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Jong-Kwan Woo (Dept. of Physics, Jeju Nat’l Univ.) 2011-10-24 Jeju N. Univ. Unipark (SeoGuiPo)

A separation method for Gamma ray and Neutron in J-parc E-14 Koto Experiment using a Pulse Shape Discrimination ( PSD ) with CsI Crystal Scintillator. Jong-Kwan Woo (Dept. of Physics, Jeju Nat’l Univ.) 2011-10-24 Jeju N. Univ. Unipark (SeoGuiPo). Abstract.

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Jong-Kwan Woo (Dept. of Physics, Jeju Nat’l Univ.) 2011-10-24 Jeju N. Univ. Unipark (SeoGuiPo)

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  1. A separation method for Gamma ray and Neutron in J-parc E-14 Koto Experiment using a Pulse Shape Discrimination (PSD) with CsI Crystal Scintillator. Jong-Kwan Woo (Dept. of Physics, Jeju Nat’l Univ.) 2011-10-24 Jeju N. Univ. Unipark (SeoGuiPo)

  2. Abstract • A brief introduction of J-Parc E14 experiment will be presented in this talk. A branching ratio of KL->π0ννdecay, a flavor changing neutral current (FCNC) violating the CP conservation, provides the lowest error among the many physical quantities predicted by a Standard Model. People concentrate on this decay mode, because the theory is very simple. And it gives a clue to understand the relation between quarks' generation because this decay mode involves the three quarks interaction simultaneously. It is also ideal to decide the Cabibbo-Kobayashi- Maskawa(CKM) parameter η indicating the mixing amplitude in the frame of the Standard Model. We expect to find a new physics beyond the Standard Model with studying of KL->π0νν decay mode. A calculation of the amplitude of KL->π0νν is simple with the minimum error while it is not easy to measure the decay. The E391a, an experiment using a proton synchrotron in KEK, showed in 2004 the first possibility proving whether the branching ratio predicted in the Standard Model is true. We will measure the amplitude of KL->π0νν decay mode more precisely using J-parc E14 detector that is the extended and the advanced version of the E391a in KEK. We hope to accumulate the first data of J-Parc E14 in December 2011. • A major detection mechanism of KL->π0νν decay is to measure the gamma ray from π0->γγ decay. So, the separation of gamma ray from neutron, background induced in beam line plays the key role for J-parc E-14 experiment. • We will introduce a pulse shape discrimination (PSD) method for separation gamma ray (Minimum Ionization Particle (MIP)) from neutron (Heavy Ionization Particle (HIP)) using a CsI crystal scintillator. 총 33장 가운데

  3. Motivation and Goal • In Experimental nuclear and particle physics, Identifying particles, especially γ-ray, neutron, and charged particles, • Is fundamental. • Ex) Dark Matter (WIMP), a Neutral kaon experiment at J-Parc E-14, Neutrino experiment… • Pulse shape discrimination(PSD; 파형모양판별법): An elastic collision between incident particle and scintillator  signal  detection with PhotoMultiplier Tube(PMT) identification incident particle. • PSD with Liquid Scintillator: higher efficiency, difficult to handle • PSD with Crystal Scintillator: lower efficiency, easy handling. • Goal for our study: to improve PSD method with Crystal scintillator 총 33장 가운데

  4. 1A Particle Physics Experiment using Pulse Shape Discrimination (PSD) Dark Matter (WIMP) • Galaxies 에 있는 물질을 직접 관측함으로써 dark Matter의 존재를 알 수 있다. • Vobj2 = GM/R • M >> Mvisible • 90~99% of Universe Mass is Not observed (hidden mass), yet. •  We call it Dark Matter . •  currently ¼. • Assume: Most of Dark matter stays in galactic halo. 총 33장 가운데

  5. * Baryonic Dark Matter MACHO: (10-7 M⊙<MBD<10 M⊙) -brown dwarfs:( MBD<0.08 M⊙) -Jupiters : (~0.001 M⊙) Neutral Hydrogen and molecular clouds * Non-Baryonic Dark Matter Hot type: (V ≥ c/100) -light neutrino Cold Type:(V ≤ c/100) -WIMP: (10GeV ~ few TeV) -axion (10-5eV) Dark Matter Candidates9*10-72M⊙(10-5eV, Axion) < MDM < 104M⊙ (Black hole) 총 33장 가운데

