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Gamma ray attenuation studies play an important role in industry, agriculture, medicine, radiation dosimetry etc. In the present study, we have made an attempt to determine the linear attenuation coefficient for 662 keV gamma rays in pure coconut oil, in paraffin oil and in a mixture of both. From the experimentally obtained linear attenuation coefficients, mass attenuation coefficients were estimated and the corresponding effective atomic number values were determined by the polynomial interpolation method. No experimental studies of this type for oil samples have been reported so far. An advanced GR1-A USB powered gamma ray spectrometer was used in the studies. A narrow beam vertical geometry was employed. The study shows that with increase in the content of paraffin oil present in the coconut oil, an increase in the values of mass attenuation coefficient and a decrease in the effective atomic number take place. Also the mass attenuation coefficient of pure coconut oil (with an average value for weight fraction of different constituent fatty acids) was estimated by the mixture rule, using mass attenuation coefficient of constituent elements obtained from XCOM. The theoretical value is compared with the experimentally obtained mass attenuation coefficient of pure coconut oil and is found to be in good agreement. The results indicate that it can be used as a non-destructive technique for the investigation of adulteration in edible oils.

Fission fragment mass–angle and mass ratio distributions have been measured for the 30Si + 180Hf reaction in the beam energy range 128–148 MeV. Quasifission signature is observed in this reaction, forming the compound system 210Rn. The results are compared with a very asymmetric reaction 16O + 194Pt, forming the same compound nucleus. Calculations assuming saddle point, scission point and DNS models have been performed to interpret the experimental results. The results strongly suggest the entrance channel dependence of quasifission in heavy ion collisions.

A light-weight multichannel analyser (MCA)-based $$\gamma $$ -ray spectrometer, developed earlier at the Inter University Accelerator Centre, New Delhi, has been used as part of the PG curriculum, to determine the effective atomic numbers for $$\gamma $$ attenuation of $$^{137}$$ Cs $$\gamma $$ -ray in different types of samples. The samples used are mixtures of graphite, aluminum and selenium powders in different proportions, commercial and home-made edible powders, fruit and vegetable juices as well as certain allopathic and ayurvedic medications. A narrow beam good geometry set-up has been used in the experiments. The measured attenuation coefficients have been used to extract effective atomic numbers in the samples. The results are consistent with XCOM values wherever available. The present results suggest that the $$\gamma $$ attenuation technique can be used as an effective non-destructive method for finding adulteration of food materials.

A $$\gamma $$ -ray spectroscopy system based on a 1 $$^{\prime \prime }\times 1^{\prime \prime }$$ NaI(Tl) detector and 1.5 $$^{\prime \prime }$$ photomultiplier tube has been developed at IUAC for teaching laboratory applications involving radioactive sources. Following along the lines of the Phoenix and Expeyes hardware developed in the laboratory earlier, a low-cost, light weight multichannel analyser also has been developed. Here the details about the same are presented. The detector–analyser system has been used as a part of the postgraduate curriculum for measuring $$^{40}$$ K content in some potassium salts and common building materials like brick, cement, concrete and sand.

Effective atomic numbers of various combinations of elements with 13 ≤ Z ≤ 50 which in effect form heterogeneous layers have been deduced using the mass attenuation values determined experimentally using 59.54 keV gamma rays. The results are compared with the theoretical values obtained using XCOM and the values calculated with an empirical formula. The coherent and incoherent scattering contributions are subtracted from the measured total cross section to get the photoelectric cross section and corresponding effective atomic numbers were also determined. The results are in good agreement with empirical estimations.

Fission fragment angular distributions have been measured for 16O + 194Pt reaction forming the compound system 210Rn, in the laboratory energy range from 79 to 90 MeV. The measured fission fragment anisotropies as a function of E c . m . / V B are compared with the predictions of standard saddle point statistical model ( sspm ). Anisotropies calculated using the average excitation energy and angular momentum values could not reasonably fit the experimental data. Statistical model calculations were performed using the pace with modified fission barrier and level density parameters. Fission probability, evaporation residue cross section and neutron multiplicity were simultaneously used to fix the statistical parameters. Model calculations incorporating the chance nature of fission decay and scaled values of the rotating finite range model (RFRM) moment of inertia could reasonably fit the fragment angular anisotropies.

