Analysis strategy of high multiplicity data Toshiyuki Gogami 24/Feb/2011

Contents 1.Introduction – Status of multiplicity and rate 2.Origin of multiplicity of HKS – Simple simulation 3.Tracking – Problems and strategy to improve – Development DC hit wire selection with KTOF 4.Outlook & Summary

Introductions

Analysis process tracking x, x’, y, y’ at Reference plane x’, y’, p at Target Missing Mass tracking x, x’, y, y’ at Reference plane x’, y’, p at Target F2T function particle ID (select K + ) HKS HES tune This talk

Multiplicity of typical layer of chamber HES HKS ~1.13 ~1.28 ~2.24 ~4.94 Multiplicity is high for HKS

Hit wires in KDC1 Overhead view KDC1 Black : hit wires Blue : selected wires Red : track Black : hit wires Blue : selected wires Red : track CH 2 52 Cr Misidentification chance in hit wires selection increase ! REAL DATA lowhighlowhigh Overhead view

Singles rate summary Up to ~30 [MHz] Up to ~15 [MHz] HES HKS HKS trigger ~ 10[kHz] HES trigger ~ a few[MHz]

Rate dependences Quadratic dependence Linear dependence Why residuals get worse with rate (Multiplicity) ? – Hardware ? – Tracking is worse ? – Parameters ?

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 )

Origin of high multiplicity (rate) in HKS

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 +

B.G. mix rate (real data) a b * hks ntulpe

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

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

Angle and momentum distribution of positrons HKS cannot accept positrons directly ! Generate these event in HKS GEANT (Next page) SIMULATION

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

Tracking

Basic 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

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

DC hit info. selection with TOF (xx’) Selective region Maximum gradient Minimum gradient Particle direction Gravity CUT ~8% ~17% Procedure in “h_dc_tofcut.f” 1.Get KTOF1X & 2X hit counter information 2.Make combination of 1X and 2X hit counter if those two are in same group (grouping) 3.Determine cut conditions on KDC1 & KDC2 4.Select Hit wires in KDC and Reorder them CUT Just applied to xx’-layers for test

Check works of the code GREEN region Selective region RED markers Selected hit wires BLACK markers Rejected hit wires Seems to work well Particle direction Gravity

Results of TOF cut with grouping CH 2, 2.0 [μA], Shift Same Residual Multiplicity CH 2, 2.0 [μA], ~2.3 ~1.2 beforeafter x x’ x

Result of TOF cut with grouping Original code With “h_dc_tofcut.f” Pure Selective region allowance KDC Too strict select Optimal allowance Good tracks hid by background appear ! Number of K + ~2[%] up

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

Check works of the code 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

Results of TOF cut with grouping (all layers) Residual Multiplicity CH 2, 2.0 [μA], Multiplicity of uu’vv’-layers CH 2 ~20% reduction 52 Cr ~5-10% reduction Same beforeafter

Results of TOF cut with grouping (all layers) Faster ! Increase ! TOF cut works well 52 Cr CH 2 52 Cr Faster ! Increase ! Parameters ?

Outlook

Summary Status of Multiplicity and rate – Higher in HKS than HES – Strongly dependent on target in HKS Origin of high multiplicity and rate – Should be e-, e+ Because of simulation results and its beta Development of Tracking for high multiplicity target – TOF cut with grouping works well Analysis time is faster by 10%. Multiplicity is decreased by 5~50%. Number of K + is increased by 25% for 52 Cr target. Residual is still bad for 52 Cr. Need to study

End

HKS detectors Strangeness 2010 at KEK 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 ≈ 250 [μm] TOF σ ≈ 170 [ps]

Strangeness 2010 at KEK 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]

TargetHypernucleusThickness [mg/cm 2 ] BeamTypical rate HES/HKS/COIN [kHz] Current [μA]Total charge[C] 7 Li 7 He / 7 / Be 9 Li / 9 / B 10 Be / 1 / C 12 B / 5 / Cr 52 V / 17 / 1.8 Data summary 22 nd Indian-summer school (SNP2010) Λ Λ Λ Λ Λ E ( 2009 Aug – Nov ) TargetHypernucleusThickness [mg/cm 2 ] Beam Current[μA]Total charge[C] CH 2 Λ, Σ H2OH2OΛ, Σ 0 ~ Physics Data Calibration Data

Analysis process tracking x, x’, y, y’ at Reference plane x’, y’, p at target Missing Mass tracking x, x’, y, y’ at Reference plane x’, y’, p at target F2T function particle ID (select K + ) HKS HES tune [mg/cm 2 ] 2.0 [μA] 38 [hours] σ = 2 [MeV/c 2 ] (NOT TUNED) p(e,e’K + )Λ p(e,e’K + )Σ 0

Multiplicity and Tracking Tracking 1.Resolution 2.Number of event Multiplicity affect

Tracking for high multiplicity Strangeness 2010 at KEK CH 2 target particle CH 2 target mean ~ 2 hit 52 Cr target mean ~ 6 hit 52 Cr target particle KDC1 tracking Blue : selected wires Black: hit wires Multiplicity of typical layer Multiplicity Tracking eff. 52 Cr CH 2 Developing new code Traditional JLab Hall-C tracking code cannot handle with high multiplicity data.

Multiplicity of typical layer in chamber CH 2 target 52 Cr target mean ~ 6 hit mean ~ 2 hit CH 2 target 52 Cr target mean ~ 1 hit 10 6 layer 6 6 HES HKS Multiplicity is high in HKS

Multiplicity for each layer TargetRun NumberBeam [μA]Multi KDC1-x Multi KDC1-x Thickness [mg/cm 2 ] CH H2OH2O Li Be B C Cr

Angular and momentum distribution of e + HKS should not accept e + directory. HKS detectors HKS D-magnet

Multiplicity Multiplicity is higher for heavy target KDC wire configuration K+K+ z y x u u’ x x’x’ v v’v’ CH 2, 2.0 [μA] 52 Cr, 7.6 [μA] Multiplicity distribution y x

Number of tracks TOP view KDC1 Black : hit wires Blue : selected wires Red : track Black : hit wires Blue : selected wires Red : track CH 2 52 Cr

Pattern recognition in KDC KDC wire configuration K+K+ z y x u u’ x x’x’ v v’v’ y x x 1.Test point 2.Space point x y 30° 90° 150° Space point

NFOM (“h_dc_tofcut.f” for all layers) Allowance applied to uuvv’ layers

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 2 nd loop

DC hit info. selection with TOF Hit Selective region Maximum gradient Minimum gradient Particle direction Gravity CUT ~8% ~17% CUT

HTRACKING / h_dc_tofcut.f Procedure in “h_dc_tofcut.f” 1.Get KTOF1X & 2X hit counter information 2.Make combination of 1X and 2X hit counter if those two are in same group (grouping) 3.Determine cut conditions on KDC1 & KDC2 4.Select Hit wires in KDC and Reorder them Just applied to x,x’-layers for test Particle direction Gravity