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223Ra is one of the most promising $$\alpha$$ -particle emitters for targeted radionuclide therapy. In this work, the possibility of producing 223Ra by neutron irradiation of 226Ra in Dhruva Reactor at Bhabha Atomic Research Centre, India has been studied. A Bateman equation solver has been developed and used to calculate the activity yield of 227Ac for various combinations of irradiation and cooling periods. Based on this analysis, optimum time of irradiation and cooling have been estimated for maximizing the activity of 227Ac while keeping the activity from other unwanted nuclides as small as reasonably possible.

Rhenium-186 [t½ = 3.7 d, 1.07 MeV β−-particles, 137 keV γ-ray] is an emerging radioisotope which holds tremendous potential in preparation of theranostic radiopharmaceuticals. This radioisotope was produced in a no-carrier-added form by irradiation of enriched 186W target via 186W(p, n) 186Re reaction in a pelletron. A facile radiochemical separation procedure based on selective solvent extraction in methylethyl ketone medium followed by column chromatography using mesoporous alumina sorbent has been developed to obtain 186Re in a form suitable for radiopharmaceutical preparation. This approach is expected to promote widespread utilization of this radioisotope for the benefit of cancer patients.

The recently observed ferroelectricity in thin films of pure and doped Hafnium oxide (HfO2) has initiated a sustaining effort to stabilize its ferroelectric phase which is the polar orthorhombic (o) phase with space group Pca21. This polar o-phase of the oxide does not appear in its phase transition sequence and is also not thought to be stabilized in bulk oxide. Here, we report the stabilization of three o-phases of this oxide in bulk with space groups Pbca, Pca21 and Pbcm in presence of Yttrium (Y) dopant. For inducing o-phase, 10 at% of Y-dopant has been used and temperature mediated phase transformation from monoclinic (m) to o-phase has been observed. The third o-phase with space group Pbcm could be stabilized for the first time in bulk oxide by Y-dopant. All the o-phases in presence of m-phase could be identified by Time Differential Perturbed γ-γ Angular Correlation (TDPAC) Spectroscopy. The TDPAC parameters assigned to Pbcm phase confirm the theoretical modelization for the phase performed by Wien2K calculation based on Density Functional Theory (DFT). The present work reports the possibility of stabilizing different o-phases including polar one and shows the widening of scope of this oxide for future ferroelectric applications.

Lanthanum-132/135 is an emerging theranostic pair of radiometals that might find widespread application in nuclear medicine. The present study describes the production of 132/135La in a low energy linear accelerator via natBa (p, n) 132/135La reaction. A robust and efficient method has been optimized for separation of no-carrier-added (NCA) 132/135La from the bulk irradiated target by electrodeposition of 132/135La on platinum anode. Near quantitative electrodeposition yield of 132/135La could be obtained when a potential of 6 V was applied for 20 min in an electrolyte solution (containing Ba and La) maintained at pH ∼ 3. After electrochemical separation, 132/135La could be obtained with > 99.99 % radionuclidic purity in a form suitable for radiopharmaceutical preparation. As a proof of concept, 132/135La-complex of a tumor avid peptide conjugate, namely, DOTA-E-[c(RGDfK)]2 was formulated with > 98 % yield and the radiolabeled complex maintained its integrity under physiological conditions over a prolonged period of time. Overall, this study amply demonstrates that electrochemical separation is a viable strategy for obtaining 132/135La for theranostic radiopharmaceutical preparation.