Mass attenuation coefficients (µ/ρ) for Zr, Nb, Mo and Pd elements around their K-edges are measured at 14 energies in the range 15.744–28.564 keV using secondary excitation from thin Zr, Nb, Mo, Rh, Pd, Cd and Sn foils. The measurements were carried out at the K α and K β energy values of the target elements by two techniques: (1) Proton-induced X-ray emission (PIXE) and (2) 241Am (300 mCi) source. In PIXE, 2 MeV proton-excited X-rays were detected by a Si(Li) detector. In the second case, X-rays excited by 59.54 keV photons from the targets were counted by an HPGe detector under a narrow beam good geometry set-up with sufficient shielding. The results are consistent with theoretical values derived from the XCOM package and indicate that the PIXE data have better statistical accuracy.

Hybrid recoil mass analyzer (HYRA) is a unique, dual-mode spectrometer designed to carry out nuclear reaction and structure studies in heavy and medium-mass nuclei using gas-filled and vacuum modes, respectively and has the potential to address newer domains in nuclear physics accessible using high energy, heavy-ion beams from superconducting LINAC accelerator (being commissioned) and ECR-based high current injector system (planned) at IUAC. The first stage of HYRA is operational and initial experiments have been carried out using gas-filled mode for the detection of heavy evaporation residues and heavy quasielastic recoils in the direction of primary beam. Excellent primary beam rejection and transmission efficiency (comparable with other gas-filled separators) have been achieved using a smaller focal plane detection system. There are plans to couple HYRA to other detector arrays such as Indian national gamma array (INGA) and 4π spin spectrometer for ER tagged spectroscopic/spin distribution studies and for focal plane decay measurements.

Fission fragment mass angle correlation and mass ratio distributions have been measured for 16 O + 194 Pt reaction forming the composite system 210 Rn in the energy range 75 MeV to 102 MeV in laboratory frame. No mass angle correlation was observed and the mass ratio distributions were compared with theoretical calculations assuming compound nucleus formation. No evidence of quasi-fission process is observed in the reaction.

The fusion excitation functions and barrier distributions for the fusion of 12C, 16O, 28Si and 35Cl on 92Zr have been calculated using one-dimensional barrier penetration model, taking scattering potential as the sum of Coulomb and proximity potential. Calculated results are compared with experimental data and CC calculations using code CCFULL. At and above the barrier the computed cross sections match well with the experimental data, whereas below the barrier, calculations with nuclear surface tension coefficient improved by Reisdorf in the proximity potential give good fit. Reduced reaction cross sections for the systems have also been described.

Evaporation residue (ER) cross sections and gamma multiplicity distributions have been measured for (16)O + (184)W and (19)F + (181)Ta systems in the excitation energy range of 50-90 MeV, leading to the same compound nucleus (200)Pb*. Comparison of experimental results of both the systems shows that ER cross sections and moments of gamma multiplicity distribution of (16)O+ (184)W system are significantly higher than those of (19)F + (181)Ta system at higher excitation energies. Present measurements directly shows the experimental signature of entrance channel effect even with the systems which are not very different with respect to their entrance channel mass asymmetry. It is further demonstrated that the reduction in the ER cross section and moments of spin distribution for (19)F + (181)Ta system is mainly due to the suppression of fusion of higher I values. (C) 2008 Elsevier B.V. All rights reserved.

We have carried out photon attenuation measurements at several energies in the range from 49.38 keV to 57.96 keV around the K-absorption edges of the rare earth elements Sm, Eu, Gd, Tb, Dy and Er using 59.54 keV gamma rays from 241Am source after Compton scattering from an aluminium target. Pellets of oxides of the rare earth elements were chosen as mixture absorbers in these investigations. A narrow beam good geometry set-up was used for the attenuation measurements. The scattered gamma rays were detected by an HPGe detector. The results are consistent with theoretical values derived from the XCOM package.

