ATLAS Forward Proton Detectors HLLHC Michael Rijssenbeek on

ATLAS Forward Proton Detectors @ (HL-)LHC Michael Rijssenbeek – on behalf of the ATLAS Forward Proton (AFP) group p Roman pot station 1. AFP Physics and data taken 4. AFP@HL-LHC ? : 2. AFP Detectors (Maciej’s talk) a. a. QGC 3. Data Analysis: b. CEP production of tt, a. Combined Performance group slepton pairs, Higgs, … b. pp p + µµ + p, Mµµ≉MZ 2016 Looking down the beam pipe 2017 SD DPEjj CEPjj A- Far – 218 m γγ → W, Z, γ , μ A-Near – 206 m TCL 6 Q 5 Patch. Panel – 212 m 19 DEC 2018 AFP@HL-LHC 1

Physics Goals – High-µ R. Staszewski, FP@LHC, 22 March 2017 Many interesting highp. T studies possible; see Wednesday & Today’s sessions ! + complementary to other – small cross section + interest well beyond the – may need additional high- + complementary to other – unclear if high signal purity BSM searches FWD community BSM searches 19 DEC 2018 can be achieved at high μ – unclear if competitive with + strong physics case – uncertain feasibility: low- + interest well beyond the FWD community To. F is not absolutely needed, but is good as an additional cross check or background reduction γγ → W, Z, γ mass acceptance ? + interest well beyond the FWD community W, Z, γ CEPjj other channels mass and low σ – Need detectors in the cold H To. F is crucial for background rejection and purity A future program at 400 m? region (HL-LHC) ! AFP@HL-LHC 2

Physics Goals – Low-µ • Physics Object: Forward proton (ξ, p. T, φ, Cov, t. To. F, δt, Q) t • Single Diffraction (one p) p – Pomeron studies: probe the Pomeron with jet+jet, γ+jet, W/Z/J/ψ+jet + good physics case – requires very low µ for purity (single vertex!) + large cross sections • Central β x – (To. F is useless) p Diffraction (double p) disappears down the beam pipe Many interesting diffractive studies possible; see Wednesday & Today’s sessions ! – Pomeron studies: t 1 jj γ+j j+j same studies as in SD, but now with two Pomerons – DPEjj other jj, jγ combinations … + good physics case – high backgrounds low-µ + medium/large cross – To. F is crucial sections • Most likely: the Low-μ diffractive program ends with Run 3? 19 DEC 2018 AFP@HL-LHC 3

Anomalous Quartic Couplings • Low Cross sections: ~few fb – AFP has a Missing-Mass resolution (from the proton measurements) p p W, Z, γ of 2 -4 % • Match with invariant central W, Z, γ object mass is efficient: (Z→ee, γγ) – powerful rejection of non-exclusive backgrounds p • Much interest in this from theory side p – e. g. “LHC Forward Physics” CERN-PH-LPCC-2015 -001) γγ→γγ 19 DEC 2018 Selection: 0. 015<ξip<0. 15, |ηγ|≤ 2. 37, p. Tγ≥ 50 Ge. V Note: selecting mγγ>500 Ge. V, only pile-up remains! 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 For 300 fb– 1 and μ=50: 0 background under 15. 1 (3. 8) signal events for anomalous coupling of 2× 10– 13 (10– 13) AFP@HL-LHC 4

Central Exclusive ttbar Production • An interesting idea and initial study by Jay Howarth at 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*→tt ; cross section turn-on – Exclusive DPE gg→ tt production – Mass threshold (> 100 fb-1) – FCNC searches. • Low <μ> run physics: – Photo produced tt and Wt with proton tag; higher cross sections but needs low-μ and To. F” 19 DEC 2018 AFP@HL-LHC 5

• 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) 19 DEC 2018 R. Staszewski, J. Chwastowski (Cracow) Nuclear Stability Nucleon Asymmetry N – Z potential • triggering • Position A/Z • d. E/dx Z horizontal (x)-position [mm] • New physics vertical (y)-position [mm] Forward Fragment Detection in HI Collisions ? AFP@HL-LHC Acceptance at ≥ 3 mm from beam 6

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 • 19 DEC 2018 we have a Central Exclusive Di-Muon Production analysis under internal review AFP@HL-LHC 7