The present work reports the microscopic details of anatase (A) to rutile (R) phase transformation in a Mn-doped TiO2 system. Titanium dioxide (TiO2) powder was synthesized at three different dopant percentages, namely 1, 5, and 10 atom% of Mn, by a coprecipitation technique. Time differential perturbed angular correlation (TDPAC) spectroscopy was used to identify the formation of the rutile-like phase (R*) during the phase-transition process and revealed interface nucleation to be promoted by the Mn dopant. Electron paramagnetic resonance (EPR) spectroscopy, synchrotron-based X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) studies showed that Mn exhibited a mixed valence states of 2+ and 4+ at different stages of the annealing process. The rutile onset temperature gradually decreased with the increase in the Mn content. The present report proposes the mechanism for the phase transformation and details the effect of Mn on the A to R phase-transformation process. This can assist in gaining a fundamental understanding of the A to R phase-transformation process and the role of the dopant in stabilizing one phase over the other.

Present work demonstrates, for the first time, the use of multiple probes in a single time differential perturbed angular correlation (TDPAC) measurement. Two different probes, viz., 111In/111Cd and 181Hf/181Ta, simultaneously have been incorporated in both pure rutile and Hafnium (Hf)-doped rutile Titanium Dioxide (TiO2) systems following a soft chemical method. The rutile structure was identified by the hyperfine parameters, viz., quadrupole frequency (ω Q) and asymmetry (η). Due to the doping of Hf at 5 and 10 at.%, the sample partially lost the purity of the crystal and the fact has been reflected at both the probe sites.

Due to technical constraints this article was published in volume 240:1 with erroneous article citation ID number 8 whereas this should have been 78 which is corrected as such. Springer Nature sincerely apologizes towards the author(s) for the inconvenience caused.

The present Time Differential Perturbed γ-γ Angular Correlation (TDPAC) measurements in bulk HfO2 report, for the first time, the presence of three regular sites at ambient condition, apart from the stable monoclinic phase (m-HfO2). Also, the effects of Gd impurity (5 at%) on HfO2 crystal structure was investigated by PAC. In pure HfO2, apart from the monoclinic component (~76%), four other minor frequency components have been found at room temperature. To further investigate the origin of these minor frequency components, PAC measurement at 673 K was performed. At 673 K, population of two of the four minor components was enhanced at the expense of the m-HfO2 as the population of m-HfO2 reduces to ~58%. On doping with 5 at% Gd, the population of monoclinic site drastically reduced to ~10% while one of the minor components got enhanced to a large extent (68%). The enhancements of the three minor components, both by temperature or by Gd impurity, indicate that these are the regular phases of HfO2 and could therefore be attributed to three orthorhombic phases of HfO2. The fourth minor component (5–10%) with values of ωQ ~ 7 Mrad/s, η = 0 can be assigned to crystalline defect site.

The Time Differential Perturbed γ-γ Angular Correlation (TDPAC) measurement has been carried out with the hydrolysis product of Hafnium(Hf)-IV ion at pH1 both in bulk and under nano confinement using 181Hf/Ta as PAC probe. The experiment was performed at two different temperatures, viz., 300 K and 280 K. Three different probe sites could be identified for the bulk complex while it is four in case the complex is inside the nanopore, at both the measuring temperatures. The major site, in case of bulk complex, has a quadrupole frequency ωQ ~ 105 Mrad/s and η ~ 0.6. However, the major site, in case the complex is inside nanopore having an average pore size of 6 nm, has ωQ ~ 210 Mrad/s and η ~ 0.3. Two different values of PAC parameters corresponding to the major probe sites for the bulk and nano-confined complex, indicate completely different hydration chemistry in the present two cases.

