1 / 21

Genetic multiplexing, or how to read up to 1831 strips with 61 channels

Genetic multiplexing, or how to read up to 1831 strips with 61 channels. Sébastien Procureur CEA-Saclay. Content. → Potential of strip multiplexing for particle detection & first idea (double sided ). → Genetic multiplexing. → Results with a 50x50 cm² Micromegas prototype.

barrettd
Download Presentation

Genetic multiplexing, or how to read up to 1831 strips with 61 channels

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. Genetic multiplexing, or how to read up to 1831 strips with 61 channels Sébastien Procureur CEA-Saclay

  2. Content → Potential of stripmultiplexing for particledetection & first idea (double sided) → Geneticmultiplexing → Resultswith a 50x50 cm² Micromegas prototype → Some applications → Conclusion and perspectives Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  3. Multiplexing and particle detectors Obvious interest: lower the number of electronic channels → easierintegration, cabling, cooling → cheaper (~1€/channel) → lowerconsumption A classical example: the Compass experiment → 12 layers of Micromegas in the hottestregion → 1,000 strips per layer, total rate ~ 30 MHz ⟹ only ~ 20 channels (2%) with signal for a given event Risks of multiplexing: → degradation of S/N ⟹ canlower the detectionefficiency → ambiguities to solve (demultiplexing) Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  4. Multiplexing: first idea → Initiated by the need to equip the CLAS12 cosmic bench with large reference detectors (tracking) → StéphanAune: 2 bulk MM on a single PCB (“double sided”) • Top sidewith n1 large strips (~1.5 cm) • Bottomsidewith n2thinstrips (~500 microns), • repeated n1 times PCB → Detector with n1xn2 strips, and read by n1+n2 channels → Optimum is n1=n2=n/2 ⟹ p=n²/4 Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  5. Double sided multiplexing 6 such detectors werebuilt at the Saclay workshop, with an active area of 50x50 cm², but: → thinstripsidesdon’treach the efficiency plateau Thinstrip capacitance: 2 nF ⟹ 10% of the real charge iscollected Partiallycompensated by the 1 cm drift gap → large stripsidesreach the plateau… Large strip capacitance: 1 nF ⟹ 17% of the real charge iscollected Partiallycompensated by the 1 cm drift gap Partiallycompensated by the cluster size of 1 → … but severalnoisy/deadstrips (3% loss per strip!) PCB PCB → Ambiguity of localization on the edge of the large strips → Unsolvableambiguity if more than 1 particle → Requires 2 workingbulks Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  6. Multiplexing & information Multiplexinginherently leads to a certain loss of information → in the previous pattern, the information on which group of thinstripssees the particleislost → thislost has to becompensated by an additional information, provided by another detector (large stripside) The best way to multiplex wouldbe to look for redundant information, and design a multiplexing pattern for which the lost information exactlycoincideswith the redundant one… → Is thereanyredundancy in the detector’s signal? Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  7. Genetic multiplexing Starting point: → in most cases, a signal isrecorded on at least 2 neighbouringstrips Wecanmake use of thisredundancy, and combine channelswithstrips in such a waythat 2 givenchannels are connected to neighbouring stripsonly once in the detector The sequence of channelsuniquely codes the position on the detector… 1 2 → blocks of thinstrips are no longer identical → the localization of the particledoesn’trequire large stripsanymore → the connection {channels}n ⟷ {strips}pcanberepresented by a p list of channelnumbers For n channels, there are a priori n(n-1)/2 unordered doublets combinations, and thus one canequip a detector with at most p = n(n-1)/2+1 strips Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  8. Genetic multiplexing Several possibilities to build the pattern, i.e. the sequence of p numbers: → generate the sequencerandomly: cannot build all the doublets channel # strip # → build the ith block from 1+k.i [n] (ideafrom Raphaël Dupré) build all the doublets if n prime → idem, but simply use the first availablechannel build almost all the doublets ∀ n Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  9. Double sided vs genetic multiplexing → Patent n° 12 62815 (S. Procureur, R. Dupré, S. Aune): « Circuit de connexion multiplexé et dispositif de connexion permettant notamment de réaliser un multiplexage » Genetic Multiplexing Saclay, 14/05/2013 S.Procureur