Evaporation residue (ER) cross sections for the $^{16,18}\mathrm{O}+^{198}\mathrm{Pt}$ reactions are measured in order to investigate fission hindrance. Compound nuclei ($^{214,216}\mathrm{Rn}$) are formed in the above fusion reactions at excitation energies in the range of 40--68 MeV. The experimental ER cross sections are compared with predictions from the statistical model calculations of compound nuclear decay where Kramers' fission width is used. The strength of nuclear dissipation is treated as a free parameter in the statistical model calculations in order to fit the experimental data.

The total γ-ray interaction cross-sections on mixed absorbers were determined at 662 keV with a view to study the effective atomic numbers for γ-ray absorption under narrow beam good geometry set-up. The measurements were taken for the combination of metallic absorbers like aluminium, copper, lead and mercury and also for the simulated absorbers by rotating the targets. ORTEC HPGe and NaI(Tl) detectors were used for detection of γ-rays. The experimental results compare favourably with theoretical values derived from XCOM package and suggest the usefulness of the concept of effective atomic numbers and the utility of the rotating absorbers technique.

We have carried out some photon interaction measurements using 59.54 keV γ-rays from a 241Am source. These include γ attenuation studies as well as photoelectric absorption studies in various samples. The attenuation studies have been made using leaf and wood samples, samples like sand, sugar etc., which contain particles of varying sizes as well as pellets and aqueous solutions of rare earth compounds. In the case of the leaf and wood samples, we have used the γ-ray attenuation technique for the determination of the water content in fresh and dried samples. The variation of the attenuation coefficient with particle size has been investigated for sand and sugar samples. The attenuation studies as well as the photoelectric studies in the case of rare earth elements have been carried out on samples containing such elements whose K-absorption edge energies lie below and close to the γ-energy used. Suitable compounds of the rare earth elements have been chosen as mixture absorbers in these investigations. A narrow beam good geometry set-up was used for the attenuation measurements. A well-shielded scattering geometry was used for the photoelectric measurements. The mixture rule was invoked to extract the values of the mass attenuation coefficients for the elements from those of the corresponding compounds. The results are consistent with theoretical values derived from the XCOM package.

L-subshell ionisation cross-sections for Ta, W and Pt by proton impact in the energy range of 2‐5.2 MeV have been determined from the experimental data on X-ray production cross-section and the currently available radiative transition probabilities, fluorescence and Coster‐Kronig factors of Krause, Werner and Jitschin and Xu. The measured ionisation cross-sections and their ratios are compared with the results of ECPSSR and RPWBA-BC theoretical calculations and previously reported experimental results. The deviations in the various L subshell ionisation cross-sections with three sets of decay yield parameters are found to be less than 20%. Our results of absolute L-subshell ionisation cross-sections and their ratios are in better agreement with the theoretical calculations as compared to previously reported experimental results. The L-subshell coupling eAects are found to be weak for the elements of Ta, W and Pt in the energy region 2‐5.2 MeV by proton impact. ” 2000 Elsevier Science B.V. All rights reserved.

Proton induced X-ray Emission (PIXE) has been used to measure the trace metals especially heavy metals in Chaliyar river water samples to assess the impact of pollutants from the industrial wastes. Water samples were collected in summer and rainy seasons from three different depths along the course of the river. Measurements were carried out with 2 MeV proton beam using a 3 MV tandem pelletron accelerator at Institute of Physics, Bhubaneswar. Results from the water Samples collected in both the seasons show that the concentrations of certain heavy metals like Hg, Zn and Pb are more than the prescribed limits. This is because of pollution due to industrial wastes, indicating a need for improvement in the industrial waste treatment.

