LHCb: Towards data taking in 2008 The LHCb experiment at the Large Hadron Collider Developments at the PI for the LHCb experiment The construction and commissioning of the LHCb experiment Palavernachmittag, 23/07/07 Sebastian Bachmann 11/14/2018

The Large Hadron Collider pp-collisions ECMS=14 TeV Max.Luminosity@LHC: 1034 cm-2s-1 First collisions expected in summer 2008 11/14/2018

Goals of the LHCb Experiment  profits from the copious number of B-mesons produced at LHC (production rate ~100 kHz@LHCb)  searchs for New Physics by - high precision measurements of CP-violating phases in decay of B-mesons. - searchs for rare and very rare decays of the B-mesons 11/14/2018

Measurement of CP violating phases: Reminder CP-transformation: Combined application of charge (C) and parity (P) conjugation. CP |Particle> → |Antiparticle> If CP is a good symmetry we have e.g. for the branching ratios of CP conjugated processes: BR (P→f) = BR(P→f) For K- and B-mesons it has been observed that CP is violated. This allows to search for effects from New Physics. 11/14/2018

Measurement of CP-violating phases Measurement of fCP is a very sensitive probe to Physics Beyond the Standard Model 11/14/2018

An example: Bs → ΦΦ + W- H- ??? Standard model prediction of the CP-asymmetry is very small the (<1%) H- ??? In many extensions of the Standard model the decay gets additional contributions.  ΦCP is altered.  CP-asymmetry might be strongly enhanced! + 11/14/2018

Production and decay of B-mesons l- π- K+ π+ B0 p D0* p - pp interaction rate: 40MHz Production rate for B-mesons: 100kHz Decay length of B0: ≈ 1cm Charged particles in acceptance: ≈ 100 11/14/2018

The LHCb detector Magnet + Tracking stations Vertex RICH locator Calorimeters + muon detectors RICH detectors Vertex locator 11/14/2018

A simulated event VeLo Magnet TT T Stations 11/14/2018

The Outer Tracking System (OT) Outer Tracker Outer tracking system: - Detector technology: Straw tubes - 56,000 straws and wires - 200,000 soldered joints - arranged in 185F and 124 S modules 5m 6m Inner tracker In total 56.000 individual, hand-made particle detectors. ~ ¼ of them produced in Heidelberg TT Station 11/14/2018

Straw tube detectors Requirements for the Outer tracking system: Track  good spatial resolution (<200µm) over entire area (~30m²)  high efficiency  fine segmentation Straw tube detectors are - light and fine segmented (i.e. small Ø) proportional counters with drift time measurement Single Double Layer 5mm straws pitch 5.25 mm Track e- 11/14/2018

Module production C.Rummel & S. Rabenecker 11/14/2018

Detector production finished end of 2005 Detector modules Detector production finished end of 2005 11/14/2018

Frontend Electronics Amplify and discriminate analog signals from anode wires (ASDBLR) Drift Time measurement (OTIS) Data Serialization and optical link (GOL) Developed at the PI 11/14/2018

Frontend boxes In total 432 frontend boxes, each box contains - 2 HV boards - 8 Amplifier boards - 4 TDC boards - 2 GOL boards (optical link) Production and test of TDC boards and optical links finished end of 2006 11/14/2018

The bridge: Support structure for the Outer Tracker. 11/14/2018

C-frames with detector modules In total 12 C-frames Frontend electronics Detector modules C-frame 11/14/2018

Quality control during installation Two examples for the commprehensive tests of C-frames and detectors performed during installation. Detector response: Leak rate Tested 60% of all wires, 21/32040 faulty wires found (0.65‰) 11/14/2018

Installation of the C-frames 11/14/2018

Current view to the Experiment 11/14/2018

Architecture of readout chain: 11/14/2018 Courtesy Rainer Schwemmer

Performance of FE-electronics in situ Drift time resolution σΔt ≈ 300ps Courtesy Jan Knopf & Rainer Schwemmer Long term time stability for 15hr Stability < 100ps Linearity of drift time 11/14/2018

Another challenge: The trigger Trigger Überblick 40 MHz Hardware Level-0: High ET / pT von m, e, g , hadrons Veto for empty or too complex events New idea: Reconstruct two body decays already at L0 confirmation. (~1ms availablê) 1 MHz (35 GB/s) Software ~1800 CPU HLT: 1. Confirm L0 2. Partial reconstruction of event (m, e , g, hadron-alley) 3. Complete reconstruction of event 2 kHz (70 MB/s) on tape 11/14/2018

