P.K. Diwan

Stopping power for heavy ions (3⩽Z⩽35) in solids at energies ∼0.5–2.5 MeV/n

Abstract The Hubert et al. formulation for stopping power calculations has been extended below its recommended range of validity, i.e. 2.5–500 MeV/n. It has been established that the extended formulation for projectiles with Z =3–35 provides a good agreement with the experimental data for elemental targets (6⩽ Z ⩽79) and complex materials e.g. CR-39, LR-115, Mylar, Kapton, polycarbonate and Havar in the energy range 0.5–2.5 MeV/n.

Slowing down of MeV heavy ions with Z=6–29 in PEN (C7H5O2)

The stopping power for heavy ions with Z ¼ 6–29 in PEN (C7H5O2)foil has been measured in reflection geometry using the elastic recoil detection technique in the energy range � 0.2–3.0 MeV/u. These measurements have been carried out utilizing the 140 MeV Ag 13þ primary beam from the Pelletron accelerator facility at Nuclear Science Centre (NSC), New Delhi, India. All these stopping power measurements are new. The calculated stopping power values based on Lindhard, Scharff and Schiott (LSS)theory, Northcliffe and Schilling, Ziegler et al. (SRIM-2000.38 code)and extended Hubert et al. formulations have been compared with the experimental values. LSS theory agrees with the experimental data in the ion velocity range � 0:7v0Z 2=3

dE/dx measurements for heavy ions with Z = 6-29 in polycarbonate

Abstract d E /d x measurements for heavy ions with Z =6–29 in the polycarbonate (C 16 H 14 O 3 ) absorber in the energy range ∼0.3–3.0 MeV/u have been carried out utilizing the Pelletron accelerator facility at Nuclear Science Centre, New Delhi, India. The experimentally measured stopping power values have been compared with those calculated using Lindhard, Scharff and Schiott theory, Northcliffe and Schilling, Ziegler et al. (with and without bonding corrections) and extended Hubert et al. formulations. Merits and demerits of these formulations are highlighted.

Registration temperature effect on sensitivity of CR-39(DOP) and SR-90 polymer track detectors

Abstract The samples of CR-39(DOP) and SR-90 polymer track detectors have been exposed to α-particles from 241 Am source in an exposure unit. The temperature of the detectors during irradiation has been varied from ∼−30°C to 70°C. These exposed samples have been etched in 6.25 N NaOH solution at 60°C for various etching times. The variation of sensitivity of these detectors as a function of registration temperature has been studied. It has been observed that at the fixed registration temperature, the sensitivity of SR-90 is more than CR-39(DOP) polymer track detector. However, the enhancement in sensitivity with the decrease in registration temperature is more pronounced in case of CR-39(DOP) than SR-90.

Dependence of hydrogen released on the charge state of incident ions

The behavior of polymers under heavy ion bombardment is of great interest. In the present study, hydrogen released from polypropylene (PP) and polyethylene terephthalate (PET) was investigated as a function of charge state (11+, 14+, and 25+) for 130 MeV 107Ag ions. It was found that hydrogen released from the polymers varies as α q n , where n was found to be 2.98 and 1.94 for PP and PET, respectively, when compared with the value of ∼3.0 reported in the literature for different polymers and ion combinations. Radii of the damaged zones or ion track formed were deduced from the slope of the hydrogen released versus ion fluence curves. This radius was also found to depend upon the charge state of the incident ion. It varies as β q m , where m is 1.25 and 0.741 for PP and PET, respectively.

Energy loss and range of α-particles in different metallic foils

ABSTRACT The energy loss and range of 5.486 MeV α-particles in Tb, Ta and Au metallic foils is measured, through transmission technique. These measured values are compared with the corresponding computed values adopting commonly used theoretical/semi-empirical formulations (Grande and Schiwietz (CasP 5.2 code), Northcliffe and Schilling, Benton and Henke, ICRU-49 report (ASTAR code) and Ziegler et al. (SRIM-2013.00 code)), with the intention to check the accuracy of the considered formulations.

Higher order moments associated with energy loss distribution of swift heavy ions in thick polyethylene napthalate polymeric foils

In continuation to our earlier studies related to energy loss and associated straggling for swift heavy ions which are generally considered as first and second order moments, respectively, in the present study, we have developed a method for the determination of skewness (third-order moment) in the energy loss distribution of the transmitted ions. In this article, the results of our measurements and their interpretation related to skewness for swift heavy ions covering Z=6−16 with maximum values of fractional energy loss (Δ E/E) upto 75% in polyethylene napthalate polymeric foils have been presented.