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Design of a Electromagnetic Calorimeter Trigger System for the Belle II Experiment
천병구 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.6
The Belle II experiment is currently being constructed at the KEK High Energy Accelerator Research Organization in Japan to probe the New Physics phenomena from mainly rare B and D mesons, and lepton weak decays with the ultimate goal of an integrated luminosity of 50 ab<SUP>−1</SUP>. If beam backgrounds are to be reduced and physics events are to be enhanced during data acquisition, a trigger system is indispensable. For this purpose, we have designed a Belle II calorimeter trigger system to generate total energy, cluster counting and Bhabha triggers that are crucial for smooth operation of the experiment. We have also measured the noise level of a trigger cell composed of 16 CsI(Tl) crystal counters at a level of 10 MeV and estimated the trigger timing latency to be 3 µs, which satisfies the requirement of global online trigger latency for the experiment.
$\Lambda_c^+$ 매혹 중입자 약한 붕괴현상의 시뮬레이션 연구
김재호,천병구,김현옥,최영일 한국물리학회 2006 새물리 Vol.52 No.2
We performed a simulation study of Cabibbo-suppressed $\Lambda_c^+$weak decays as a preliminary work for branching ratio measurementsof $\Lambda_c^+ \rightarrow p \pi^{-} \pi^{+}$ and $\Lambda_c^+\rightarrow p K^{-} K^{+}$ relative to $\Lambda_c^+ \rightarrow pK^{-} \pi^{+}$. For this purpose, the EVTGEN event generator and theGEANT-based GSIM full simulator were used. The calculated selectionefficiencies of $\Lambda_c^+ \rightarrow p \pi^{-} \pi^{+}$ and$\Lambda_c^+ \rightarrow p K^{-} K^{+}$ decays turned out to be$23.5 \pm 1.3~\%$ and $15.3 \pm 0.4~\%$, respectively. We expectfurther data analyses using more than 500-fb$^{-1}$ Belle datatogether with the efficiencies calculated in this study, to giveinsight into the Cabibbo-suppressed decay mechanism and todistinguish right from wrong results in the experiments done so far.
Belle 전자기 열량계를 이용한 트리거 시스템의 개선 연구
송상현,천병구,김선기,김재호,김현옥,이명재,이상은,최영일 한국물리학회 2007 새물리 Vol.54 No.5
The Belle calorimeter trigger system is indispensable for selectingcharm and beauty meson physics events out of beam backgrounds andunnecessary physics events generated from beam collisions in ahigh-luminosity $e^+ e^-$ KEKB collider. The trigger system mainlyuses two types of triggers, the total energy and the number ofisolated clusters. In this paper, we have described the upgrade ofthe cluster counting modules (CCM) and the trigger master (ETM),which are the same types of modules, but with different downloadedtrigger logic, as these inside Xilinx. To address the aging effectof the CCM and the ETM, as well as the calorimeter trigger timinginstability, we have produced new types of modules and have solvedthe problems.
Ionization balance for Ni ions under coronal equilibrium
선광일,박일흥,천병구,남육원,한원용 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.43 No.I
The available electron-impact ionization cross-sections and recombination rate coefficients for Ni ions are reviewed, and the fit parameters to Younger's empirical formula for the ionization crosssections of Ni1+, Ni3+, and Ni5+ through Ni8+ are updated. Also presented are the calculations of the ionization balance for the ions under coronal equilibrium. The calculated ionic abundance fractions are compared with those of previous work. A possible implication of the long-standing problem of Nickel overabundances in several classes of astronomical objects is also discussed.
A Study of the Electromagnetic Calorimeter Trigger Signal for the BELLE Experiment
H. Ikeda,천병구 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.I
We measured the peaking time and the noise level of the fast-shaping signal to be used for the electromagnetic calorimeter trigger of the BELLE experiment performed at the $e^{+}e^{-}$ collider (KEKB). After this measurement, we chose a shaping time of 200 ns for the fast shaper. For this case, the electronics noise was estimated to be 6030 electron-hole pairs, which corresponds to a 2.0-MeV energy deposit in CsI(T$l$) crystal. The corresponding peaking time is 760 ns, which is suitable for the requirement of BELLE global trigger timing latency.
Detector Bias Study for a CP Asymmetry Analysis in Rare B Meson Decays
Yuuji Unno,천병구 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.5
We describe a detector bias analysis for the charge asymmetry between high momentum track combinations of K+π− and K−π+ by using a D*+−tagged D0 → hh (h = K/π) and K0S π0 sample based on the data set collected by the Belle detector at a asymmetric-energy e+e− collider named the KEKB factory. This detecor bias analysis is crucial for ACP (B0 → K+π−) charge-parity (CP) asymmetry measurements to observe direct CP violation in rare B meson weak decays. We estimate the systematic error from detector bias to be −0.0053 ± 0.0081.