Routine availability of high specific activity

The cumulative yields of various fission products in the 6.35, 8.53, 9.35 and 12.52 MeV quasi-mono-energetic neutron induced fission of 238U have been determined by using the off-line γ-ray spectrometric technique. The mass chain yields were obtained from the fission product yields by using charge distribution correction. From the mass yield data, the peak-to-valley (P/V) ratio, the average value of light mass ( 〈 A L 〉 ), heavy mass ( 〈 A H 〉 ) and thus the average number of neutrons ( 〈 υ 〉 expt ) were obtained in the 238U( n , f ) reaction for the above mentioned four neutron energies. The present and literature data in the 238U( n , f ) and 238U ( γ , f ) reactions at various energies were compared to arrive at the following conclusions. (i) The yields of fission products for A = 133 – 134 , A = 138 – 140 , and A = 143 – 144 and their complementary products in the 238U( n , f ) and 238U( γ , f ) reactions are higher than other fission products, which has been explained from the point of even–odd effect and standard I and standard II asymmetric mode of fission. (ii) The yields of symmetric products increase and thus the peak-to-valley (P/V) ratios decrease with excitation energy, whereas the 〈 ν 〉 expt values increase with excitation energy. (iii) The variation of 〈 A L 〉 , 〈 A H 〉 and 〈 υ 〉 expt values with excitation energy behave differently in between 238U( n , f ) and 238U( γ , f ) reactions, which may be due to the different types of reaction mechanism for the neutron and photon with 238U.

The present work reports the microscopic details of anatase (A) to rutile (R) phase transformation in a Mn-doped TiO2 system. Titanium dioxide (TiO2) powder was synthesized at three different dopant percentages, namely 1, 5, and 10 atom% of Mn, by a coprecipitation technique. Time differential perturbed angular correlation (TDPAC) spectroscopy was used to identify the formation of the rutile-like phase (R*) during the phase-transition process and revealed interface nucleation to be promoted by the Mn dopant. Electron paramagnetic resonance (EPR) spectroscopy, synchrotron-based X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) studies showed that Mn exhibited a mixed valence states of 2+ and 4+ at different stages of the annealing process. The rutile onset temperature gradually decreased with the increase in the Mn content. The present report proposes the mechanism for the phase transformation and details the effect of Mn on the A to R phase-transformation process. This can assist in gaining a fundamental understanding of the A to R phase-transformation process and the role of the dopant in stabilizing one phase over the other.

We have presented direct evidence of crystallographic structural phase coexistence in a fast-neutron-irradiated Ce(Fe0.96Ru0.04)2 intermetallic compound. The ferromagnetic (FM) cubic phase slowly transforms into antiferromagnetic (AFM) rhombohedral phase at low temperature. Though the FM to AFM transition is first order in nature, the coexistence continues well below the transition temperature. Using Maxwell's relation we have deduced the magnetic entropy change, ΔSM. Remnant FM domains nucleated around the quenched defects, created by fast-neutron irradiation, is principally responsible for a diminution of ΔSM.

The yields of various fission products in the 3.72, 5.42, 7.75 and 10.09 MeV quasi-mono-energetic neutron-induced fission of 238U fission have been determined using off-line γ-ray spectrometric technique. The mass-chain yields were obtained from their fission product yields using charge distribution correction. The peak-to-valley (P/V) ratio, the average value of light mass ( 〈 A L 〉 ), heavy mass ( 〈 A H 〉 ) and the average number of neutrons ( 〈 ν 〉 ) at four different neutron energies of present work and at other energies from literature in the 238U(n, f) were obtained from the mass yield data. The present and the existing literature data in 238U(n, f) at various energies were compared with the similar data in the 232Th(n, f). The following observations were obtained: (i) The mass yield distribution in 238U(n, f) is double humped unlike in the 232Th(n, f), where it is triple humped. (ii) The yields of fission products for A = 133 – 134 , A = 138 – 139 , and A = 143 – 144 and their complementary products in the 238U(n, f) at four neutron energies are higher than those of other fission products as in the 232Th(n, f). The fine structure in the mass yield distribution has been explained from the point of view of standard I and standard II asymmetric mode of fission besides even–odd effect. (iii) The yields of fission products for A = 133 – 134 are higher in the 238U(n, f) than in the 232Th(n, f), whereas it is reversed for A = 143 – 144 . This has been explained from the point of shell combination of complementary fragments. (iv) In both the 238U(n, f) and 232Th(n, f), the yields of symmetric products increase with excitation energy, which causes the decrease of peak-to-valley (P/V) ratio with excitation energy. (v) At the same excitation energy, the yields of symmetric products are lower in the 238U(n, f) than in the 232Th(n, f). This causes higher value of P/V in 238U(n, f) than in 232Th(n, f) for same excitation energy. (vi) The approach of symmetric split with excitation energy is slower in the 238U(n, f) than in the 232Th(n, f). This is due to the different type of potential energy surface for the fissioning system 233Th⁎ than in the fissioning system 239U⁎.

