電子線を用いた中重ラムダハイパー核分光実験の為 の 高多重度用飛跡再現コードの開発 Department of Science, Tohoku University Toshiyuki Gogami ( 後神 利志 ) JPS 2011 autumn meeting, T.Gogami1 JLab E collaboration, 2009, JLab Hall-C 全体・解 析 18aSG-2 川間

Contents 1.Experimental Setup of JLab E Motivation of Tracking Code Development 3.New Tracking Code 4.Summary & outlook JPS 2011 autumn meeting, T.Gogami2

Contents 1.Experimental Setup of JLab E Motivation of Tracking Code Development 3.New Tracking Code 4.Summary & outlook JPS 2011 autumn meeting, T.Gogami3

Experimental setup of JLab E JPS 2011 autumn meeting, T.Gogami4 2× [msr] 3 – 12 [deg] 2× [msr] 2 – 12 [deg] 7 Li, 9 Be, 10 B, 12 C, 52 Cr p(e,e’K + )Λ ( 7 Λ He, 9 Λ Li, 10 Λ Be, 12 Λ B, 52 Λ V ) [μA] [THz] Tracking Data taking : Aug-Nov 2009 HKS chamber wire configuration

Contents 1.Experimental Setup of JLab E Motivation of Tracking Code Development 3.New Tracking Code 4.Summary & outlook JPS 2011 autumn meeting, T.Gogami5

Background event of HKS z [cm] y [cm] x [cm] KDC1 KDC2 KDC1 KDC2 9 Be, 38.4 [μA] REAL DATA SIMULATION ~2.24 ~4.94 e + from pair creation JPS 2011 autumn meeting, T.Gogami6 H2OH2O

Discrepancy of Number of Λ Lost events that we are interested in in tracking procedure. JPS 2011 autumn meeting, T.Gogami7 Black : hit wires Blue : selected wires Red : track Black : hit wires Blue : selected wires Red : track REAL DATA ΛΛ Σ0Σ0 Σ0Σ0 CH 2 Target H 2 O Target 12 C quasi-free Acc. b.g. 16 O quasi-free Acc. b.g.

Contents 1.Experimental Setup of JLab E Motivation of Tracking Code Development 3.New Tracking Code 4.Summary & outlook JPS 2011 autumn meeting, T.Gogami8

Conventional JLab Hall-C tracking procedure Good TDC Pattern recognition Track fit Solve left right Select good combination Black : hit wires Blue : selected wires Red : track CH 2 target KDC1 52 Cr target Combination selection with TOF counters Reduce hit wire combinations (h_tof_pre.f) High multiplicity Real data JPS 2011 autumn meeting, T.Gogami9

New tracking scheme Good TDC Pattern recognition Track fit Solve left right Select good combination Combination selection with TOF counters Reduce hit wire combinations (h_tof_pre.f) High multiplicity Reduce hit wires to analyze Point JPS 2011 autumn meeting, T.Gogami10

DC hit info. selection with TOF Selective region Maximum gradient Minimum gradient Particle direction Gravity CUT ~8% ~17% CUT JPS 2011 autumn meeting, T.Gogami11

Check works of the code GREEN region Selective region RED markers Selected hit wires BLACK markers Rejected hit wires Particle direction Gravity JPS 2011 autumn meeting, T.Gogami12

JPS 2011 autumn meeting, T.Gogami Results of Introduction of new Tracking Code Increased ! CH 2 52 Cr H2OH2O 13

Contents 1.Experimental Setup of JLab E Motivation of Tracking Code Development 3.New Tracking Code 4.Summary & outlook JPS 2011 autumn meeting, T.Gogami14

Summary & outlook JPS 2011 autumn meeting, T.Gogami15 全体・解 析 18aSG-2 川間

END JPS 2011 autumn meeting, T.Gogami16 Thank you for your attention E experiment, JLab Hall-C, 2009

HKS detectors K + p, π + Drift chambers -KDC1,KDC2- TOF walls -2X,1Y,1X- (Plastic scintillators) Cherenkov detectors -AC,WC- Aerogel (n=1.05) Water (n=1.33) 1 [m] June 2009 in JLab Hall-C HKS trigger CP = 1X ×1Y × 2X K = WC × AC  CP × K ~18 [kHz] (8 [μA] on 52 Cr) − π+π+ K+K+ p σ ≈ 200 [μm] TOF σ ≈ 170 [ps] APFB2011 in Korea (T.Gogami)17

APFB2011 in Korea (T.Gogami) HES Detectors Drift chambers - EDC1, EDC2 - TOF walls - EH1, EH2 - (Plastic scintillators) HES D magnet HES trigger EH1 × EH2 ~2 [MHz] (8 [μA] on 52 Cr) e Time Of Flight σ ~ 300 [ps] 18

Data Summary JLab E (2009/June – 2009/Nov) APFB2011 in Korea (T.Gogami)19

Singles rate summary Up to ~30 [MHz] Up to ~15 [MHz] HES HKS HKS trigger ~ 10[kHz] HES trigger ~ a few[MHz] APFB2011 in Korea (T.Gogami)20

