ATLAS Forward Proton Upgrade Andrew Brandt University of
ATLAS Forward Proton Upgrade Andrew Brandt, University of Texas, Arlington AFP concept: adds new ATLAS sub-detectors at 220 and 420 m upstream and downstream of central detector to precisely measure the scattered protons to complement ATLAS discovery program. These detectors are designed to run at a luminosity of 1034 cm-2 s-1 and operate with standard optics (need high luminosity for discovery physics) beam 420 m LHC magnets p’ p’ AFP Detector AFP Components 1) 2) 3) 4) 220 m H Rad-hard edgeless 3 D silicon detectors with resolution ~10 m, 1 rad Timing detectors to reject overlap background (SD+JJ+SD) New Connection Cryostat at 420 m 1 “Hamburg Beam Pipe” instead of Roman Pots
What does AFP Provide? Acceptance >40% for wide range of resonance mass Combination of 220 and 420 is key to physics reach! 420420 420220 220220 • Mass and rapidity of central system, assuming central exclusive production (CEP) process, where momentum lost by protons goes into central system • Mass resolution of 3 -5 Ge. V per event Allows ATLAS to use LHC as a tunable s glu-glu or collider 2 while simultaneously pursuing standard ATLAS physics program
P is for Proton, that’s good enough for me Forward Proton, Central Physics! http: //www. youtube. com/watch? v=dh. UFxaau. NTE 3
How does CEP work? Typical Higgs Production pp gg H +x + “ ” = “ ” CEP Higgs pp p+H+p • Extra “screening ” gluon conserves color, keeps proton intact (and reduces your ) • CEP defined as pp p+X+p , where protons are scattered at small angles, but remain intact, with all of their lost energy going towards production of the system X • Central system produced in Jz=0++ (C-even, P-even) state, this results in di-quark production being suppressed • Process observed by CDF: exclusive dijets PR D 77, 052004 (2008) and exclusive χc PRL 102, 242001 (2009) Find a CEP resonance (for ex. Higgs) and you have measured its quantum numbers (0++ )!! 4
MSSM and CEP Models with extended Higgs sectors, such as the MSSM, typically produce a light Higgs (h) with SM-like properties and a heavy Higgs (H) which decouples from Gauge boson. This implies: • no HVV coupling (V=W, Z) R= (MSSMH)/ (SMH) • no weak boson fusion H→bb, mhmax, μ = 200 Ge. V • no H ZZ R=300 • big enhancement in • pseudoscalar A does not couple to CEP m. A (Ge. V) For the MSSM and related models, AFP is likely to provide the only way to determine the Higgs quantum #’s and the coupling to b-5 quarks, and will provide an excellent mass measurement
AFP Evolution • 2000 Khoze, Martin, Ryskin (KMR): Exclusive Higgs prediction Eur. Phys. J. C 14: 525 -534, 2000, hep-ph/0002072 • 2003 -2004 Joint CMS/ATLAS FP 420 R&D collaboration forms • 2005 FP 420 LOI presented to LHCC CERN-LHCC-2005 -0254 “LHCC acknowledges the scientific merit of the FP 420 physics programme and the interest in exploring its feasibility” • 2006 -7 Some R&D funding, major technical progress, RP 220 formed • 2008 AFP formed, cryostat design finished, LOI submitted to ATLAS • 2009 “AFP year in review”, FP 420 R&D document published “The FP 420 R&D Project: Higgs and New Physics with Forward Protons at the LHC, ” FP 420 Collaboration, ar. Xiv: 0806. 0302 v 2, published in J. Inst. : 2009_JINST_4_T 10001, http: //www. iop. org/EJ/abstract/1748 -0221/4/10/T 10001. • Nov. 2009 2010 AFP LOI approved, physics case acknowledged, encouraged to prepare Technical Proposal for 2011 6
AFP Devolution • August 5, 2010, A day that will live in infamy… UK funding for AFP project terminated (moment of silence) • October 3, 2010 AFP institutions send letter to ATLAS management, Steve Watts resigns as project leader. 7
