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A new LHC device for the LHC: implementation aspects/options/cost estimates

A new LHC device for the LHC: implementation aspects/options/cost estimates. Detector Readout chain Gas target organization. This is a brain dump. the detector. New Device for LHC.

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A new LHC device for the LHC: implementation aspects/options/cost estimates

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  1. A new LHC device for the LHC: implementation aspects/options/cost estimates Detector Readout chain Gas target organization This is a brain dump

  2. the detector

  3. New Device for LHC NB: itwillmeasurebeamshapes→ must be able to measureaccuratelyabsolute value of functionat the device position! Specifications: • providemeasurement of emittance • stat accuracy of <5% in 5 min for 1011 p • systuncertainty <5% (dominated by understanding of vtxresolution ?) • for 1.5 < n/um < 4 and 0.45 < E/TeV < 7 • bunch by bunch(max bunches per measurement to bedefined?) • should not affect beamoperation By-products: • measurement of ghost charge (crucial for lumicalib) seeA. Alici et al. (BCNWG note4), CERN-ATS-Note-2012-029 PERF • measurement of relative bunch charges (to benormed by DCCT) see G. Anders et al. (BCNWG note3), CERN-ATS-Note-2012-028 PERF Possible add-on: (not in baselinediscussedhere) • timing detector with < ~100ps resolution, wouldprovide longitudinal profile as well

  4. Starting point (educatedguess) Last detector First detector Accept: 3 <  < 5 ( 100 > /mrad > 15 ) window radius Rw R2 given by beam pipe max min R1 L/2 -L/2 z1 z2 0 ∆z Z range to becovered by acceptanceTake: L = 1m ( VELO: R1 = 8mm, L = ~0.5-1m ) z1 = L/2 + R1 / tan(min) Take: R1 = 15, 20, 25 mm Rw = (z1 + L/2) tan(max) R2 = (z2 + L/2) tan(max) • small R1impliessmall (compact) detector (probablysilicon) • larger R1implieslarger detector (probablySciFi)

  5. Simplest solution with straight segmented detectors all tracks within radius R2 are accepted R22 = R12 + (H-R1)2 + some bonus outside, in the corners... beam pipe H R2 2R1 x’ y’ x y x y x’’ y’’ «minimum» number of planes (4) JUST AN EXAMPLE z

  6. Comments to geometry We must find the place withthe smallestratio Rpipe/beam • Wantsmallaperture, but large beams!! :-) • Option not consideredhere: movabledevice (in vacuum) • complexity (and cost) increasessubstantially, but allows to come closer Whatis the smallest possible radius ? (even if smallerbeam size) • Drives whetherweshould use siliconor SciFi Performance/costoptimization to bedone • Inclined detectors, stereo angle, ... • Sawtoothbeam pipe ? • Put ring1 devicesuchthat no bkg to ring2 device (and vice versa) • Can we live with 4 planes (xyx’y’) using vertex-constrainedtracking ? • etc...

  7. recycle fromLHCb ? silicontrackers (straight strips) BOTH TO BE REPLACED AT LS2 (LHCb Upgrade) TT IT

  8. LHCb TT in more details One plane (out of four) One stave (half module) • 34 staves/plane x 4 planes = 136 staves • Cooled to about 0 oC • Issue: sensors are glued on the stave (7 by 7) about 70cm about 10cm Sensorthickness pitch dim (mm2) 500 um 183um 96.4x94.4

  9. LHCb IT in more details One plane (out of twelve) One module • 14 osm/plane x 12 planes = 168 osm • 14 tsm/plane x 12 planes = 168 tsm • Cooled to about 0 oC module type thickness pitch dim (mm2) one-sensor modules (osm) 320 um 198um 76x110 two-sensor modules (tsm) 410 um 198 um 76x110

  10. Silicon modules in LHCb TT (TrackerTuricensis) (or Trigger Tracker) IT (InnerTracker) • Both working well • Apart perhaps from central part of TT, the detector modules will have little radiation damage, but will be activated (lightly radioactive material) 1- or 2-sensor high 1,2,3- or 4-sensor high

  11. ScintillatingFiber modules in LHCb ? • No SciFi detector in LHCb currently, but... • Important R&D effort ongoing to consider SciFi for upgrade • would replace central part of Outer Tracker and the Inner Tracker • Already some short modules available as a spare for the IT boxes • ~11cm long fibers • More modules being fabricated for Upgrade R&D, with several lengths (22cm, 80cm, 250cm) • Groups: EPFL, Dortmund, Heidelberg, CERN, ...

  12. Movable vs not movable Movable detector device: • can come closer to beam • improvesresolution, compactifies the detector • increasescomplexity of detector • mechanics, vacuum, protection, etc... • Issues: • onlymovable in StableBeams ? • difficult to access detector (repair, maintenance) Mypersonalbias: «if itcanbedonewith a fixed detector, don’tmakeitmovable…»

  13. Possible add-onto beconsidered/studied 25ns slot • Currently, in LHCb: 25ns integration time, 40MHz synchronous • OK for nominal RF buckets • But for ghost charge, had to check detectionefficiency vs time Fast timing detectors • Seee.g. AFP: based on cerenkovradiation, quartz rodswith MCP-PMT canreach ~ 20ps • Wouldallowmeasuring the longitudinal profile • satellites, bunchlengths, ... • Scintillatorswith ~ 0.3 ns are sufficient for satellite measurements, but we need < ~100 ps for proper bunch length measurement Nominal rf bucket ghost charge anywhere See Plamen’s thesis