AFP Participation in ATLAS Data Taking • Installation YETS 2015 -16 – Single-Arm special runs in 2016 • Completed installation in YEST 2016 -17 • 2018 campaign better than 2017 • However: No To. F data (very low- – start of full-lumi running in 2017 19 DEC 2018 AFP@HL-LHC efficiency in 2017) 8

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 19 DEC 2018 AFP@HL-LHC 9

AFP Insertions in 2018 • 2018 insertions : – The In-Physics flag indicates AFP in ATLAS Combined DAQ 16 April 00: 00 – 30 July 2018, 00: 00 19 DEC 2018 AFP@HL-LHC 10

Detector and TDAQ (2017) • Layout: • Si. T: • • • A- A- C- C- 3 D Pixels 50 μm (x) × 250 μm (y) σx≃7 μm/Si. T see AFP TDR: ATLAS-TDR-024 Si. T Trig/IO Hit. OR-LTB 2/4 Planes To. F 2/4 Planes PMT CFD , μ HPTDC Si. T FPGA To. F Trigger Opto-Board 19 DEC 2018 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. RF Switch 320 m 280 m RCE-HSIO CTP AFP@HL-LHC 2/4 bars/train 11

Time-of-Flight: Recap: Ultra-Low Efficiency in 2017 Reasons: 1. PMT life time (≲ 1 C/cm 2) was exceeded: ~3 -6 C/cm 2 gain deterioration 2. PMTs gain goal was 5× 104: actual gain @2. 0 k. V 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 Ømust measure the PMT gain vs HV (To. T) !! In situ !! – reduce noise/pick-up to ≲ 10 m. V for MIP=~30 m. V at PAb out: successful; 2. 2 m. Vrms @beam test rd stage amplifier PAc + inverter (need ~10× gain): (done) – add 3 Øexpect naively: σTo. F = trise/(S/N) = 250 ps / (250 m. V/22 m. V) = 22 ps (rms, excluding σTDC) – replace HPTDC (18 ps) by pico. TDC (2 ps) for Run 3 To. F review was passed – green light was given to install in TS 1 – but: both PMTs broke down in vacuum 19 DEC 2018 … repair one, but did NOT find 2 PMTs that both work … AFP@HL-LHC 12

AFP Progress toward Physics … • AFP Combined Performance group – bi-weekly meetings: – twiki (linked from PC page) with: • • • contact info and goals (forward proton object: p 4, To. A, 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 → p. F+μμ+p. F – close to finalized; under internal review … – search for exclusive photon, Z, (and W) pairs as in pp → p. F+(γγ/ZZ/Zγ/WW)+p. F – started – low-μ photo-production of single top … (needs To. F) 19 DEC 2018 AFP@HL-LHC 13

Central Exclusive µµ Production pp→p 1+µµ +p 2 • Observable process with current luminosity – Kinematics: • • µ for di-photon induced processes, outgoing proton p. T is small the di-μ analysis is used for ξ-calibration … W, Z, γ µ – use x vs ξ relationship: xi[mm] = – 119ξi – 164ξi 2 (± 0. 2 mm at small p. T) • select di-muons below and above the Z-mass: – HLT_2 mu 14, – from muons, derive ξ 1µµ and ξ 2µµ, the predicted proton kinematics for pp→p 1+µµ+p 2: – compare the predicted ξiµµ to the ξip from hit x-positions in AFP NEAR and FAR stations µ 1 Central ATLAS Detector x 1 p 2 AFP C-FAR AFP C-NEAR AFP A-FAR p 1 x 2 AFP Acceptance: 0. 015<ξi<0. 15 19 DEC 2018 AFP A-NEAR AFP@HL-LHC µ 2 14

• to compare to AFP, select ξ 1µµ and ξ 2µµ> 2% (in AFP acceptance) – events in AFP acceptance: • • 19 DEC 2018 ξ 1µµ vs. ξ 2µµ mµµ>105 Ge. V, mµµ<75 Ge. V AFP-A acceptance AFP-A and AFP-C acceptance outside AFP acceptance AFP-C acceptance a single proton in AFP A or C a proton in both A and C AFP@HL-LHC 15

