The developed fission systematics depicts the projectile energy and the target mass dependence of fission cross-sections of heavy nuclei. The developed model is fitted using experimental fission cross-section data of 500–1665 MeV negative pion induced fission in [Formula: see text]Sn, [Formula: see text]Au and [Formula: see text]Bi. The same systematics is further fitted using the cascade exciton model (CEM) calculations of the above-mentioned fission reactions. Parameterization of the model is performed by calculating its parameters and uncertainties in them. A comparison of the systematics predictions with experimental data and CEM calculations is made. Validation of the systematics using new target nuclei [Formula: see text]Eu, [Formula: see text]Ta, [Formula: see text]Hg and [Formula: see text]At (not included in the systematics development) over an extended range of pion energies, from 80 MeV to 2500 MeV, builds trust in it. The systematics is not valid for [Formula: see text]Th and [Formula: see text]U. The systematics is found to be valid for target nuclei from [Formula: see text]Sn to [Formula: see text]At and for incident negative pion energies from 80 MeV to 2500 MeV. Results are discussed in detail. Merits and demerits of the developed systematics have been concisely described. Valid conclusions and future perspectives are also given.

A data bank of negative and positive (80–1665[Formula: see text]MeV) pion-induced experimental fission cross-sections of heavy nuclei from 119 Sn to 238 U is compiled using present results and published data from the literature. Corresponding calculations of fission cross-sections, using the cascade exciton model (CEM) are also included in the compilation. Fission cross-sections compiled in the data bank are examined critically. Mass and energy dependences of fission cross-sections are analyzed. Fission cross-sections of 238 U targets are the highest and scale down approximately, for other targets studied, with fissility, [Formula: see text]. In the fissility expression, [Formula: see text] and [Formula: see text] are atomic and mass numbers of the target while [Formula: see text] refer to positive and negative pion projectiles. The presented data bank is of interest for students and researchers involved in the investigation of energetic light particle-induced fission of heavy nuclei. Nuclear fission of heavy nuclei has been classified into three regimes. Phenomenological discussion of the fission process is also given.

The influence of pre-exposure thermal annealing on CR-39 etch rates has been studied here thoroughly. Annealing experiments were conducted on CR-39 detectors prior to their exposure to 252Cf fission fragment source. The bulk etch rates were measured by using the weight loss method (WLM) and the fission track diameter method (FTDM). We report here a new quantitative result that the bulk etch rate decreases from the original surface of each CR-39 detector initially rapidly and then more slowly along the depth mimicking the exponential trend. These quantitative results are more pronounced for cases of higher annealing temperatures and larger annealing time intervals. This exponential drop of the bulk etch rate suggests that the interior of the CR-39 detector material is almost out of pre-exposure annealing. Our results reveal that the etch rates and the registration properties of the heavy ions are considerably altered in the near-surface layer of the annealed PADC.

Rana track annealing model 2007, based on an Arrhenius approach, is significantly modified, including new assumptions, fitting parameters, and analysis, to yield a new phenomenological model for annealing of fission tracks in apatite. Construction and optimization of the new six parameter model have been described in detail. The model shows a hybrid behavior. In Arrhenius plot, for higher temperatures (laboratory data included), iso-annealing lines are curved while, for low temperatures (geological time scale), iso-annealing lines become parallel straight lines. This is a new feature for any such model and has produced promising results. C-axis projected lengths from laboratory experiments on Durango apatite are employed to find model parameters. KTB borehole fission-track data are added to build the temperature function that modifies the original equation. Partial annealing zone (PAZ), closure temperature (T-C) and total annealing temperature (T-A) were calculated and compared to geological benchmarks. The predictions of the present model agreed well with low and high temperature benchmarks. PAZ, T-C and T-A predictions were also compared to the Fanning Curvilinear Arrhenius model predictions, resulting in good agreement. The present model is flexible enough to be applied to other fission- track systems, like zircon, muscovite and titanite.

Bulk etch rates for CR-39 detector were measured and studied over a wide range of NaOH aqueous solution concentrations (2–20 N) with different ethanol volumes. This wide range of etching concentration is divided into two major parts: soft etching part (2–8 N NaOH) and dense etching part (8–20 N NaOH). This classification will be explained and discussed. The etchant viscosity in the two parts was measured and compared. The effect of ethanol in both parts was deduced through a new parameter called ‘reduced bulk etch rate’. This new parameter helps in analyzing the dependence of bulk etching on the amount of ethanol in the etchant. It was found that conducting the etching process in the dense etching part reduces the etching time significantly. Etching in the dense part is not far away from equilibrium where Mushtaq, Multi-hit and Arrhenius fitting equations are applicable. The fitting of measured bulk etching data was carried out in the soft (low), dense (high) and the whole etching concentration ranges. Generally, a good agreement was found between physical data and model calculations.

