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WBS 1.05 Commissioning Detector Specifications & Design

Detailed outline of US Project Scope, commissioning schedule, test results, and final designs of the Belle-II detectors. Covers support structures, PIN diode system, TPC fast neutron detectors, and more.

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WBS 1.05 Commissioning Detector Specifications & Design

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  1. WBS 1.05 Commissioning DetectorSpecifications & Design Sven Vahsen University of Hawaii

  2. Talk Outline • Intro • US Project Scope • SuperKEKB commissioning schedule & Phases • Pre-prototype test results & Final Designs • Support Structure • PIN diode system • TPC fast neutron detectors • Summary Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  3. US Project Scope Part of US Belle II Project Lead design, simulation, DAQ integration (off-project) Construct support structure Prototype & construct PIN-diode radiation dose monitoring system Prototype & construct micro-TPC neutron monitoring system Perform acceptance tests at KEK Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  4. Latest Belle II Schedule (This plan has changed repeatedly. Our mandate is to be ready for any commissioning scenario.) https://docs.google.com/spreadsheet/ccc?key=0Ap1uZWWWy6I0dFpSZzlMRllsTU9DM1Y1ZjBaN1o3NUE&usp=drive_web#gid=19 Key dates: Phase I (No QCS, No Belle Detector): Jan 2015 Phase II (QCS, Belle, no VXD): Feb 2016 Phase III (QCS, Belle, VXD): October 2016 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  5. Commissioning Detector Configurations • Phase I • Main task is vacuum scrubbing of beam pipe. • No collisions. Belle will not roll-in. • Support Structure and PIN diode system needed. • 2 TPC prototypes will be deployed. • Phase II • Belle rolled in. • No VXD detectors. • 8 Final TPCs needed. Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  6. Support Structure Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  7. Mechanics • (German VXD group + KEK taking on mechanical design for PXD/SVD/BGO mounting in phase II) • Hawaii designs + builds phase I mechanical mounting structure • Lead: Rosen Phase I Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  8. PIN Diodes velcroed to beam pipe (not shown) • TPCs and other systems attached to fiberglass unistrut structure • simple, (very) inexpensive • can be reconfigured in minutes • non-magnetic • low activation TPC BGO Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  9. Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  10. PIN diode system Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  11. PIN Diode System Proposed diode pair positions Phase 1 Phase 2 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  12. Dose Monitoring System CLEO Measurements Synchrotron fan Lead: David Cinabro (Wayne State) Use PIN diodes, Siemens SFH 206K PIN, to measure ionizing radiation dose Inexpensive & robust Successfully used in for ~10 years and integrated a dose of < 3 Megarads. Every 2nd diode (in phi) coated with gold-paint Allows separating dose from charged particles and xrays Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  13. PIN Diode System Prototyping Commercial preamp and readout boards (from Cremat) Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  14. Prototype System Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  15. Final System Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  16. DAQ for final system (off project) Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  17. TPC fast neutron detectors Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  18. Motivation for TPCs • Neutron Backgrounds • Difficult both to predict & measure accurately, caused problems already for Belle and Babar • Will be critical for Belle-II operation and lifetime • KLM deadtime, ECL electronics lifetime, iTOPphotocathode lifetime • Idea: neutrons produced at specific loss-positions along the beam-line. Fast neutrons preserve directional information and can be directionally reconstructed. Use them to “image” loss spots. Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  19. How TPCs will be used • Commissioning phase II: He-3 tubes and micro-TPCs in dock space • Complimentary detectors • TPCs image direction of incoming fast neutrons, but detected rate is low • He-3 tubes measure rate of thermal neutrons, which is high Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  20. Recoil anglein Backward TPCs Directional detection motivation Isolate neutrons coming directly from beam lines (rather than re-cattered) Measure neutron flux versus polar angle (beam line position)  validate/tune simulation Correct rates, but low MC statistics • nominal beams:RBB HER dominates •  measure • Run single beams • no RBB • measure Touchek • vacuum bump  measure Coulomb Higher statistics & re-normalized Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  21. TPC Pre-Prototypes • July 2013: Larger volume& less plastic • 5 x higher neutron detection efficiency • 10 x lower background rate Used for ~2 years of detailed performance measurements Used to demonstrate neutron detection with higher efficency Performance of these detectors studied in great detail, well understood Commissioning Detector TPCs : further scale-up in size to increase neutron detection efficiency Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  22. Demonstration of Directional Neutron Detection He-recoil measured in HeC02gas at p=1atm L ~ 4 mm E ~ 400 keV/c2 Mean direction of nuclear recoils corresponds to neutron source location Nuclear recoil Source Present Source Absent Incoming neutron Scattered neutron neutron source Clear excess & peaks in expected direction! Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  23. Angular and Energy Resolution, Nuclear Recoils Po-210 α-source inside vacuum vessel. How well can we locate it? HeC02at p=1atm σϕ= 1.0° α σθ= 2.2° • Selected events clearly point back to a single source • No BG after good-track selection • consistent with σφ,θdetector ~1◦ Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  24. Angular resolution versus “track size” Analytical “prediction”: σϕ~ σPOINT/(L√N) The above allows us to extrapolate our results to other energies and gas pressures Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  25. Technical Status Pre-prototypes of micro-TPCs have met and exceeded all Key Performance Parameters Documented in Technical Design Report Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  26. Final TPC Prototype Design Sensitive volume Field cage Charge amplification(GEMs) Charge Detection (Pixel Chip) Aluminum vacuum vessel Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  27. Final TPC Prototype Construction • Design finalized • Two final prototypes are in production • Testbeam in 2014. • Install two at KEK fall 2014, eight in 2015. Final DAQ board Vacuum vessel Field cage assembly Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  28. TPC Prototype Testing: Ongoing Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  29. Conclusion • WBS 1.5 Technical Designs are Mature • Detector (PIN diodes and TPCs) performance demonstrated with (pre-)prototype systems • Satisfy all KPPs • Final systems: Same detections principles, scaled up • More channels for PIN diodes • Larger sensitive volume for TPCs • Project Ready for CD-2/3 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

