Papers by Hyoung C. Bhang
AIP Conference Proceedings, 2001
In spite of the recent progresses achieved at BNL and KEK, a consistent understanding of the non-... more In spite of the recent progresses achieved at BNL and KEK, a consistent understanding of the non-mesonic weak decay is yet to be achieved. The rapid saturation of total decay rate in its mass dependence, Gamman/Gammap ratio puzzle, opposite sign of decay asymmetry parameter between Lambda5He and Lambda12C, and DeltaI=1/2 rule of non-mesonic weak decay are the current concerns, but not understood yet. The difficulties are largely in the treatment of the final state interaction. In the paper, we discuss on the role of final state interaction in the interpretation of the newly measured decay particle spectra in the non-mesonic weak decay of Lambda hypernuclei. .
We have measured the branching ratio of the three-body process in the nonmesonic weak decay of {s... more We have measured the branching ratio of the three-body process in the nonmesonic weak decay of {sub ¹²}C to be 0.29+-0.13. This result was obtained by reproducing the nucleon and the nucleon pair yields introducing a measured final state interaction. At the same time, we have determined the absolute decay widths, GAMMA{sub n} and GAMMA{sub p}, along with GAMMA{sub 2N}, whose relative ratio has been a long-standing puzzle. Including the three-body process, we have successfully reproduced the nucleon energy distribution, the coincidence two-nucleon angular correlation, and the momentum sum distribution simultaneously.
IEEE Nuclear Science Symposium Conference Record, 2012
A scintillating crystal that contains a candidate isotope for DBD provides a promising technique ... more A scintillating crystal that contains a candidate isotope for DBD provides a promising technique for the high detection-efficiency and good energy resolution. The AMoRE (Advanced Molybdenum based Rare process Experiment) collaboration is studying the potential of CaMoO4 scintillation crystals for searches for looMo 0v DBD.
Nuclear Physics A, 2000
We have measured the asymmetric emission of protons and pions from the nonmesonic decay of the po... more We have measured the asymmetric emission of protons and pions from the nonmesonic decay of the polarized 5LambdaHe prodiced by the (pi+, K+) reaction. The polarization was derived by the observed asymmetry of the mesonic decay pions for the first time. The asymmetry parameter of the nonmesonic decay has been evaluated using the obtained polarization and the asymmetry of the decay protons. The positive asymmetry parameter contradicts theoretical prediction based on meson exchange model. The discrepancy can be attributed to insufficient knowledge of the weak LambdaN interaction, especially at short range, which may consistently explain the discrepancy seen in the partial decay rates of the nonmesonic decay.
Journal of Physics: Conference Series, 2012
AIP Conference Proceedings, 2011
ABSTRACT We will measure the X‐rays from kaonic 3He3d → 2p transition with a precision below 2 eV... more ABSTRACT We will measure the X‐rays from kaonic 3He3d → 2p transition with a precision below 2 eV. It can provide crucial information on the kaon‐nucleus strong interaction. The experiment (J‐PARC E17) will be performed as Day‐1, which is one of the first experiments in the J‐PARC hadron facility in the year 2011. An overview and the present status of the J‐PARC E17 experiment are described.
The Identification of Dark Matter - Proceedings of the Fifth International Workshop, 2005
The Korea Invisible Mass Search(KIMS) collaboration has developed low background CsI(Tl) detector... more The Korea Invisible Mass Search(KIMS) collaboration has developed low background CsI(Tl) detectors and constructed a new experimental hall in the 700 m deep underground facility in Yangyang, Korea. Successful reduction of the internal background of CsI(Tl) crystal has been realized. We constructed a new shield composed of 60 tons of pure materials and the muon detector with full coverage of
We have measured the angular correlation of the pair nucleons np and nn emitted from the nonmeson... more We have measured the angular correlation of the pair nucleons np and nn emitted from the nonmesonic weak decay (NMWD) of Lambda12C produced via the (pi+,K+) reaction in coincidence measurement. The Lambdap --> np and Lambdan --> nn modes were clearly identified by measuring the back-to-back correlation of the emitted nucleon pairs which is the characteristic of two-body kinematics. From
EPJ Web of Conferences, 2010
EPJ Web of Conferences, 2010
The serious inconsistency problem between the values of experimental and theoretical Γ n /Γ p rat... more The serious inconsistency problem between the values of experimental and theoretical Γ n /Γ p ratio of the nonmesonic weak decay of Λ hypernuclei has been resolved recently. We have shown that the reason behind the problem was the quenching of the nucleon yields which in turn was due to the contribution of the three-body process. We have measured that the branching ratio of the three-body process in nonmesonic weak decay, 0.29±0.13, is so large that the absolute values of Γ n and Γ p must be determined taking account of the contribution of the 3-body process. In this paper, the recent studies toward the finding of the 3-body process via the exclusive coincidence experiments are presented.