The radionuclide 99Mo, which has a half-life of 65.94 h was produced from 238U(γ, f) and 100Mo(γ, n) reactions using a 10 MeV electron linac at EBC, Kharghar Navi-Mumbai, India. This has been investigated since the daughter product 99mTc is very important from a medical point of view and can be produced in a generator from the parent 99Mo. The activity of 99Mo was analyzed by a γ-ray spectrometric technique using a HPGe detector. From the detected γ-rays activity of 140.5 and 739.8 keV, the amount of 99Mo produced was determined. For comparison, the amount of 99Mo from 238U(γ, f) and 100Mo(γ, n) reactions was also estimated using the experimental photon flux from 197Au(γ, n)196Au reaction. The amount of 99Mo from the detected γ-lines is in agreement with the estimated value for 238U(γ, f) and 100Mo(γ, n) reactions. The production of 99Mo activity from 238U(γ, f) and 100Mo(γ, n) reactions is a relevant and novel approach, which provides alternative routes to 235,238U(n, f) and 98Mo(n, γ) reactions, circumventing the need for a reactor. The viability and practicality of the 99Mo production from the 238U(γ, f) and 100Mo(γ, n) reactions alternative to 235,238U(n, f) and 98Mo(n, γ) reactions has been emphasize. An estimate has been also arrived based on the experimental data of present work to fulfill the requirement of DOE.

In this article, we describe a simple and facile approach for the production of 125I from the neutron-irradiated natural Xe using wet chemical distillation. First, we outline the design of the irra...

The 238U(n, γ)239U reaction cross-section at average neutron energy of 3.7 ± 0.3 MeV from the 7Li(p, n)7Be reaction has been determined using activation and off-line γ-ray spectrometric technique. The 238U(n, γ)239U and 238U(n, 2n)237U reaction cross-sections at average neutron energy of 9.85 ± 0.38 MeV from the same 7Li(p, n)7Be reaction have been also determined using the above technique. The experimentally determined 238U(n, γ)239U and 238U(n, 2n)237U reaction cross-sections were compared with the evaluated data of ENDF/B-VII, JENDL-4.0, JEFF-3.1 and CENDL-3.1. The experimental values were found to be in general agreement with the evaluated value based on ENDF/B-VII, and JENDL-4.0 but not with the JEFF-3.1 and CENDL-3.1. The present data along with literature data in a wide range of neutron energies were interpreted in terms of competition between different reaction channels including fission. The 238U(n, γ)239U and 238U(n, 2n)237U reaction cross-sections were also calculated theoretically using the TALYS 1.2 computer code and were also found to be in agreement experimental data.

The reaction cross-sections for 64Ni(n, γ) 65Ni at En = 0.025 eV and 58Ni (n, p) 58Co at En = 3.7 MeV have been experimentally determined using activation and off-line γ-ray spectrometric technique. The thermal neutron flux used is from the thermal Column of the reactor APSARA at BARC, Mumbai, whereas the neutron energy of 3.7 MeV is from the 7Li(p, n) reaction at Pelletron facility, TIFR, Mumbai. The 64Ni(n, γ) 65Ni and 58Ni(n, p) 58Co reactions cross-sections from present work are compared with the available literature data and found to be in good agreement. The 58Ni(n, p) 58Co reaction as a function of neutron energy is also calculated theoretically using TALYS computer code version 1.2 and found to be higher than the experimental data.

