E.U. Khan

Environmental radioactivity in Dera Ismail Khan and its adjacent area - Pakistan

Abstract Natural radioactivity in air, soil and water samples has been determined in Dera Ismail (D.I.) Khan city and its adjacent areas in Pakistan. CR-39 detectors were used for investigating radon concentration in the air of different kinds of rooms. HPGe detectors were employed for gamma ray activity measurements in the soil used normally to produce the construction materials. 235U concentration was determined from water by drying the water drops on CN-85 detectors and irradiating them with thermal neutrons.

Sequential fission studies in the interaction of 9.03 MeV/N 238U with natU using mica track detectors

Abstract The heavy ion interaction 9.03 MeV/N 238 U + nat U has been investigated using mica Solid State Nuclear Track Detector (SSNTD) in 2π-geometry. Numerical analysis of the track data yielded masses and energies of the reaction products formed in two-, three- and four-prong events. It has been observed that sequential fission, yielding three or four heavy fragments in the exit channel, is the main mode of the interaction. The five particle exit channel occurred with a considerable smaller probability. The relative yield of the four-particle exit channel increases with total kinetic energy loss (TKEL). But at the highest TKEL this trend is reversed and we observe the same amount of three-prong events as four-prong events. This might be explained by the large mass transfer forming surviving intermediate masses relatively stable against fission.

Estimation of internal and external equivalent dose rates for dwellers of Dera Ismail Khan, Pakistan

Abstract Data on radon concentration in the dwellings of Dera Ismail Khan area in Pakistan and gamma ray activities in the brick samples used in that area has already been reported. Based on that data we have estimated the internal dose to respiratory tract due to radon daughters and the external dose to lungs and whole body from gamma ray activity in the rooms made of clay bricks. For internal dose calculations the radon concentration has been converted to equilibrium equivalent concentration (EEC) by multiplying it with equilibrium factor of 0.4 as recommended in UNSCEAR. The EEC has been converted to equivalent dose rate using conversion factor of ICRP-50. The external dose from gamma ray activity has been determined by using a mesh adaptive method developed at our centre (CNS) for model rooms constructed from various materials.

Sunlight effect on sensitivity and performance of the CR-39 detector

Abstract The effect of sunlight on CR-39 detector has been investigated. It has been found that the response of the detector to full energy α particles from a 252 Cf source and neutrons from an Am-Be source drops by ∼ 60% and 87%, respectively. The detectors exposed to sunlight for more than 60 days were found to be completely fogged and there physical properties were totally destroyed when etched for more than two hours in 6M NaOH at 70 °C.

Analysis of three-prong events in the heavy ion interaction of 17.0 MeV/u 132Xe + 238U

Abstract The heavy ion nuclear interaction 132 Xe + 238 U has been investigated at the beam energy of 17.0 MeV/u, employing the 2π-geometry technique and using mica as a Solid State Nuclear Track Detector (SSNTD). After measuring the spherical polar coordinates of the correlated tracks, event-by-event, the three-prong events have been analysed numerically using an empirical range-mass-energy relationship. The coefficients of this relationship were deduced from the experimental data of the elastic events as well as three-prong events in a self-consistent manner. The intermediate stage of the reaction has been constructed from the knowledge of the relative velocities of the fragments observed in the final stage of the reaction and hence mass transfer between projectile and target has been determined. The emission of final fission fragments were examined in both in-plane and out-of-plane of the reaction.

Mica track microfilters applied in a cascade particle fractionator at an industrial plant

Mica Track Microfilters (MTM) are produced by irradiation of mica discs with heavy ions. The air throughput V is investigated experimentally within the temperature range 20°C ⩽ T ⩽ 300°C and described by a simple formula. MTM are placed in a Cascade Particle Fractionator and applied in the filtration of hot and radioactive gas under industrial conditions.

On the reaction cross-section of various heavy ion interactions

Abstract Since the development of the 2π geometry technique, the studies of Heavy Ion Interactions have been carried out in various laboratories of the world using different SSNTD. The first parameter which is usually determined in such studies is the reaction cross section. The simplest method of determining the reaction cross section is to use the number of inelastic events scanned as well as the number of projectile and target nuclei in certain area of the sample. This cross section is normally cross checked using the elastiv two prong events for determination of the quarter point angle and hence the reaction cross section. This paper reviews the reaction cross sections of various interactions at different energies. Theoretical cross sections have also been calculated using two models. These cross sections have been compared with the experimental results. Moreover, the experimental cross sections of U+U at five different energies have been used to obtain radius of interaction and hence theoretical cross sections which satisfy experimental data above 10 MeV/N beam energies.

Reproduction of projectile and target masses from the binary data in the heavy ion interaction of 17.0 MeV/N 132Xe with 238U

Abstract We have collected track data of the observed binary events in the heavy ion interaction of 132 Xe + 238 U at 17.0 MeV/N beam energy after etching the detectors for various times from 20 to 80 min. It has been observed that data reveal proper information regarding the associated energies after the 80 min of etching. The elastic events were selected from the binary data on the basis of Rutherford scattering which was then used to look for the coefficients of Gottschalks range-mass-energy relationship. These coefficients, when used along with the track lengths and angles of the elastic events, reproduced the masses and energy of the reaction partner.

Etching characteristics and sensitivities of various commercially available CR-39 and SR-86 detectors

An experiment was carried out to study and compare the etching characteristics and sensitivities of SR-86 and various commercially available and most widely used CR-39 polymeric track detectors. In this context, samples were obtained from Pershore Mouldings Ltd. (UK), American Acrylics (USA) and SR-86 (Japan) and were exposed to α particles and fission fragments from a thin disc 252Cf source. A number of the above detectors were also irradiated with neutrons from an Am-Be source. It was found that SR-86 and CR-39 detectors have their maximum sensitivities in about 7M NaOH and 6M NaOH at 70°C, respectively. The SR-86 detector was found to be relatively more sensitive than those of CR-39 detectors to α particles of ∼6 MeV. However, for neutrons from an Am-Be source, all the detectors under investigation have almost similar sensitivities. The SR-86 detector has been found to be severely affected by the ageing. After one year of storage in a refrigerator, SR-86 samples were completely fogged and their physical properties were totally ruined due to the ageing when etched for 30 minutes in 7M NaOH at 70°C.

Study of heavy ion ranges in mica

Abstract Beams of various heavy ions with a maximum energy of 20 MeV/N have been produced at UNILAC (GSI), Darmstadt, F.R. Germany, for the last several years. Using this facility, we have irradiated mica with various heavy ions at an angle of 45 degree. The tracks of these heavy ions were revealed by usual etching process and the ranges were determined. In this paper we report the experimentally determined values of ranges for Xe, Pb, and U ions in mica at different energies between 1.4 MeV/N and 17.0 MeV/N. The experimental results have been compared with those of two theoretical methods for the calculation of heavy ion ranges in the insulating media.