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Guest Lecture
Report
LECTURE ON INTERACTION OF ALPHA PARTICLES WITH SOFT MATERIAL
DATE- 11 January 2018
VENUE- AV Hall, The IIS University, Jaipur
SPEAKER-Prof. Y.K. Vijay, Director, Vivekananda Global University and President IAPT RC- 6
BENEFICIARIES-UG and PG (Physics students)
Professor Vijay started the lecture by explaining the properties of alpha particles and also its similarity with Helium atom on the basis of its mass and charge.He informed the audience about the Alpha spectrometer that they have procured from IUAC New Delhi and the source of Alpha particles AM-241 from BRIT BARC Mumbai He also described that in condensed matter the nucleus of different atoms do not interact with each other, the interaction only takes place between the electron clouds of the atoms. Soft material is any material by which we can see through for example curtains, thin films etc. He explained the Rutherford model of atomic structure which can be used to determine the size of nucleus of gold atoms experimentally. He demonstrated the arrangement of atoms in a crystal with the help of a laser pointer fitted with some filters on the top which produced different patterns on the wall which was very fascinating.
He further elaborated the technique in which the high energy ion scattering spectroscopy is used to determine the structure and composition of materials by using alpha particles. He then explained the working of table top alpha spectrometer which can be used to detect the alpha particlesscattered by the sample placed in vacuuminside the alpha spectrometer. He further explained that the presence of air in the chamber shifts the peak of spectrum due to loss of energy. He explained the working of the apparatus with many samples such as aluminum foil of different thickness with holes of different diameters like 5mm and 2mm, HDP foil, PVC collimator, Mylar-Al and Al-Mylar and compared their peaks. He also described the effect of increasing the number of holes and decreasing their diameter. The motive behind explaining this technique is to study the porous nature of the softmaterial. He ended his lecture by explaining the photoluminescence spectra of ZnS andZnCuSnanocrystals /polymer composite films in which he described the conduction of surface related to non radiated recombination is still obvious and Cu does not provide an effective radiative path for exicitons.
