DPEjj

1. AFP@HL-LHC • AFP Physics and data taken • AFP Detectors (Maciej’s talk) • Data Analysis: • Combined Performance group • pp  p + µµ + p, Mµµ≉MZ • 4. AFP@HL-LHC ?: • aQGC • CEP production of tt, slepton pairs, Higgs, … p ATLAS Forward Proton Detectors @ (HL-)LHCMichael Rijssenbeek – on behalf of the ATLAS Forward Proton (AFP) group Looking down the beam pipe Roman pot station 2016 2017  , μ W,Z,γ SD DPEjj CEPjj γγ→ , μ W,Z,γ A- Far–218m A-Near–206m TCL6 Q5 PatchPanel–212m

2. Physics Goals – High-µ R. Staszewski, FP@LHC, 22 March 2017 • Required Physics Object: “Two FWD protons with vertex match” • Physics: Exclusive production of Dijets, Di-Vector Bosons, and possibly Higgs (in Phase II ?): • New physics in exclusive high-mass IVB pair production: • Exclusive jets (SM & BSM) • Exclusive Higgs (-decay, spin, QCD mechanism): Many interesting high-pT studies possible; see Wednesday & Today’s sessions ! H ToF is not absolutely needed, but is good as an additional cross check or background reduction CEPjj ToF is crucial for background rejection and purity W,Z,γ γγ→ A future program at 400 m? W,Z,γ AFP@HL-LHC

3. Physics Goals – Low-µ • Physics Object: Forward proton (ξ,pT,φ,Cov, tToF,δt, Q) • Single Diffraction (one p) • Pomeron studies:probe the Pomeron with jet+jet, γ+jet, W/Z/J/ψ+jet • Central Diffraction (double p) • Pomeron studies:same studies as in SD, but now with two Pomerons • DPEjj • Most likely: the Low-μ diffractive program ends with Run3? t Many interesting diffractive studies possible; see Wednesday & Today’s sessions ! p disappears down the beam pipe β x p t1 j+j jj γ+j other jj, jγ combinations … AFP@HL-LHC

4. Anomalous Quartic Couplings • Low Cross sections: ~few fb • AFP has a Missing-Mass resolution (from the proton measurements) of 2-4 % • Match with invariant central object mass is efficient: (Z→ee, γγ) • powerful rejection of non-exclusive backgrounds • Much interest in this from theory side • e.g. “LHC Forward Physics” CERN-PH-LPCC-2015-001) p p W, Z, γ W, Z, γ γγ→γγ γγ→γγ “Probing anomalous quartic gauge couplings using proton tagging at the Large Hadron Collider”, M. Saimpert, E. Chapon, S. Fichet, G. von Gersdorff, O. Kepka, B. Lenzi, C. Royon; 23/05/2014 p p For 300 fb–1and μ=50: 0 background under 15.1 (3.8) signal events for anomalous coupling of 2×10–13 (10–13) Selection: 0.015<ξip<0.15, |ηγ|≤2.37, pTγ≥50 GeV Note: selecting mγγ>500 GeV, only pile-up remains! AFP@HL-LHC

5. Central Exclusive ttbar Production • An interesting idea and initial study by Jay Howarthat the March 2018 ATLAS Forward Physics workshop: • “Top physics mostly interesting in exploiting elastic or semielastic events with one or two proton tags. • A lot of interesting top physics, including some things that cannot be studied in the standard program. • High <μ> run physics: • Central Exclusive Photo-Production γ*γ*→tt̅ ; cross section turn-on • Exclusive DPE gg→ tt̅ production • Mass threshold (> 100 fb-1) • FCNC searches. • Low <μ> run physics: • Photo produced tt̅ and Wt with proton tag; higher cross sections but needs low-μ and ToF” AFP@HL-LHC

6. Forward Fragment Detection in HI Collisions ? • New physics potential • triggering • Position A/Z • dE/dxZ R. Staszewski, J. Chwastowski (Cracow) vertical (y)-position [mm] horizontal (x)-position [mm] Nuclear Stability • AFP acceptance covers a good fraction of known nuclides – mostly heavier ones • ATLAS decision: NOT for 2018 (needs more performance and physics studies), maybe in Run 3 (2021 and later) Nucleon Asymmetry N – Z Acceptance at ≥3 mm from beam AFP@HL-LHC

7. BSM: SUSY etc. • At this workshop (and other meetings) several very interesting studies were reported: • Photon Collider Opportunities for New Physics: SUSY & Dark Matter,L. Beresford and J. Liu • Searches for Dark Matter at the LHC in forward proton mode,V. Khoze, L. Harland-Lang, M. Ryskin and M. Tasevsky • Anomalous quartic gauge couplings and searches for axion-like particles in p-p, p-A and A-A collisions at the LHC, C. Baldenegro • This is driven by • non-observation (so far) of New Physics • existence of areas of parameter space mostly inaccessible to standard analyses • This should lead to increased analyzer interest in physics with forward proton tags • we (AFP) must deliver a ‘validated’ Forward Proton physics object to the community • demonstrate the use with a ‘standard’ analysis • we have a Central Exclusive Di-Muon Production analysis under internal review AFP@HL-LHC

