E12-06-105 (“x>1”) PAC47 Jeopardy presentation John Arrington drhgfdjhngngfmhgmghmghjmghfmf John Arrington Donal day Nadia Fomin Argonne National Laboratory Univ. Virginia Univ. Tennessee PAC47 July 30, 2019 Newport News, VA

High-momentum nucleons (Short-Range Correlations) N-N interaction Hard interaction at short range Pairs of high-momentum nucleons (up to 1 GeV/c) Nucleon momentum distribution in 12C n(k) [fm-3] Mean field part k [GeV/c] N-N interaction as source of SRCs  SRCs should exhibit universal 2-body behavior in nuclei

Experimental Goals Inclusive SRC ratios (moderate Q2, x>1) A/D ratios for nuclear and isospin dependence of 2N SRCs EMC/SRC correlation investigation First observation of a 3N plateau DIS at x>1 (high Q2) Nuclear parton distributions N. Fomin, et al., PRL 108, 092052 (2012) Observation of universal behavior – inclusive ratios independent of x, Q2 Triple-coincidence data show strong dominance of np pairs

Experimental Goals Inclusive SRC ratios (moderate Q2, x>1) N. Fomin, et al., PRL 108, 092052 (2012) J. Seely, et al., PRL103, 202301 (2009) Inclusive SRC ratios (moderate Q2, x>1) A/D ratios for nuclear and isospin dependence of 2N SRCs EMC/SRC correlation investigation First observation of a 3N plateau DIS at x>1 (high Q2) Nuclear parton distributions A dependence in light nuclei (impact of e.g. cluster structure) Separating A dependence and isospin dependence: Varying N/Z for roughly fixed mass or density Same nuclei for SRC and EMC proposal

Experimental Goals Inclusive SRC ratios (moderate Q2, x>1) A/D ratios for nuclear and isospin dependence of 2N SRCs EMC/SRC correlation investigation First observation of a 3N plateau DIS at x>1 (high Q2) Nuclear parton distributions More nuclei (greater N/Z range) to test Simple pictures of EMC-SRC connection EMC scales with number of high-p (np) pairs? EMC scales with number of short-distance (NN) pairs? Calculations predicting a2 for range of nuclei JA, A. Dainel, D. Day, N. Fomin, D. Gaskell, P. Solvignon, PRC 86, 065204 (2012) B. Schmookler, et al., Nature 566 (2019) 354 JA, N. Fomin, PRL 123 (2019) 042501

Experimental Goals Inclusive SRC ratios (moderate Q2, x>1) A/D ratios for nuclear and isospin dependence of 2N SRCs EMC/SRC correlation investigation First observation of a 3N plateau DIS at x>1 (high Q2) Nuclear parton distributions Z. Ye, et al., PRC 97 (2018) 065204

Search for a 3N SRC plateau N. Fomin, et al., Ann. Rev. Nucl. Part. Sci. 67 (2017) 129  Z. Ye, et al., PRC 97 (2018) 065204 α3N_MIN=1.6 Where does 2N contribution become negligible? αi represents the light-cone momentum fraction of 3N SRCs carried by the correlated nucleon i αi –min = 1.6  scaling for Hall C data (blue diamonds) should set in at x~2.4 Data consistent with plateau, but limited statistics and single Q2 values do not allow for statement on 3N-SRCs We will extract 4He/3He ratios for Q2 of approx. 2.5 and 3.5 GeV2 Examine both x and Q2 dependence with high statistics

qD(x) Experimental Goals two-nucleon only 5% 6 quark bag Inclusive SRC ratios (moderate Q2, x>1) A/D ratios for nuclear and isospin dependence of 2N SRCs EMC/SRC correlation investigation First observation of a 3N plateau DIS at x>1 (high Q2) Nuclear parton distributions Difference only ~1% piece of EMC effect? two-nucleon only 5% 6 quark bag Simple model where overlapping nucleons yield EMC effect through direct quark exchange in overlapping protons (modeled as small 6q bag contribution) Modification is at percent-level for x<1 Potentially 100-1000% effect for x>1 Measure for deuteron (carbon); compare deuteron to simple p+n convolution

