M M Musthafa

The evaporation residue (ER) cross sections for the reaction F 19+ 187 R e→ 206 P o⁎ are measured, in the excitation energy range of 86.1 to 118.4 MeV. The measured cross sections are compared with that of 30 Si+ 176 Yb reaction populating the same compound nucleus. Theoretical calculations are performed using the coupled-channels calculations for the capture cross sections and statistical model calculations for the ER cross sections. The dependence of quasi fission on entrance channel parameters such as charge product (Z 1 Z 2), mass asymmetry (α), target deformation (β 2) and effective fissility (χ e f f) are studied.

The transparency of the spherical optical potential barrier to an incident neutron with energy between 70 and 200 MeV has been calculated. The spherical optical barrier transparency for neutrons in the presence of angular momentum with iron group nuclei is calculated in this work by modifying the collision matrix. In addition, the neutron-nucleus cross section is calculated. The results were compared with the experimental data and theoretical values obtained using the nuclear model TALYS-1.96 code, and a good agreement was found. The nuclear reaction will be significantly influenced by a finite number of the angular momentums \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ell=1 …

Technetium-99 is a radioactive waste produced primarily in nuclear reactors. It is also left as radioactive waste in hospitals, directly from 99 m Tc isomeric state. To bring down the quantity of technetium-99 radioactive waste, the nuclear reactions using photon beam is explored. The integral cross section of the reaction 99 Tc (γ, γ′) 99 m Tc has been determined using the photo-nuclear activation method. The experiment was done using bremsstrahlung photons having endpoint energies viz. 6, 9, 12, 16, and 20 MeV. 115 In (γ, γ′) 115 m In reaction has been used as a monitor reaction, for the flux normalization of the bremsstrahlung spectrum. Theoretical model calculations have been done using the nuclear reaction code Talys 1.9. Theoretical parameter values are optimized with the presently obtained data. Total cross sections are estimated and investigated the feasibility of re-utilization of the technetium-99 …

The yield of R 105 u and R 105 h produced through proton induced fission of U 238 are measured using stacked foil activation technique. The results are compared with theoretical calculations using TALYS 1.95. As the R 105 h shows a higher cross-section for neutron absorption in the thermal region, production of this isotope will act as a reactor poison. Hence the reactivity equivalent of R 105 h is also calculated and is found to be− 0.84%.

Total neutron cross-sections for iron group nuclei with energies 30 MeV≤ En≤ 100 MeV have been theoretically calculated, for ℓ≠ 0 case. In this work, the collision matrix has been modified for a smooth spherical optical potential, which varies slowly with distance inside of target nucleus. Results agree well with the experimental data and TALYS 1.9 code. It has been found that a finite number of the angular momentum will contribute appreciably to the nuclear reaction. This study on smooth optical potential leads to useful insights into the mechanisms of neutron induced reactions, particularly for medium nuclei at high energies.

A comprehensive test of level density models for explaining the decay of excited compound nuclei, 54 Mn, 56 Fe, 58 Co, 60 Ni, 61 Ni and 63 Cu, in the energy range of 28 - 36 MeV has been performed. The compound nuclei of interest in the desired ranges are populated using 6 Li based transfer reactions. The proton decay spectrum for each excitation energy bins has been measured. The measured proton spectrum has been reproduced using statistical model calculations with different level density models. A variance minimised approach has been employed for analysing the prediction capability of different level density models. This approach has been converged to Gogny Hartree-Fock-Bogoliubov(HFB) microscopic level density model and which is attributed as the most accurate model for the desired nuclei.

CR-39 SSNTD is used to measure the photoneutron spectrum produced by a medical linear accelerator in an intense γ-ray background. The spectroscopic resolution and the neutron detection threshold have been improved by introducing the event selection criteria, based on the track diameter-brightness correlation. The CR-39 detector’s efficiency is determined by adapting the 1 H (n, el) cross section from the ENDF/B-VIII. 0 evaluations. The measured spectrum was reproduced through Talys-1.96 calculations by implementing the Gogny-HFB microscopic level density model.

Materials and methodsThis method utilizes one set of jaws and the multileaf collimator (MLC) to form a symmetric field and then a 180o collimator rotation was utilized to determine the radiation isocenter defined by the jaws and the MLC, respectively. The difference between these two isocentres is then directly correlated with the beam focal spot offset of the linear accelerator. In the current study, the method has been used for Varian ClinaciX and Elekta Versa HD linear accelerators. Since an Elektalinac with the Agility® head does not have two set of jaws, a modified method that making use of one set of diaphragms, the MLC and a full 360o collimator rotation is implemented.

A significant amount of alpha particles, upto 35 MeV are produced in the reactor environment. Alpha induced reaction on natural Zirconium, a reactor component, upto 40 MeV has been measured using stacked foil activation technique. The total neutron production cross section from all possible channels for energies upto 35 MeV is also estimated using TALYS 1.96. The isomeric cross section ratio for the production of the radionuclide has been measured and reported for the first time.

