Person: ŞAHİN, ÖZKAN
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ŞAHİN
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ÖZKAN
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Publication Excitation energy transfer model for Ne-CO2 and Ne-N2 mixtures(IOP, 2021-03-01) Şahin, Özkan; ŞAHİN, ÖZKAN; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü; I-9715-2017The excited states of neon are capable of ionizing the CO2 and N-2 molecules through Penning energy transfer mechanisms. Probability of such additional ionizations can be calculated from the measured gas gain fits. In the present work, Penning ionization processes for Ne-CO2 and Ne-N-2 mixtures have been investigated with a newly developed model. The decreases in the transfer rates observed at high molecular gas concentrations indicate the existence of a remarkably interesting transfer mechanism for the excited neon atoms.Publication Intermolecular magnetic spin-spin interactions in solution state at 1.53 mT(Taylor, 2015-01-01) Yıldız, Fevkani; Şahin, Özkan; Peksöz, Ahmet; Yıldız, Fevkani; ŞAHİN, ÖZKAN; PEKSÖZ, AHMET; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü; KQV-0698-2024; AAH-6445-2021; AAG-9772-2021; I-9715-2017Overhauser dynamic nuclear polarization (DNP) technique can provide a dramatic increase in the signal obtained from nuclear magnetic resonance experiments owing to the magnetic spin-spin interactions between H-1 nuclei of the solvent and electrons delocalized on the asphaltene in crude petroleum or asphalt. Studies on H-1 Overhauser DNP enhancements at 1.53 mT are reported for benzene solvent medium with three different radical sources: Iran crude petroleum, MC30 liquid asphalt, and MC800 liquid asphalt for a range of radical concentrations. The results show that protons of benzene are good detectors for dipolar coupling.Publication Accurate γ and mev-electron track reconstruction with an ultra-low diffusion xenon/tma tpc at 10 atm(Elsevier, 2015-12-21) Gonzalez-Diaz, Diego; Alvarez, V.; Borges, F. I. G.; Camargo, M.; Carcel, S.; Cebrian, S.; Cervera, A.; Conde, C. A. N.; Dafni, T.; Diaz, J.; Esteve, R.; Fernandes, L. M. P.; Ferrari, P.; Ferreira, A. L.; Freitas, E. D. C.; Gehmani, V. M.; Goldschmidt, A.; Gomez-Cadenas, J. J.; Gutierrez, R. M.; Hauptman, J.; Hernando Morata, J. A.; Herrera, D. C.; Irastorza, I. G.; Labarga, L.; Laing, A.; Liubarsky, I.; Lopez-March, N.; Lorca, D.; Losada, M.; Luzon, G.; Mari, A.; Martin-Albo, J.; Martinez-Lema, G.; Martinez, A.; Miller, T.; Monrabal, F.; Monserrate, M.; Monteiro, C. M. B.; Mora, F. J.; Moutinho, L. M.; Munoz Vidal, J.; Nebot-Guinot, M.; Nygren, D.; Oliveira, C. A. B.; Perez, J.; Perez Aparicio, J. L.; Querol, M.; Renner, J.; Ripoll, L.; Rodriguez, J.; Santos, F. P.; dos Santos, J. M. F.; Serra, L.; Shuman, D.; Simon, A.; Sofka, C.; Sorel, M.; Toledo, J. F.; Torrent, J.; Tsamalaidze, Z.; Veloso, J. F. C. A.; Villar, J. A.; Webb, R.; White, J. T.; Yahlali, N.; Azevedo, C.; Aznarab, F.; Calvet, D.; Castel, J.; Ferrer-Ribas, E.; Garcia, J. A.; Giomataris, I.; Gomez, H.; Iguaz, F. J.; Lagraba, A.; Le Coguie, A.; Mols, J. P.; Rodriguez, A.; Ruiz-Choliz, E.; Segui, L.; Tomas, A.; Veenhof, R.; Şahin, Özkan; ŞAHİN, ÖZKAN; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi; I-9715-2017We report the performance of a 10 atm Xenon/trimethylamine time projection chamber (TPC) for the detection of X-rays (30 keV) and gamma-rays (0.511-1.275 MeV) in conjunction with the accurate tracking of the associated electrons. When operated at such a high pressure and in similar to 1%-admixtures, trimethylamine (TMA) endows Xenon with an extremely low electron diffusion (1.3 +/- 0.13 mm-sigma (longitudinal), 0.95 +/- 0.20 mm-sigma (transverse) along 1 m drift) besides forming a convenient Penning-Fluorescent' mixture. The TPC, that houses 1.1 kg of gas in its fiducial volume, operated continuously for 100 live-days in charge amplification mode. The readout was performed through the recently introduced microbulk Micromegas technology and the AFTER chip, providing a 3D voxelization of 8 mm x 8 mm x 1.2 mm for approximately 10 cm/MeV-long electron tracks. Resolution in energy (epsilon) at full width half maximum (R) inside the fiducial volume ranged from R = 14.6% (30 keV) to R = 4.6% (1.275 MeV).This work was developed as part of the R&D program of the NEXT collaboration for future detector upgrades in the search of the neutrino-less double beta decay (beta beta 0 nu) in Xe-136, specifically those based on novel gas mixtures. Therefore we ultimately focus on the calorimetric and topological properties of the reconstructed MeV-electron tracks. In particular, the obtained energy resolution has been decomposed in its various contributions and improvements towards achieving the R =1.4%root MeV/epsilon levels obtained in small sensors are discussed.Publication Measurements and calculations of gas gains in methane-based TEG mixtures(IOP Publishing, 2022-11-01) Kowalski, T.; Şahin, Özkan; ŞAHİN, ÖZKAN; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü; LJG-5233-2024; H-8662-2013The gas gains in the methane-based tissue equivalent gas (TEG) mixture (64.4% CH4 + 32.5% CO2 + 3.1% N-2) were measured in single wire proportional counters and calculated with Magboltz simulation program for various mixture pressures. The calculated gain values were always greater than the measured ones for all pressures. The source of the discrepancies was investigated in terms of dissociation of the molecules and non-equilibrium conditions. The impacts of both energy loss mechanisms on gas gain rise as the mixture pressure decreases.