Run plan: Targets 1H 2H 3He 4He 6,7Li 9Be 10,11B 12C 27Al 40*,48Ca Light nuclei: Reliable calculations of nuclear structure (e.g. clustering) Run plan: Targets x>1 uses wide range of nuclear targets to study impact of cluster structure, separate mass and isospin dependence on SRCs Additional foil targets (dark blue) added to original proposal. No additional beam time required, no special target issues All targets measured for SRCs at high-rate kinematics. Select targets run at higher Q2 to study Q2 dependence or extend kinematic reach 1H 2H 3He 4He 6,7Li 9Be 10,11B 12C Targets selected to match 12 GeV EMC experiment 27Al 40*,48Ca 48Ti 54Fe 58,64Ni 64*Cu 108*Ag 119*Sn 197*Au 232Th Heavier nuclei: Cover range of N/Z at ~fixed values of A

Physics impact: 2019 More As important now as when approved and rated “High Impact” All questions addressed in the original proposal are still relevant today New data on 3N-SRCs, but no clear observation of scaling Theory suggestions that ~3 GeV2 may be sufficient Data in this region (~2.8 GeV2) from Hall C has limited statistics We can provide good statistics for Q2 values (~2.5 and 3.5 GeV2) Connection between SRCs and EMC effect Several works looking at the potential connection ‘Overlap’ of nucleons in short-distance configurations Off-shell effects of high-momentum nucleons in SRCs Raises question of flavor dependence in EMC effect arising from isospin structure of SRCs Existing data do now allow clean separation of A and N/Z dependence Better theory support than when originally proposed Complimentary to ‘tagged’ measurements 2N-SRCs still relevant

Experimental Goals Inclusive SRC ratios (moderate Q2, x>1) A/D ratios for nuclear and isospin dependence of 2N SRCs EMC/SRC correlation investigation First observation of a 3N plateau DIS at x>1 (high Q2) Nuclear parton distributions Combined kinematics for this experiment and EMC DIS at x>1 3N SRC search 2N SRC scan EMC effect

backups

Nuclear Targets N/Z vs A N/Z vs density Light nuclei – sensitivity to some nuclear structure (clusters, halos, etc...) Heavier nuclei – N/Z isospin lever

Experimental Goals Inclusive SRC ratios (moderate Q2, x>1) A/D ratios for nuclear and isospin dependence of 2N SRCs EMC/SRC correlation investigation First observation of a 3N plateau DIS at x>1 (high Q2) Nuclear parton distributions 6 GeV data suggests that even for x (x) > 1, data consistent with QCD-inspired fit

Run plan: Kinematics overview Both experiments cover range of angles (20-55º) to examine Q2 dependence of structure functions [angles shifted from proposal to increase compatibility] Main PDF measurements at 20, 33º (EMC), or x≥1: modest pion backgrounds High-x SRCs requires small angle Need SHMS for E’ ≈ 11 GeV Need ‘medium’ beam pipe HMS: 20-55º, 1.4-6.4 GeV/c SHMS: 8-33º, 1.4-10.6 GeV/c All data taking at 11 GeV Focus on target ratios Light nuclei: cluster structure Heavier nuclei: vary N/Z EMC x>1 EMC effect vs A, N/Z Larger Q2 pushes to highest x PDFs at x>1 x, Q2 dependence A-dependence of SRCs

Run plan overview [x>1+EMC from ERR] Basic Run plan: 23 PAC days EMC, 32 days x>1 Assume 2 days will be completed during Hall C commissioning 7 days for EMC effect at 20º [all targets, HMS and SHMS in parallel] 6 (3) days for selected targets at 35 (40) degrees 6 days overhead, calibrations, … 4 days for x>1 at 8º [SHMS] 4 days for selected targets at 10º 17 days for high Q2 x>1 (2H,C,Cu) EMC x>1 EMC effect vs A, N/Z Larger Q2 pushes to highest x PDFs at x>1 x, Q2 dependence Notes: Proposed 80uA; assuming 60uA Single ladder with all solid targets Start with 1,2H, taking data with all targets; 1 day target changeover before running 3,4He (+C, dummy) Updated cross section models from 6 GeV x>1 suggests that cross section for 12 degrees is too small Probably can’t wait until the VERY end to switch over to 3He/4He, but would normally make 55 degree data last, which DOES require hydrogen/deuterium. Hmmm….. EMC really needs A-D together. 3He/4He ONLY for EMC He/2H (20/33 degrees) and very large x. Some advantage to doing 3He/4He first? A-dependence of SRCs