1.88A GeV ^56Fe 중이온에 의해 원자핵건판 내에서 회절들뜸 및 준회절들뜸 기구로 생긴 다중발생
김종오,김태연,천병구,박인곤,송진섭,윤천실,박상렬,이경언,김재률,김태익,박명렬,임인택,장한일,박복남 慶尙大學校 기초과학연구소 1990 基礎科學硏究所報 Vol.6 No.-
원자핵건판 내에서 1.88A GeV의 에너지를 갖는 ^56Fe 중이온(heavy ion)의 평균자유행로는 비적추적법(along-the-track scanning method)을 사용하여 8.01±0.27㎝로 측정되었다. ^56Fe 주이온에 의한 회절들뜸반응을 KHP 판정법으로 찾아내었으며, 회절들뜸반응에 대한 평균자유행로는 0.86±0.10m로 측정되었다. 입사중이온의 정지계 내에서 ^56Fe 중이온에 의한 80개의 회절들뜸 및 준회절들뜸반응에 대한 알파입자와 단일하전 입자의 의사신속도 분포는 각각 (γ_a-η_b)_max=3.31, (γ_a-η_b)_max=2.30에서 최대값을 갖는 가우스분포함수 형태를 이루었다. By employing the method of along-the -track scanning. the mean free path of inelastic collisions for 1.8A GeV^56Fe heavy ion in nuclear emulsion is measured to be 8.01±0.27㎝. "Diffractive Excitation" events are identified by using the KHP method and the mean free path of diffractive excitation is measured to be 0.86±0.10m. The distributions of pseudorapidities of alpha and singly-charged fragments for diffractive excitation of 1.88A GeV ^Fe heavy ion are well fitted by Gaussian distribution function with peaks having (γ_a-η_b)_max=3.30 and (γ_p-η_b)_max=2.24.
Camera−PMT Calibration of Fluorescence Telescopes for the Telescope Array Experiment
신복균,김항배,김지현,조은정,천병구 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.6
The Telescope Array is the largest cosmic ray experiment in northern hemisphere to study ultrahigh-energy cosmic rays at energies greater than 10 18 eV by using a hybrid detector technique. It consists of fluorescence telescopes to measure the longitudinal development of an extensive air shower due to a primary cosmic ray particle and plastic scintillation detectors to measure the lateral distribution of secondary particles that hit the ground. In this paper, we describe the camera-PMT calibration of the fluorescence telescopes by using YAP and xenon sources. For the energy and the shower profile measurements of an extensive air shower, calculating the correct fluorescence lightyield from each PMT light output is important. An absolute PMT gain variation related to aging is measured by using a standard YAP source and shows a variation of 3% or less over a three-year operation of the TA experiment. The relative PMT gain variation in each camera is measured by using a xenon flasher and turns out to be 4% or less.
유제 형태로부터의 원자핵건판 펠리클 모듈의 제작과 200 A GeV ^32S 선속에의 조사 및 처리
김종오,김태연,남신우,천병구,박인곤,송진섭,박상렬,김재률,김준원,김태익,박명렬,임인택,장한일 慶尙大學校 기초과학연구소 1991 基礎科學硏究所報 Vol.7 No.-
(5×10×~0.06㎤)×(~30매)로 된 4개의 원자핵건판 펠리클 모듈을 Fuji ET-7B 유제를 재료로 하여 만들고, CERN의 SPS를 이용하여 ∼6×10exp(4) particles/㎠ 밀도의 200A GeV ^32S 선속을 성공적으로 조사시켜. 원자 핵건판내의 선속 분포, 제작, 현상과정 및 그 특성을 살펴보았다. 평균최소 은입자 밀도는 26.6±1.6/100μm. 조사된 200A GeV ^32S의 평균 δ-선 밀도는 11.87±1.85/100μm 로 측정되었다. 또한 제작된 원자핵건판은 630±7μm로 균일한 두께를 가졌다.
14.6 A GeV ^28Si 중이온이 원자핵건판내에서 발생시킨 핵반응에서 생성된 2차입자의 발생각 분포
김종오,김태연,남신우,신택수,우종관,이세병,임계엽,장세덕,조재희,천병구,임인택,김기영 慶尙大學校 기초과학연구소 1990 基礎科學硏究所報 Vol.6 No.-
14.6A GeV^28Si 중이온이 원자핵 건판내에서 발생시킨 N_h=1인 핵반응에서 생성된 47개의 파쇄 α 입자와 537개의 단일하전 2차입자의 발생각들을 측정하여 변수 exp(γ-η_b)의 포괄적 분포를 회귀함수 dN=exp[a+χ{exp(γ-η_b)d{exp(γ-η_b)}로 적합시켰다. 여기서 의사신속도 γ=arctanh(cosθ)=-ln tan(θ/2)이고, 입사 중이온의 신속도 η_b=3.445이다. 그 적합결과 파쇄 α입자의 경우 χ=-0.052±0.011이고, 파쇄 p입자의 경우 χ=-0.141±0.015이었다. For LS emission angles of 47 α fragments and 537 single-charged shower particles, produced by the N_h (the number of heavyprongs)=1 interactions of 14.6 A GeV^28Si nuclei in the nuclear emulsion, the distribution of the parameter exp(γ-η_b) is well expressed by dN=exp[a+χ{exp(γ-η_b)d{exp(γ-η_b)}with χ=-0.052±0.011 for αfragments and χ=-0.141±0.015 for p 'fragments', where the pseudorapidity of secondaries γ=arctanh(cosθ)=-ln tan(θ/2) and the rapidity of incident heavy ions, η_b=3.445.