Hit wires event display (2) GREEN region Selective region RED markers & lines Selected hit wires BLACK markers & lines Rejected hit wires v v’ u u’u u’ x x’ v v’ u u’u u’ x x’ KDC1 KDC2 particle APFB2011 in Korea (T.Gogami)21

KTOF multiplicity ~2.7~1.8 ~6.5 ~3.8 CH 2, Cr, Multiplicity of KDC are not only high but also TOF counters are! (for heavy target ) APFB2011 in Korea (T.Gogami)22

Background event from NMR port z [cm] y [cm] x [cm] These particles come from NMR port HKS dipole magnet NMR port KDC1 KDC2 KDC1 KDC2 KDC1 KDC2 KDC1 KDC2 Background events 9 Be, 38.4 [μA] Events on HKS optics Overhead view Side view Β ≈ 1 e -, e + APFB2011 in Korea (T.Gogami)23

B.G. mix rate (real data) a b * hks ntulpe APFB2011 in Korea (T.Gogami)24

e + simulation SIMULATION To see 1.Number of event 2.Angle & momentum of e + generated in target To see 1.Number of event 2.Angle & momentum of e + generated in target APFB2011 in Korea (T.Gogami)25

Target thickness dependence (Simulation) H2OH2O 52 Cr 9 Be 12 C CH 2 10 B 7 Li Consistent with B.G. mix rate ! SIMULATION APFB2011 in Korea (T.Gogami)26

Angle and momentum distribution of positrons HKS cannot accept positrons directly ! Generate these event in HKS GEANT (Next page) SIMULATION APFB2011 in Korea (T.Gogami)27

e, e + background in GEANT simulation Vacuum chamber (sus304) NMR port (sus304) KDC1KDC2 e -, e + Generated particle : e + Distribution : spherical uniform Momentum : 860 – 1000 [MeV/c] Angle : 0 – 2 [mrad] 1000 events Number of e + (Simulation) B.G. mix rate (Real data) Correlation e + generated in target make HKS dirty APFB2011 in Korea (T.Gogami)28

Apply to u,v-layer Applied to uu’ and vv’ layers, too. Selective region determined by 1X and 2X Convert v v’-layer x x’-layer APFB2011 in Korea (T.Gogami)29

Hit wires event display (2) GREEN region Selective region RED markers & lines Selected hit wires BLACK markers & lines Rejected hit wires v v’ u u’u u’ x x’ v v’ u u’u u’ x x’ KDC1 KDC2 particle APFB2011 in Korea (T.Gogami)30

Spectroscopic experiment by (e,e’K + ) reaction p n γ*γ* Λ K+K+ e-e- e + p ➝ e’ + K + + Λ ee target nucleus Feynman diagram u u d u s s u d – p K+K+ Λ γ*γ* 1.Large Momentum transfer Λ can be bounded in deeper orbit 2.Λ’s spin at forward angle Spin flip ~ spin non-flip 3.Proton  Λ Absolute mass value calibration e’-Spectrometer K + -Spectrometer p e’ p K+ Missing Mass H HY APFB2011 in Korea (T.Gogami)31

JLab E experimental setup 2× [msr] 3 – 12 [deg] 2× [msr] 2 – 12 [deg] e + p → e’ + Λ + K + 7 Li, 9 Be, 10 B, 12 C, 52 Cr (e,e’K + ) experiment 1.Coincidence experiment (K + and e - ) 2.Small cross section ( ~100 [nb/sr] ) 1/ Energy resolution Sub MeV (FWHM) Primary beam High intensity  Thin target (~100 [mg/cm 2 ]) High quality APFB2011 in Korea (T.Gogami)32

APFB2011 in Korea (T.Gogami) JLab CEBAF ( Continuance Electron Beam Accelerator Facility ) (e,e’K + ) experiment 1.Coincidence experiment (K + and e - ) 2.Small cross section ( ~100 [nb/sr] ) 1/ Energy resolution sub MeV (FWHM) 100 [m] Requirements for accelerator 1.High duty factor (~100%) 2.High intensity ( >a few 10 μA ) 3.Small emittance ( ~2 [mm ・ μrad] ) Small ΔE/E ( <1×10 -4 ) CEBAF was unique facility before MAMI updated Experimental Hall 33

Coincidence time vs. Mass square APFB2011 in Korea (T.Gogami)34

Cherenkov cut APFB2011 in Korea (T.Gogami)35

Cherenkov light APFB2011 in Korea (T.Gogami)36

HES の構成 ED1 Max. Field Gradient7.8[T/m] Max. Current800[A] Total magnet weight2.8[ton] EQ2 Max. Field Gradient5.0[T/m] Max. Current800[A] Total magnet weight3.1[ton] ED Max. Field1.65[T] Max. Current1065[A] Total magnet weight36.4[ton]