AFP Moving Forward • October 28, 2010 Christophe Royon, Interim Project Leader, meets with ATLAS management to discuss way forward for AFP • November 11, 2010 ATLAS response -integrate with new ATLAS Forward Detector (FD) group (Chair Marco Bruschi) to get technical scrutiny -prepare technical proposal; after endorsement by FD group and ATLAS review AFP can be moved under Upgrade umbrella and be prioritized with other upgrade projects • Our plan: a staged approach with 220 m system (at minimum movable beam pipe +infrastructure, but ideally pixel based tracker + timing detectors) installed in 2013 shutdown • 420 m stations to be installed in 2016 shutdown 8
Current AFP Groups 9
Stage I: 220 m Detector Stations Movable beam pipe houses silicon and timing detectors (four of these stations at +/- 216 and 224 m) New connection cryostat with integrated movable beam pipe houses 3 -D silicon and timing detectors 10
Stage I • What is first step? Need to prepare Technical Proposal based on previous work for Feb. /March 2011. Two months estimated for ATLAS review (!) • If approved AFP will be official part of upgrade(to be prioritized). ATLAS management will then contact Accelerator Division to enable Hamburg pipe development starting April/May. Perhaps HPS can get started earlier? • Who will develop Hamburg pipe? Initial work done by Louvain. UK funding for this (left over from NCC design work), but not authorized by ATLAS, funds subsequently retracted. Italian engineer identified, but group did not join AFP. Recent development, Alberta engineer may be available to work on this. • When should it be installed? Ideally by late 2012 if no LHC run extension, else late 2013. Requires LHCC approval. • What can we put in the Hamburg pipe? -Work in progress on adapting pixel detector for 220 m Stage I detector (Prague) -Developing Stage I timing detector: QUARTIC+full electronics chain (UTA, Alberta, Stony Brook, Giessen); GASTOF (Saclay) • What about physics case for Stage I? QCD, di-photon, Higgless models (via anomalous coupling), extradimensions, high mass resonance searches 11
Stage I Physics 12
Stage I Physics 13
Stage I: 220 m Collimator Issue 14
Stage I: 220 m BPM’s Need to identify manpower to work on this (uncovered in AFP). HPS? 15
Stage I: Silicon Pixel Detector 16
Stage I: Why Pixel and not 3 D Propose to start with pixel detector instead of 3 D due to resources available at Prague (with careful planning, should be straight forward to replace with 3 D detector for Stage II). Note extra. 3 to. 5 mm dead space for pixel detector becomes important for Stage II, motivating 3 D (also radiation issues? ). 17
Stage I: Advantages 1) Trigger not required 2) No “significant” accelerator modifications (NCC not needed) 3) PMT lifetime not a big issue due to lower rates from lower lum, increased distance from beam (in fact, timing is mostly critical only for low mass states, such as light Higgs) 4) Less expensive ___________________________ Lack of low mass acceptance motivates move to Stage II as soon as possible 18
Stage II: Add 420 m New connection cryostat with integrated movable beam pipe houses 3 D silicon and timing detectors Requires NCC, 3 D silicon, L 1 trigger, 10 ps fast timing (with resolution of PMT lifetime issue or alternative detector) 19
Optimistic Timeline 20
Forward Proton Fast Timing WHY? Pileup Background Rejection Ex: Two protons from one interaction and two b-jets from another How? How Fast? Use time difference between protons to measure z-vertex and compare with tracking z-vertex measured with silicon detector 10 picoseconds is design goal (light travels 3 mm in 10 psec!) gives large factor of background rejection; Stage I: 2013 220 m lum up to several 1033 t < 20 ps Stage II: 2016 add 420 m 1034 t < 10 ps
