A. Waheed

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.

Registration of low energy protons in CR-39 for use in fast neutron dosimetry

Abstract This paper gives some results on the registration of protons, in the energy range from 60 keV to 727 keV, incident normally on CR-39 detectors and etched chemically in 6N NaOH at 70°C. An increase in the track diameter ‘D’ with increasing proton energy ‘E p ’, has been observed. The response function V (=V t /V g ) for different energy protons has been experimentally determined and correlated with the calculated values of ‘V’ by the polynomial V =∑ a n V n . The variation in the response function ‘V’ with the proton range ‘R’ and REL (200) function are well described by the relations V=1+aR n and V= a n(REL) n , respectively. The critical angle, ϴ c ′, calculated as a function of the proton energy E p is given by the relation ϴ c = ∑a n (1n E p ) n .

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.

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.

A study of the radiobiological effectiveness with track etch detectors

CR-39 nuclear track detectors have been used in this experiment to study the killing effect of low energy protons on V79-753B Chinese hamster cells and to monitor the proton beam. The estimated surviving fractions and the beam parameters are comparable to those found with conventional electronic devices. The surviving fractions fitted by the linear quadratic model support the idea of single-hit mechanism for the cell killing.

Use of track detectors in biomedical sciences.

The CR-39 track detectors have been applied to irradiate the Chinese hamster V79-753B cells for survival studies. The survival curves have given satisfactory results. Energies of the incoming as well as outgoing proton beams evaluated from the track diameters are found to be close to the values found separately by surface barrier detector (SSBD).

Proton radiographic characteristics of thin CR-39 detector

Abstract Two parameters, track registration sensitivity and densitometric response in radiography with a low energy ( ∼ 4.5 MeV) proton beam and a stack of thin (100 μm) CR-39 detector foils were investigated. The optimum image quality was obtained at a layer removal thickness of about 1 μm. The image obtained under these conditions is characterized by a high track registration sensitivity (∼60%), high image contrast (the maximum value of the net optical density is ∼ 0.7) and high spatial resolution ( ∼1 μm). The application of the technique in biomedicine is illustrated by proton radiographs of botanical samples.

Study of ‘8.5 MeV/nucleon 208Pb+Pb (Natural)’ interaction using mica track detectors

Abstract Interaction of 8.5 MeV/nucleon- 208Pb with Pb (natural) has been studied using mica track detectors in 2π -geometry. Multiprong events have been analysed for track parameters and their inter correlation. The data so obtained have been used to obtain the partial cross-sections and the total reaction cross-section. Value of the total reaction cross-section has also been calculated and compared with the one obtained experimentally. Possible modes of interaction have been discussed in the light of the experimental data.

Use of rectangular geometry for radon dosimetry

Abstract A method is presented to calculate the track density distribution of Radon Alpha particles in the plastic track detectors placed along the wall of a rectangular dosimeter. Volume of a sphere of radius ‘R’ has been found in a rectangular box of dimensions, a × a × b, as a function of the distance ‘n’ of the centre of the sphere from the edge of the box. The distribution so obtained has been compared with the experimental track density distribution of Radon Alpha particles found in CN85 plastic track detectors placed along the wall of a rectangular box of 6 × 6 × 8 cm 3 in an artificial mine in the laboratory. Conclusions regarding the suitability of rectangular geometry as compared to the cylindrical geometry have been drawn.

USE OF CYLINDRICAL GEOMETRY FOR RADON DOSIMETRY

ABSTRACT The paper describes a method to calculate the track density distribution of radon alpha particles in a plastic track detector placed along the wall of a cylindrical dosimeter. The calculations have been carried out for the volume of the sphere of radius ‘R’ enclosed in a cylinder of radius ‘a’ as a function of the distance ‘Z’ of the centre of the sphere from the edge of the cylinder. ‘R’ is comparable to the range of alpha particle. From a comparison with the experimental radon alpha track distribution, obtained by CA 80-15 plastic detector in the laboratory, it has been concluded that the best choice for the size of the cylindrical dosimeter is, R ≃ 2a.