ABSTRACT Light Λ hypernuclear structure has been investigated through the (π+, K+) reaction with ... more ABSTRACT Light Λ hypernuclear structure has been investigated through the (π+, K+) reaction with use of the SKS spectrometer. Preliminary excitation energy spectra of Λ7Li, Λ9Be, Λ13C and Λ16O have been measured in the KEK-PS E336 experiment. The spectra of Λ12C and Λ16O were discussed in view of the ΛN interaction. It was shown that the high-quality Λ hypernuclear spectra provide us with a valuable mean for the investigation of the ΛN interaction.
The Identification of Dark Matter - Proceedings of the Fifth International Workshop, 2005
Searches for weakly interacting massive particle(WIMP) is being carried out at the underground la... more Searches for weakly interacting massive particle(WIMP) is being carried out at the underground laboratory, Yangyang, Korea. Characteristics and internal background of CsI(Tl) crystal have been investigated. In our extensive R&D, we developed a technique to reduce internal background in the CsI(Tl) crystal. With the latest CsI(Tl) crystal, we have achieved 6 counts/keV/kg/day level of background. Further reduction of internal background
Physics Letters B, 2008
A search for tribaryon states was performed at KEK-PS. We adopted the 4 He(K − stopped , p) react... more A search for tribaryon states was performed at KEK-PS. We adopted the 4 He(K − stopped , p) reaction to populate the states with strangeness −1, charge 0 and isospin 1. No significant narrow structure was observed in the mass region from 3000 to 3200 MeV/c 2 in an inclusive missing mass spectrum. The upper limit of the formation branching ratio was determined to be (1 ∼ 3) × 10 −4 , (0.7 ∼ 2) × 10 −3 and (2 ∼ 8) × 10 −3 /(stopped K −) with 95 % confidence level for narrow states with an assumed width of 0, 20 and 40 MeV/c 2 , respectively.
Physics Letters B, 2010
ABSTRACT We have recently reported on an indication of the strange tribaryon state, S+, with a ma... more ABSTRACT We have recently reported on an indication of the strange tribaryon state, S+, with a mass M˜3140 MeV/c2 and width Γ<23 MeV/c2, in the neutron time-of-flight (TOF) spectrum of the He4(Kstop-,nπ±) reaction of the KEK-PS E471 experiment in a search for the deeply bound narrow K-ppn (total isospin T=0) state. In an attempt to confirm the state and search for other possible T=0, 1 tribaryonic states, we have re-measured the neutron energy spectrum of the same reaction in the KEK-PS E549 experiment with an upgraded setup for which the TOF resolution was improved 1.5 times and the statistics was increased 6 times. However, in the neutron spectra, we find such a smooth distribution that we conclude the state is either not so strong to stick out of the inclusive background or too broad to be identified as a distinct peak. We estimated the upper limits of the formation probability of the possible tribaryonic state for three widths, 0, 20, and 40 MeV/c2. The obtained upper limit (95% CL) for a state as narrow as 20 MeV/c2 is at most 1% per stopped kaon over the wide mass range of 3000-3200 MeV/c2, while it reaches to 4˜5% at around 3140 MeV/c2 for Γ⩾40 MeV/c2, implying the possible existence of unknown processes including tribaryonic formation.
Physical Review C, 2001
Quasielastic scattering cross sections have been measured with a 950 MeV/c Ϫ beam on targets of 2... more Quasielastic scattering cross sections have been measured with a 950 MeV/c Ϫ beam on targets of 2 H, 6 Li, C, Ca, Zr, and 208 Pb, over a range of three-momentum transfers from 350 through 650 MeV/c. Results for carbon are compared to a finite-nucleus continuum random-phase approximation calculation including distortions. The pion spectra at our lowest range of momentum transfers show less scalar/isoscalar correlation than predicted.
Physical Review D, 2008
The atmospheric neutrino background for proton decay via p → e + π 0 in ring imaging water Cheren... more The atmospheric neutrino background for proton decay via p → e + π 0 in ring imaging water Cherenkov detectors is studied with an artificial accelerator neutrino beam for the first time. In total, 3.14×10 5 neutrino events corresponding to about 10 megaton-years of atmospheric neutrino interactions were collected by a 1,000 ton water Cherenkov detector (KT). The KT charged-current single π 0 production data are well reproduced by simulation programs of neutrino and secondary hadronic interactions used in the Super-Kamiokande (SK) proton decay search. The obtained p → e + π 0 background rate by the KT data for SK from the atmospheric neutrinos whose energies are below 3 GeV is 1.63 +0.42 −0.33 (stat.) +0.45 −0.51 (syst.) (megaton-year) −1. This result is also relevant to possible future, megaton-scale water Cherenkov detectors.
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Papers by Hyoung C. Bhang