Study of D Resonance Abundance in 158 AGe

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Susumu SATO Contents 1) Introduction ~ Relativistic heavy ion collision ~ 2) Thesis motivation ~ D measurement ~ 3) Experimental setup ~ WA 98 at CERN-SPS ~ 4) Data analysis ~ corrections and errors ~ 5) Experimental Results ~ p, p spectra & D yield ~ 6) Discussion ~ low mt enhancement of inclusive p spectrum ~ • Summary CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Picture of Relativistic Heavy Ion collisions [1: Before collision (g ~17 at SPS)] - Lorentz contracted [2: During collision (Dt ~1 fm/c)] →stopping/heating →hot/dense fireball [3: After collision] →(thermal/chemical equilibrium) →”cooling with expansion” →thermal/chemical freeze out Fireball →hadrons(p, K, p, …), e, g, …detection To understand fireball, need picture during “cooling with expansion” CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Single Particle Spectra (pp collisions) Nucl. Phys. B 100(75)237 (1)Similar shape, and (2)Similar slope for different particle species (called mt-scaling) mt – m (Ge. V) mt-scaling in proton – proton collisions CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Single Particle Spectra (nucleus - nucleus collisions) Nucl. Phys. A 610(96)175 c (1)Different shape, and (2)Different slope for different particle species mt – m (Ge. V) Different shape and slope are observed. CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Two particle HBT correlation quantum interference to measure source size (R) R C 2: detection probability of two particles at the momentum of p 1 and p 2 (R=6 fm, l=1) Source size as a function of relative momentum CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Two particle HBT correlation in nucleus collisions Transverse Direction (x, y) q Beam Direction (z) Eur. Phys. J. C 2(98)661 Source size as a function also of average momentum CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Expanding Fireball Model (1) mass dependence of mt spectra slope NPA 610(96)175 Slope(Ge. V) p p－ K－　 K+ p+ p－ →linear mass dependence 　　　　　↓ 　　parameterized 　　naively 　T = Tf +mass・〈bf〉2 Mass(Ge. V/c 2) Naively, Expansion Fireball is applicable ! CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Expanding Fireball Model (2) ~ example of good parameterization ~ (1) Single spectra: transverse kinetic energy (mt) spectra PRL 80(98)3467 →parameterization for different particle species Tf ~139 Me. V, 〈bf〉 ~0. 42 c (2) Two particle HBT correlation Habilitation(’ 97/T. Peitzmann) →Boost invariance for expansion 〈bf〉=DR/tf ~ 0. 43 0. 16 c Good explanation both for singles and two particle correlation, but not using lower mt-region CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Thesis Motivations (1) Measurement of particle production of a new particle species; →D(1232) in 158 A Ge. V Pb + Pb central collisions. (2) As a basic problem to understand both single particle spectra and HBT correlation, low mt pion enhancement is observed. →By using the result of explicit measurement of D resonance, 　the contribution of D to low mt enhancement is acquired, then aiming to get footing of the validity of the expanding fireball model. CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Authors Contributions Design of experimental detector ●　Time-of-Flight (TOF) detector ●　Optimal alignment of chambers in magnetic spectrometer Construction, test, installation, and operation of detectors ●　TOF detector ●　Streamer tube tracking (STD) detector ●　Start counter Programming of control and reconstruction software ●　HV control for TOF ●　Online monitoring for TOF, STD ●　Momentum reconstruction Physics Analysis ●　Pion and proton single spectrum ●　Yield of D(1232) resonance CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Δ++ 　resonance Lowest resonance of nucleon ● M ~ 1232 Me. V (in Breit-Wigner function） ● ct ~ 1. 8 fm; (G~111 Me. V) ● Isospin 3/2, Spin 3/2 ● Decay into pion and proton with >99% branching ratio ●　 Pt(mt)(Ge. V/c) 0. 8 0. 4 D++ p p+ 0 0 -1 1 y ● Decayed pion gives lower transverse kinetic energy CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS WA 98 experimental setup TOF (Stop counter) LEDA(EM. Cal. ) Streamer Tube Det. ZDC(Had. Cal. ) PAD Cham. MIRAC(Had. Cal. ) Magnet PMD m 5. 