Brief Overview of E 1039 Carol Johnstone External

Brief Overview of E 1039 Carol Johnstone External Beams Group Meeting March 22, 2018

b ic La ph f J ra o G sy rte ou C Looking inside a proton Just three valence quarks? NO!! And quark distributions change in a nucleus http: //www. sciencecartoonsplus. com/index. htm

Sea Quarks are formed from gluons In the nucleon: Sea and gluons are important: – 98% of mass; 60% of momentum at Q 2 = 2 Ge. V 2 Not just three valence quarks and QCD. Shown by E 866/Nu. Sea d-bar/u-bar data What are the origins of the sea? Significant part of LHC beam. CTEQ 6 m In nuclei: The nucleus is not just protons and neutrons What is the difference? – Bound system – Virtual mesons affects antiquarks distributions

Antiquark Flavor Asymmetry: Assume u and d quark equally populated in sea u g q q Naïve Assumption: NMC (Gottfried Sum Rule) NA 51 Drell-Yan confirms d-bar(x) > u-bar(x)

Flavor Asymmetry: Experiment and Theory NA 51 (Drell-Yan) E 866/Nu. Sea (Drell-Yan, (800 Ge. V protons) Knowledge of distributions is data driven – Sea quark distributions are difficult for Lattice QCD

Advantages of 120 Ge. V Main Injector The (very successful) past: The future: Fermilab E 866/Nu. Sea Fermilab E 906 Data in 1996 -1997 1 H, 2 H, and nuclear targets 800 Ge. V proton beam Data in 2010 1 H, 2 H, and nuclear targets 120 Ge. V proton Beam Cross section scales as 1/s – 7× that of 800 Ge. V beam Backgrounds, primarily from J/ decays scale as s – 7× Luminosity for same detector rate as 800 Ge. V beam 50× statistics (in theory) 6 10 June 2009 Paul E.

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E 1039: • • 8 It is well known that the proton is a spin-1/2 particle, but how the constituents (quarks and gluons) assemble to this quantized spin is still a mystery. There is a worldwide effort to map out the individual contributions to the proton spin. It is established that the quark spins contribute around 30%, while the gluon intrinsic angular momentum is still under active investigation. Fully resolving the proton spin puzzle requires information on the orbital angular momentum (OAM) of both quarks and gluons. From a detailed analysis of the azimuthal distribution of the produced particles from a transversely polarized nucleon, one can deduce properties of the nucleon structure. Presenter | Presentation Title 1/2/2022

Polarized protons • Frozen ammonia (NH 3) is the target material and paramagnetic radicals (roughly 1019 spins/ml) are created by irradiation with a high intensity electron beam at NIST. (~80% irradiation) • While the magnetic moment of the proton is too small to lead to a sizable polarization in a 5 T field through the Zeeman effect, electrons in that field at 1 K are better than 99% polarized. • By doping a suitable solid target material with paramagnetic radicals to provide unpaired electron spins, one can make use of the highly polarized state of the electrons. • The dipole-dipole interaction between the nucleon and the electron leads to hyperfine splitting, providing the coupling between the two spin species. • By applying a suitable microwave signal, one can populate the desired spin states. The target spin direction will be reversed once every 8 hours by microwave frequency changes, while the magnet field is unchanged. 9 Presenter | Presentation Title 1/2/2022

NH 3 target assembly 10 Presenter | Presentation Title 1/2/2022