8. AFP Participation in ATLAS Data Taking • Installation YETS2015-16 • Single-Arm special runs in 2016 • Completed installation in YEST2016-17 • start of full-lumi running in 2017 • 2018 campaign better than 2017 • However: No ToF data (very low-efficiency in 2017) AFP@HL-LHC

9. AFP Insertions in 2017 Distance of the Roman pots to nominal beam center determined for each run in 2017 Important input to calculation of forward proton relative momentum loss ξ AFP@HL-LHC

10. AFP Insertions in 2018 • 2018 insertions : • The In-Physics flag indicates AFP in ATLAS CombinedDAQ 16 April 00:00 – 30 July 2018, 00:00 AFP@HL-LHC

11. Detector and TDAQ (2017) • Layout: • SiT: • 3D Pixels • 50 μm (x) ×250 μm (y) • σx≃7 μm/SiT SiT LHC optics: use Mad-X simulations to derive transformation between (x, y, z, θx, θy, ξ)* at IP and (x, y, θx, θy)Det at the detector. A- A- C- C- ToF see AFP TDR: ATLAS-TDR-024 SiT Trig/IOHitOR-LTB 2/4 Planes SiT Trig/IOHitOR-LTB 2/4 Planes PMT , μ , μ CFD HPTDC FPGAToF Trigger 2/4 bars/train Opto-Board RF Switch 280 m 320 m CTP RCE-HSIO AFP@HL-LHC

12. Time-of-Flight: Recap: Ultra-Low Efficiency in 2017 Reasons: • PMT life time (≲1 C/cm2) was exceeded: ~3-6 C/cm2 gain deterioration • PMTs gain goal was 5×104: actual gain @2.0 kV was 1-2×104 CFD threshold inefficiency … • Glue transparency deteriorated by <15% (measurements): expectation for 2018 is same … Cures: • ALD coating = long-life • Gain goal: ~104 high rate capability to ~10 MHz • must measure the PMT gain vs HV (ToT) !! In situ !! • reduce noise/pick-up to ≲10 mV for MIP=~30 mV at PAb out: successful; 2.2 mVrms@beam test • add 3rd stage amplifier PAc + inverter (need ~10× gain):(done) • expect naively: σToF = trise/(S/N) = 250 ps / (250 mV/22 mV) = 22 ps (rms, excluding σTDC) • replace HPTDC (18ps) by picoTDC (2 ps) for Run3 ToF review was passed – green light was given to install in TS1 • but: both PMTs broke down in vacuum … repair one, but did NOT find 2 PMTs that both work …     AFP@HL-LHC

13. AFP Progress toward Physics … • AFP Combined Performance group • bi-weekly meetings: • twiki (linked from PC page) with: • contact info and goals (forward proton object: p4, ToA, errors, di-proton vertex, ID vertex match, …) • current status of the (di-)forward proton object • uncovered task list (expert tasks, qualification tasks) • Physics “Flagship Analyses”: • single diffraction (standard optics, low-μ special runs) – several analyses nearing completion • exclusive di-muon production pp → pF+μμ+pF – close to finalized; under internal review … • search for exclusive photon, Z, (and W) pairs as in pp → pF+(γγ/ZZ/Zγ/WW)+pF– started • low-μ photo-production of single top … (needs ToF) AFP@HL-LHC

14. Central Exclusive µµ Productionpp→p1+µµ +p2 • Observable process with current luminosity • Kinematics: • for di-photon induced processes, outgoing proton pT is small • the di-μ analysis is used for ξ-calibration … • use x vs ξ relationship: xi[mm] = –119ξi – 164ξi2 (±0.2 mm at small pT) • select di-muons below and above the Z-mass: • HLT_2mu14, • from muons, derive ξ1µµ and ξ2µµ, the predicted proton kinematics for pp→p1+µµ+p2: • compare the predicted ξiµµ to the ξipfrom hit x-positions in AFP NEAR and FAR stations  µ µ µ1 W,Z,γ Central ATLAS Detector AFPA-NEAR AFPA-FAR W,Z,γ p1 AFPC-NEAR AFPC-FAR p2 x1 AFP Acceptance: 0.015<ξi<0.15 µ2 x2 AFP@HL-LHC

15. ξ1µµ vs. ξ2µµ • to compare to AFP, select ξ1µµand ξ2µµ> 2%(in AFP acceptance) • events in AFP acceptance: • a single proton in AFP A or C • a proton in both A and C mµµ>105 GeV, mµµ<75 GeV AFP-A acceptance AFP-A and AFP-C acceptance outside AFP acceptance AFP-C acceptance AFP@HL-LHC

16. AFP@HL-LHC • New LHC Layout • New (smaller !) Pots & Detectors 2016 2017 – … 2021  … (after LS2) AFP @ HL-LHC W,Z,γ γγ→ SD DPEjj CEPjj H W,Z,γ

