The E906/Seaquest Experiment

The E906/SeaQuest Experiment

Kun Liu (on behalf of E906/SeaQuest Collaboration) Los Alamos National Laboratory

48th Annual Fermilab Users Meeting, June 9-12, 2015 E906/SeaQuest experiment at Fermilab

Aimed at measuring dimuon production in

Drell-Yan process and charmonium decay

Absorber wall and proportional tube based Muon} ID

Spectrometer magnet

Δpt = 0.4 GeV Focusing magnet }

and solid iron dump

t = 2.9 GeV Δp }

Beam 13 protons per spill 120 GeV proton from Main Injector 19ns RF, 5s spill, 1×10 25 m

Target system Liquid H and D Solid C, Fe, W Tracking detectors Drift chambers and hodoscope scintillators

2 A brief history

Analyzable data E605, E772, E906 ﬁrst Detector E789, E866 proposal First assembled proton! Main injector Future Run-I Run-II Run-III upgrade upgrades of polarized New Drift Chamber program

80’s - 90’s 1999 2011 2012 2013 2014 2015 2016 1.6E18 • Run-I: 2-month commissioning, ﬁrst J/ψ signal protons • Run-II: solved almost all the technical delivered problems and substantial improvement in beam quality, ﬁrst physics results • Run-III: 0.7E18 high quality beam protons - recorded - new station-1 DC to increase the x2 coverage • Polarized projects (target and/or beam) will take over in summer 2016

Our heartfelt thanks to Accelerator Division for their remarkable work on improving the beam quality

3 Drell-Yan at SeaQuest (E906): a Clean Access to Sea Quark

Accepted! E906/SeaQuest Collaboration small! Events! target!! beam!valence! sea!quark! quark!

Abilene Christian University Mississippi State University u¯t(xt) ub(xb) dominates!

Ryan Castillo, Michael Daugherity, Donald Isenhower, Noah · ! Lamiaa El Fassi projected! Kitts, Lacey Medlock, Noah Shutty, Rusty Towell, Shon Watson, ¯ Ziao Jai Xi University of Maryland d Betsy Beise, Yen-Chu Chen, Kazutaka Nakahara target Academia Sinica ¯u x Wen-Chen Chang, Ting-Hua Chang, Shiu Shiuan-Hao University of Michigan Christine Aidala, McKenzie Barber, Catherine Culkin, Vera Argonne National Laboratory Loggins, Wolfgang Lorenzon, Bryan Ramson, Richard Raymond, John Arrington, Don Geesaman*, Kawtar Hafidi, Josh Rubin, Matt Wood xbeam! Roy Holt, Harold Jackson, David Potterveld, National Kaohsiung Normal University Paul E. Reimer*, Brian Tice Rurngsheng Guo, Su-Yin Wang Quark! Distribu1on! University of Colorado RIKEN Ed Kinney, Joseph Katich, Po-Ju Lin Yoshinori Fukao, Yuji Goto, Atsushi Taketani, Manabu Togawa

Fermi National Accelerator Laboratory Rutgers, The State University of New Jersey Chuck Brown, Dave Christian, Su-Yin Wang, Jin-Yuan Wu Ron Gilman, Ron Ransome, Arun Tadepalli

University of Illinois Tokyo Tech Bryan Dannowitz, Markus Diefenthaler, Bryan Kerns, Hao Li, Shou Miyaska, Kei Nagai, Kenichi Nakano, Shigeki Obata, xtarget! Naomi C.R Makins, Dhyaanesh Mullagur R. Evan McClellan, Florian Sanftl, Toshi-Aki Shibata Strong)ﬂavor)asymmetry)in)the)sea.) Jen-Chieh Peng, Shivangi Prasad, Mae Hwee Teo, Mariusz Witek, Yangqiu Yin Yamagata University Could)sea)quarks)carry)a)signiﬁcant)amount)of)angular)momentum)?)) Yuya Kudo, Yoshiyuki Miyachi, Shumpei Nara 10/26/13! Polarized!Target!DrellGYan!SSA! 5! KEK

Shin'ya Sawada + µ+

µ ( q Los Alamos National Laboratory Resonance(produc-on( Gerry Garvey, Xiaodong Jiang, Andreas Klein, David Kleinjan, q,#g# q − Mike Leitch, Kun Liu, Ming Liu, Pat McGaughey, Joel Moss η µ ( µ

γ 2009 @ Los Alamos 2013 @ Tokyo Tech

4 E906 kinematic coverage

The Drell-Yan process: target x

small% xbeam

_ qt(xt): target sea quark at low/intermediate x qb(xb): beam valence quark at high x

xtarget xbeam

5 Flavor asymmetry in light quark sea

• Assuming charge symmetry, ignoring nuclear effects of deuterium and heavy quark contributions:

• Naively we_ would_ expect ﬂavor symmetry between u and d • E866/NuSea experiment reveals a striking asymmetry in the sea distributions at moderate x • Caused by virtual pions?

