Update on the Color Transparency Experiment 28 January 2019 John - PowerPoint PPT Presentation

Update on the Color Transparency Experiment 28 January 2019 John Matter HMS e' e - e Target e - beam p p' p SHMS � 1

Summary e' e p p' • CT Definition • Why do we care? Complete transparency 1.0 • A Brief History CT onset T A • E12-06-107 Glauber Q 2 ➝ Q 02 2

CT Definition e' e p p' • Color transparency: the vanishing of initial and final state interactions of hadrons with the nuclear medium in exclusive processes at large momentum transfer Q 2 • Not predicted in a strongly interacting hadronic picture • Arises in quark-gluon picture; the color Complete transparency 1.0 field of singlet objects vanishes as size is CT onset reduced T A Glauber • Point-like configuration (PLC): small, color-neutral quark system formed that passes through nuclear medium Q 2 ➝ undisturbed Q 02 3

CT Definition e' e p p' • Transparency T is a ratio of cross sections • Conventional Glauber calculations predict constant T Complete transparency 1.0 • Clear signature of CT would be CT onset T A dramatic rise in T around Q 2 = 10 Glauber GeV 2 Q 2 ➝ Q 02 4

A Brief History V q x ʹ x ʹ -x • CT is well-established at high energies! p ʹ p • Vanishing FSI assumed for QCD factorization CT theorems and Bjorken Experiments scaling • Clear experimental evidence Meson Baryon exists of CT onset in meson u u production u ū d • No unambiguous signs of CT A(p,2p): BNL A( 𝝆 ,di-jet): FNAL A(e,e’p): SLAC, JLab onset for baryons A( 𝛅 , 𝝆 - p): Jlab A(e, e’ 𝝆 + ): JLab • Where is the onset in Q 2 ? A(e, e’ 𝛓 0 ): DESY & JLab 5

A Brief History Clear onset of CT for mesons A(e,e ’ ρ 0 ) • Meson electroproduction • Quasielastic A(p,2p) • Quasielastic A(e,e’p) PRC 68, 021001R (2003) PRL 99, 242502 (2007) PRC 81, 055209 (2010) PRB 712, 326 (2012) 6

A Brief History Ambiguous A(p,2p) BNL rise/fall • Meson electroproduction • Quasielastic A(p,2p) • Quasielastic A(e,e’p) Glauber (shaded band) PRL 87, 212301 (2001) PRL 81, 5085 (1998) PRL 61, 1698 (1988) 7

A Brief History No onset… yet! A(e,e’p) • Meson electroproduction • Quasielastic A(p,2p) • Quasielastic A(e,e’p) Solid points = JLab PRL 72, 1986 (1994) PRB 351, 87 (1995) Open points = other PRL 80, 5072 (1998) PRC 66, 044613 (2002) PRC 72, 054602 (2005) PRC 45, 780 (1992) 8

E12-06-107 12 C(e,e’p) ● E12-06-107 • Coincidence trigger: 
 proton in SHMS, electron in HMS • Targets: 10 cm LH 2 (Hee’p check), 
 6% 12 C (production), Al dummy (background) • Q 2 = 8—14.3 GeV 2 SHMS Q 2 SHMS central HMS angle HMS central angle [GeV 2 ] P [GeV/c] [deg] P [GeV/c] [deg] A(p,2p) V e G 4 . 6 m a e b 8.0 17.1 5.122 45.1 2.131 9.5 21.6 5.925 23.2 5.539 V e G 6 . 0 1 m a e b 11.5 17.8 7.001 28.5 4.478 14.3 12.8 8.505 39.3 2.982 9

E12-06-107 • Coincidence trigger: 
 proton in SHMS, electron in HMS Event Selection • Targets: 10 cm LH 2 (Hee’p check), 
 6% 12 C (production), Al dummy (background) 0.8 < H.cal.etottracknorm <1.15 • Q 2 = 8—14.3 GeV 2 H.cer.npeSum > 0.0 PID P .hgcer.npeSum < 0.1 || P .hgcer.npeSum < 0.1 0.6 < P .gtr.beta < 1.4 HMS 0.8 < H.gtr.beta < 1.2 e - Kinematics -8 < H.gtr.dp < 8 -10 < P .gtr.dp < 15 Target e - beam LH2 0.85 < H.kin.primary.W < 1.03 P .kin.secondary.emiss < 0.1 C12 p abs(P .kin.secondary.pmiss) < 0.1 SHMS 10

Holly E12-06-107 Szumila-Vance Optics Track reconstruction LH2 Q 2 =8 Gev 2 agrees with SIMC Blue = data Red = MC 11

Holly E12-06-107 Szumila-Vance Optics Invariant mass looks good across range of momenta LH2, Q 2 =8 Gev 2 LH2 Q 2 =9.5 Gev 2 Blue = data HMS p 0 = 5.539 GeV HMS p 0 = 2.131 GeV Red = MC 12

Holly E12-06-107 Szumila-Vance Optics E miss Blue = data Green = MC without radiative e ff ects Radiative e ff ects in Red = MC with radiative e ff ects agreement with SIMC 6% C12 target, Q 2 =8 Gev 2 1.5% C12 target, Q 2 =9.5 Gev 2 E miss E miss 13