  30. BACKUP SLIDES 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3) 30

  31. Recoil angle distribution in Forward TPCs Correct rates, but low MC statistics • nominal beams:RBB LER dominates •  measure • Run single beams • no RBB • measure Touchek • vacuum bump  measure Coulomb Higher statistics & re-normalized

  32. BEAST Subsystem • U.S. Contributions • PIN diode dose monitoring system (Wayne State) • TPC directional fast neutron detectors (Hawaii)  dedicated talks • Non-U.S. Contributions • BGO crystal luminosity monitors (NTU) • He-3 tube thermal neutron detector (Victoria, Canada) • PXD, SVD ladders, beam abort, synchrotron spectrum measurements: VXD groups (Bonn, MPI etc)

  33. BEAST DAQ & Control • Stand-alone BEAST DAQ proposed • ~1Hz pseudo-events • Independent of Belle II Phase I

  34. Introduction • Commissioning detector will characterize radiation near SuperKEKB interaction point during beam commissioning. • Sub-systems supplied by a number of Belle II institutes, mounted on common mechanical support structure. • WBS 1.5 captures U.S. contributions to this effort “BEAST” - KEKB commissioning detector in 1998 – effort led by U. Hawaii

  35. Commissioning Detector Objectives Determine if dose rate safe for Belle II roll-in and later operation at design luminosity (Belle I: hole in beampipe and damage to silicon vertex detector) Provide real-time measurements of luminosity and backgrounds (needed by SuperKEKB during beam commissioning) Validate Belle II beam background simulation (Distinguish different beam background sources (Touschek, RadiativeBhabha, Beam-gas, Synchrotron) System tests for Belle II (Beam abort system, moveable mask positions, pixel detector cooling, inner detector occupancies)

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