Nuclear quadrupole interaction study using Time Differential Perturbed Angular Correlation technique has been carried out to identify the sites where hafnium can reside in hydroxyapatite in order to mimic the behavior of plutonium adsorption on hydroxyapatite. Hf(IV) has been found to occupy three sites with the quadrupole interaction frequency(ωQ) and its asymmetry(η): (i) ωQ = 136.7(5) Mrad/s, η = 0.54(1); (ii) ωQ = 300.1(9) Mrad/s, η = 0.35(2); (iii) ωQ = 124.6(5), η = 0.0(1). Narrow frequency distributions indicate the sites are well-defined. This study has been extended to barium orthophosphate to confirm our inference for the apatite structure.

Role of Zr atom on the quadrupole interaction of 181Ta in rutile TiO2 has been investigated by time differential perturbed angular correlation (TDPAC) study. The quadrupole frequency remains same as that in the pure rutile TiO2 but its distribution increases with the amount of Zr. This indicates a metal-metal interaction between probe atom and Zr-atom in the nearest neighbour.

Bianchi Type-I cosmological models in Lyra’s geometry are obtained when the source of gravitational field is a perfect fluid coupled with massless mesonic scalar field. Some physical and kinematical properties of the models are also discussed.

A problem of static plane symmetric metric in the perfect fluid, the mesonic massive scalar field and in their coupling is studied in Rosen’s (1973) bimetric theory of relativity. It was found that the matter field like either perfect fluid or mesonic massive scalar field or their coupling does not survive in bimetric theory of gravitation when the space–time is governed by n-dimensional static plane symmetric metric.

A new method for the possible incorporation of nuclear wastes has been attempted here by using ceramic matrix of TiO2 as a host precursor for confinement. Hafnium is used as a simulant for actinide high-level waste. After incorporating 181Hf tracer into TiO2 matrix, the leaching property of the resulting matrix was studied in water, sodium chloride and humic acid solutions. The leaching was measured in each of the case by following the radioactivity of 181Hf. TiO2 matrix has also been exposed to γ-radiation in order to simulate the radiation field for nuclear waste. It has been investigated with a nuclear technique called time differential perturbed Angular Correlation (TDPAC) that the lattice structure of titania remains undisturbed even under a strong radiation field. The leaching of 181Hf has also been studied after irradiating the TiO2 matrix with γ-radiation and the leaching behavior was observed not to change from that before irradiation.

The cumulative yields of various fission products in 232Th(n, f) with average neutron energies of 6.35, 8.53 and 10.09 MeV have been determined using an off-line $\gamma$ -ray spectrometric technique. The neutron beam was produced from the 7Li(p, n) reaction. From the cumulative fission yields, the mass chain yields were obtained by using charge distribution correction of medium energy. The peak-to-valley ( $P/V$ ) ratio, the average value of light mass ( $\langle A_{L}\rangle$ ), heavy mass ( $\langle A_{H} \rangle$ ) and the average number of neutrons ( $\langle\nu \rangle$ ) at the three different neutron energies of the present work and at other energies from the literature in the 232Th(n, f) reaction were obtained from the mass yield data. The present and the existing literature data in the 232Th(n, f) reaction at various excitation energies were compared with similar data in the 238U(n, f) reaction. The fine structure in the mass yield distribution was interpreted from the point of nuclear structure effect such as shell closure proximity and even-odd effect. The role of standard I and standard II asymmetric mode of fission was discussed. The different types of mass-yield distributions between 232Th(n, f) and 238U(n, f) reactions were explained from different types of the potential energy between the two fissioning systems. The role of excitation energy was also investigated.

