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Nonmesonic Weak Decay of the double-A Hypernucleus 6AAHe
Jung-HwanJun 한국물리학회 2002 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.41 No.3
The nonmesonic weak decay of the double-$\Lambda$ hypernucleus $\He6dL$ is studied. In addition to the $\Lmd N \ra NN$ transition, the $\Lmd\Lmd \ra n\Lmd$ and $\Lmd\Lmd \ra N\Sigma$ transitions are investigated. The one-pion-exchange (OPE) interaction for the $\Lmd N \ra NN$ and $\Lmd\Lmd \ra N \Sigma$ transitions and the $K$-$\eta$ exchange interaction for the $\Lmd\Lmd \ra n\Lmd$ transition are considered along with possible four-baryon-point (4BP) interactions. The $\Lmd N \ra NN$ transition is shown to be the most dominant nonmesonic decay mode in the decay of $\He6dL$. It is found that the total nonmesonic decay rate, $\Gnm$, of $\He6dL$ via the $\Lmd N \ra NN$ transition is about 4 times larger than that of $\HeL5$. However, the ratio of the neutron-induced decay rate $\Gn$ to the proton-induced decay rate $\Gp$, $\Gr$, in the $\Lmd N \ra NN$ decay mode is $1.2$, which is about the same as those for the decays of single-$\Lmd$ hypernuclei such as $\HeL5$ and $\C12L$. The $\Delta S=2$ weak decay for the $\Lmd\Lmd\ra nn$ transition via the OPE interaction and the possible 4BP interaction based on the Glashow-Iliopoulos-Maiani mechanism is also discussed.
Extension of the Four-Baryon-Point Interaction Model to the Nonmesonic Weak Decay of A11B
Jung-HwanJun 한국물리학회 2002 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.40 No.3
Based on the successful model for the nonmesonic weak decay of hypernuclei, namely, the four-baryon-point interaction model for the short-range part and the traditional one-pion-exchange interaction for the long-range part, I calculated the partial and the total nonmesonic decay rates of ${}^{11}_{\Lambda}\rm{B}$. It is shown that the proton-induced decay rate $\Gp$ agrees extremely well with the experimental data and that the ratio, $\Gr$, of the neutron-induced decay rate $\Gn$ to the proton-induced decay rate $\Gp$ is also well within the experimental error range.
박희철(Heecheol Park),정환준(Hwanjun Jung),김석호(Seokho Kim),박민원(Minwon Park) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.5-3
HTS (High Temperature Superconductor) technology enables compact and high efficient power generators. To keep the superconducting state, the HTS rotor should be cool down to cryogenic temperature. In general, it is known that the optimum operation temperature is about 30 K considering the cost of the HTS conductors and cooling system. Therefore, cooling system should be designed to keep the temperature of the HTS rotor around 30 K. This can be realized by using the liquid neon thermosyphon cooled by crycooler. This paper describes the design process and experimental results for liquid nitrogen re-condensing cooling system. Heat loss of the torque tube is estimated. Flow areas for liquid and gaseous neon are determined considering the pressure drop. Experiments are performed to estimate the background loss of the cooling system itself and to investigate the heat loss through the torque tube. Additional heating is applied to verify the performance of the cooling system.
Design of a 400 mH 400 A Toroid-Type HTS DC Reactor Magnet
Kwangmin Kim,Jin-Geun Kim,Hwanjun Jung,Seokho Kim,Sangjin Lee,Minwon Park,In-Keun Yu IEEE 2013 IEEE transactions on applied superconductivity Vol.23 No.3
<P>Large electric power systems, such as high voltage direct current (HVDC) transmission systems, need dc reactors with large inductance and high transport current. Such systems experience a lot of electrical loss due to the resistance of their copper winding. Employing superconducting magnets for the reactors provides some advantages such as high current density, low electrical loss, and so on. This paper describes the design of a toroid-type high temperature superconductor (HTS) dc reactor magnet. The target inductance and the current level of the HTS dc reactor were 400 mH and 400 A, respectively. The toroid-type HTS magnet reduced leakage flux and increased the critical current of the reactors. The HTS dc reactors were designed using 2G HTS wires. The Finite Element Method was used for the design and analysis of the toroid-type HTS dc reactors.</P>