  14. readoutchain

  15. IT/TT FE electronics In principle, all these beautiful electronics are to be «scrapped» at LS2...

  16. LHCbreadoutchain (IT and TT) FE electronics Readoutboard Now Upgrade network CPU farm L0 electronics 1 MHz max 1MHz data ZS 1-40MHz 40MHz data ZS near detector ... 100m ... electronics rack

  17. At the LHC, a simple view... readoutnetwork CPU farm readout boards LHCb upgrade Hw trigger decision tunnel FE electronics gastarget tracking detectors timing/trig detectors

  18. Data rate (to be refined at a later stage…) • Assumption: • zero-suppressed IT-like detector (3072 channels per Tell1 board) • 20 tracks per primary vertex per plane (conservative) • Each hit is a double-strip cluster encoded in 12 bits (channel address) + 3 bits for interstrip distance • Data size per vertex (one ring): 15 bits/clus x 20 clus/plane x 8 planes = 300 Bytes • Data rate: 300 Bytes x 100 Hz/bunch x 2800 bunches = 84 MB/s Say: ~ 100 MB/s ZS cluster data ~ few hundred TB/yr (no trigger selection, no data reduction by online processing) + noise! Raw (good) event rate ~ 280 kHz + bkg! + headers…

  19. Detector costestimate: Silicon «à la LHCb Upgrade» • 1 plane = 48 sensors • ladder = 3 sensorsbonded • 3 chips per ladder • 1 chip = 128 channels Quick & dirty estimation ~30x30cm2 2 rings 8 planes no sparestakenintoaccount => shouldadd 10-15% cost

  20. Detector costestimate: SciFi«à la LHCb Upgrade» Quick & dirty estimation 1 plane = 4x12x128 channels (1 SiPM = 128 channels) 1 plane = 5-fiber layer, 0.25mm diameter 12 SiPM ~38.4x38.4cm2 2 rings 8 planes 0.25mm NB1: cost almost doesn’t change with increasing size of detector NB2: hard to get fiber diameter down... no sparestakenintoaccount => shouldadd 10-15% cost

  21. gastarget

  22. The gastarget Requirements: • must givesufficientbeam-gas rate from the nominal gas z-range: R(nom. range) > ~100Hz/1011 p and sufficientlylowbkg (from non-nominal z range) R(bkg) < R(nom. range) • Also: minimize «useless» radiation damage to detector • largest possible trackmultiplicity per vertex • Xe betterthan Ne betterthan He ... • must be able to operatecontinously (whenbeam in machine) • no effect on beamoperation • lifetime due to injectedgas >100h • contamination of nearby section to bekeptlow • check SEY for gettered or cryosorbedgasspecies

  23. Whichgas ? Inelastic cross section pA ≈ pp∙ A2/3 Charged pion multiplicities MpA ≈ Mpp∙ (a+b∙A1/3) a≈0.65, b≈0.3 Larger A  larger cross section and largermultiplicity per vertex Getterable / non-getterable ? (or cryosorption ?) • getterable: e.g. CO2, N2, O2 ... • Very local pressure bump • Requiresregenerating (changing ?) the NEG sporadically • non-getterable: e.g. Ne, Xe, … • Longer pressure bump, requiresdifferentialpumpingaround the target • Some contamination of nearbycryo section surfaces ? MG, DR, Z. Phys C65, 215-223 (1995)

  24. Gastarget (sketch!!) gas injection and accumulation WF suppression long (small diameter) pipes act as flow restrictions detector beam detector pumping pumping cold surface (increase density for same amount of injected gas) this must be transparent! (thin) p more realistic pressure profile ideal pressure profile z Reminder: contrary to VELO/LHCb, here gas injection must be continuous (with beam)... Consider impact on machine!

  25. organization

  26. Three (parallel) activities • «Off-the-trunk» device: (immediate) • install asap in LHC (LS1 or winter stop thereafter) • proof of principle, gain experience • only one LHC ring ? • Full-blown solution for LHC: (mid-term) • enough detectors (redundancy, acceptance) • one device per per ring in LS2 • buy new or recycle LHCb ? • Further applications: (long-term) • SPS, PS, etc.

  27. Nextsteps: tentative list • Write down specifications of the new imaging device for LHC • detector • gas target • Find best place in LHC ( smallest Rpipe/beam ) • Organization: who works on what ? • The device is mostly a beam diagnostics instrument project led by BE-BI, with strong support from TE-VSC, BE-ABP, LHC-OP, LHC-MP and PH • Detector • Mechanics • Sensors • FE electronics • RO board • Ctrl electronics • Ctrl s/w • Acq f/w • Reconstr s/w • Monitoring s/w • ... • Gas Target • Vacuum sys • Gas injection • Cryocooling • Impedance • Ctrl s/w • Monitoring s/w • ...

  28. Weneed a (generic) name for such a device !! Device Detector Beam Gas Interaction Imaging Vertex Shape Locator Accelerator Reconstructor Analyzer Make your own suggestion!!

  29. backup

  30. Option 2 for the detector arrangement (one XY plane) plane 1 (X) plane 2 (Y)

  31. Option 3 for the detector arrangement (one XY plane) Two modules types (two lengths) plane 2 (Y) plane 1 (X)

  32. Option1 for the detector arrangement (one XY plane) plane 2 (Y) plane 1 (X) number of sensors in one square isarbitrary (as long as theyform a square) electronics one sensor

  33. LHCbelectronics architecture

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