New Physics: Sae Mulli

Aims and Scope

The origin of New Physics: Sae Mulli (NPSM, ISO abbreviation: New Phys.: Sae Mulli.): Sae Mulli (새물리 in Korean characters means ‘new physics’) is the oldest Korean pure scientific journal. It was first published in 1961 just after the Korean War by the Korean Physical Society (KPS). The primary mission of Sae Mulli was to start building up Korean physics research community from almost nothing and in fact Sae Mulli had made tremendous contributions to the Korean science community. Through a peer-review system, Sae Mulli had continued elevating the level of scientific researches, consequently becoming a cornerstone of the economic miracle of Korea...

Editor-in-Chief : Sunglae CHO
New Physics: Sae Mulli Editorial Board

pISSN : 0374-4914
eISSN : 2289-0041

Tel : +82-2-556-4737
Fax : +82-2-554-1643
E-mail: npsm@npsm-kps.org

Research Papers

Research on Reactor Neutrino Event Selection by Using the Machine Learning Technique

Chang Dong SHIN¹, Kyung Kwang JOO*¹, Dong Ho MOON¹, Myoung Youl PAC², Junghwan GOH³

¹Institute for Universe & Elementary Particles, Department of Physics, Chonnam National University, Gwangju 61186, Korea

²Institute of High Energy Physics, Dongshin University, Naju 58245, Korea

³Department of Physics, Kyung Hee University, Seoul 02447, Korea

For the next-generation massive neutrino experiments, selecting a signal in the background events is very important. To do this, we investigated the results of applying a machine learning technique to the selection of neutrino signals. The neutrino signal after inverse beta decay and the background events in a gadolinium-loaded liquid scintillation detector were reproduced by using Monte Carlo simulations. The inverse beta decay process is well-known and has relatively high statistical quantities for this simulation. In this study, an efficiency of signal selection through machine learning was obtained, and in this paper several results are briefly described. Finally, the machine learning technique is expected to become an important tool for use in the next-generation neutrino experiment.

New Phys.: Sae Mulli 2019; 69: 813-817

Photoluminescence Study of Type-II Submonolayer Quantum Dots

inseak KIN¹, Hyun-Jun JO¹, Mo Geun SO¹, Jong Su KIM¹*, Yeongho KIM², Sang Jun LEE², Seung Hyun LEE³, Christiana B. HONSBERG⁴, Heedae KIM⁵

¹Department of Physics, Yeungnam University, Gyeongsan 38541, Korea

²Division of Convergence Technology, Korea Research Institute of Standards and Science, Daejeon 34113, Korea

³Department of Electrical and Computer Engineering, Ohio State University, Columbus, USA

⁴School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, USA

⁵School of Physics, Northeast Normal University, Changchun 130024, China

We have studied the optical properties of InAs/GaAsSb submonolayer quantum dots (SML-QDs) through excitation intensity ($I_{\text{ex}}$) and temperature dependent photoluminescence (PL) experiments. The SML-QDs with type-I (T-1) and type-II (T-2) band structures were grown using a GaAsSb spacer with a Sb composition of 0\% and 15.8\%. At 13~K, the PL signals from the T-1 and the T-2 samples were observed at 1.42~eV and 1.37~eV, respectively, when the $I_{\text{ex}}$ was 8.7~mW/cm$ ^{2}$. The PL signal of the T-1 sample is due to the recombination of electrons and holes in the InAs SML-QDs. The PL signal of the T-2 sample is due to the recombination of electrons (in the GaAs electron band) and holes (in the GaAsSb spacer hole band) by type-II band alignment formed between GaAs and GaAsSb. The full widths at half maxima (FWHMs) of the T-1 and the T-2 samples were 7.09~meV and 24.6~meV, respectively, because the T-2 sample has a lower uniformity than the T-1 sample. As the excitation intensity was increased, the PL signals of the T-1 and the T-2 samples shifted to lower energy because of the quantum-confined Stark effect. As a result of these temperature-dependent PL experiments, the activation energy of the T-1 sample was found to be 30~meV.

New Phys.: Sae Mulli 2019; 69: 794-799