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

Contents

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

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

Singles rate summary target, Run #, current Water Carbon Cr Carbon Carbon Boron Boron Lithium CH Be Cr Carbon target, Run #, current Water Carbon Cr Carbon Carbon Boron Boron Lithium CH Be Cr Carbon

Rate dependences Multiplicity : linear dependence with rate Residual : quadratic dependence with rate

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 NMR port KDC1 KDC2 KDC1 KDC2 KDC1 KDC2 KDC1 KDC2 Background event 9 Be, 38.4 [μA] Event on HKS optics

B.G. mix rate (real data) TargetRunBeam current [μA]B.G. mix rate [%] CH H2OH2O Li Be B C Cr Ranktarget 1 52 Cr 2H2OH2O 3CH C 5 9 Be 6 7 Li 7 10 B a b

e + simulation SIMULATION To see Positron’s – Number of event – Angle & momentum at the target

Target thickness dependence (Simulation) H2OH2O 52 Cr 9 Be 12 C CH 2 10 B 7 Li ranktarget 1 52 Cr 2H2OH2O 3CH C 5 9 Be 6 7 Li 7 10 B

Angle and momentum distribution of positrons HKS cannot accept positrons directly ! Generate these event in HKS GEANT

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

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

Cut region selection with TOF Hit Selective region Maximum gradient Minimum gradient Particle direction ~17% ~8% Gravity

Multiplicity correlation between KTOF and KDC Multiplicity of KDC are not only high but also TOF counters are! (for heavy target ) CH 2, Cr, 77124

Conditions Applied conditions in presented talk – Max. multi in KTOF1X = 4 – Max. multi in KTOF2X = 4 – Allowance = 0 [cm]

Real data ( 52 Cr) GREEN region Selective region RED markers Selected hit wires BLACK markers Rejected hit wires

Result of TOF cut with grouping Residual Number of event Number of Kaon Analysis time

Result of TOF cut with grouping Residual Number of event Number of Kaon Analysis time

B.G. event と event on optics のチェレンコフ等の相関

Summary and outlook

End