PHENIX VTX Detector KoreaJapan PHENIX Collaboration workshop November

PHENIX VTX Detector Korea-Japan PHENIX Collaboration workshop November 27, 2012 Y. Akiba (RIKEN/RBRC)

Heavy Quark (charm, bottom) Quarks u up c ~2 Me. V d down ~5 Me. V charm t ~1. 3 Ge. V s strange top ~170 Ge. V b ~0. 1 Ge. V bottom 約4. 2 Ge. V (mass of proton ~ 0. 94 Ge. V) • Protons and neutrons are made of u and d quarks (+gluons, etc) • u, d, s quarks are light and can be made in later stage of nuclear reaction • c, b quarks are heavy (mc, mb > LQCD) 　They can only be produced at hard collisions at the initial stage Their production rate can be calculated by p. QCD Very useful probe for both of Quark Gluon Plasma and nucleon structure

Probing Quark Gluon Plasma with heavy quarks PHENIX measured heavy quark production in Au+Au collisions via single electrons from heavy flavor decays PRL 98, 172301 RAA of b, c e Strong suppression of electron from heavy flavor decay is observed Large energy loss of heavy quark in QGP v 2 of b, c e Large elliptic flow strength v 2 of single electrons from heavy flavor decay is observed Heavy quark flows in QGP medium In these previous measurements, b e and c e were not separated Measure b e and c e separately

Probing nucleon spin with heavy quarks ar. Xiv: 1209. 3278 ALL of single electrons AN of single electrons • ALL of charm is a clean probe of DG(x) • Significant AN of charm (~0. 02) is predicted by Tri-gluon correlation (Z. B. Kang et al, PRD 78, 114013)

VTX: Separate b and c using the difference in decay length e D Decay length (ct) D 0 : 125 mm B 0 : 464 mm DCA n latio u m i S B e Background c quark b quark Separate b and c by a fit in DCA distribution Reduction of BG momentum(Ge. V/c) DCA (mm)

Overview of VTX üFine granularity, low occupancy 50 mm× 425 mm pixels for L 1 and L 2 R 1=2. 5 cm and R 2=5 cm ü Stripixel detector for L 3 and L 4 80 mm× 1000 mm pixel pitch R 3 ≈ 11. 5 cm and R 4 ≈ 16. 5 cm üLarge acceptance |h|<1. 2, almost 2 p in f plane üStand-alone tracking capability Pixel Strip z plane f plane Installation in PHENIX IR was completed on December 1, 2010.

Parameters of VTX Big Wheel (for Electronics holding and cooling) 2 stripixel layers 2 pixel layers Cutaway view from beam axis Side view Structure : 2 pixel layers, 2 stripixel layers Layer Kind R(cm) Z(cm) # ladder RO Channel Occupancy(Au+Au) X 0 0 Pixel 2. 5 10 10 1, 310, 720 0. 53% 1. 28% 1 Pixel 5 10 20 2, 671, 440 0. 16% 1. 28% 2 Stripixel 11. 7 16 16 122, 880 4. 5% 5. 43% 3 Stripixel 16. 6 19 24 221, 184 2. 5% 5. 43% 2011/2/15 Focus Seminar, Takashi HACHIYA 7

Pixel Detector 57 mm (32 x 4 pixel) 13 mm 256 pixel Sensor module 50 mm x 425 mm Pixel bus SPRIO Pixel sensor modules Pixel stave (with cooling) Full ladder Pixel detector = inner 2 layers of VTX 1 st layer: 10 full pixel ladders = 20 half ladders = 40 sensor modules 2 nd layer: 20 full pixel ladders = 40 half ladders = 80 sensor modules ~4 mm 8

Stripixel detector 80 mm x 30 mm “stripixel” 80 mm x 1 mm pixel size Stripixel sensor(Z. Li, BNL) 1 side, 2 direction read-out (384 X + 384 U strips) x 2 silicon module SVX 4 Strip Ladder 5 (L 3) or 6 (L 4) silicon modules Read-out by 1 LDTB 1 sensor + ROC + 12 SVX 4 Read-out by RCC board 128 ch/chip 8 bit ADC 9

Barrel 0 (Pixel) Barrel 1 (Pixel) 5 ladders 10 ladders Barrel 2 (Stripixel) Barrel 3 (Stripixel) 8 ladders 12 ladders 10

VTX Barrel BEAM VIEW SIDE VIEW beam 11

Stand. Alone Tracks in Event Display • 2012/3/26 日本物理学会＠関西学院大学 12

2011 RUN + 2012 RUN 11 RUN 12 commissioning during 500 Ge. V pp 200 Ge. V Au. Au ~790/ub (>5 B evts) within VTX also ~5 M evts @19 Ge. V and ~15 Mevts@27 Ge. V 200 Ge. V pp ~3/pb within VTX 510 Ge. V pp ~11/pb within VTX 193 Ge. V U+U ~108 /ub (~6/pb N+N) 200 Ge. V Cu. Au ~2. 9/nb (~36/pb N+N) 13

p. T and centrality dependence • Simulation : prediction presented at VTX Review 2009. • DCA resolution close to predicted is achieved 14 • Centrality dependence is studied.