Reconstruction of J/ψ → μμ Courtesy Johannes Albrecht Reconstructed mass peak from J/ψ → μ+μ- . CPU consumption reduced from 15 ms to 3-4 ms. Aim tCPU ≈1ms is well within reach. minv[GeV] mJ/ψ 11/14/2018

LHCb – towards data taking in 2008: Summary LHCb is on a good track to take first data when the Large Hadron Collider goes into operation in summer 2008. The Outer Tracking System is installed, now the focus is to commission the system. First light (from cosmics or radioactive source) is expected in ~September. There are versatile contributions from the PI to the Outer Tracking System in the field of detector, electronics and software development. 11/14/2018

The LHC experiments: Alice: Atlas and CMS: LHCb: LHCf and Totem: See talk by Rainer Schicker. Atlas and CMS: General purpose experiments. Main goal: Search for new particles, e.g. the Higgs or Supersymmetric particles. LHCb: Search for new physics by high precision measurements. Study mainly B-Mesons, but also D-Mesons, τ‘s … LHCf and Totem: Special purpose experiments. 11/14/2018

Search for rare decays: Bs→μ+μ- µ- µ+ Z x Many decays of B-mesons are forbidden in first order in the SM (GIM mechanism), e.g. Bs→µ+µ-: In higher order decays are possible, but branching ratio is only ~2x10-9 : b s µ- µ+ Z W t Branching ratio might be strongly enhanced by contributions from New Physics (e.g. SuSy): b s µ- µ+ H0/A0 t ~ χ 11/14/2018

The Outer Tracking System C-Frames Bridge Modules 11/14/2018

Contributions for LHCb at the PI Detector technology: - Development, test and construction of the Straw Tube detectors for the Outer Tracking System*. - Assembly and commissioning of the Outer Tracking System at CERN**. Electronics: - Development and testing of an ASIC for drift time measurements. - Development and testing of the optical readout chain for the OT*. Software: - Development of the Experiment Control System for the OT*. - Development of tracking & alignment algorithms***. - Development of trigger algorithm***. * In collaboration with NIKHEF and Krakow ** in collaboration with NIKHEF *** in the framework of the LHCb soft- ware 11/14/2018

Performance of straw tubes Results from a test beam experiment in 2005 at DESY with final detectors and final frontend electronics: Efficiency, ε Resolution (µm) amplifier Threshold (mV) amplifier Threshold (mV) 11/14/2018

Rasnik: Observing movements Task: Monitor movements of the detectors with Respect to reference. On C-frame On bridge TopMux Observing mask with camera allows to survey movements of the C-frames. 11/14/2018

Results from Rasnik y 3 2 100 µm x 1 12 days 11/14/2018

The phenomenon Gas flow Ratio Plot: I(after)/I(before) Irradiate with 2 mCu 90Sr source Gain loss “in the neighborhood” of the irradiation point: Croissant? Bean? Kidney? Upstream of gas flow Gas flow Courtesy Niels Tuning 11/14/2018

Finding the culprit Compare test modules: Left: Production like (Use Araldite) - 7% gain loss after 90h of irradiation - Effect reproduced for the first time in test modules. Right: Trabond used - no ageing after 393h of irradiation With Araldite, 90h 7% gain loss No Araldite, 393h no ageing source Courtesy Tanja Haas 11/14/2018

Beneficial effects HV training: Flushing: Beneficial effects: Courtesy Niels Tuning HV training: 2nd HV training 1st HV training 3rd HV training  Relative Gain  Irradiation Time (hours) Beneficial effects: Flushing HV Training Heating Flushing:  Flushing Time (weeks)  Gain loss (%) 11/14/2018

Heating procedure Two very similar set-ups: Heidelberg and NIKHEF set-up cover the module with thin aluminium plates wrap the module in electric blankets take a module and flush for n days Insulate, then keep 2 weeks at 4042C 11/14/2018

Heating: Results from Heidelberg set-up Courtesy Tanja Haas Heidelberg 20 before 20 after 7 before 7 after 27 before 27 after NIKHEF N123 before N 005 before N005 after N058 befor N058 after N123 after N058 NIKHEF W023 before W023 after W2.5m before W2.5m after - All modules benefit, but level of improvement varies. Improvement is a convolution of heating and additional flushing. Warsaw 11/14/2018