The Chaliyar river, located in Kerala, India has shown preoccupying pollution levels, that constitute a threat to public health and the ecological system. PIXE and PIGE techniques have been employed to measure the elemental concentrations in the river sediment samples. Thick targets were prepared out of the sediment samples collected from various sites along the course of the river. The measurements were carried out using 3 MeV proton beam obtained from 3 MV Tandem pelletron accelerator at Institute of Physics, Bhubaneswar. The elemental concentrations, especially that of heavy metals, at different sites are discussed in detail. Our results show that sediments from a site where the industrial activities are high are significantly high in concentrations of heavy metals ( Cr , Ni , Cu , Zn , Hg and Pb ) than those collected from non-industrial sites. The measured values are compared with the average composition of unpolluted river sediments and other national and international river sediments.

L X-ray production cross sections and their ratios in Ta, W and Pt have been measured for the bombardment of protons in the energy range 2–5.2 MeV in steps of 0.4 MeV. The data in the energy range 3.8–5.2 MeV have not been reported so far. The X-ray production cross sections compare well (within 10%) with theoretical values obtained using the decay yield parameters of Krause and ECPSSR and Relativistic Plane Wave Born Approximation-with Binding energy and Coulomb deflection correction (RPWBA-BC) ionization cross sections. The derived relative X-ray intensity ratios are in good agreement with theory, within the combined uncertainties of theory and experiments. Comparison with previously published experimental results is also presented in this paper.

Trace elements present in bottled mineral water have been studied by PIXE and ICP-MS. Samples from ten different brands of bottled mineral water were prepared by preconcentration techniques. Measurements were carried out using the 2 MeV proton beam obtained from 3 MV Tandem pelletron accelerator at the Institute of Physics, Bhubaneswar. Our results are compared with Indian standard packaged natural mineral water specifications, World Health Organisation (WHO) and European guidelines for drinking water standards. Concentration of aluminium was found to be more in one of the brands. In general, our results are comparable to the above standards.

Measurements of sub-barrier transfer reactions are reported for the systems , and using the recoil mass spectrometer HIRA in kinematic coincidence mode. The problem related to M/Q-ambiguity in measurements with mass separators has been resolved. Excellent mass resultion with a large solid angle is obtained by correction of the aberrations. Simplified coupled-channels calculations are carried out for these systems with transfer form factors extracted from the measured transfer probabilities. The surface vibration coupling is treated up to two phonon states with second-order coupling terms.

Excitation functions for one- and two-nucleon transfer in {sup 28}Si + {sup 68}Zn system have been measured at energies below the Coulomb barrier. The experiment was carried out by detecting the forward recoiling targetlike nuclei using the recoil mass separator, HIRA. With a pulsed beam, the time-of-flight of the recoils was measured and used to resolve the M/q ambiguity. This enabled the determination of the two-nucleon transfer yields. The role of one- and two-nucleon transfer in the sub-barrier fusion cross-section enhancement has been investigated. It turns out that the coupling of the positive Q-value two-neutron transfer channel results in a significant contribution to the enhancement. Coupling to both the transfer and the inelastic channels is able to explain the observed enhancement. {copyright} {ital 1997} {ital The American Physical Society}

Received 21 February 1996According to Stelson’s neutron flow model the threshold barrier is correlated to the onset of neutron flow. Asystematic study of a large set of systems indicates that there exists a very good correlation between thethreshold barrier and the intersurface distance after including the zero point motion of collective surfacevibrations of the colliding nuclei in the prescription of Stelson. S0556-2813 96 02908-1PACS number s : 25.70.Jj, 24.10.Nz

