Study of polarized sea quark distributions in polarized pp collisions at sqrt(s)=500 Ge. V with PHENIX Oct. 4, 2008 Tsutomu Mibe (KEK) for the PHENIX collaboration 1
Sea Quarks are Polarized? • A fundamental question to further break down the quark spin contents DS ~0. 25 • Flavor sensitive measurements required – Semi-inclusive – Weak interaction • W production • Neutrino scattering …
W+ Production in pp Collisions • Only Left-Handed Quark and Right-Handed Anti-quark will contribute Up Neutrino nm Anti-muon m+ Hi-momentum n Flavor is almost fixed Anti-down n Best suited for Spin-Flavor Polarized pp Collisions at 500 Ge. V Structure Studies 3
Projected Sensitivity • Forward and Backward Asymmetries • Momentum resolution is fully incorporated 4
The PHENIX detector 5
Current Muon System • North and South Arms – DOE, RIKEN, and PHNX-F • Muon Tracking Chambers – 3 stations of Cathode strip chambers – 3 gaps + 3 gaps + 2 gaps – Each gap has non-stereo-plane, and anode plane • Muon Identifier – 5 layers of Iarocci tubes in x and y directions – 80 cm of steel plate absorber (total) – Provides LL 1 trigger based on road-finding Mu. ID Mu. Tr St#1 St#2 St#3 Same configuration in South 6
Trigger Rate and Rejection Design Luminosity √s = 500 Ge. V σ=60 mb L = 1. 6 x 1032/cm 2/s REAL DATA m momentum dist. At vs=200 Ge. V PT>10 Ge. V/c HQ signal Total X-sec rate＝ 9. 6 MHz PT>20 Ge. V/c DAQ LIMIT W signal =1 -2 k. Hz （for μ arm） Required RF 10, 000 BUT Mu. ID LL 1 RF=200 ~ 500 25 50 Momentum Ge. V/c Need Momentum Selectivity in the LVL-1 Trigger! 7
Trigger Algorithm • Momentum selectivity through online sagitta measurement – Uses Mu. TR 1, 2, 3 and RPC 1, 3 planes PHENIX LL 1 decision time 40 x. BCLK (4 ms) Implement trigger using fast, parallel logic on FPGA’s RPC 1 RPC 3 8
Current readout system IR Counting House LV 1 Trig accept B Mu. Tr FEE Data Collecting Module 9
Upgraded read out system IR Counting House Level 1 Trigger Board Amp/Discri. Transmit 5% Mu. TRG ADTX 2 plane 95% Mu. Tr FEE Trigger LV 1 Trig accept Mu. TRG MRG LV 1 Trig accept Data Merge Data Collecting Module 10
Mu. Tr Front End Electronics (FEE) Existing readout New addition 11
Amplifier-Discriminator board (Mu. TRG -ADTX) Analog signal from Mu. Tr (64 ch) 6. 5 V Dry air Regulators (3. 3, 2. 5, 1. 2 V) Cooling Water 9. 4 MHz 1. 2 Gbps Cooling Water 12
Installation plan in 2008 n South Arm n North Arm n Station 1, 2, 3 (1/2 octant) n Station 1 (8 octants) n RPC prototype D (2 x 1/2 octants) n Station 2 (8 octants) n Absorber prototype (1 octant) n Station 3 (8 octants) St. 3 St. 2 St. 1 Collision point St. 1 RPC prototype St. 2 St. 3 35 cm absorber 13
Production status n Chassis (130 pcs) üCompleted mass production üCompleted QA n ADTX boards (220 pcs) üCompleted production of 132 boards üCompleted QA of 102 boards (RIKEN/KEK) üFinal production and QA in progress 14
Installation status New platform New racks New LV/optical distributions Cooling water plumbing. . . ü Completed mounting all chassis. ü Completed installing the ADTX boards to North station 1 (Oct 3). N Station 1 15
And its working! Events • Test pulse input at chamber strip • Read out by ADTX board (100 triggers) • North Station 1 Octant 5 Gap 3 Plane 2 Strip 4 Test pulse from chamber was successfully recorded by new trigger system! Time (Beam Clock counts) 16
Data merging : ADTX MRG • Merging and reformatting strip data from ADTX boards Strip hit data from ADTX To LL 1 Strip hit data from ADTX • The first prototype was produced. • Successfully receive and reformat the data from multiple ADTX boards. • Initial communication tests with LL 1 and DCM has been done. To DCM 17
Summary • PHENIX muon arm is being upgraded to measure the AL of W boson production in pp collisions at 500 Ge. V. • The Mu. Tr FEE upgrade has been making steady progress as scheduled. – Production and installation to the PHENIX North muon arm will be completed during this year’s shutdown. 18
Current knowledge of helicity distributions u and d quark helicities are already fairly well known Sea helicities only limited in size, magnitude and sign still unkown Spin PWG meeting, August 6 R. Seidl: W physics in the muon arms 28
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