Internal Radiation Dose formalism, derived from the equation of continuity, is one of the formalisms for interpreting radiation stress corrosions in critical systems, radiotherapy using α emitting isotopes etc. Implementation of this formalism requires the measurement of α spectrum at the points of interest [2]. This is challenging for practical situations as the source is spread in the medium. This is the situation for the α therapy and molten salt type critical systems. The spectroscopy using an active detector has limitations, as it cannot be used in a liquid medium. Further, it doesn’t obey the radiation equilibrium requirement for dosimetry, as they are sensitive to direction. The other passive methods like radiochromic films are not linearly sensitive to the dose for alphas, and cannot produce the energy specific information corresponding to each event. Conventional passive detectors are not often used for studying alpha particles in this environment, especially when the source is in the form of a liquid. This is due to the formation of unreal tracks, by improper etching, cosmic ray events, track detector aberrations, etc. These will produce a significant level of wrong biasing and resolution broadening in the measurements. The present work introduces the development of the alpha spectroscopy method with CR-39 solid state nuclear track detector (SSNTD), by removing the unreal tracks and aberrations. The α spectrum resolving capability of CR-39 has been investigated in this study, by introducing the computational tool for analyzing the track profiles. The CR-39 is immersed in the liquid source, which measures the alpha spectrum at the point of interest, by …

The mass distribution of nuclear fission products has importance in accelerator driven sub critical systems in the energy production domain. The ADS is utilizing an effective neutron spectrum, thermal to 50MeV, with a huge neutron flux in the range of 1016 cm2 s− 1 [1]. This holds a significant fraction of high energy neutrons capable of initiating significant pre-equilibrium components in nuclear reactions. Further, it is well accepted that pre-equilibrium mechanism significantly effects the breakage of clustering in the nuclei due to the formation of exciton.Recent studies show that, as the excitation energy goes higher than the shell binding energy, the shell effect is getting meltdown. This produces a higher population in the symmetric fission modes [2, 3]. Which alters the original fission mass distribution. Altering of this mass distribution will cause the integral bench marked characteristics of the reactor to deviate from its original behavior. The isotopic yields calculated from the spectrum averaged mass distribution are significantly affected by neutron multiplicity as well as the neutron capture cross section of isotopes. Hence, the evaluation of such situations requires accurate theoretical models. Studies show that there is an effect of pre-equilibrium mechanism on the population of fission modes. In the preequilibrium region, the isotope production is different from the design curve of a reactor as expected. It has to be taken into account for an accelerator driven systems (ADS) to reduce the risk of supercriticality.

[en] Proton therapy for cancer treatment gained significant attention due to its high conformity towards dose deposition. Proton therapy is performed by utilizing high-energy proton beams up to 250 MeV. The current study incorporated the direct and pre-equilibrium components of nuclear reactions, along with the compound nuclear component. The statistical calculations are optimized based on the available experimental residue cross sections. Our study is confined to nuclear reactions and Rutherford scattering is not accounted. However it is also contributing much to out of field dose since it’s cross section is high compared to the nuclear reaction cross sections. The current study is limited to theoretical only, an accurate measurement on double differential cross sections is required for an accurate determination of the out of field contribution

Porous silicon (PSi) samples were irradiated in the epithermal neutron spectrum for 17 h and drastic changes were observed in its electrical, optical and morphological characteristics. The FE-SEM analysis showed that the mean pore size increases with irradiation, which could be due to the formation of atomic displacements in the silicon (Si) lattice. The electrical properties changed significantly after irradiation and showed an enhancement in the conductivity of PSi due to the 31P levels which were formed via Neutron Transmutation Doping (NTD). Simultaneously, it has been observed that the surface composition as well as the transmittance of the porous Si wafer was modified as there were enough number of unbounded Si atoms as well as the 31P levels in the lattice structure. Hence it is recommended that the detailed understanding of damage events as well as a vast knowledge on the neutron induced …

Even today, theoretical modelling of the nuclear fission process is a subject of intense research. Different statistical and dynamical models are used to explain the nuclear fission mechanism. Heavy ion induced fission is a complex phenomenon due to the involvement of many degrees of freedom. Statistical models encompass several approximations, making a bits simple, whereas the dynamical models deal with more realistic real-time evolution of a compound system [1, 2]. In both the variants, excited compound nuclei are considered to form a thermodynamic ensemble that evolves according to its collective driving potential (Helmholtz’s free energy) and temperature. Further, stochastic dynamical models presume the collective time-evolution of an excited nucleus to be similar to the motion of a Brownian particle in a heat bath. Moreover, compound nuclei are generally considered to be equilibrated in all degrees of freedom including excitation energy, mass, shape etc. Nuclear dissipation in the stochastic Langevin dynamics can be obtained from the classical wall friction, where intrinsic nucleonic motions are assumed to be fully chaotic. A more realistic calculation can be performed with the chaos-wighted wall friction (CWWF)[3]. All these model considerations affect the fission lifetime and other fission observables as well.