Primary Vertex Resolution West – East in X West – East in Y 300 um West – East in Z 600 um 300 um 89 um 45 um 49. 6 um 24. 8 um 39. 7 um (sim) 29. 2 um (sim) (cm) 150 um 75 um 48. 8 um (sim) (cm) • 15

Hadron DCA in RUN 11 Au+Au 200<Bbc. Q<300 (50 -60%) RUN 11 Au+Au Data Sim total(K 0 s + Lambda) Sim K 0 s Sim Lambda Random background DCA(cm) • Large exponential tail seen in inclusive DCA distribution is due to Ks and Lambda 16

Measurement of High p. T hadrons DCA < 0. 1 && EMC match • PHENIX central arm alone suffered by fake high p. T tracks • VTX can eliminates these fake high p. T track by requiring small DCA

Charged hadron spectrum • RUN 11 charged hadron with VTX DCA cuts agree very well with the published data

measurement of v 2 and v 3 • v 2 and v 3 of h± has reduced background by application of DCA cut < 200 um. • v 2 are consistent with previous measurements of p 0 v 2 in high p. T region. • Extend to high p. T region for v 3. Ø Good agreement with previous data in low p. T region. Maki Kurosawa SRC Meeting 6 -8 Nov 19

V 2 measurement by VTX stand-alone tracking • Charged hadron v 2 was measured with VTX stand-alone tracking Ø Cover wider eta range (|eta|<1. 5) • Good agreement with the previous • So far no h dependence observes within relatively large sys/stat uncertainties • Error is to be reduced in future analysis Maki Kurosawa SRC Meeting 6 -8 Nov 20

Electron measurement: conversion veto • A main source of BG for heavy flavor decay electron is photon conversion and Dalitz decays • These BG electron comes with conversion/Dalitz partner near itself Isolation cut Associated Hit B-field 90% heavy flavor e • VTX can reject those BG electrons by requiring that electorn track should be isolated. • About 90% purity of heavy flavor electron is achieved by the isolation cut RHF = e. HF/einc Hit by track 21

Distance of Closest Approach (DCA) Raw DCA distributions for charged hadrons and electrons p+p and Au+Au MB at 200 Ge. V s(DCA) 138 mm s(DCA) ~ 70 mm s(DCA) 70 mm Note: hadron contamination for electron DCA distributions is not subtracted in these plots

Electron Distance of Closest Approach (DCA)

Electron Distance of Closest Approach (DCA)

Electron Distance of Closest Approach (DCA)

Electron Distance of Closest Approach (DCA)

Electron Distance of Closest Approach (DCA)

Electron Distance of Closest Approach (DCA)

Electron Distance of Closest Approach (DCA)

Electron Distance of Closest Approach (DCA)

Electron Distance of Closest Approach (DCA) c/(b+c) = 0. 92 ± 0. 02

Electron Distance of Closest Approach (DCA) c/(b+c) = 0. 78 ± 0. 06

Bottom to HF(b+c) ratio in p+p From Fit of the DCA distribution First direct measurements of bottom production at RHIC in High p. T Physics at LHC, Takashi Hachiya 33 p+p 2012/10/23

Bottom to HF(b+c) ratio in Au+Au From Fit of the DCA distribution

Nuclear Modification of Charm and Bottom QM 2012 preliminary This is extracted assuming p. T distribution of B and D in PYTHIA Systematic effect due to the change in the p. T distributions is not corrected. (This can affect the results for p. T<2 Ge. V/c

Many more things to do • Finalize b e and c e RAA • Reaction Plane measurement using VTX – Improve RP resolution by a factor of ~2 • • v 2 and v 3 of charged hadrons in wide p. T and eta range v 2 and v 3 of b e and c e High pt charged hadron p. T distribution Direct reconstruction of charmed hadrons – – – D 0 Kp and other modes D+ Kpp and other modes Ds KKp, KK 0 and other modes Lc -> p. K 0, p. Kp and other modes D* -> Dp • B J/Psi + X

Many more things to do (cont. ) • Reconstruction of multiple collision vertex in 200 Ge. V and 500 Ge. V pp • Confirmation of W e tracks in VTX and isolation cut • AN of charm • ALL of charm, bottom • Correlation of central arm track and VTX standalone tracks – Hadron – hadron correlation – e (HF) – hadron correlation – photon/pi 0 – hadorn correlation • Measurement of L, S, Ks • Measurement of direct photons via conversion • Charmed hyper-nuclei

Many more things to do (cont. ) • Datasets so far analyzed – RUN 11 Au+Au @ 200 Ge. V (only ½ was analyzed) – RUN 12 pp @ 200 Ge. V (only inclusive e is analyzed) n. DST of these datasets will be reproduced after VTX codes are updated • Dataset not analyzed yet – – – RUN 11 Au+Au @ 19 Ge. V RUN 11 Au+Au @ 27 Ge. V RUN 12 pp @ 510 Ge. V RUN 12 U+U @ 193 Ge. V RUN 12 Cu+Au @ 200 Ge. V ~5 M evts ~11/pb within VTX ~108/ub within VTX ~2. 9/nb within VTX • Many more data coming in the coming RUNs – RUN 13 – RUN 14 mainly 500 Ge. V pp 200 Ge. V Au. Au and pp

Summary • A new silicon vertex tracker VTX was installed in PHENIX and started taking data in RUN 11 • VTX achieved its design performance • First results from RUN 11 Au. Au obtained – Suggesting large suppression of b e • Reaping harvest from VTX detector – Many more physics can be done with VTX – large amount of data are waiting for analysis – More data are coming