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The recent successful detection of gravitational waves has been a century long Odyssey involvinga remarkable experiment and an elegant theory. In the latter aspect, it was made possible by a critical understanding of physical effects of gravitational waves and an improved understanding of the problem of two body motion in general relativity. This talk is a personal broad brush overview of how an unforgiving experiment drove an exquisite theory to create a sophisticated data analysis infrastructure to detect gravitational waves and to decipher their properties.

The Cryogenic Storage Ring (CSR) [1] located at Max-Planck-Institut für Kernphysik in Heidelberg,Germany is an ideal experimental setup to perform collision studies of photons and cold electrons as well neutrals with the stored molecular ions of kinetic energies between 20-300 keV. The circumference of the ring is 35 m and being fully electrostatic, it has no mass limit for stored ions. The cryogenic temperature of about 6 K offers unique storage capabilities in extremely high vacuum conditions of below 140 rest-gas particles per cm³ and almost vanishing blackbody radiation. An electron cooler(ecool) is installed in one straight section of the CSR which uses a photocathode to produce cold electrons. These cold electrons can further reduce the momentum spread of the stored ion beam upon interaction. A tunable optical parametric oscillator (OPO) laser system in the same section allows photon interaction studies from the ultraviolet (225 nm) to the infrared (2600 nm) regime. The CSR is equipped with two independent ion source platforms, which can deliver ions up to an energy of 60 and 300 keV per charge state, respectively. The low energy platform can be used to produce neutral beams by photodetachment of the negative ions. Whereas the 300 kV platform presently contains a metal ion sputter source, a Penning source and an electron cyclotron resonance source; extension by a laser vaporization and an electrospray ionization ion source is in progress. The entire facility enables to perform photodissociation, electron-ion recombination, and ion-atom interaction studies with ro-vibrationally cooled stored positive and negative ions as well as clusters and highly charged ions. Further experiments aim to study decay rates of metastable ions and radiative lifetimes. The first experimental results,machine characteristics as well as future experimental possibilities of this unique infrastructure will be discussed [2, 3].

References
[1] R. von Hahn, et al., Rev. Sci. Instrum. 87, 063115 (2016).
[2] A. O’ Connor, et al., Phys. Rev. Lett. 116, 113002 (2016).
[3] C. Meyer, et al., Phys. Rev. Lett. 119, 023202 (2017).

Swift Heavy Ion (SHI) irradiation of semiconductor nanostructures is arapidly developing area of nanomaterials research which resultssignificant changes in structural and physical properties of such lowdimensional systems. The present study describes SHI irradiation effect onbare and silica (SiO2) coated semiconductor nanoparticles embedded ininsulating polymer (polyvinyl alcohol) and on a composite of semiconductornanoparticles and conductingpolymer(2-methoxy-5-(2-ethyl-hexyloxy)-pphenylene vinylene). The nanosemiconductor samples of PbS, CdS and ZnS were prepared following aninexpensive chemical route. Characterizations of the samples were carriedout with X-ray diffraction, optical absorption spectroscopy,photoluminescence and transmission electron microscopy. The UV–Visabsorption spectra reveal blue shift relative to bulk material inabsorption energy while PL spectra suggest that surface state and nearband edge emissions are dominating in case of bare and coated samplesrespectively. The samples were irradiated with 160 MeV Ni-ion beam withfluences in the range of 1e12 to 1e13 ions/cm2. The investigation afterSHI irradiation showed fluence dependent luminescence behavior and sizeenhancement of bare nanoparticles while reduction of particle size wasobserved in the composite system. However, coated samples exhibit betterstability upon SHI irradiation compared to the bare one.