홍병식 교수

Solid-state devices to detect photons are under active research and development because they, unlike photomultiplier tubes (PMT), can be used under high-magnetic-field and radio-frequency environments, such as in magnetic resonance imaging (MRI) scanners. In addition, some of the solid-state devices have a higher particle detection efficiency and only a slightly less gain than PMTs, currently the first choice to detect photons in positron emission tomography (PET) scanners. We have tested solid-

We present the beam-test results for a real-size prototype resistive plate chamber (RPC) for the endcap region of the Compact Muon Solenoid (CMS) experiment at CERN Large Hadron Collider (LHC). The chamber built with relatively low resistivity bakelite was tested at the Gamma Irradiation Facility (GIF) at CERN under a high photon-flux environment with an effective cluster rate up to about 1.2 kHz/cm2. The characteristics of the present chamber are compatible with the previous results for the muo

GEANT is a toolkit for simulating the passage of particles though matter. It contains a complete range of functionality, including tracking, geometry, physics models, and hits. In this article, an attempt to use a GEANT4 Monte Carlo code to watch the resistive plate chamber’s (RPC) response to neutrons is presented. The simulation calculations for the RPC have been evaluated as a function of neutron energy in the range 1 × 10.10 MeV . 10 GeV. In order to evaluate the response of the RPC detector

We review the development of the endcap resistive plate chambers for the Compact Muon Solenoid experiment at the Large Hadron Collider. The standard double gap geometry, which was designed and constructed by the Korea Detector Laboratory, satisfies all CMS requirements including the efficiency, the time resolution, and the working high-voltage plateau range. These results clearly demonstrate that the present design of the chamber is suitable for the muon trigger system in the endcap region of th

We present the design, the building procedure, and the test results for a prototype multigap resistive plate chamber (RPC) using normal glass plates as the resistive material. A detection efficiency of almost 100 % and a time resolution of about 340 ps were achieved at the operational plateau region, which extended more than 400 V regardless of the discriminator threshold. These results open a possibility that the multigap RPC can be used for charged particle identification in nuclear-collision

We present the design, construction, and performance of a prototype multigap resistive plate chamber made of glass plates. A time resolution of 580 ps with a detection efficiency above 95 % was achieved at the working high-voltage plateau with cosmic ray muons.

An intensive aging study for the forward resistive plate chambers (RPCs) was performed by using a 200 mCi 137Cs gamma-ray source. For the systematic aging study, four double-gap RPCs, 40 ￡ 40 cm2, were manufactured and tested for cosmic muons and the gamma rays irradiated from the source. The aging of the RPC gap is expected to be proportional to the integrated avalanche charge per unit area of the RPC. In this paper, a few diagnostic methods to observe aging phenomena are discussed, and the tes

We present the neutron-detection efficiencies of a Gd-coated single-gap resistive plate chamber (RPC) and a LiF-coated double-gap RPC. The experiments were performed by using indirect neutrons provided by the MC50 cyclotron at the Korea Institute of Radiological and Medical Science. Both RPCs show a decrease in the efficiency with increasing beam current, especially the Gd-coated RPC at the highest beam current (50 nA) that we received. Such a decrease in the efficiency could be understood in te

We report the performance of hybrid plastic scintillator detectors for low-energy neutron measurements. Boron- and gadolinium-loaded hybrid scintillator detectors were manufactured and tested with slow and fast neutrons. The low-energy slow neutrons were provided by moderated neutrons from a 252Cf source, whose energy ranged from 10 to 600 meV with a peak at 75 meV. To distinguish slow neutrons from fast neutrons or gamma rays, we employed the pulse-shape analysis method. For the boron-doped sci

In this paper, we report investigations of the detector characteristics for boron-loaded plastic scintillators for neutron measurements. The detectors were tested with fast neutrons emitted from fission decays of a 5-$\mu$Ci $^{252}$Cf source and with slow neutrons provided by the MC50 cyclotron at the Korea Institute of Radiological and Medical Science. The energy spectrum of the fast neutrons was obtained by applying a time-of-flight method to the coincident measurement of neutrons and gamma r

We report development of a current-mode scintillation-fiber detector for precise measurements of accelerator-induced fast-neutron beams. 1-mm thick single-clad scintillation fibers were used to manufacture an array of detector pixels. The scintillation-fiber detector were equipped with a 46-channel silicon photodiode and a current-mode signal processor. The test result with X-rays to perform the calibration for the channel sensitivity shows that the fast-neutron detector, composed of scintillati

We present the results of charmonium production at Relativistic Heavy Ion Collider (RHIC) energies by using a hybrid model that directly creates cc pairs in early-stage hard scatterings and hadronizes open and hidden charm particles according to the statistical law at chemical freeze-out of the deconned quark-gluon plasma. The eect of possible normal nuclear absorption due to the dissociation of charmonia in the expanding hadronic reball is also investigated. We nd that about two-thirds of the t

We compile experimental data on the production yields of protons, deuterons, and pions from 1 to 200 GeV of psNN, and interpret them in the context of the nucleon density of a hot, dense fireball and the entropy production. The d/p yield ratio decreases with beam energy, implying that the nucleon density also decreases with beam energy. However, the entropy per nucleon increases with beam energy. In particular, the rate of the entropy increase changes dramatically at psNN ' 2 GeV, where nuclear

In this report, we present a newly developed hybrid resistive plate chamber (RPC) for the detection of low-energy neutrons. Lithium-°uoride (LiF) enriched for the 6Li isotope was chosen as the material sensitive to low-energy neutrons for the construction of the hybrid RPC. The LiF-coated RPC was tested by using the 252Cf neutron-irradiation facility at the Korea Atomic Energy Research Institute (KAERI). The detection e±ciency of the double-layered LiF-coated RPC to neutrons in the energy range

We present the design and the construction of a resistive plate chamber (RPC) with a Gdcoated electrode for the detection of low-energy neutrons. The signals were read out by using two perpendicular strip planes. The sensitivity of the RPC was tested by using the 252Cf source at the Korea Atomic Energy Research Institute. After the background had been properly subtracted, the neutron detection efficiency was determined to be about 3 % and 2 % for the backward and the forward scattered electron