[en] The low energy nuclear reactions producing extreme low energy neutrons in the exit channel have a renewed interest due to their larger involvement in nuclear astrophysics and radiation dosimetry. Most of the reactions in this range belongs to direct reactions only and those neutrons are not accompanied by any γs. The unfolded spectrum of neutrons, compared with the theoretical spectrum. This shows that the spectrum is similar and the low energy with a starting point of 100 keV is well measured. The experiment shows that this method clearly discriminates low energy neutrons and γs and can be effectively utilized for the situations of nuclear astrophysics where low energy neutrons in the exit channel are present

MATERIALS AND METHODSA hybrid ion source has been designed and fabricated at Nuclear and Radiation Physics division, Department of Physics, University of Calicut. A TEM01 type rectangular waveguide, having two harmonics in length and quarter wavelength in the transverse direction has been used as the cavity. The cavity has been designed for the 2.4 GHz characteristic frequency. A 2 KW 2.4 GHz magnetron has been coupled as the inductive load to the cavity. The RF coupling has been established at the position of the first antinodal point of the cavity. A Quartz tube of 2.5 cm internal diameter has been mounted at the second antinodal point of the cavity and used as the gas ionization volume. Two permanent magnets are configured with a 5 cm separation, to provide plasma confinement. This configuration produces a maximum magnetic field of 100 mT at the center of the magnet, and drops to a value near to 5 mT at the mid plane of the plasma cell. This gives an effective confinement for the plasma. The schematic diagram of the setup is illustrated in Figure 1.

Conclusion: SPC tools can be adopted among institutions for consistent and comparable QA programs. If the QA process monitored using SPC falls outside the CL, cause-and-effect diagrams can be used to extract all possible contributing factors that lead to such a process state.

To perform nuclear reaction experiment, very good quality, uniform and thin targets are necessary. In order to carry out evaporation residue cross section measurement of 19F+187Re reaction using Hybrid Recoil mass Analyzer (HYRA) facility at Inter - University Accelerator Center (IUAC) 187Re targets of thickness 200 μg/cm2 are required. More than 20 targets of 187Re of 200 μg/cm2 thickness with thin carbon backing have been prepared using 70 mg of 187Re. Being one of the highest melting points of all elements, high temperature involved in the process and limited amount of available isotopic material are the major constraints during the target development of 187Re. The targets have been successfully used for the nuclear reaction experiment. The method used for the development of several 187Re targets with minimum material consumption and the detailed characterization techniques applied for studying …

[en] Traditional medicine from herbs and herbal formulations are is becoming increasingly popular, as indigenous medicines and source of primary health care, with many chronic conditions responding to it well. However, a scientific approach for precise reference standard to ensure the quality and efficacy of these formulations is yet to be evolved. The trace elements present in the herbals play a vital role in the formation of active chemical constituents present and mediating vital biochemical activities. Very limited studies have been conducted on trace elemental analysis of herbs using PIXE, XRF, ICPMS, NAA, AAS, etc. and a few analyses on compound formulations. In the present work, we report the trace elemental analysis of some of the compound ayurvedic formulations like Thiphala, Nishakatakadi and their constituent herbs, using NAA. The activation was done at KAMINI reactor, IGCAR. The activities induced in the sample were followed using HPGe detector coupled with multichannel analyzer. From the observed intensities of characteristic gamma rays, the yield of specific isotopes was estimated from which the concentration of specific trace elements was determined. We have employed combination techniques for trace elemental analysis covering wide range of elements effectively. Though NAA is high sensitive, the technique is limited to isotopes of measurable half-lives. Prompt Gamma Neutron Activation Analysis (PGNAA) can provide information on entire range of nuclei and hence is a better approach. Though accumulation of large number of gammas, particularly that the sample contains large number of isotopes make data …

[en] Here, we report the development of an innovative method for the direct measurement of neutron energy spectra, using CR-39 SSNTD as a passive detector. Neutrons produced from Am-Be source is used for the measurement. 5.48 MeV α particle from the 241 Am source undergo fusion with 9 Be to form the compound nucleus of 13 C at an excitation energy of around 14.4 MeV. Depending on the thickness of Be the excitation energy of 13 C may vary from 10.6 MeV to 14.4 MeV. Neutron from such resonance populate various states of 12 C depending on the structure of states. The expected neutron spectrum from Am-Be were measured using CR-39 detector from University of Calicut. The neutron energy spectrum thus obtained analyzed using the simulated spectrum from nuclear reaction code EMPIRE 3.2, Alpha straggling and tunnelling affected to spectrum is also taken in to consideration