Timing System Requirements • • • 10 ps or better resolution Acceptance over full range of proton x+y Near 100% efficiency High rate capability Segmented : for multi-proton timing and L 1 trigger Robust: capable of operating with little or no intervention in radiation environment (tunnel) - PMT’s, detectors, cables, and electronics must be able to tolerate radiation levels (for PMT’s this includes tolerance to external radiation damage, as well as to internal photocathode damage) - Backgrounds from other particles must not impair operation Sep. 6, 2010 Andrew Brandt (UTA) AFP Workshop Prague 22
QUARTIC is Primary AFP Timing Detector ph ot on s proton M CP -P M T UTA, Alberta, Giessen, Stonybrook 4 x 8 array of 5 x 5 mm 2 fused silica bars Only need a 40 ps measurement if you can do it 16 times: 2 detectors with 8 bars each, with about 10 pe’s per bar Multiple measurements with “modest” resolution simplifies requirements in all phases of system 1) We have a readout solution for this option 2) We can have a several meter cable run to a lower radiation area where electronics will be located 3) Segmentation is natural for this detector 23 4) Possible optimization with quartz fibers instead of bars
MCP-PMT Requirements Excellent time resolution: 20 -30 ps or better for 10 pe’s High rate capability: Imax ~ 3 A/cm 2 Long Lifetime: Q ~ 10 to 20 C/cm 2/year at 400 nm Multi anode: pixel size of ~6 mm x 6 mm Pore Size: 10 m or better Tube Size: 40 mm round, 1 or 2 inch square Photek 240 (1 ch) Hamamatsu Photonis Planacon (8 x 8) SL 10 (4 x 4) Need to have capability of measurements in different parts of 24 tube between 0 -2 ns apart, and in same part of the tube 25 ns apart
A Long Life MCP-PMT e+ Arradiance coating suppresses positive ion creation (NSF SBIR Arradiance, UTA, Photonis) Ion Barrier keeps positive ions from reaching photocathode (developed by Nagoya with Hamamatsu Use Photek Solar Blind photocathode or similar (responds only to lower wavelength/more robust) Improve vacuum Seal (Nagoya/ Hamamatsu) Increase anode voltage to reduce crosstalk (UTA) Run at low gain to reduce integrated charge (UTA) + + photon Photocathode Photoelectron Dual MCP DV ~ 200 V DV ~ 2000 V Gain < ~ 10 1056 MCP-PMT 500 V DV ~ 200 V Anode
Le. Croy Wavemaster 6 GHz Oscilloscope Hamamatsu PLP-10 Laser Power Supply Established with DOE ADR, Texas ARP funds, some supplemental support for UG’s - Ian Howley (Ph. D. student), Ryan Hall (was UG, now in UTA Ph. D. program), both students moving on soon… - Monica Hew, Keith Gray, James Bourbeau (UG)+… 10/14/2009 Laser Box mirror MCP-PMT beam splitter filter lenses Andrew Brandt UTA laser 26
UTA Laser System (a) Beam Mode (b) (c) Fiber Mode 27 (d)
UTA Laser Results Timing vs. Gain If NPE x Gain ≥ 5 x 105 then timing independent of HV/gain Saturation the reduction in amplitude due to busy pores is a local phenomena With sufficient amplification there is no dependence of timing on gain over x 10 range Tube will meet rate needs of AFP
Electronics Layout t~5 ps t~25 ps Stony Brook t~5 ps SLAC t~15 ps UTA ZX 60 4 GHz amplifier CFD Louvain, Alberta HPTDC Alberta 29
Fermilab Test Beam Sunday Nov. 21 Setup FNAL studying si. PM; UTA studying QUARTIC 2 x 2 mm Trigge r Scint Use 3 mm si. PM (with quartz bar) as reference timing for evaluating QUARTIC
QUARTIC bar studies: Time Difference Between Adjacent Bars Strobing QUARTIC bars with si. PM gives total resolution of 26 -30 ps/bar Time Difference between adjacent bars is <20 ps, implies <14 ps/bar including bar, PMT, CFD! Too good to be true, due to charge sharing and light sharing, bars are correlated. Time Difference between “distant bars” 4 and 7 is 37 ps, implies 25 ps/bar (better than QUARTIC design goals!!!)
Conclusions si. PM-avg of 3 quartic bars reduced from ~28 ps (for single bar) to 21 ps consistent with N expectations
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