1 / 21

Linear Collider Vertex Detector R&D

Linear Collider Vertex Detector R&D. Natalie Roe UCSC Linear Collider Workshop June 27-29, 2002. R&D: General Goals & Strategy. R&D should be undertaken to mitigate risk and ensure a project will succeed

ataret
Download Presentation

Linear Collider Vertex Detector R&D

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Linear Collider Vertex Detector R&D Natalie Roe UCSC Linear Collider Workshop June 27-29, 2002

  2. R&D: General Goals & Strategy • R&D should be undertaken to mitigate risk and ensure a project will succeed • Technical risk for new, unproven techniques or significant extensions of existing methods • Schedule risk for long-lead development or procurements • R&D strategy: identify areas of technical or schedule risk with biggest physics impact • Focus on most critical areas needing early R&D investment to ensure the project’s success and to maximize the physics reach N. Roe LBNL LC Workshop 6/28/02

  3. What type of R&D is required for LC Detectors? • Hard to argue schedule risk at this stage… • There is time for new technical developments with significant physics impact • First step is to write down machine constraints and physics-driven requirements • Next, devise a focused R&D plan to address the technical issues associated with the requirements that: • a) have biggest physics impact, and • b) are most challenging N. Roe LBNL LC Workshop 6/28/02

  4. Requirements for an LC Vertex Detector • Accelerator-related requirements, such as • Beam-pipe radius, thickness, machine stayclear • Radiation levels & background rates • Event rate and time structure of collisions • etc. • Physics requirements, eg vertex flavor tagging, driven by: • Impact parameter resolution • Two-track/two-hit separation • Efficiency, fake track rate • Solid angle coverage • etc. N. Roe LBNL LC Workshop 6/28/02

  5. Quantifying Requirements: Accelerator constraints • Machine design is not yet finalized • Detailed design studies exist for several machines - consider worst case parameters • Experience suggests conservative assumptions eg, radiation levels generally get worse with more realistic machine studies, bkgds go up etc. • Critical design areas may require iteration with accelerator experts, additional efforts on machine simulations N. Roe LBNL LC Workshop 6/28/02

  6. Quantifying Requirements: Accelerator constraints I • Beam pipe radius: determined by beamstrahlung and synchrotron radiation backgrounds. Present thinking: • NLC: r = 1 cm for z = ± 2.5 cm, then increases to 2.2 cm • Tesla: r = 1.4 cm • Radiation & background rates: • Tesla: • beam-beam e+e- pairs produce 0.03 hits/mm2/BX, resulting in ~20kRad/yr ionizing radiation for B= 4T and r = 1.5 cm • Neutron fluence ~ 109 1 MeV neutrons/cm2/yr • NLC: • beam-beam e+e- pairs produce 3 hits/mm2/train =0.015 hits/mm/BX at B=3T and r = 1.2 cm • Neutron fluence estimates vary from 107 to 1011 n/cm2/year Maruyama - 2.3 x 109 n/cm2/year • What about beam gas backgrounds? N. Roe LBNL LC Workshop 6/28/02

  7. NLC Bkgds B=6T, no crossing angle B= ? See talk this morning by Maruyama N. Roe LBNL LC Workshop 6/28/02

  8. Quantifying Requirements: Accelerator constraints II Tesla500 Tesla800 NLC A 200 ms 250 ms 8.3ms B 337 ns 176ns 1.4 ns C 950 us 860us 266 ns C/B 2820 4886 190 C/BA 14kHz 19.5kHz 23kHz L(1034) 3.4 5.8 2.0 • Time Structure & Event Rates • Layer 1 hit occupancies (bkgd dominated): • At NLC 190 x 0.015 hits/mm2/BX = 2.85 hits/mm2/train = 1 x 10-3 occupancy for 20x20um pixels => read out between bunch trains • At Tesla 2820 x 0.030 hits/mm2/BX = 84.5 hits/mm2/train = 3.4 % occ for 20x20 um pixel => readout during train B C A N. Roe LBNL LC Workshop 6/28/02

  9. Reality Check: NLC vs Tesla background rates • Tesla = 0.03 hits/mm2/BX at 4T, r=1.5 mm • NLC = 0.015 hits/mm2/BX at 3T, r=1.2 mm • Why are NLC bkgds lower with smaller B field and radius? • Bkgds/BX should be proportional to lumi/BX • Tesla: 3.4x1034 / 14kHz • NLC: 2x1034 / 23kHz • Factor of 3 lower lumi/BX at NLC => compensated for by lower B and r • More detailed comparisons needed, eg compare rates at same B field and radius. • Understand beamgas and synchrotron backgrounds and compare N. Roe LBNL LC Workshop 6/28/02

  10. Quantifying Requirements: Accelerator constraints III • Beam pipe thickness (scale: 100 um of Si ~ 0.1%X0): • Tesla studies assume a beampipe of ~ 0.25 mm Be = 0.07%X0 • Matches first detector layer thickness of 0.06% X0 • NLC studies: assumptions ranging from 0.160 - 0.180 mm Be(?) • NLC beampipe has stepped radius from 1.2 -> 2.4 cm to avoid backgrounds - does this create problems with showering? • Multiple scattering in beampipe sets scale for thickness of first detector layer and for point resolution at low p • Radius and thickness of beampipe are critical inputs for vertex detector; think of beampipe as part of detector N. Roe LBNL LC Workshop 6/28/02