21 Start Beam ( 208 Pb: 158 AGe. V) Target +P. ball, SPMD (208 Pb: 0. 239 mg/cm 2) Characterize Fireball from various aspects • • • [Hadron] momentum + PID; w/Mag. Spectr. [Photon] Eg; w/EM. Cal. [Hadron] global ET, E 0; w/Had. Cal. [Photon] mult. distr. ; w/PMD [Charged particle] mult. distr. ; w/SPMD, P. ball CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS σp / p Detector resolutions (p, Tstart, Ttof) s. T~1. 3 mm, s//~2. 1 mm (PAD 1) s. T~2. 6 mm, s// ~7. 0 mm(STD 1) 2% 5 k 0 N 800 s~85 ps tof ～ 1% at 2 Ge. V/c 0 Tdif (ns) -0. 4 1. 5 % 1% 0. 5 % N s~30 ps start 10 k 0 1 2 3 4 p(Ge. V/c) 5 0. 4 400 Ttof (ns) -0. 8 0 0. 8 Magnetic spectrometer is in good operation CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS 8 6 p+ p K＋ 4 2 0 σ m 2 (Ge. V/c 2)2 p(Ge. V/c) Particle Identification 0. 10 0 0. 5 1 1. 5 m 2(Ge. V 2/c 4) ~0. 02 (Ge. V/c 2)2 at 2 Ge. V/c for π 0. 05 0. 00 0 1 2 3 4 p(Ge. V/c) • Clear Particle Identification by To. F method CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Parameterization [1] for p+, p single particle spectra Kinematical parameters Lorentz invariant differential yield Transverse kinetic energy (longitudinal) rapidity if f symmetry : Lorentz invariant CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS mt-m(Ge. V) Geometrical Acceptance Fireball (←ytarget =0) ycm=2. 9 ( ybeam=5. 8 →)　 　Measure around mid-rapidity, where hot fireball is expected the most. CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Data selection ADCstart 2 [ch] • Event selection Single beam (3 s in ADCstart) FEE linear region (5. 7% in Tdynamic) not after-chamber-spark (0. 8 sec) event • Track selection image on target (3 s in B// direction) image on TOF 2 (2. 5 s on 2 -D plane) • PID selection ADCstart 1 [ch] m 2 (2. 5 s in the p) CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Geometrical acceptance and Efficiency correction By the Monte Carlo Simulation (GEANT 3. 15) y p+ PAD 1 PAD 2 p STD 1 STD 2 eg mt CERN-SPS-WA 98 Y Averaged eff. e PAD 1 83% e PAD 2 80% e STD 1 91% e STD 2 97% ec X Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Single spectra Slope (Me. V) WA 98 NA 44(*) π+ 142 ± 3 156 ± 3 p 251 ± 25 289 ± 7 mark in plot filled open (*) Nucl. Phys. 610(96)175 mt-m(Ge. V) Consistent shapes with other experiments CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Parameterization [2] for D yield by invariant mass method Invariant mass distribution Invariant mass (Ge. V) should be evaluated CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Mixed Event technique example EVENT 1 p p+ Invariant mass (Ge. V) EVENT 2 p p+ Mixed events: p and p+ from different events paired in 100 every events Combinatorial background is assumed to be proportional to mixed events CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Two normalization methods (1) Tail method normalize only in higher minv region (2) Breit-Wigner + Background method Invariant Mass (Ge. V) normalize in any minv region, assuming Yield. D++ follows Relativistic Breit-Wigner (PRL 79(’ 97)4354) q: relative momentum of the pair in its C. M. frame, m: 180 Me. V/c Two methods should be consistent CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Tail method E 0=1. 237 0. 006 G=0. 086 0. 014 (Ge. V) Invariant mass (Ge. V) Clear yield can be extracted by tail method CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Breit-Wigner + Background method Invariant mass (Ge. V) Again, clear yield can be extracted by B. W. +BG. method CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Systematic error of ND / ev. on extraction method (2) Tail method: 0. 021 ND / ev. (3)Local multiplicity (Np) on TOF 0. 10 Np=2 0. 05 0. 022 Np=3 0. 022 Poisson <Np> =2. 6 Nev. (1) Breit-Wigner + B. G. method: 0. 022 2 k 1 k 0 0 2 4 6 Np Np=4 0. 018 0 1. 4 1. 5 1. 6 1. 7 1. 4 1. 5 Mth. (Ge. V) Less dependence on extraction parameters CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Statistical Error For , Error propagation gives ( 50. 0% ) ( 49. 9% ) ( < 0. 1% ) Major contribution of error is large Combinatorial Back Ground CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Isospin consideration Factor from Np/ND++ to Nnucleon/ND is 2. 0. CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Yield summary table Value and Statistical Error D++ / spectrometer /ev. (raw) 0. 022 0. 010 proton / spectrometer/ev. (raw) 1. 080 0. 010 D++/proton (raw) 0. 021 0. 009 e trk (3 or 4 cham. ) 0. 79 0. 02 e. PID 0. 60 0. 02 e geo 0. 145 0. 005 D++/proton (e trk , e. PID, e geo corrected) 0. 31 0. 14 D/nucleon (isospin corrected) 0. 62 0. 28 (stat. ) (45%) Systematic Error Uncertainty of Tracking efficiency 0. 06 (sys. ) (10%) Difference in normalization method 0. 02 (sys. ) ( 4%) Difference for different local multiplicity 0. 08 (sys. ) (13%) At SPS, delta yield is, for the first time, directly measured CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Δ(1232) (%) nucleon Population ratio: Δ/ nucleon PLB 477 (2000) 37 -44 100 80 60 40 20 0 1 Acquired from D / p, Isospin correction 10 100 done for Ebeam(AGe. V) Higher population is seen at SPS CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Low mt enhancement in Pb + Pb (1) 103 102 10 1 p+ Neighboring several points for local mt slope mt – m (Ge. V) 0 0. 2 0. 4 0. 6 0. 8 1 Low mt enhancement is seen in local mt slope (Next) CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Local slope (Ge. V) Low mt enhancement in Pb + Pb (2) Center of fitting region in mt – m (Ge. V) The mt enhancement is seen in p+ spectrum in Pb + Pb collisions CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS pp collisions 100 p+ at mid-rapidity Nucl. Phys. B 100(’ 75)237 Fitting Line y=a exp(-x/b) a=82. 5± 3. 7 b=0. 153± 0. 003 c 2/n. d. f=8. 8/6 10 1 0 0. 2 0. 4 0. 6 mt – m (Ge. V) pp collision is described well in mt exponential CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Candidates of low mt enhancement (1) Collective motion e. g. Collective radial expansion p+ (2) Coulomb effect Repulsion/Attraction from Charges D++ (3) Resonance decay p D decay gives lower mt p by kinematics p+ Pt(mt)(Ge. V/c) D++ p 0. 8 0. 4 0 p+ -1 There are more than one candidates CERN-SPS-WA 98 0 Susumu　SATO 1 y

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Collective motion (Thermal+expansion) PRL 80(’ 98)3467 Describing well for different particle species except low mt p, and shape of p is little affected by collective motion T=139 Me. V 〈b〉=0. 42 c Dashed line: exponential for eye guide mt – m (Ge. V) consistent also with two particle HBT correlation p spectra shape is little affected by Collective motion CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Coulomb effect Coulomb Low mt Enhance 2. 0 w/Coulomb 1. 0 No Coulomb 0 0 0. 2 0. 4 mt – m (Ge. V) Low mt enhancement is seen in both charge, + and – Coulomb effect appears as difference between p and p. CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Contribution of Δ Resonance D included evaluation Δ( invariant mass) with a factor (1+α) (a. u. ) + mt – m (Ge. V) →consistent with simulation thermal model T=139 Me. V, 〈b〉 =0. 42 c “thermal source” + “Δ resonance decay” is consistent with the low-mt enhancement of π＋. CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS Conclusion (1) For the systematic study of hadron production in 158 A Ge. V Pb + Pb collision, magnetic spectrometer with good PID capability is constructed. (2) At 158 A Ge. V Pb + Pb collisions, p+ and p inclusive single mt spectra are measured. Inverse slopes are 142 3 Me. V (fitting region: mt – m > 0. 2 Ge. V) for p+ and 251 25 Me. V for proton. In the pion spectrum, clear low mt enhancement is observed. (3) 158 AGe. V Pb + Pb collisions, D resonance yield is, for the first time, measured directly. The D/nucleon ratio is 0. 62 0. 28 (stat. ) 0. 16 (sys. ). 　　　 (4) Spectrum shape with consideration of D decay on thermal expanding fireball follows low-mt enhancement of π＋. The additional factor is consistent with a cascade simulation that gives contribution of D decay with re-scattered proton. CERN-SPS-WA 98 Susumu　SATO

Study of D++ Resonance Abundance in 158 AGe. V Pb + Pb Collisions at CERN-SPS D at AGS (not directly measured) and Measured PID at SPS PLB 351(95)93 in RQMD At AGS, good description with D decay At SPS, D is not measured, while AGS tells its importance CERN-SPS-WA 98 Susumu　SATO