The fusion excitation functions for the 46 Ti+ 64 Ni , 50 Ti+ 60 Ni and 19 F+ 93 Nb systems have been measured from ∼ 10% below to 15% above the nominal Coulomb barrier, utilizing the recoil mass separator, HIRA at the Nuclear Science Centre, New Delhi. Mean spins have been deduced from the fusion cross sections by two different methods, one using the statistical model and the second by a fit to the fusion cross sections. Good agreement is found between them. It is seen that the simplified coupled-channel calculations, with couplings to the lowest surface inelastic excitations alone, do not explain both the observed fusion cross sections and mean spins in the low energy domain for all the three systems. A systematic comparison is made between the systems 46 Ti+ 64 Ni and 50 Ti+ 60 Ni which have quite different ground-state transfer Q -values ( Q gg ) for the transfer channels. The 46 Ti+ 64 Ni system shows a significant enhancement of the sub-barrier fusion cross section and mean spin as compared with the 50 Ti+ 60 Ni system, indicating the importance of the transfer channel coupling. Fusion cross section and mean spin have been studied for the near and sub-barrier fusion of the highly mass asymmetric system 19 F+ 93 Nb and compared with those for the 48 Ti+ 64 Ni system leading to the same compound nucleus via the nearly symmetric entrance channel. Since the 19 F+ 93 Nb system has a large positive Q gg for one-proton pick-up, the fusion data have been complemented by one-nucleon transfer measurements at energies around the Coulomb barrier. A simultaneous analysis of the fusion excitation functions and mean spin data indicates no significant effects that may be related to the entrance channel mass asymmetry.

Fusion process in the near and sub-barrier region has been investigated for the systems $^{48}\mathrm{Ti}$${+}^{58,60,64}$Ni using the heavy-ion reaction analyzer (HIRA). Fusion excitation functions and the mean angular momenta are obtained from the measured evaporation residue cross sections. Significant enhancements both in the cross section and mean angular momentum data are seen with respect to the predictions of the one-dimensional barrier penetration model. Simplified coupled channel calculations incorporating linear coupling to the inelastic channels (lowest ${2}^{+}$ and ${3}^{\mathrm{\ensuremath{-}}}$ states of both the projectile and the target) are not able to explain the observed enhancements. A systematic analysis of the data indicates lack of isotopic dependence in the sub-barrier fusion for these three systems. \textcopyright{} 1996 The American Physical Society.

Gas amplification factors have been measured for isobutane and P10 gases in single wire proportional counter and parallel plate avalanche counter geometries for reduced field strength value ranging from 140 to 1000 V cm −1 Torr −1 . Data using the SWPC were found to satisfy the Aoyama formula for gas amplification with m = 0 and also the Diethorn formula. The PPAC data are satisfactorily described again, by the Aoyama formula with m = 0 as well as by the Zastawny formula. The values of the relevant parameters in the formulae used have also been extracted from the fits.

Evaporation residue (ER) excitation function in the complete fusion of 16O with 194Pt is measured around the Coulomb barrier using gas-filled mode of the HYbrid Recoil mass Analyser (HYRA) at the Inter University Accelerator Centre (IUAC), New Delhi. Measured ER excitation function is compared with statistical model calculation. Nuclear dissipation strength β = 1.5 is required to explain the experimental data at higher excitation energies.