  10. Prototype 50x50 cm² active area, readwith n = 61 channels (highest prime numberbelow 64…) - 488 micron pitch - could have equiped up to 61x60/2+1=1831 strips (~90 cm) - p= 1024 strips → Smallest k-upletrepeated: k=15 Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  11. Prototype 50x50 cm² active area, readwith n = 61 channels (highest prime numberbelow 64…) - 488 micron pitch - could have equiped up to 61x60/2+1=1831 strips (~90 cm) - p= 1024 strips PCB Bulk connector mesh defect 50 cm Strip capacitance: 1.3 nF (compared to 2 nF for thinstripfrom double sided) Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  12. Results with cosmics Prototype tested in the CLAS12 cosmicbench (60x60 cm² couple of scintillators) • 1 cm drift gap • 128 micron amplification gap • Gas: Ar+5%isobutane • Edrift=300 V/cm • 1.5 m cable (70 pF/m) • T2K electronics (AFTER) • Shaping time: 200 ns • Samplingfrequency 60 ns • Offline common mode subtraction event display amplitude [ADC] → Demultiplexingneeded! time sample → Almost all strips OK (1020/1024) → position distribution as expected → mean noise on strips: 3,950 electrons Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  13. Results with cosmics Prototype tested in the CLAS12 cosmicbench (60x60 cm² couple of scintillators) Efficiency @ 430 V Y [mm] artefact of the cosmic bench → good effective gains in spite of large capacitances X [mm] → ~ 90%, but not maximal gain → < 2% of eventswith a cluster size of 1 (cannotbelocalized), as expected → not an issue with (shifted) resistivestrips Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  14. Genetic multiplexing and flux 1st simulation of the ambiguityprobability at ≠ flux and for ≠ degrees of multiplexing • Samegeometry (gaps, size, pitch) • Primaryelectrons on Poisson distribution • Transverse diffusion • Time window: 100 ns • Assume independentparticles → can stand up to 0.5 kHz/cm² in this configuration (1 MHz in total) → at 10 kHz/cm², the electronicscanbe reduced by a factor of 2 (1% ambiguities) Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  15. Some applications → Homeland security: scan large volumes requires large detectors with high resolution recentstudies on scans withcosmic muons → high resolution small size K. Gnanvoet al., GEM detectors Simulation with large Micromegas S. Pesenteet al., drift chambers (8 minutes!) → large area, poorresolution Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  16. Some applications - Muon tomography for volcanology: requires large detectors withlowconsumption first resultswith 80x80 cm² scintillators (~1 cm resolution) N. Lesparreet al. → ~ 50 W for the whole installation, hostile environment - Dosimetry need light, portative setup → lowconsumption TPC with 250k pixels, 10k channels - Applications in particlephysics → sLHCproject: > 1,000 m² of MPGDs, millions of electronicchannels (~1€/channel) → ILC TPC ( ~ 1 million pads): randommultiplexing? Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  17. Conclusion & perspectives Modern particlephysics and many more applications require: → large area setups → high spatial resolution → integration, lowconsumption → tight budget! Multiplexingbecomes more and more feasiblethanks to advances in instrumentation & electronics → concept of geneticmultiplexingvalidatedwith a Micromegas → almost no multiplexing at a spectrometerlevel⟹ a lot to bedone Optimizationneeded for a given flux/configuration → if n channelssuffice for 99% of the interestingevents, isit relevant to have 2n, 3n channels more for the remaining 1%? Next steps for geneticmultiplexing: - Flux studies to validate the preliminary simulations - Resistive, multiplexed Micromegas to furtherincrease S/N (ELVIA, thisyear) → Goal: 1m² detector with 100 micron 2D-resolution and < 200 channels Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  18. Back up

  19. Double sided multiplexing → 6 such detectors werebuilt at the Saclay workshop, with an active area of 50x50 cm² • Top sidewith 32 large strips (~1.5 cm) • Bottomsidewith 32 thinstrips (488 microns), x32 1stsmall prototype Event display with 4 detectors 50 cm Thinstrips Large strips → Efficiency plateau reached for large stripsonly Genetic Multiplexing RD51, 05/07/2013 S.Procureur

  20. Genetic multiplexing A signal canbe deposited on more than 2 strips… so the repetition of k-uplets (k>2) shouldbechecked → A priori no problem, as there are much more k-upletsthan doublets… → But the repetition of small k-upletsdoesappear in this construction: i=1 i=2 i=3 Repetition of the triplet 9-1-5 i=4 i=5 → Can beimproved by reordering the blocks: i=1 i=3 Repetition of the quadruplet 3-6-9-1 i=2 i=4 i=5 Genetic Multiplexing RD51, 05/07/2013 S.Procureur

More Related