TheThe E-906E-906 // SeaQuestSeaQuest experimentexperiment atat FermilabFermilab
Markus Diefenthaler University of Illinois at Urbana-Champaign TheThe SeaQuestSeaQuest collaborationcollaboration
● Abilene Christian University: Donald ● Los Alamos National Laboratory: Christine Isenhower, Tyler Hague, Rusty Towell, Shon Aidala, Gerry Garvey, Mike Leitch, Han Liu, Ming Watson Liu, Pat McGaughey, Joel Moss, Andrew Puckett
● Academia Sinica: Wen-Chen Chang, Yen-Chu ● University of Maryland: Betsy Beise, Kazutaka Chen, Shiu Shiuan-Hal, Da-Shung Su Nakahara
● Argonne National Laboratory: John Arrington, ● University of Michigan: Chiranjib Dutta, Donald F. Geesaman (co-spokesperson), Wolfgang Lorenzon, Richard Raymond, Michael Kawtar Hafidi, Roy Holt, Harold Jackson, David Stewart Potterveld, Paul E. Reimer (co-spokesperson), Joshua Rubin ● National Kaohsiung Normal University: Rurngsheng Guo, Su-Yin Wang ● University of Colorado: Ed(ward) Kinney, Joseph Katich, Po-Ju Lin ● University of New Mexico: Younus Imran
● Fermi National Accelerator Laboratory: Chuck ● RIKEN: Yoshinori Fukao, Yuji Goto, Atsushi Brown, Dave Christian, Jin-Yuan Wu Taketani, Manabu Togawa
● University of Illinois: Bryan Dannowitz, Markus ● Rutgers University: Lamiaa El Fassi, Ron Diefenthaler, Bryan Kerns, Naomi C.R Makins, Gilman, Ron Ransome, Brian Tice, Ryan R. Evan McClellan, Jen-Chieh Peng Thorpe, Yawei Zhang
● KEK: Shin'ya Sawada ● Tokyo Tech: Shou Miyaska, Kenichi Nakano, Florian Sanftl, Toshi-Aki Shibata ● Ling-Tung University: Ting-Hua Chang ● Yamagata University: Yoshiyuki Miyachi2 TheThe innerinner structurestructure ofof thethe nucleonnucleon
origin of origin of the nucleon sea nucleon spin
nucleons in nuclei 3 ComplimentaryComplimentary processesprocesses Deep-inelastic scattering Drell-Yan scattering
4 AA laboratorylaboratory forfor seasea quarksquarks
The Drell-Yan process x target
x beam
beam: valence quarks at high-x target: sea quarks at low/intermediate-x 5 ProbingProbing thethe protonproton seasea
● perturbative sea: g → qq, flavor-symmetric, u = d
● analysis of cross-section differences → sensitivity to d - u in valence region
● measurement of cross-section ratios
→ sensitivity to u and d in proton sea 6 InsightsInsights intointo thethe protonproton seasea
d > u
alternate degrees of freedom? 7 SeaQuestSeaQuest probingprobing thethe protonproton seasea
Global NLO PDF fit
extend measurement SeaQuest: Syst. ~ 1% 8 NucleonsNucleons embeddedembedded inin nucleinuclei
● Do nucleons change their internal properties when embedded in a nucleus?
Fermi motion
● Is confinement influenced by the nuclear medium?
● Do quarks and gluons play any role in the understanding of nuclear forces?
● Can the model of nuclear forces be replaced by a fundamental theory based on the strong interaction between quarks and gluons? 9 TheThe EMCEMC effecteffect
antishadowing
shadowing
10 TheThe EMCEMC effecteffect inin Drell-YanDrell-Yan
valence quark effect?
no antishadowing
shadowing
antiquark feature?
11 TheThe innerinner structurestructure ofof aa nucleusnucleus
● nuclear force mediated by meson exchange
large effects to antiquark PDF predicted as x increases
no antiquak enhancement
● Where are the nuclear pions? 12 Spin-orbitSpin-orbit correlationscorrelations
● angular dependence of the Drell-Yan cross-section:
● Lam-Tung relation: Boer-Mulders TMD
13 TheThe SeaQuestSeaQuest missionmission
● significant increase in physics reach
● unique access to sea quarks at high-x
● What is the structure of the nucleon?
● What is d / u?
● What are the origins of the sea quarks?
● What is the high-x structure of the proton?
● How are quark spin and orbital motion correlated?
● What is the struture of nucleonic matter?
● Where are the nuclear pions?
● Is antishadowing a valence effect?
● Do colored partons lose energy in cold nuclear matter? 14 TheThe protonproton beambeam forfor SeaQuestSeaQuest
● extracted from Fermilab Main Injector fixed target beam lines Tevatron 800 GeV Main Injector 120 GeV
12 ● 2x10 protons / s for 5s spills each minute
● 120 GeV proton beam instead of a 800 GeV proton beam (as used for E-866 / NuSea):
● Drell-Yan cross section scales as 1/s
● decay (dominant background) scales as s 15 ● 50x luminosity as E-866 (for same rate) TheThe SeaQuestSeaQuest targettarget luminosity: liquid 3.4x1035/cm2/s hydrogen
liquid deuterium
Carbon
Calcium
Tungsten
16 TheThe SeaQuestSeaQuest spectrometerspectrometer
~25m spectrometer magnet
focusing magnet
hadron absorber
hadronhadron absorber hodoscope beam(iron dumpwall) tracking 17 ReuseReuse andand recylcerecylce
18 ““JoyJoy andand toiltoil asas FermilabFermilab sendssends firstfirst particlesparticles toto SeaQuest”SeaQuest”
Fermilab Today: On the night of March 7, SeaQuest celebrated the detection of their first particles – a new milestone for the experiment. 19 TheThe futurefuture ofof SeaQuest:SeaQuest:
PolarizedPolarized Drell-YanDrell-Yan measurementsmeasurements atat FermilabFermilab TheThe SiversSivers functionfunction
● transverse-momentum dependent PDF:
● rather exotic in being naive-time-reversal-odd ↔ initial (Drell-Yan) and final state (SIDIS) interactions → single-spin asymmetries:
● close relationship to quark orbital angular momentum
● challenging the concept of factorization and universality
● fundamental QCD prediction:
● remains to be experimentally tested
● polarized Drell-Yan measurement required 21 PolarizedPolarized Drell-YanDrell-Yan experimentsexperiments
in 2014: well-understood experiment, optimized for Drell-Yan sensitive to valence quark effects → large asymmetries expected → sign, magnitude and shape of the Sivers effect 22 ReestablishingReestablishing spinspin atat FermilabFermilab
* based on RHIC 4-helical dipole design polarized H- ion source superconducting siberiansiberian snakessnakes*
75% polarization
enginiering & superconducting fabrication: 2yr spin rotator 23 TheThe SeaQuestSeaQuest missionmission unique laboratory for sea quarks at high-x → structure of nucleons and nucleonic matter finally: commissioning of the experiment → data taking until shutdown in April 2012 due to main-injector update (~11 months) → continue data taking in 2013
exciting extensions possible
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