HPS: High Precision CMS Detectors to measure leading protons, tracks for momenta and timing for pile-up rejection. HPS will have two pairs of stations: 1) At z = +/- 240m, to install in LS1, data in ) At z = +/- 420m ( ?) We are working on phase I, the detectors at +/- 240 m

After “Higgs-like particle” at 125 GeV observation Is it a Standard Model Higgs, or BSM Higgs or something else? Now LHC has a > 10 year program to measure all its properties: Branching fractions and couplings, production mechanisms, spin, CP, width etc. OBVIOUSLY : We should measure it every way we can. We propose a different, complementary way: [esp. Khoze, Ryskin, Stirling, Martin, et al. (Durham+ Group)] CENTRAL EXCLUSIVE PRODUCTION: p + p  p + H + p (a.k.a. “double pomeron exchange” by some definitions) CP must be ++ Spin must be J = 0 or 2, and we can distinguish them Coupling to gluons via q-loop (May want exclusive γγ to calibrate σ) Mass (σ(M) ~ 2 GeV per event, Missing Mass to protons, and can calibrate that)

Several tracking programs have been used (HECTOR, FPTrack). Full transport line simulation in CMSSW. HPS acceptance as a function of ξ and t 240m Stage 1 420m Stage 2 CMS Collision point ξ = 1 - x F t 4 t

Mass acceptance for two arms for small |t| at Stations 1 & 2 (Assumes Δx(min) from beam = 3 mm at 240m) Each arm at 240m by itself has ~ superimposed light blue and red. Stage 2 has ~ all 3 superimposed, and light blue x 2. For IP + IP |t| is larger and acceptance shifts. For H(125) best is [ ] & [ ]

At 420 m missing magnet, pipe straight but cold. It requires a cryogenic by-pass At 240 m the beam pipe is exposed, so it’s relatively easy to install the detectors:

Moving pipe mechanics – “Hamburg” moving beam pipe Long pockets for long detectors. No atmosphere - vacuum forces

Physics for stage one:One proton measured, still some physics: M(min) ~ 100 GeV. No M(X) from p’s, no PH rejection by timing, but very clean central states may be accessible. E.g. p(detected) p (not detected... too high momentum) X = W + W -  leptons X = e + e -, μ + μ -, τ + τ - from γγ (or SMH!?) X = Z photoproduction  e + e -, μ + μ -, τ + τ No additional tracks on X vertex (already very selective) In e + e -, μ + μ -, τ + τ - cases Δ ϕ = π and p T (X) ~ 0 3-momentum of X (~ p z ) determines both proton momenta Distinguishes fully exclusive p + X + p from p* dissociation. e + e -, μ + μ - already calibrates HPS spectrometers (don’t need both p’s)

HPS has 2 main components: tracking and timing: A tracking detector (silicon based) to measure  Position and angle, combined with the beam magnets, allow to determine the momentum of the scattered proton and in turn the missing mass (from both p’s) Two pockets ~ meters apart: Momentum reconstruction:  p/p ~  Position precision of 10  m  Angular resolution of 1-2  rad Need precision track detectors (~ 10 μm), Rad Hard, edgeless (on one side) but small: ~ 5 cm 2 per layer, ~ 10 layers per arm. Can be same but <~ of CMS Central tracker upgrade (Good practice!) + space for innovative tracking devices (diamond eg) Discussions with CMS tracking experts (hopefully will join if supported) Turin is participating in a sensor 3D pixel development [SI] Cooperation with several manufactures and with ATLAS

Design of test module (made 2) SiPM proton Radiator bar (30 mm) Light guide bar (40 mm) Principle: All Cherenkov light is totally internally reflected to back of radiator bar. ~ 50% goes up light guide bar. Maintain Total Internal Reflection: nothing touches surfaces, except minimally at corners. Bars separated by fine wire (100 um)... keep TIR. Q-bars L-BAR QUARTIC: LBQ proton FERMILAB

Test beam L-bar QUARTIC box (1 of 2) [Fermilab, Steve Hentschel]

Four units in test beam, 2mm x 2mm trigger counter + 40mm MCPPMT reference (10 ps) proton trigger counter (Drawings glued on boxes for alignment only) Two boxes can be slid apart in z  DRS4 5 GHz waveform digitiser 200 ps/point 20 mV/div. & 2 ns/div) One event: 3 bars in line MCPPMT ref σ(t) = 32 ps/bar = 16 ps/4bars Technical issues solved, except: Radiation levels in SiPM “cave” to be calculated and measured. HPTDC-DAQ to integrate CMS readout. Several improvements possible  10 ps Option: MCP-PMT replacing SiPMs

Designing 24-channel L-Bar Quartic module (Steve Hentschel, Fermilab) Housing: Thin (100 um) sheet for optical isolation (not structural). Mounting for SiPM array board BEAM Now: not 3x8 but 4x6 = 12mm x 18mm (have flexibility) Moving SiPMs out of beam plane is important to minimize radiation. Hadron fluences fall fast with y: few / cm 2 at y = 10cm in 100 fb-1 Can also shield at that position X

LLNL adapting system demonstrated by SLAC for LCLS experiments: RF cable with feedback to keep clocks synchronized at each end Measured timing jitter = 1.2 ps/C using LCLS spare system and 520 m coax => well within HPS timing requirements How to synchronize two points separated by a significant distance? Reference Timing system

240 meter: Installation during LS1 in 2014 shutdown with tracking and timing detectors. is a step towards 420 and beginning of physics programme: Installation in ~ ; new connecting cryostats and four (2x2) stations with tracking and timing detectors. Situation (Sept 2012) The HPS community is working toward the installation in 2014 of the first station, m. Hope for approval and funding, in Possible connections and/or collaboration with TOTEM group is currently under analysis. A document on the HPS is available at:

Preparations for LS1 The HPS community is working hard for the detector R&D A first estimation of services : A)BeamPipe (strong collaboration with BE people) Displacement bellows Beam position monitors Under-pressure chamber hosting the detectors Moveable support table Positioning motors infrastructure and controls B)Detector (strong collaboration with EN-MEF-LE) : We intend to install most of services in RR region for Electronics, HV and LV Gas supply RF signal for Master Clock synchronization Routing signal, optical fibers, network cables back to USC electronics from RR All services have to be further estimated and quantified Main worry is the SEU effect on electronics on the RR region

The HPS community meets weekly. There are roughly 50 physicists interested, ~15 active from several institutions: Boston Univ, USA Fermi National Accelerator Lab. USA IHEP Protvino, Russia ITEP Moscow, Russia Univ Louvain, Belgium Lawrence Livermore National Lab. USA (Douglas Wright PI) Kansas Univ. USA Piemonte Orientale U. Novara Italy University of Iowa. USA Rockefeller Univ. USA Rio de Janeiro CBPF, Brazil INFN Torino Italy IPM Tehran, Iran CERN