Deepak E12-06-107 Bhetuwal Calibrations h h h h H.gtr.beta {H.cer.npeSum>0.5 && H.cal.etottracknorm<1.2 && H.cal.etottracknorm>0.8} P.gtr.beta {P.hgcer.npeSum<0.1 && P.ngcer.npeSum <0.1 && H.cer.npeSum>0.5 && H.cal.etottracknorm<1.2 && H.cal.etottracknorm>0.8} Entries Entries 5787 5787 Entries Entries 5301 5301 Mean Mean 1.003 1.003 Mean Mean 0.9923 0.9923 240 120 Std Dev 0.02752 Std Dev 0.02752 Std Dev 0.04814 Std Dev 0.04814 β HMS = 1.01 ± 0.02 β SHMS = 0.99 ± 0.04 220 Underflow Underflow 59 59 Underflow Underflow 237 237 Overflow Overflow 18 18 Overflow Overflow 686 686 200 100 Integral Integral Integral Integral 5710 5710 4378 4378 180 160 80 140 120 60 100 80 40 60 40 20 20 0 0 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 H.cal.etottracknorm {H.cer.npeSum>0} h h h h H.cer.npeSum {H.cal.etottracknorm<1.2 && H.cal.etottracknorm>0.8} Entries Entries 6100 6100 Entries Entries 6627 6627 Mean Mean 8.285 8.285 Mean Mean 1.007 1.007 Std Dev 0.03557 Std Dev 0.03557 Std Dev 3.905 Std Dev 3.905 300 HMS E / p = 1.009 ± 0.03 HMS NPE = 9 Underflow 0 Underflow 0 Underflow Underflow 834 834 250 Overflow 7 Overflow 7 Overflow Overflow 1 1 Integral Integral Integral Integral 6093 6093 5792 5792 250 200 200 150 150 100 100 50 50 0 0 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 14 0 5 10 15 20 25 30

E12-06-107 Coincidence time Each particle time corrected for: • Particle traveling along central ray to focal plane • Path length variations t coin = t tar − t tar e p • Di ff erence in time between hodoscope start and focal plane time t tar = t trigger − Δ t corr Special run taken to Typical CT run showing very observe accidentals low accidental rate ep ep e π + 15

E12-06-107 Efficiency Example: HMS Calorimeter should = ( 𝛾 cut) && ( 𝜀 cut) && (H.cer.npeSum>1.0) did = should && (H.cal.etottracknorm ≅ 1) n i , did ϵ ϵ 1.0 ϵ i = n i , should 0.95 ∑ i w i ϵ i 0.90 ϵ = ∑ j w j 0.85 0.80 w i = 1/ σ 2 i 𝜀 HMS 16

E12-06-107 Efficiency HMS SHMS NA 1.00 Calorimeter 0.99 ● ● 0.98 target ● 0.97 ● C12 ● Calorimeter, 1.00 ● ● ● ● Cherenkov Cherenkov, ● LH2 ● 0.99 ● ● hodo 3/4 0.98 mostly ~99% efficiency 0.97 1.00 ● ● ● ● ● ● ● ● Hodo 3/4 0.99 0.98 0.97 1.00 SHMS ● ● ● ● 0.95 tracking Tracking ● ● ● 0.90 e ffi ciency is 0.85 80—95% 0.80 ● 8 10 12 14 8 10 12 14 Q 2 [ GeV 2 ] Q2 17

E12-06-107 SHMS proton absorption Can get estimate based on geometry/materials (should confirm with the detector gods) Working on a Google spreadsheet* for this purpose Current estimate is ~ 9% * https://docs.google.com/spreadsheets/d/ 1LeaFrQjKTuOeliKTEN8QAHqDkFCYzW18bMMjTKu1ejQ/ 18

E12-06-107 SHMS proton absorption p Target, magnets path through spectrometer NGCER DC HODO HGCER AERO * https://docs.google.com/spreadsheets/d/ 1LeaFrQjKTuOeliKTEN8QAHqDkFCYzW18bMMjTKu1ejQ/ 19

E12-06-107 SHMS proton absorption NGCER List of each component of the system material properties contribution to absorption A = 1 − exp { − ∑ λ i } x i i * https://docs.google.com/spreadsheets/d/ 1LeaFrQjKTuOeliKTEN8QAHqDkFCYzW18bMMjTKu1ejQ/ 20

E12-06-107 SHMS proton absorption Listed all the sources I consulted in notes columns. Corrections are welcome! * https://docs.google.com/spreadsheets/d/ 1LeaFrQjKTuOeliKTEN8QAHqDkFCYzW18bMMjTKu1ejQ/ 21

E12-06-107 SHMS proton absorption • Empirically, compare elastic ep yields in HMS singles and coincidence runs A = 1 − ( Q singles ) n ep , coin n ep , singles Q coin / • Will have this soon 22

E12-06-107 Preliminary results 23

E12-06-107 We hope to have transparency results by the end of the year, until then… "let’s be patient: much remains to be known: there may come re-evaluation: if we don’t have the truth, we’ve shed thousands of errors" from Tape For The Turn Of The Year A. R. Ammons, 1965 � 24 https://www.theparisreview.org/interviews/1394/a-r-ammons-the-art-of-poetry-no-73-a-r-ammons