Systematic CR-39 bulk etching experiments were conducted over a wide range of concentrations (2–30 N) of NaOH-based etchant. Critical analysis and a deep discussion of the results are presented. A comprehensive nuclear track chemical etching data bank was developed. Three regimes of CR-39 bulk etching were identified. Regime I spans etchant concentrations from 2 to 12 N. Regime II spans concentrations from 12 to 25 N. We call this the dynamic bulk etching regime. Regime III is for concentrations greater than 25 N. In this regime, the bulk etch rate is saturated with respect to the etchant concentration. This classification is discussed and explained. The role of ethanol in NaOH-based etchants is explored and discussed. A parameter called the "reduced bulk etch rate" is defined here, which helps in analyzing the dependence of bulk etching on the amount of ethanol in the etchant. The bulk etch rate shows a natural logarithmic dependence on the density of ethanol in the etchant.

Issues of high level nuclear waste disposal which involve a number of known and unknown risk factors are discussed. Implementation of nuclear waste disposal has to be based on multi-criteria decision making. Some of the major aspects of the issues are analyzed and described briefly to build a perception of the ethical implications and risks involved. This brief account on state of the nuclear waste disposal problems would be helpful for researchers working on radioactivity containment and disposal.

A grid computing facility was developed at sister institutes Pakistan Institute of Nuclear Science and Technology (PINSTECH) and Pakistan Institute of Engineering and Applied Sciences (PIEAS) in collaboration with Large Hadron Collider (LHC) Computing Grid during early years of the present decade. The Grid facility “PAKGRID-LCG2” as one of the grid node in Pakistan was developed employing mainly local means and is capable of supporting local and international research and computational tasks in the domain of LHC Computing Grid. Functional status of the facility is presented in terms of number of jobs performed. The facility developed provides a forum to local researchers in the field of high energy physics to participate in the LHC experiments and related activities at European particle physics research laboratory (CERN), which is one of the best physics laboratories in the world. It also provides a platform of an emerging computing technology (CT).

The recent development of high repetition-rate free-electron laser (FEL) facility has brought new challenges for the self-seeding scheme, mainly the problems of heat load and radiation damage on the monochromator. In this paper, a simple technique is proposed to mitigate the effect of heat-load on the monochromator of a self-seeding FEL. We combine the reverse undulator taper with the harmonic lasing technique to enhance the spectral brightness of the radiation pulse. In this way, the required radiation power for the first stage of self-seeding can be significantly reduced. Theoretical analysis and numerical simulation at 2.86 nm are performed and the results demonstrate that the proposed method can decrease the heat-load on the monochromator by nearly one order of magnitude. At the same time, the peak power of final radiation can be enhanced and the total length of undulator can be reduced comparing with the conventional self-seeding. The proposed technique can be implemented at current existing FEL facilities with variable-gap undulators.

This data bank is the result of systematic experiments on nuclear track etching, fission fragment track annealing, and radiation detection & measurement. Data highlights from a comprehensive nuclear track data bank, and related physics and chemistry are described here briefly and clearly. Uncertainties in the reported data are also presented. All the data presented were collected using the most sensitive nuclear track detector CR-39, or Poly Allyl Diglycol Carbonate (PADC), over two decades. Closely related data sets from the published literature are also reviewed. Necessary details of the reviewed data and their citations are clearly given in the data bank. Aim here is to present tabulated experimental raw data with essentially needed calculations. All the necessary information related to the data bank is described clearly. Study presented here is useful for research students and scientists who possess the rudimentary knowledge of nuclear track detection. Single tabulation of the data, instead of plots, is aimed at making easy access of the data to users.

