Prospects and Results from the AFP Detector in ATLAS Grzegorz Gach on behalf of the ATLAS Collaboration AGH University of Science and Technology 1 December, 2016 Multiple Partonic Interactions at the LHC 2016 Grzegorz Gach (AGH UST) 1 1 December, 2016 1 / 22
ATLAS Forward Detectors A TLAS F orward P roton detectors dedicated for diffractive processes measurements four stations — two on each side detectors mounted in horizontal roman pots 3D pixels and time-of-flight detectors acceptance in ξ = ( E − E ′ ) /E ≈ (0 . 02 , 0 . 12) Grzegorz Gach (AGH UST) 2 1 December, 2016 2 / 22
Possible Measurements 1 proton kinematics 11 heavy quarks 2 rapidity gaps 12 Drell-Yan, W 3 gap survival probability 13 exclusive jets 4 energy flow 14 exclusive lepton production 5 event shapes 15 photon–photon scattering 6 jets 16 WW production 7 jet–gap–jet 17 ZZ production 8 jet–photon 18 resonant production 9 Pomeron structure Grzegorz Gach (AGH UST) 3 1 December, 2016 3 / 22
AFP Installation AFP 0+2 — 2016 AFP 2+2 — 2017 Grzegorz Gach (AGH UST) 4 1 December, 2016 4 / 22
AFP 0+2 Installation ✓ installation of two stations on one side in the tunnel ✓ installation of tracking detectors in the stations ✓ LHC qualification ✓ integration with ATLAS DCS ✓ integration with ATLAS DAQ ✓ integration with ATLAS triggers ✓ data acquisition in special runs Grzegorz Gach (AGH UST) 5 1 December, 2016 5 / 22
AFP 0+2 3(4) layers of pixel detectors in each station 336 × 80 pixels of 50 × 250 ➭ m 2 pixel modules are similar to the ones used in ATLAS IBL with proven radiation hardness detectors are tilted by 14 ◦ with respect to vertical direction data collected in special low- µ runs with L ≈ 500 nb − 1 Grzegorz Gach (AGH UST) 6 1 December, 2016 6 / 22
AFP 0+2 Performance Pixel rows in Plane 1 1 Pixel hits [a.u.] Events [norm.] 0.5 ATLAS Preliminary 300 0.4 250 Pixel rows in Plane 1 1 Pixel hits [a.u.] 300 − 1 10 200 250 0.3 10 − 1 200 150 150 0.2 10 − 2 100 10 − 2 100 50 ATLAS Preliminary 0.1 3 0 10 − 0 50 100 150 200 250 300 50 Pixel rows in Plane 0 ATLAS Preliminary 0 0 − 3 10 1 2 3 4 5 6 7 8 9 10 0 50 100 150 200 250 300 Pixel hits per event Pixel rows in Plane 0 in almost 50 % events 2 hits are observed in each plane very good correlation of hits between two planes (first and second) Grzegorz Gach (AGH UST) 7 1 December, 2016 7 / 22
AFP 0+2 Performance ATLAS Preliminary 1 Distance from sensor edge, y [mm] Pixel hits [a.u.] AFP 212 track position in y [mm] 2 10 18 ATLAS Simulation 15 16 14 1 10 10 − 12 10 5 10 8 2 10 − beam 6 0 center 4 2 -5 β s = 14 TeV * = 0.55 m 0 3 10 − 16 14 12 10 8 6 4 2 0 − − − − − − − − 1 -115 -110 -105 -100 -95 Distance from sensor edge, x [mm] AFP 212 track position in x [mm] hits in AFP near (205 m) station at 5 σ + 400 ➭ m from the beam centre visible pattern of diffractive protons Grzegorz Gach (AGH UST) 8 1 December, 2016 8 / 22
AFP 0+2 Physics Single Diffractive Dissociation (P) (P') relatively high cross section special runs with pile-up free environment provide clean events single proton detectable in AFP AFP provides access to so far non-measurable quantities like ξ = ( E − E ′ ) /E or t = ( P − P ′ ) 2 Grzegorz Gach (AGH UST) 9 1 December, 2016 9 / 22
AFP 0+2 Physics — Inclusive Single Diffraction SS Data 2015 ATLAS s = 7 TeV ATLAS R 0.18 Pythia8 SS µ -1 s =13 TeV, L=60.1 b ε Pythia8 DL, =0.085 Elastic only 0.16 ε Pythia8 DL, =0.060 TOTEM ε Pythia8 DL, =0.10 Lumi-independent 0.14 Pythia8 MBR -independent ρ EPOS LHC 0.12 QGSJET-II ALICE 0.1 0.08 MinBias 0.06 ATLAS Elastic 0.04 60 65 70 75 80 85 90 0.1 0.15 0.2 0.25 0.3 0.35 0.4 ( )[mb] pp X σ → f inelastic D Nuclear Physics B (2014), Phys.Rev.Lett. 117 (2016) 486-548 182002 σ SD + DD measured together with inelastic cross-section at 7 TeV and 13 TeV using MBTS signal on one side combination of ALFA and ATLAS σ inelastic at 7 TeV gives σ SD for ξ < 5 . 1 × 10 − 6 Grzegorz Gach (AGH UST) 10 1 December, 2016 10 / 22