Coherent and incoherent scattering cross section measurements have been carried out using a HPGe detector on elements in the range of Z = 13 - 50 using 241Am gamma rays. The cross sections have been derived by comparing the net count rate obtained from the Compton peak of aluminium with the corresponding peak of the target. The measured cross sections for the coherent and incoherent processes are compared with theoretical values and earlier reported values. Our results are in agreement with the theoretical values., {"references":["P P Kane, Phys. Rep. 218, 67 (1992)","D A Bradley, O D Goncalves, P P Kane, Radiat. Phys. Chem., 6, 125\n(1999)","N Ramachandran, K Karunakaran Nair, K K Abdullah and K M Varier,\nPramana - J. Phys., 67, 507 (2006)","M J Berger, J H Hubbell, S M Seltzer, J S Coursey and D S Zucker,\n-XCOM: Photon Cross Section Database (version 1.2)- [Online], National\nInstitute of Standards and Technology, Gaithersburg, MD (2003);\nM J Berger and J H Hubbell, XCOM : \"Photon cross sections on a\npersonal computer\", Program manual, Centre for Radiation research,\nNational Bureau of investigations Standards MD20899 (1990) and M J\nBerger and J H Hubbell, XCOM version 3.1 - NIST Standard Reference\nData Base (1999)","K K Abdullah, N Ramachandran, K Karunakaran Nair, B R S Babu,\nAntony Joseph, Rajive Thomas and K M Varier,Pramana - J.Phys., 70,\n633 (2008)","K K Abdullah, K Karunakaran Nair, N Ramachandran, K M Varier, B\nR S Babu, Antony Joseph, Rajive Thomas, P Magudapathy and K G M\nNair, Pramana - J. Phys., 75, 459 (2010)","E Casnati, C Baraldi and A Tartari, Phys. Rev., A 42, 2627 (1990)","L. Kissel, R H Pratt and S C Roy, Phys. Rev. A 22, 1970 (1980) and P\nP Kane, L Kissel, R H Pratt and S C Roy Phys. Rep., 140 75 (1986)","J S Shahi, S Puri, D Mehta, M L Garg, N Singh and P N Trehan, Phys.\nRev., A 57, 4327 (1998)\n[10] J S Shahi, Ajaykumar, D Mehta, S Puri, M L Garg and N Singh, Nuc.\nInst. and Methods in Phys Res. B 179, 15 (2001)\n[11] I S Elyaseery, A Shukri, C S Chong, A A Thajuddin and D A Bradley,\nPhys. Rev., A 57 , 3469(1998); and I S Elyaseery, A Shukri, C S Chong,\nA A Thajuddin and D A Bradley, Radiat. Phys. Chem, 59 211 (2000)\n[12] J H Hubbell, W J Veigele, E A Briggs, R T Brown, D T Cromer and\nR J Howerton, J Phys. Chem. Ref. Data 4, 471(1975).\n[13] O Simsek, J.Phys. B, 33, 201 (2000).\n[14] O Simsek and M Ertugrul, Inst. SCi. and Technol., 29, 407 (2001).\n[15] O Klein and Y Z Nishina, Z. Phys., 52 853 (1929).\n[16] K J Mork, Phys. Rev., A4, 917 (1971)\n[17] M Ram and P Y Wang, Phys. Rev. Lett., 26 476 (1971); erratum in 26\n1210 (1971)\n[18] A I Smirnov, Sov. Phys. J., 16, 443 (1973).\n[19] L M Brown and R P Feyman, Phys. Rev., 85, 231 (1952).\n[20] G V Frolov, Yad. Fiz., 17, 355 (1973).\n[21] CERN laboratory in Geneva, Switzerland\n[22] N Govinda Nayak, Gerald Pinto and K Siddappa, Rad. Phys. and Chem.,\n60, 555 (2001).\n[23] B K Chatterjee and S C Roy, J. Phys. Chem. Ref. Data, 27, 1011 (1998)\n[24] D Schaupp, M Schumacher, F Smend, P Rullhusen and J H Hubbell,\n12, 467 (1983)"]}

Fission fragment mass ratio distributions have been measured for the reactions $^{16}\mathrm{O}+^{194}\mathrm{Pt}$ and $^{24}\mathrm{Mg}+^{186}\mathrm{W}$, both leading to the same compound nucleus, $^{210}\mathrm{Rn}$, at near-barrier energies. The measured fission fragment mass ratio variances for $^{16}\mathrm{O}+^{194}\mathrm{Pt}$ and $^{24}\mathrm{Mg}+^{186}\mathrm{W}$ are compared with the calculations assuming compound nucleus formation. Mass variances of fragments from the $^{24}\mathrm{Mg}+^{186}\mathrm{W}$ reaction show a dramatic deviation from the compound nucleus behavior. This suggests strong evidence for onset of the quasifission process in this reaction.

Evaporation residue (ER) and fission cross sections were measured for the reaction O+ forming the compound nucleus 212Rn. Fission fragment angular distributions and anisotropies are consistent with the saddle point model predictions. Measured ER cross sections were fitted with statistical model calculations assuming shell-corrected free energy fission barrier height. The non-zero dissipation strength required to fit the ER cross section supports the dissipative nature of fission dynamics in heavy ion fusion. In the present study shell closure effects are not observed in the dissipation strength.

Fission fragment anisotropies and fusion cross sections were measured for {sup 13}C+{sup 232}Th in the energy range 0.9 {alpha}{sub BG}). It is found that the observed anisotropies are much closer to that of the {sup 12}C+{sup 232}Th system.