  6. Neutralino (candidate for WIMP) • MSSM predicts the neutralino that is consisted of supersymmetric partners of photons, Z bosons and Higgs. • Neutralios (WIMP) are localized in the galactic scale. . 총 33장 가운데

  7. 2A Particle Physics Experiment applying Pulse Shape Discrimination (PSD) • The meeting of Matter and Anti-matterannihilates each other with radiating photon. Matter - Anti matter Annihilation Anti-matter matter  • Evidently, however, matterwon against antimatter. • Just a tiny deviation from perfect symmetry seems to have been enough – (particles of matter: particles of antimatter = 1010+1 : 1010) This excess of matter was the seed of our whole universe, which filled with galaxies, stars and planets – and eventually life. But what lies behind this symmetry violation in the cosmos is still a major mystery and an active field of research. 총 33장 가운데

  8. Through the looking glass Natural laws should be perfectlysymmetrical and absolute.  But not always. • Three Symmetries in Elementary Particle Physics • P (Parity) x  -x • C (Charge) Cmatter=-Canti-matter • T (Time) t  -t : motion should be independent whether forwards or backwards in time. Symmetries in Physics should be conserved. Ex) Energy conservation before and after event  Energy is symmetrical in time. Ex) Charge conservation  symmetry in electromagnetic theory 총 33장 가운데

  9. Solving the mystery of the broken symmetry • Maybe, Sakharov’s conditions  (incorporated) SM of physics. Then the surplus of matter created at the birth of the universe.  Fitch and Cronin found doubly broken symmetry. • Why a considerably smaller broken symmetry exist in kaons decay. (SM couldn’t explained). • 1972, Makoto Kobayashiand Toshihide Maskawa(University of Kyoto), who were well acquainted with quantum physics calculations, found the solution in a 3 x 3 matrix. • SU(3)quarkSU(3) color 총 33장 가운데

  10. 노벨상 위원회의 2008 년 노벨 물리학상 공식 발표 symmetry broken (대칭 깨짐)이 수상 동기 총 33장 가운데

  11. KOTO Experiment, KEK, J-PARCE-14 KL 0experiment 60 members/16 institutes/6 countries Korean Participants 우종관, 김용주, 고재우, 임계엽1, 김은주2, 박인규3, 정명신3, 강서곤3, 김유상3, 안정근4, 이효상4, 백광윤4 (제주국립대학교1KEK   2전북대학교   3서울시립대학교   4부산대학교) = K0 at Tokai K0TO 총 33장 가운데

  12. Neutral Kaon Decay KL 0 BR (=2.8±0.4ⅹ10-11 by SM) 측정 determination Cabibbo-Kobayashi-Maskawa (CKM) parameter η (측정오차가 가장 큼) CKM: Matter-Anti Matter symmetry breaking comes from mixing with quarks in 3 generations. Reason and Amplitude=?  Experiment will give the Answer. • KL 0 BR 계산 (이론) 매우 간결하나 측정(실험) 매우 까다로움 • KL 0measurement by using measurement 0e+e- •  Problem: BR<1% • 0 (BR=99%): Kinematical Constraint • 실험 제안 1989 • 2004 KEK-PS e391a  실험의 가능성을 보여줌 • 2008 J-Parc E-14  실험 제안 proved (건설 및 빔 테스트 완료 2010) • 2011년 4월 실험 예정 총 33장 가운데

  13. Flavor Changing neutral Current (FCNC) KL 0 (sd FCNC process) Interaction with Lepton-current of  (intermediated by t). 붕괴 진폭은 약상호작용 만의 미지의 파라미터에 의해서 결정됨 (K→eπʋ과 비교해서 알 수 있음). J. Ellis 총 33장 가운데

  14. KOTO at hadron hallin KEK J-Parc 총 33장 가운데

  15. KL 0 measurement at KEK e391a • Measurement KL 0 using 0 • New method: 1) reduce missing  with photon detector covering 4. 2) Get rid of transverse momentum of KL Pt=0 for . need the smallest KL beam cross section. (optimized by GEANT4 simulation) • Major back ground (Neutron making 0 easily : n+An+A+0 )  Currently unique Sol.; High Vacuum (10−5 Pa) reduce collision n & A. 총 33장 가운데