AFP 0+2 Physics — Inclusive Single Diffraction [mb] [mb] 2 µ -1 2 µ -1 10 ATLAS Data L = 7.1 b 10 ATLAS Data L = 7.1 b F PYTHIA 6 ATLAS AMBT2B F PYTHIA 8 4C s = 7 TeV s = 7 TeV η η ∆ p > 200 MeV ∆ p > 200 MeV PYTHIA 8 4C Non-Diffractive /d /d T T σ σ Single Diffractive PHOJET d d 10 10 Double Diffractive 1 1 MC/Data MC/Data 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8 1.5 1.5 1 1 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8 ∆ η ∆ η F F Eur. Phys. J. C72 (2012) 1926 Eur. Phys. J. C72 (2012) 1926 ATLAS dedicated measurement done only at √ s = 7 TeV possible large contribution of double diffraction background no measurement of differential cross sections dσ/dξ or dσ/dt improvement and extension of current measurements by tagging protons in 13 TeV Grzegorz Gach (AGH UST) 11 1 December, 2016 11 / 22
AFP 0+2 Physics — Single Diffractive Jets jet1 > 20 GeV jet1 > 50 GeV SD Jet production, p T SD Jet production, p T AFP 204 m, √ s = 13 TeV, β * = 055 m, d AFP = 2.85 + 0.3 mm AFP 204 m, √ s = 13 TeV, β * = 055 m, d AFP = 2.85 + 0.3 mm, nb = 10, τ = 100 h 10 4 1 AFP tag AFP tag + one vtx significance, S / √ (S + B) + one vtx 10 3 0.8 purity, S / (S + B) 10 2 0.6 10 1 0.4 10 0 0.2 10 -1 0 0.01 0.1 1 0.01 0.1 1 mean pile-up, < µ > mean pile-up, < µ > ATLAS-TDR-024-2015 ATLAS-TDR-024-2015 probing Pomeron universality between ep and pp colliders measurement of gap survival probability Monte Carlo tuning Grzegorz Gach (AGH UST) 12 1 December, 2016 12 / 22
AFP 0+2 Summary ✓ despite challenging schedule the installation was successful ✓ very good detector performance ✓ collected more data than initially planned ✓ good data for soft diffraction analysis ✓ very good data for detector performance and background studies Grzegorz Gach (AGH UST) 13 1 December, 2016 13 / 22
AFP 2+2 Installation installation of two missing stations on the other side in the tunnel installation of tracking detectors installation of timing detectors on both sides LHC qualification integration of timing detectors triggers with ATLAS data acquisition in special runs data acquisition in standard runs Grzegorz Gach (AGH UST) 14 1 December, 2016 14 / 22
AFP 2+2 Time-of-Flight Detectors time resolution 10 ps or better efficiency not smaller than 90 % fast enough to provide trigger signal pile-up background reduction useful but not critical in special low- µ run necessary in standard runs with high pile-up Grzegorz Gach (AGH UST) 15 1 December, 2016 15 / 22
AFP 2+2 Physics — Single Diffractive Dissociation (P) (P') only in special low- µ runs clean pile-up free environment doubled number of events with respect to AFP 0+2 Grzegorz Gach (AGH UST) 16 1 December, 2016 16 / 22
AFP 2+2 Physics — Central Diffraction special as well as standard runs give access to processes with medium and relatively small cross-sections double proton tag with time measurements allows direct observation of central diffraction with suppressed backgrounds (including pile-up) direct access to proton kinematics Grzegorz Gach (AGH UST) 17 1 December, 2016 17 / 22
AFP 2+2 Physics — Central Diffractive Jets 5 (pb) 10 (pb/GeV) ν =-1 gluons ν =-1 gluons s) ν =-0.5 0.015 < ξ < 0.15 ν =-0.5 0.015 < ξ < 0.15 2 ξ 1 standard (HERA Fit PDF) standard (HERA Fit PDF) ξ T /dp 10 2 / 20% uncertainty bar 20% uncertainty bar dijet dijet /d(W ν =0.5 ν σ =0.5 4 10 d ν =1 ν =1 dijet σ d 10 3 10 10 2 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 40 50 60 70 80 90 100 p (GeV) mass fraction T Phys.Rev. D88 (2013) no.7, Phys.Rev. D88 (2013) no.7, 074029 074029 probing gluon structure of Pomeron sensitive to gap survival probability testing Pomeron universality between ep – pp colliders Grzegorz Gach (AGH UST) 18 1 December, 2016 18 / 22
AFP 2+2 Physics — Central Diffractive γ –jet /dM T d/u = 0.25 /dp d/u = 0.25 d = s, u + d + s = const. dijet d = s, u + d + s = const. d/u = 0.5 d/u = 0.5 dijet σ 0.0015 < ξ < 0.02 d/u = 1 /dM/d d/u = 1 ξ 0.0015 < < 0.02 σ d/u = 2 d/u = 2 /d jet d/u = 4 d/u = 4 T γ σ /dp SCI model d SCI model jet γ σ d -3 10 -3 10 20 22 24 26 28 30 32 34 36 38 40 42 p (GeV) 60 80 100 120 140 160 180 200 220 240 T M(GeV) Phys.Rev. D88 (2013) no.7, Phys.Rev. D88 (2013) no.7, 074029 074029 probing quark structure of Pomeron testing Pomeron universality between ep – pp colliders interesting variables p T and M = √ sξ 1 ξ 2 Grzegorz Gach (AGH UST) 19 1 December, 2016 19 / 22
Recommend
More recommend