AFP @ HL-LHC • • New LHC Layout New (smaller !) Pots & Detectors 2016 2017 – … SD 2021 … (after LS 2) DPEjj CEPjj γγ→ W, Z, γ H W, Z, γ 19 DEC 2018 AFP@HL-LHC 16

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-ξ and high-ξ; a single location is not likely to exist – Big question: collimator settings ? Q 5 TCL 4 possible B-B Compensator (if crab cavities do not work) (not before LS 4) 11. 5 m @184. 5/IP Q 4 Q 6 TCT TCL 5 Q 7 TCL 6 EDMS LHCLSXH_0002 AFP 19 DEC 2018 ~5 m @220. 3 m/IP ALFA AFP@HL-LHC 17

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 ? Crab Q 4 TCL 4 Cavities ~7. 6 m @161. 3 m/IP EDMS LHCLSXGH_0003 AFP ~15 m @420 m/IP 19 DEC 2018 AFP@HL-LHC 18

Example of ξ Acceptance • Location: 233 m from Point 1 (between Q 6 and Q 7) – Note: NO acceptance for Horizontal crossing angle! – Crossing angle plane is very important! • Very Preliminary studies by Cracow IFJ PAN Vertical crossing angle – 2 x 2 cm 2 detector, 15σ + 0. 5 mm distance to beam – NO Collimator settings applied – even so: no great high-mass acceptance • Study needs to be updated with newest HL-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 ! 19 DEC 2018 AFP@HL-LHC 19

Example of Excellent Low-ξ Acceptance • Location: 324 m from Point 1 (in the cold!) Vertical crossing angle 19 DEC 2018 Horizontal crossing angle AFP@HL-LHC 20

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 … • Better cooling of ferrites … – beam heating will possibly be more severe – depending of detailed geometry of the gap • Motors, controls: – copy (again) the LHC collimator movements system? Probably YES – are smaller radhard motors used in the (HL-)LHC? – LVDT replacement? 19 DEC 2018 AFP@HL-LHC 21

AFP @ HL-LHC: New Pot & Stations! • at the HL-LHC assume: – small detectors: 20 x 20 mm 2 – pixelated timing with LGADs or the like ➨ we should develop small “pots” – simplifies design: smaller forces • but: would like better accuracy • narrow clearance required for low impedance – round or rectangular entry? 40 mm – 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 … ID 80 mm • Must do RF simulation to determine the effect on the beam, and pot heating … 19 DEC 2018 • AFP@HL-LHC Cost estimate? 60 KCHF/station ? 22

New Detectors … • Tracking with small pixels (50 x 50 µm 2 or smaller) – profit from ATLAS ITk upgrade work … – non-uniform irradiation favors 3 D pixel design! Must be thoroughly tested ! • Time of Flight – <10 ps resolution and t 0 from ATLAS (σt 0≲ 10 ps after averaging? ) • LGAD or similar? Note: current To. F = 35 mm thick: 16 layers of 20 ps LGADs = 5 ps? – good pixellation (≃1 x 1 mm 2) • Trigger: – need better selectivity at µ=200: develop a two-proton trigger with vertex match at L 1 ? • 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 To. F; FP collaborations cannot develop the devices on their own … (especially the FE chips required) 19 DEC 2018 AFP@HL-LHC 23

• Requirements: Time-of-Flight Detectors – Pixel size 1× 1 mm 2 or similar ( 200 -400 channels) • size is not a problem, but acceptance/uniformity may be … – Very high and non-uniform irradiation expected: 1016 /cm 2 and more … – edgeless … – To. F resolution: <10 ps ! • Candidate technologies: – Fast 3 D Silicon ? Still early days ! – LGAD ? Very promising but not (yet) radiation-hard enough … – other ? • Electronics: – analog front-end ? PA 1(on-sensor) PA 2+CFD+Trigger TDC DAQ ? – example: pico. TDC 19 DEC 2018 AFP@HL-LHC 24

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: 1. Physics arguments • Must ultimately be based on full simulations with full HL-LHC optics … • • ξ- and t-reach, mass reach ξ, t, and mass resolution • • (common? ) design (common? ) prototyping • • Tracker (3 D pixel) Time-of-Flight … 2. HL-LHC optics optimization, and optimal detector locations (challenging, multiple locations) 3. mini-Roman Pot (or other) beam interface 4. Detector technology 19 DEC 2018 AFP@HL-LHC 25