• Important constraints on light sea polarization • No models until recently (Peng et al, PLB 736 2014, 411) could incorporate the sign E906’s x coverage: 0.1 - 0.45 change at x > 0.25 6 µ+ q,#g# q

q − Quark energy loss in DY µ

Nucl. Phys. A 879 (2012) • Fundamental probe to study matter properties, like QGP produced at RHIC and LHC • Observables result from convolution of initial and ﬁnal state interactions • Drell-Yan provides a clean baseline measurement

• Early data from E866 - Correction must be made for shadowing effects • Garvey & Peng PRL 90 (2003) - NO partonic energy loss if all effects from shadowing • Vasiliev et al., PRL 83 (1999) - Signiﬁcant parton energy loss, ~1.2 GeV/fm if all from energy loss

• Johnson et al., PRC 65 025203 (2002) 0802.0139 arXiv:

Both yield 20~30% effects in RpA

7 E906 Drell-Yan dimuon acceptance

Nucl. Phys. A879 (2012) • Parton initial energy: 30 - 120 GeV (relevant to RHIC and LHC parton energy) • Direct test on various models: - Gavin and Milana: - Brodsky and Hoyer: - Baier et al:

• Sea quark x = 0.1 ~ 0.3 • Minimal shadowing • 1/s enhanced dE/dx effect

First unambiguous determination of dE/dx in CNM 8 Data from FY 2014 (Run-II)

1800 • Monte Carlo describe data well 1600 E906 preliminary • Resolution better than expected ~ 5% of expected statistics - σM(J/ψ) ~ 180 MeV, σM(DY) ~ 220 MeV 1400 - J/ψ ψ’ separation 1200 - Cleaner DY sample • Good target/beam dump separation 1000 - J/ψ Monte Carlo - ψ’ Monte Carlo 800 - Drell-Yan Monte Carlo • Beam quality worse than expected (instantaneous rate much higher than average) Events / 100 MeV 600 - Random Background - Combined MC and bkg - live time of spectrometer greatly reduced by the ‘super’ 400 RF buckets - Reconstruction efﬁciency lower than expected because 200 of the high detector occupancy 0 0 1 2 3 4 5 6 7 8 9 10 Mass (GeV) • All “good” dimuons in data ◦ Data with dump cut ◦ Data with target cut - Dump MC • Entire beam interacts upstream of - Target MC SeaQuest spectrometer • Pointing resolution very poor along beam axis • Dominated by random coincidences

Zvtx (cm) 9 _ _ E906 preview measurements on d/u

• Only consists of 5% of the total expected statistics

• Well consistent with E866 results at low x2

• Interesting behavior at high x2, with large statistical uncertainties. New larger drift chamber and more statistics will help us pin down this point.

• Current systematic error mainly comes from LD2 impurity and unresolved rate-dependence. We expect ﬁnal systematic uncertainty to be ~1%

10 Quark energy loss at E906

C/D Fe/D W/D 1.6 .6 .6 SeaQuest Preview 1.4 .4 < 5% of expected statistics .4 Mass > 4.2 GeV d) .2 .2 1.2 xTarget > 0.15 p+ ( σ

1 1

A 1 A

0.8 .8 EKS Shadowing .8 A)

2 p+ q = 0.016 GeV /fm ( .6 0 .6

σ 0.6

2 d q = 0.032 GeV /fm 0 A .4 .4 0.4 Systematic uncertainty: ~ 14%

0.2 .2 .2 0.4 0.5 0.6 0.7 0.8 0.9 0.4 0.5 0.6 0.7 0.8 0.9 0.4 0.5 0.6 0.7 0.8 0.9 x Beam 1.6 SeaQuest Preview • Too early to make any conclusion on p+Fe as 1.4 < 5% of anticipated data limited by the statistics (p+d)

σ 1.2 • A consistently negative slope beyond the A D C Fe 1 shadowing strength is observed in p+W data. Mass > 5 GeV W x > 0.15 With 20x more statistics, we will be able to 0.8 Target • (p+A) / A xBeam > 0.6 σ

clearly distinguish between: d Systematic uncertainty: ~ 14% A 0.6 ➢ -dE ∝ A1/3 (or ∝ L) 0.4 2/3 2 123456 ➢ -dE ∝ A (or ∝ L ) A1/3 11 Summary Run-II: 5% of total statistics: • conﬁrmed the large light sea quark asymmetry at x2 ~ 0.15, while the sign change at x2 > 0.3 still waits for more statistics • observed a negative slope beyond the extent of shadowing

Ongoing Run-III: ~20x of Run-II statistics

Other ongoing physics analysis: • EMC effect in Drell-Yan • Transverse momentum broadening • Difference between J/ψ and ψ’ suppression in pA • Angular distribution of DY and J/ψ produced in beam dump • Search for dark photons • ... Future polarized program • target: sea quark Sivers asymmetry in DY • beam: valence quark Sivers asymmetry in DY

xBeam 12 Backup slides EMC effect in DY