Journal of Nuclear Research and Applications
Volume:2 Issue: 2, Spring 2022

In this paper‎, ‎we study the nature of the dynamics in second-order Quantum Phase Transition (QPT) between vibrational ( ) and -unstable ( ) nuclear shapes‎. ‎Using a transitional Hamiltonian according to an affine SU(1,1) algebra in combination with a coherent state formalism, Shape Phase Transitions (SPT) in odd-nuclei in the framework of the Interacting Boson Fermion Model (IBFM) are investigated‎. ‎Classical analysis reveals a change in the system along with the transition in a critical point‎. ‎The role of a fermion with angular momentum j at the critical point on quantum phase transitions in bosonic systems is investigated via a semi-classical approach‎. ‎The effect of the coupling of the odd particle to an even-even boson core is discussed along with the shape transition and‎, ‎in particular‎, ‎at the critical point‎. Our study confirms the importance of the odd nuclei as necessary signatures to characterize the occurrence of the phase transition and determine the critical point's precise position‎.

For the ion beam analysis of insulating materials, we have investigated the design and calibration of an ion beam chopper. The chopper consists of a holder, a chopper plate, four photo sensors, a stepper motor, and an electronic control unit. The chopper plate was designed based on sharing an equal fraction of the ion beam between the chopper and the target. The situation of the chopper to the ion beam is controllable by using four photo-sensors around it. The time intervals in which the material is analyzed and the number of incident ions measured are determined via gate pulses governed by the sensors’ signals. The ion beam current was measured by charge integration at the chopper plate. We calculated the charge correction factors to eliminate the contribution of secondary electrons to the measurements. The measurements were done via Rutherford backscattering spectroscopy (RBS) analysis of a thin Au layer deposited on Si wafer with helium and proton ions in the energy range of 1–2.2 MeV with a precision of less than 5%. The charge correction factors are independent of the ion beam current.

A microwave electrothermal thruster (MET thruster) has been constructed, consisting of a microwave plasma chamber 12 cm long and 8 cm in inner diameter and a micronozzle 10 mm long with 1 mm in diameter. The microwave plasma is produced by 2.45 GHz microwave frequency at a power of 1 kW, and the feed gas is Ar at a pressure of 10^-3mTorr. Microwave energy is transmitted into the cavity and electrons sre connected to the wave's electric field. Thus, the electrons are accelerated by microwave electric fields. Microwave plasma discharge is formed based on the interaction of electrons with neutral gas particles. Then, the plasma acts as a resistive load and absorption of microwave energy, raises the temperature of the gas or plasma. Gas heating increases the gas pressure and is released through the nozzle. The plasma density and electron temperature are 2.35×〖10〗^17  m^(-3) and 1.2 eV, respectively. The thrust and specific impulse are 10 mN and 100 s

In this paper, the response matrix of Superheated Drop Detector was analyzed and investigated using Evaluated Nuclear Data. Elastic, nonelastic and total neutron cross sections were extracted and used for calculating the probability of the production of charged particles as a result of neutron interaction with superheated liquid nuclei. The values of the response functions in each energy are proportional to the probability of the production of charged particles. It was proposed that the response function can be represented as the multiplication of the total neutron cross sections by a monotonic probability function. The parameters associated with this function change with changing the physical properties of the detector such as temperature or external pressure. The growth rate of this function decreases when the temperature decreases or the external pressure on detectors increases due to increase in threshold energy for the generated charged particles. So the growth rate and shape of this function are set by parameters which are dependent on the physical properties of Superheated Drop Detectors.

[68Ga] DOTATATE as a radiolabeled tracer is used for in vivo detection of neuroendocrine tumors in the PET/CT examinations. This study aims to calculate S-values in various organs in a voxelized-based Monte Carlo simulation approach for each patient individually. PET/CT images of 9 patients suspected of neuroendocrine cancer were acquired 60 minutes after injection of [68Ga] DOTATATE. After reshaping and registering CT images to the size of PET images, GATE/GEANT4 Monte Carlo (MC) toolkit was used with two inputs of CT images as voxelized attenuation map and PET images as a voxelized activity map for the calculation of the different organs dose. Voxelized dose maps were extracted in the target organs for different source organs. S-value volume histogram and absolute S-values based on the MIRD formalism were calculated. The highest S-values were observed for spleen, bladder, kidneys, liver, pituitary, and the lung with 6.26E-05 ± 1.47E-05, 5.17E-05 ± 3.08E-05, 3.41E-05 ± 7.68E-06, 2.08E-05 ± 4.12E-06, 1.62E-05 ± 5.74E-06 and 8.47E-06 ± 2.47E-06 mGy/MBq.S, respectively. The difference between the amounts of the calculated S-values and those presented in OLINDA software is mainly related to the anatomical difference of the patients with the standard phantom in OLINEDA software. This study showed that patient-specific dosimetry is necessary to calculate S-values.

Fresh leafy vegetables are great source of vital nutrients, to promote health and prevent diseases but they can transmit pathogenic microorganisms to human beings. Shelf life of these products is very limited post harvest and after three days at refrigeration temperature, they will spoil. Radiation processing combined with modified atmosphere packaging and refrigeration temperature is a practical treatment to ensure safety and enhance vegetables shelf life even to be used in international trades. The effects of irradiation doses at 0, 0.25, 0.5 and 1 kGy on fresh leafy vegetables packed under air, N2 and vacuum atmospheres up to10 days of storage at 4 °C were studied. According to the results of microbial tests, and antioxidant activity of DPPH°, gamma radiation at dose of 0.5 kGy under N2 packing atmosphere are recommended as optimal storage conditions up to 10 days at 4 °C for fresh garlic chives, basil, mint and parsley.