes with non-monochromatic laser fields theoretically based on the semi-classical theory. Firstly, three bandwidth models, including the chaotic field model, de-correlation model, and phase diffusion model, are introduced into the density matrix equations. The numerical results are compared with each other comprehensively. The phase diffusion model is selected for further simulations in terms of the correspondence degree to physical practice. Subsequently, numerical calculations are carried out to identify the influences of systematic parameters, including laser parameters (Rabi frequency, bandwidth, relative time delay, frequency detuning) and atomic Doppler broadening, on photoionization processes. In order to determine the optimal match among different systematic parameters, the ionization yield of resonant isotope, and selectivity factor are adopted as evaluation indexes to guide the design and optimization process. The results in this work can provide a rewarding reference for laser isotope separation.

Coherent kinetics of a multistage λ scheme for laser isotope separation

Analytical solutions of the Schr?dinger equations for coherent excitation of an atom in the scheme of two- and three-stage photoionization are obtained as applied to the problem of laser isotope separation. A feature of the study is the introduction of laser excitation from an additional initial state to increase the fraction of the atoms involved in the separation process. The optimal from the points of view of photoion ratios of radiation intensities at individual photoionization stages are found. Key words: laser photoionization, laser isotope separation.

Dysprosium enrichment and collection using AVLIS in Brazil: Preliminary results

Rare Earth elements (RE) play an important role in the high-tech industry. Displays, fine electronic devices, sensors, optoelectronics, and many other fields rely on the use of these elements to deliver the technology we depend on. The possibility of improving the capacity of all these applications is attractive and there are a few ways to achieve that, one of them is to purify the REs to get only one isotope. Given that, one of the few techniques able to separate RE isotopes is the Atomic Vapor Laser Isotope Separation (AVLIS) which is the technique used in the Brazilian facility for isotope separation via laser. In this work we are going to show the latest results on the Brazilian AVLIS applied to enrich dysprosium. As a preliminary result, it was observed an enrichment by means of a mass spectrometer coupled to the experimental setup and a thin film was collected with an enrichment factor of 1.37 (163Dy).

Development of the laser isotope separation method to study for the neutrino-less double beta decay of 48Ca

Search for the ultra-rare process, neutrino-less double beta decay, is a powerful tool to test the Majorana nature of neutrinos. Among the potential double beta decay nuclei, 48Ca has the largest Q-value, hence we can expect the measurement with least background. On the other hand, due to its low natural abundance, isotope enrichment is essential to achieve the sensitivity in the region of interest (inverted/normal mass hierarchy of neutrinos).We have been developing a laser isotope separation method using a tunable semiconductor laser that can excite only a specific isotope (48Ca). The laser is irradiated perpendicular to the collimated calcium vapor beam. Only 48Ca atoms are separated by deflecting them from the original atomic beam by momentum transfer due to multiple absorption and emission of laser photons. The isotope separation is confirmed by irradiating an ionization laser and time-of-flight measurement.Following the success of the proof-of-principle experiment, we are now developing the mass production system which include efficient generation of atomic beams, frequency-stabilized high-power laser, efficient laser irradiation method, and collection method of deflected isotope beams. In this paper, we report on the status and prospects of these developments.

Isotope selective three-step photoionization of 176Yb

Atomic vapor laser isotope separation of 176 Y b has been investigated through the density matrix analysis of laser–atom interactions in a three-step photoionization process. For the first time, to our knowledge, the method has been applied for both odd and even isotopes of Yb. The effects of peak power densities of the lasers, bandwidth of the excitation lasers, angular divergence, and number density of the atoms on the degree of enrichment have been studied. Peak power densities of the first, second, and third excitation lasers of 20, 20, and 40 , 000 W / c m 2 , respectively, and full angle divergence of the atomic beam of 120° were found to be optimum for the isotope separation of 176 Y b . The effects of resonant charge exchange collisions and atomic number densities on the degree of enrichment and production rates have also been studied. It has also been observed that the atomic number densities in the laser–atom interaction region should be limited to 1 × 1 0 12 a t o m s / c m 3 to obtain ∼ 90 % degree of enrichment of the 176 Y b isotope. At higher number densities of 1 × 1 0 13 a t o m s / c m 3 , the degree of enrichment decreases to 43.9%. The optimum range of bandwidths of excitation lasers is found be 90–120 MHz. At optimum conditions, the computed production rate of 22 mg/h is in good agreement with the previously reported value of 20 mg/h.