17. HL-LHC Layout (Optics 1.3) • Layout significantly different from present; space at 210-220 m for XRPs very limited ! • Impact of Crab Cavities on forward protons ?? • Need optimal locations for low-ξand high-ξ; a single location is not likely to exist • Big question: collimator settings ? Q5 TCL4 TCL5 possible B-B Compensator (if crab cavities do not work) (not before LS4) 11.5m @184.5/IP Q4 Q6 Q7 TCL6 TCT EDMS LHCLSXH_0002 AFP~5 m @220.3 m/IP ALFA AFP@HL-LHC

18. HL-LHC Layout (Optics 1.3) Other possible locations: • locations for high-ξ, and very small ξ (SM Higgs)? • Crab Cavities? Optics simulations needed! • operational collimator settings ? Q4 TCL4 Crab Cavities ~7.6 m @161.3m/IP EDMS LHCLSXGH_0003 AFP~15 m @420m/IP AFP@HL-LHC

19. Example of ξAcceptance • Location: 233m from Point 1 (between Q6 and Q7) • Note: NO acceptance for Horizontal crossing angle! • Crossing angle plane is very important! • Very Preliminary studies by Cracow IFJ PAN • 2 x 2 cm2detector,15σ+ 0.5mm distance to beam • NO Collimator settings applied • even so: no great high-mass acceptance • Study needs to be updated with newestHL-LHC lattice, optics, and collimator settings • Preliminary conclusions: • HL-LHC optics is very challenging • Multiple locations are necessary for best mass reach • Vertical crossing angle ! Vertical crossing angle AFP@HL-LHC

20. Example of Excellent Low-ξ Acceptance • Location: 324 m from Point 1 (in the cold!) Vertical crossing angle Horizontal crossing angle AFP@HL-LHC

21. New Roman Pots • Roman Pots are preferable over Hamburg Beam Pipe (in my opinion): • cheaper • less impedance ? However: this must be simulated and verified! • Small-size RPs: detectors are smaller, thus also pots? • 40 mm ID? smaller force: 13 kgf (cfr 160 kgf now) • thinner window (150-200µm); Cu/NEG coating (not done for present AFP pots) • secondary vacuum will remain a requirement !  feedthroughs … • beam heating will possibly be more severe – depending of detailed geometry of the gap • Better cooling of ferrites … • Motors, controls: • copy (again) the LHC collimator movements system? Probably YES • are smaller radhard motors used in the (HL-)LHC? • LVDT replacement? AFP@HL-LHC

22. AFP @ HL-LHC: New Pot & Stations! • at the HL-LHC assume: • small detectors: 20 x 20 mm2 • pixelated timing with LGADs or the like • we should develop small “pots” • simplifies design: smaller forces • but: would like better accuracy • round or rectangular entry? • narrow clearance required for low impedance • better detector alignment? use a quartz viewport for positioning? • common R&D project together with LHC? • also: More radiation! • motors, switches, motion/position sensors … • all new devices must pass LHC review … • Must do RF simulation to determine the effect on the beam, and pot heating … 40 mm ID 80 mm • Cost estimate? 60 KCHF/station ? AFP@HL-LHC

23. New Detectors … • Tracking with small pixels (50x50 µm2or smaller) • profit from ATLAS ITk upgrade work … • non-uniform irradiation favors 3D pixel design! Must be thoroughly tested ! • Time of Flight • <10 ps resolution and t0 from ATLAS (σt0≲10 ps after averaging?) • LGAD or similar? Note: current ToF = 35 mm thick: 16 layers of 20 ps LGADs = 5 ps? • good pixellation(≃1x1 mm2) • Trigger: • need better selectivity at µ=200: develop a two-proton trigger with vertex match at L1 ? • In principle, the detector package could be pre-evacuated and vacuum-sealed, and inserted/moved inside the beam aperture via UHV feedthroughs … • better LHC protection (no thin windows needed)? • needs a detailed feasibility study and prototyping … • We must rely on HL-LHC developments for tracking and ToF; FP collaborations cannot develop the devices on their own … (especially the FE chips required) AFP@HL-LHC

24. Time-of-Flight Detectors • Requirements: • Pixel size 1×1 mm2 or similar ( 200-400 channels) • size is not a problem, but acceptance/uniformity may be … • Very high and non-uniform irradiation expected: 1016 /cm2 and more … • edgeless … • ToF resolution: <10 ps ! • Candidate technologies: • Fast 3D Silicon ? Still early days ! • LGAD ? Very promising but not (yet) radiation-hard enough … • other ? • Electronics: • analog front-end ? PA1(on-sensor)  PA2+CFD+Trigger  TDC  DAQ ? • example: picoTDC AFP@HL-LHC

25. Conclusion • Need to study FP at the HL-LHC: • started but a write-up is needed • in ATLAS framework and FP@LHC WG • in order of importance: • Physics arguments • Must ultimately be based on full simulations with full HL-LHC optics … • HL-LHC optics optimization, and optimal detector locations (challenging, multiple locations) • ξ- and t-reach, mass reach • ξ, t, and mass resolution • mini-Roman Pot (or other) beam interface • (common?) design • (common?) prototyping • Detector technology • Tracker (3D pixel) • Time-of-Flight … AFP@HL-LHC