  11. Physics Requirements I • Flowdown of requirements: • Science requirement: Precision on particular physics quantities, eg error on Br(H-> cc) • Performance requirement: high-level event parameter, eg specified flavor tag purity at a given efficiency • Detector requirement, eg impact parameter resolution or tracking efficiency vs fake rate for a given detector subsystem • A number of LC vertex detector studies have already been performed at all 3 levels. N. Roe LBNL LC Workshop 6/28/02

  12. Selected Previous Vertex Performance Studies • Sinev:http://blueox.uoregon.edu/~jimbrau/talks/IEEE-99/ieee99.pdf • Abe(ghost tracks): http://www.slac.stanford.edu/~toshi/LCDstudy/toshi_ghost.pdf • Schumm (vertex parameters): http://scipp.ucsc.edu/~schumm/talks/fnal2000/fnal2000_ag.ps • Oregon vertex detector parameters study: http://blueox.uoregon.edu/~jimbrau/LC/vxd-studies.PDF • Chou (H->cc): http://www-sldnt.slac.stanford.edu/nld/meetings/ChicagoJan2002/BRHccJan8.pdf • Potter et al (Higgs branching ratios ): http://www.slac.stanford.edu/econf/C010630/forweb/P118_potter.pdf • Iwasaki - top: http://www.slac.stanford.edu/~masako/LC_study/Chicago2002/Top.pdf • Walkowiak:http://www.slac.stanford.edu/~walkowia/lcd/talks/ chicago2002/lcChicago010802-1.pdf • LCFI studies : ( http://hep.ph.liv.ac.uk/~green/lcfi/home.html ) N. Roe LBNL LC Workshop 6/28/02

  13. Physics Requirements II • Impact parameter resolution: • Simplified formula for i.p. resolution in 2 layer device with measurements at r1,r2 and errors  : • Dominated by resolution of first hit • Multiple scattering dominates for low momenta; material in beampipe and first detector layer must be minimized, along with radius of 1st hit • Intrinsic point resolution dominates at high momenta - includes misalignment effects N. Roe LBNL LC Workshop 6/28/02

  14. Impact Parameter Resolution Studies - Schumm 10 um Pt resolution dominated dR (cm) M.S. dominated 2-3 um N. Roe LBNL LC Workshop 6/28/02

  15. Impact parameter study • resolution • ladder thickness • beampipe radius • outer radius http://scipp.ucsc.edu/ ~schumm/talks/fnal2000/ fnal2000_ag.ps B. Schumm N. Roe LBNL LC Workshop 6/28/02 “Standard L2” = 1.2 cm beampipe, 160 um Be, 5 um resolution

  16. How does i.p. resolution affect flavor tagging? • Compare i.p. resolution to typical impact parameters at LC • For B decay products, i.p. ~ 300 um>>10 um • B-tagging should not depend strongly on pt resolution, beampipe radius or thickness • For charm decay products, i.p. ~ 80-100 um • Might see mild dependence • To correctly assign tracks to both b and c vertices to determine charge or mass will be more challenging • Needs a level 2/level 3 study N. Roe LBNL LC Workshop 6/28/02

  17. Study of Charm Tagging • Mild detector dependence: 15% change going from 10 um, 1.0%X0 to 1 um, 0.03%X0 detector • Beampipe radius = 1 cm • What was the beampipe thickness? • What bkgd levels? N. Roe LBNL LC Workshop 6/28/02 A. Chou

  18. Error on Higgs BRs - Oregon Study MH = 140 GeV/c2 , s = 500 GeV, L = 500 fb-1 RINNER(cm) 1.2 2.4 1.2 2.4 1.2 hit res (mm) 5.0 5.0 3.0 3.0 4.0 H  bb 3.8% 3.8% 3.8% 3,8% 3.8% H  tt 10% 10% 10% 10% 10% H  cc 46% 47% 42% 46% 42% H  gg 23% 22% 22% 22% 22% H  WW* 3.5% 3.5% 3.5% 3.5% 3.5% Error on Higgs branching ratios is essentially independent of radius and resolution, with mild dependence for H-> cc Potter, Brau, Iwasaki http://blueox.uoregon.edu/ ~jimbrau/LC/vxd-studies.PDF N. Roe LBNL LC Workshop 6/28/02

  19. Vertex R&D - paper studies & simulations • Write down assumptions for NLC/Tesla/JLC beampipe, backgrounds, radiation levels; compare/rationalize different results, get improved estimates if possible (=>run accelerator simulations) • Consider dependence of i.p. resolution on beampipe thickness as well as detector thickness; engineering study of beampipe construction? • Consider effects of material at large radius as well (cryostat can decouple vertex from outer tracking, reduce effective lever arm for tracking) • Consider design where L1 is special: thinner, faster readout, better resolution. (may want L2 also for backup) • Document a set of science-driven requirements (goals) for vertex detector performance, with a clear link from specific measurements to the required performance parameters. N. Roe LBNL LC Workshop 6/28/02

  20. R&D: Hands-on studies • Leading candidates: CCDs, hybrid pixels, active pixels … + time to develop new ideas! • General areas for R&D • Radiation hardness • Readout speed, especially in Tesla context • Minimizing material thickness including mechanical structures and beampipe N. Roe LBNL LC Workshop 6/28/02

  21. Summary • There are interesting vertex detector issues to address both in simulation and in hands-on R&D • To coordinate US efforts, please provide a brief description, list of participants and proposed budget • Should aim to cooperate on global level with international partners N. Roe LBNL LC Workshop 6/28/02

More Related