The development of NTD Ge sensors for use in cryogenic bolometric detector to search for neutrinoless double beta decay (Ovββ) in 124 Sn is reported. The samples made from device grade Ge wafers are irradiated with thermal neutrons at Dhruva reactor, Bhabha Atomic Research Centre (BARC), Mumbai. The carrier concentration in irradiated Ge samples is estimated by Hall effect measurement at 77K. The fast neutron induced defects are studied using Positron Annihilation Lifetime Spectroscopy and Channeling. It is found that vacuum annealing of the samples at 600°C for 2 hours is necessary to cure the defects. Sensors are made from annealed NTD samples using Au-Ge Ohmic contact. Preliminary measurements have shown a significantly large dR/dT ~ 2.3 kΩ/mK at 100 mK. Details of these measurements are presented.

The after effects of β− -decay on time differential perturbed angular correlation (TDPAC) spectra of II–VI semiconductor CdS have been studied using β− -emitting111Ag as well as111mCd as probe nuclei. The TDPAC spectrum of111Ag in CdS exhibits a time dependent interaction indicating that the preceding β− -decay leaves the daughter nucleus in an excited state. The recovery time (τg) of the probe atom was found to be 16±6 ns while Abragam and Pound's relaxation time (τkr) was found to be 9±2 ns. The results show that β− -decay does change the chemical environment around the probe atom.

We have shown the effect of fast neutron irradiation on the magnetic phase transition and magnetocaloric effect (MCE) in a doped Ce(Fe0.96Ru0.04)2, intermettalic. We show that this leads to suppression of MCE and a to a disordered ferromagnetic phase.

Magnetic field induced Anti-ferromagnetic (AFM) to ferromagnetic (FM) phase transition on a sample of Ce(Fe0.96Ru0.04)2 is studied by magnetic measurements before and after fast neutron irradiation performed in CIRUS reactor at BARC, Trombay. Irradiation induced material defects caused the transition to move to lower fields, increased the zero field magnetic susceptibility and suppressed the logarithmic relaxation rate in the hysteretic transition region.

The 232Th(n, $ \gamma$ ) reaction cross-section at average neutron energies of 3.7±0.3 MeV and 9.85±0.38 MeV from the 7Li(p, n) reaction has been determined for the first time using activation and off-line $ \gamma$ -ray spectrometric technique. The 232Th(n, 2n) reaction cross-section at the average neutron energy of 9.85±0.38 MeV has been also determined using the same technique. The experimentally determined 232Th(n, $ \gamma$ ) and 232Th(n, 2n) reaction cross-sections were compared with the evaluated data of ENDF/B-VII, JENDL-4.0 and JEFF-3.1 and were found to be in good agreement. The present data along with literature data in a wide range of neutron energies were interpreted in terms of competition between different reaction channels including fission. The 232Th(n, $ \gamma$ ) and 232Th(n, 2n) reaction cross-sections were also calculated theoretically using the TALYS 1.2 computer code and were found to be slightly higher than the experimental data.

An alternative reaction route for the production of111In from rhodium target bombarded with a12C beam has been developed. Sulfate fusion was adapted for dissolution of the irradiated rhodium metal target. Indium was coprecipitated with La(OH)3 and purified by solvent extraction of the InBr3 complex into di-isopropyl ether and back extraction in 6M HCl. The chemical yield of the separation, determined using105Rh as tracer, was found to be above 90%. The radionuclidic purity of the separated111In satisfies the requirement prescribed for radiopharmaceutical preparations. The radioactivity yield achieved using this route was about 0.2 MBq/μAh.

Effect of fast neutron irradiation induced defects on the anti-ferromagnetic (AFM) to ferromagnetic (FM) transition in Ce(Fe0.96Ru0.04)2 is studied by magnetic measurements. We observe that at a given temperature, AFM–FM transition occurs at a lower field in irradiated specimens compared to that in pristine samples. While irradiation does not seem to affect the hysteresis of the transition, zero field susceptibility is enhanced by more than an order of magnitude. Analysis of reversible magnetization vs field data at low fields indicates superparamagnetic behavior of nano-sized FM domains, which are conjectured to nucleate on the crystal defects produced by the fast neutron irradiation. The number density and size of the nano-sized domains in the irradiated and pristine samples are estimated from the magnetization data.