H.J. Kim

The measurement of direct photons from Au+ Au collisions at s N N= 39 and 62.4 GeV in the transverse-momentum range 0.4< p T< 3 Gev/c is presented by the PHENIX collaboration at the BNLRelativistic Heavy Ion Collider. A significant direct-photon yield is observed in both collision systems. A universal scaling is observed when the direct-photon p T spectra for different center-of-mass energies and for different centrality selections at s N N= 62.4 GeV is scaled with (d N ch/d η) α for α= 1.21±0.04. This scaling also holds true for direct-photon spectra from Au+ Au collisions at s N N= 200 GeV measured earlier by PHENIX, as well as the spectra from Pb+ Pb at s N N= 2760 GeV published by ALICE. The scaling power α seems to be independent of p T, center of mass energy, and collision centrality. The spectra from different collision energies have a similar shape up to p T of 2 Gev/c. The spectra have a local inverse …

We report the results of a search for inelastic scattering of weakly interacting massive particles (WIMPs) off I 127 nuclei using NaI (Tl) crystals with a data exposure of 97.7 kg· years from the COSINE-100 experiment. The signature of inelastic WIMP− I 127 scattering is a nuclear recoil accompanied by a 57.6 keV γ-ray from the prompt deexcitation, producing a more energetic signal compared to the typical WIMP nuclear recoil signal. We found no evidence for this inelastic scattering signature and set a 90% confidence level upper limit on the WIMP-proton spin-dependent, inelastic scattering cross section of 1.2× 10− 37 cm 2 at the WIMP mass 500 GeV/c 2.

The measurement of direct photons from AuAu collisions at and 62.4 GeV in the transverse-momentum range Gev/ is presented by the PHENIX collaboration at the Relativistic Heavy Ion Collider. A significant direct-photon yield is observed in both collision systems. A universal scaling is observed when the direct-photon spectra for different center-of-mass energies and for different centrality selections at GeV is scaled with for . This scaling also holds true for direct-photon spectra from AuAu collisions at GeV measured earlier by PHENIX, as well as the spectra from PbPb at GeV published by ALICE. The scaling power seems to be independent of , center of mass energy, and collision centrality. The spectra from different collision energies have a similar shape up to of 2 GeV/. The spectra have a local inverse slope increasing with of GeV/ in the range GeV/ and increasing to GeV/ for GeV/. The observed similarity of low- direct-photon production from to 2760 GeV suggests a common source of direct photons for the different collision energies and event centrality selections, and suggests a comparable space-time evolution of direct-photon emission.

We present results from a search for solar bosonic dark matter using the annual modulation method with the COSINE-100 experiment. The results were interpreted considering three dark sector bosons models: solar dark photons, Dine-Fischler-Srednicki-Zhitnisky (DFSZ) and Kim-Shifman-Vainshtein-Zakharov (KSVZ) solar axions, and Kaluza-Klein solar axions. No modulation signal compatible with the expected from the models was found from a dataset of 2.82 yr, using 61.3 kg of NaI (Tl) crystals. Therefore, we set a 90% confidence level upper limits for each of the three models studied. For the solar dark photon model, the most stringent mixing parameter upper limit is 1.61× 10− 14 for dark photons with a mass of 215 eV. For the DFSZ and KSVZ solar axion, and the Kaluza-Klein axion models, the upper limits exclude axion-electron couplings, g a e, above 1.61× 10− 11 for axion mass below 0.2 keV; and axion …

The purpose of developing high transparency radiation shielding materials and luminescence materials with stoichiometric ratio of xGd2O3:10La2O3:10ZnO:(79-x) B2O3: 1Sm2O3 where x = 0, 5, 10, 15, and 20 mol% using melt quenching technique. The physio-optical properties such as molar volume, density, concentration of rare-earth ions, polaron radius, inter-ionic radius, optical basicity, average distance between rare-earth ions, and optical packing density of the present glasses has been evaluated. The glass samples obtained show high density which is vital factor for radiation shielding. The absorption spectra show significant of bands Sm3+ ions. The FTIR results of Gd-La-Zn-B-Sm (Gd-1Sm) glass samples show signature borate BO3 and BO4 vibrational units in Gd-1Sm glass samples. The μ, μm, HVL, TVL, and MFP were evaluated and showed that the values decrease with increasing X-ray energy …

Various concentrations of samarium (Sm3+) ion‐activated oxyfluoroborate (ANCB:AlF3‐NaF‐CaF2‐B2O3) glasses are fabricated for its applications in red‐emitting lasers and scintillators. From the optical absorption spectrum, Ω2,4,6 intensity parameters and several radiative parameters along with the high value of absorption (2.96 × 10−21 cm2) and emission (14.13 × 10−22 cm2) cross sections are calculated. By stimulating at 403 nm, a transition corresponding to 4G5/2 → 6H7/2 (596 nm) is very intense and emits orange‐reddish luminescence of Sm3+ ion in ANCB glasses. The decay curves are fit to the Inokuti–Hirayama (I–H) model to determine the energy transfer in Sm3+: ANCB glasses. The X‐ray‐excited luminescence (XEL) spectra are determined with an X‐ray source by supplying the voltage of 50 kV and current 30 mA. The lasing parameters like stimulated emission cross section (14.13 …

In order to solve the shortage of roughage supply for dairy farm in Korea, winter cereal forage production after harvesting of rice in the fallow paddy field was studied. Two parts are already reported at the previous paper-One was the model development of the mechanized production, and the other was the study of feasibility of the model and its desirable direction in Korea. In this study, the model system is applied for a winter cereal wrap silage production model to practice in Kyungbook National University farm on 3ha scale for 3 years. Results of the research are summarized as followsIt takes 2 or 3 working days to process the wrap silage in middle of May in Daegu region. Also, not much particular problem can be found during the application test of mechanized wrap silage production.

The optical, photo, and X‐ray luminescence properties of Sm3+ ion‐doped Li2O–Al2O3–Gd2O3–B2O3–P2O5 glasses are evaluated. The glasses are fabricated by the melt quenching technique. The absorption spectra exhibit the hypersensitive transitions 6H5/2→6P3/2 and 6H5/2→6F7/2 at the visible and near‐infrared range respectively. The glasses display four major transitions characteristic of Sm3+ ion for photoluminescence and X‐ray luminescence, with the most intense one corresponding to the 4G5/2→6H7/2 transition. The best emitting samarium concentration obtained by X‐ray excitation is compared to BGO crystals. The integral scintillation efficiency of glass is determined by total area under all of peak spectrum. The results indicate the promising application of these glasses in scintillators and for X‐ray sensing devices.