In this short paper, a new model for annealing of latent nuclear tracks is developed. Physical phenomenological picture or foundation of the model is presented using experimental spectra of Cf-252 fission fragment tracks annealed at 75-175 degrees C for 5-30 min. Here, annealing of nuclear tracks refers to the reduction of track lengths during annealing or thermal treatment. A new annealing parameter (t/T-2) is identified in the model, which is useful in understanding and analysis of annealing of nuclear tracks. In definition of the annealing parameter above, the quantities t and T are annealing time and temperature, respectively. The model allows deduction of the activation energy of annealing simultaneously from track annealing data, collected over all the annealing conditions (t, T). This model provides a quick methodology to study kinetics of nuclear track annealing. The presented model is validated using the experimental results of annealing of fission tracks in CR-39 detector. The determined value of activation energy of annealing is 0.204 +/- 0.012 eV. Presented results and discussion can be extended to swift heavy ion (SHI) tracks.

Hawking induced a knowledge revolution in theoretical physics. His bedrock concepts and explanations reshaped modern physics.

A new method is proposed here aiming at designing a shielding wall with the efficiency significantly higher than that of traditional designs. This new design arises from the idea of using channeling in multilayered shielding wall structure, each layer composed of bent crystallites distributed in a way that each layer covers a small section of 2π angular range of which wall is exposed. Part of the incident charged particles will get channeled in bent crystallites in each layer. Bending of channeled particles in bent crystallites will change their directions in the wall increasing their path lengths in the wall which would enhance its shielding efficiency for charged particle radiations. Proposed design is useful for radiation shielding in fission power plants, future fusion reactors and air travel.

The influence of preservation period of CR-39 detectors, in refrigerator and in the laboratory atmosphere, on bulk etch rate is studied. The effect of etching solution usage time on the bulk etch rate is also investigated. Analyses and quantitative results in the said cases are presented. Finally, precision results on the use of CR-39 as a charged particle detector are presented in a systematic manner. These results are selected from our radiation detection and measurement experiments, ranged over last two decades. Selected results (unpublished and published) include CR-39 measurements of 5.9 MeV antiprotons, 6.12 MeV alpha particles and spontaneous fission fragments of 252Cf. Our published results, presented here, are further analyzed and presented in comparison with new results and discussion. Experimental procedures of exposures, chemical etching, track measurements using the optical microscopy are described, keeping in view the new users and research students. Computer codes TRACK_Vision and SRIM were employed to provide a comparison with measurements of track parameters, where possible.

Swelling of CR-39 nuclear track detectors due to fission fragment and alpha particle induced damage is studied through thickness measurements. Exposure periods for irradiation damage spans from 1 to 350 h. In follow-up experiments, swelling of irradiated CR-39 detectors due to their soaking in water for a wide range of periods, from 1.5 h to 6 months, is also investigated. It is observed in a quantitative manner that the water incorporation by CR-39 nuclear track or radiation detectors during soaking increases quickly with increase of the radiation damage up to soaking time of 60 days after which thickness increases with slower rate up to soaking of 120 days. Thicknesses of detectors remain practically same between soaking of 120-180 days. It is concluded that the interaction of radiations breaks the atomic bonds in surface layer of CR-39 leading to the emission of gases (H-2, C2H2, CO2 and O-2) which makes the exposed CR-39 porous. During soaking water is incorporated in the empty space in CR-39. Based on measurements, dynamic and static regimes are characterized explaining the dependence of swelling in soaking on the pre-soaking radiation damage. Unswellable CR-39 polymer track detectors (at room temperature) become swellable when the radiation exposure exceeds a certain limit. Thickness measurement results are supported by scanning electron microscopy (SEM) of undamaged and damaged CR-39 samples.

The field of nuclear agriculture is introduced very briefly. Nuclear agriculture research/development system in Pakistan is described highlighting the achievements of the system partners. Description and discussion are generalized in concluding remarks at the end of the article. This article is an experimental guide for a developing nuclear agriculture system.

Manufacturing is the backbone of a modern state and has a direct impact on life style of a common person of a society. We present here the development and manufacturing of Polymerase Chain Reaction (PCR) machines by the Pakistan Atomic Energy Commission (PAEC), Pakistan. Steps of the development and manufacturing of PCR machines are explained. Important design features of MERADD PCR machines and their implementation are documented here. Results of the MERADD PCR machine are compared with those of competitive imported machines. MERADD is the sole manufacturer of PCR machines in Pakistan. Quality assurance and cost analysis are also given. MERADD PCR machines produce as good results as by the imported machines, but cost is significantly lower. This paper is useful for a broad community of developers/manufacturers of medical devices and biomedical engineering in developing countries around the world.

A concise analysis is presented in this paper about the Chernobyl nuclear reactor accident on 26 April 1986 discussing the important points and available data. The analysis and discussion here selected important facts of the nuclear disaster.