  16. KL  0   e391a Signal region BG by material BG by CO2 총 33장 가운데

  17. Direct Detection Mechanism usingPSD method with a Liquid Scintillator 총 33장 가운데

  18. Nucl.Inst. & Meth. 196 101 (1982) Nucl.Inst. & Meth. 3 207 (1982) P.R. B20 3486 (1979) P.R. B21 2632 (1979) J.Luminescence 18/19 487 (1979) J. Chem Phys. 50 3143 (1969) J. Chem Phys. 42 4250 (1965) 총 33장 가운데

  19. Singlet and Triplet states of ExcimerX2* • Meta-stable target molecule X2* same as 2-body analysis • Two nuclei can have 4 spin states. • |X1,X2> =|↑,↑> • |X1,X2> =|↑,↓> + |↓,↑> • |X1,X2> =|↑,↓> - |↓,↑> • |X1,X2> =|↓,↓> • Total spin s =1ℏ or 0 target nucleus’ spin 1/2ℏ . s=1: sz=mℏ, m = 1, 0, -1 (triplet state) s=0: sz=mℏ, m = 0 (singlet state) • Τtriple =(27 ns) << Tsingle(2.2 s) • 입사입자에 따라서 핵자의 단일항 (singlet) 상태와 삼중항 (triplet) 상태에서 방출하는 광자의 세기와 방출시간의 비율이 다름. 총 33장 가운데

  20. Direct Detection Mechanism usingPSD method with a Liquid Scintillator 총 33장 가운데

  21. Amplification Processes JKPS 50-2 (2007) p524,JKPS 49-1 (2006) p266 총 33장 가운데

  22. An Excitation process in Crystal Scintillator 총 33장 가운데

  23. (NS/NT)MIIP> (NS/NT)HIP Previous Studies NT: Amplitude of Fast signal from Triplet state. • NS: Amplitude of Slow signal from Singlet state. Heavy Ionization Particle (HIP), Minimum Ionization Particle (MIP) Neutron, Proton, MuonHIP, Gamma RayMIP 총 33장 가운데

  24. Experimental Setup • MC-50 proton cyclotron at KIRAMS(원자력의학원) produces p (50 MeV). •  p collides Be Target.  produce. n or . 총 33장 가운데

  25. Beam Specification and Beam Current:40 μA Average proton Energy:35 MeV Neutron Production rate: 2.75*1011/hr/cm2  Spreading 120 cm belowcollimator N-Beam scanning Area: 54X54 cm Square region. Place CsI crystal (7.5*7.5*20 cm) Scintillator at 10, 27, and 50 cm from center of N-beam. 총 33장 가운데

  26. Typical Signals • X : time [s] Y: amp [v] • left) signals form neutronbeam, right) signals form cosmicray. 총 33장 가운데

  27. Pulse Shape Analyzing •  integrating Pulse •  Finding Break point after 3-dim fitting(right) •  Calculating the ratio of areas the tail to Body 총 33장 가운데

  28. Slowsignal VS Fast signal • X: amp of slow signal (tail) • Y: amp of fast signal (head) • 중성자가 많은(rich) 실험일수록 fastsignal (Y)의 비율이 커짐 • Cosmic 그림에서 두 개의 묶음에서 위쪽(좌측)의 묶음이 중성자 • Slope약 18인 (y=18x+5)선을 기준으로 나뉨 총 33장 가운데

  29. Histogram of Slowsignal VS Fast signal • x: ratio of (amp of Fast/amp of slow)/5 • Deeps  Slope 18 (at previous page) 총 33장 가운데

  30. Comparison Liquid and Crystal Scintillator after applying my PSD method CsI Crystal Scintillator Xe Liquid scintillator 총 33장 가운데

  31. Comparison signals between CsI crystal withmyPSDand Liquid Scintillator with classical PSD CsI crystal Scintillator (cosmic ray) BC501A Liquid Scintillator (artificial source) 총 33장 가운데

  32. Comparison signals between CsI crystal withmy PSDandLiquid Scintillator with classical PSD(Exposured by Cosmic Ray) CsI crystal Scintillator Xe Liquid Scintillator [APH 28 132 (2007)] Detail analysis  will be published soon. 총 33장 가운데

  33. Summary • We established a Pulse shape discrimination (PSD) method with CsI crystalScintillator. • We found the possibility of PSD method using CsI crystal scintillatorto separate the neutron signal from gamma ray signal. • Recommend this PSD method for the rare event experiment. NextStep • We need the additional and more detail experiments. • And, more precise analysis tool. 총 33장 가운데

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