Coherent and incoherent scattering cross sections have been measured using a high purity germanium detector on elements in the range of Z = 13–50 using 241Am gamma rays. The cross sections have been derived by comparing the net count rate obtained from the Compton peak of aluminum with the elastic/Compton peak of the target element. The measured cross sections for the coherent and incoherent processes are in agreement with the theoretical values.

Cross sections for the elastic scattering of 59.54 keV gamma rays through 141° by Al, Cu, Mo, Yb, Ta, Au and Pb have been accurately determined using a Si(Li) detector. The values of the cross sections have been obtained by a normalization technique based on a comparison with the Compton scattering from the essentially free electrons from an Al scatterer. For the lower-Z elements Al, Cu and Mo the experimental cross sections are more or less in agreement with the form-factor predictions as well as the S-matrix calculations. For the heavier elements Ta, Au and Pb the experimental results deviate strongly from the form-factor values but agree favourably with the S-matrix values. As a by-product, incoherent scattering functions have been evaluated for Cu, Mo and Yb. Also, a clear indication has been obtained for resonant Raman scattering in the case of Yb.

Attenuation coefficients have been measured for aluminum for x rays in the energy region 7--15 keV. The x rays were obtained by proton excitation of copper, tantalum, and lead targets. A new method has been used to extract the attenuation coefficients of the individual components of the copper K x rays and the L x rays of tantalum and lead without necessitating an analysis of the component peaks of the x-ray spectrum for each absorber.

Elastic scattering cross-sections of lead, tantalum and molybdenum were determined with the help of a Ge (Li) detector for 1.17 and 1.33 MeV rays between 30° and 115°. Theoretical evaluations of the cross-sections are based on a coherent addition of the well-known nuclear Thomson scattering amplitudes, the Rayleigh amplitudes calculated by Kissel and Pratt and the Delbruck amplitudes given by Papatzacos and Mork. The fairly good agreement between experiment and theory reveals the importance of the real Delbruck amplitudes. However, the experimental results in the 30–60° range tend to lie slightly but systematically below the calculated cross-sections.

The bremsstrahlung background in the PIXE spectra of thick non-conducting targets has been studied in detail using proton and alpha particle beams. Using targets of mica, ceramic and quartz, spectra were taken for various positions of bombardment along the length of the target. The variation of the endpoint energy Emax was studied under various conditions. The nature of the variation of Emax indicates a method to minimise the interference from the bremsstrahlung background.

PIXE analysis of human hair samples was carried out with 2 MeV protons. The trace elemental contents in hair samples collected from different parts of the same person had standard deviations ranging from 17 % to 28% whereas those from hair samples of different persons had standard deviations ranging from 26 % to 69 % . Significant differences in the trace levels in samples from different parts of the body of the same person suggests that the trace elemental absorption and accumulation in hair depends on the location of the hair in the body. The trace concentrations in white hair and black hair also showed differences.

The proton-induced X-ray emission (PIXE) technique was applied to the identification and analysis of gunshot residues. Studies were made of the type of bullet and bullet hole identification, firearm discharge element profiles, the effect of various target backings, and hand swabbings. The discussion of the results reviews the sensitivity of the PIXE technique, its nondestructive nature, and its role in determining the distance from the gun to the victim and identifying the type of bullet used and whether a wound was made by a bullet or not. The high sensitivity of the PIXE technique, which is able to analyze samples as small as 0.1 to 1 ng, and its usefulness for detecting a variety of elements should make it particularly useful in firearms residue investigations.

Large enhancements have been observed in the sub-barrier fusion cross sections for Ti+Ni systems in our previous studies. Coupled channel calculations incorporating couplings to 2+ and 3− states failed to explain these enhancements completely. A possibilty of transfer channels contributing to the residual enhancements had been suggested. In order to investigate the role of relevant transfer channels, measurements of one- and two-nucleon transfer were carried out for 46,48Ti+61Ni systems. The present paper gives the results of these studies.