WBS 1.05 Commissioning Detector Specifications & Design Sven Vahsen University of Hawaii

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

Sven Vahsen, Belle II Directors Review (Pre CD-2/3) US Project Scope 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 Part of US Belle II Project 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

Latest Belle II Schedule 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 (This plan has changed repeatedly. Our mandate is to be ready for any commissioning scenario.) 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

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

Sven Vahsen, Belle II Directors Review (Pre CD-2/3) Support Structure 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

Sven Vahsen, Belle II Directors Review (Pre CD-2/3) Mechanics Hawaii designs + builds phase I mechanical mounting structure Lead: Rosen (German VXD group + KEK taking on mechanical design for PXD/SVD/BGO mounting in phase II) Phase I 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

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

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

Sven Vahsen, Belle II Directors Review (Pre CD-2/3) PIN diode system 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

Sven Vahsen, Belle II Directors Review (Pre CD-2/3) PIN Diode System Phase 1 Proposed diode pair positions Phase 2 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

Dose Monitoring System 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 CLEO Measurements Synchrotron fan 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

PIN Diode System Prototyping Commercial preamp and readout boards (from Cremat) 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

Sven Vahsen, Belle II Directors Review (Pre CD-2/3) Prototype System 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

Sven Vahsen, Belle II Directors Review (Pre CD-2/3) Final System 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

DAQ for final system (off project) 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

TPC fast neutron detectors 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

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

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

Recoil angle in 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 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

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

Demonstration of Directional Neutron Detection Source Absent He-recoil measured in HeC02 gas at p=1atm L ~ 4 mm E ~ 400 keV/c2 Mean direction of nuclear recoils corresponds to neutron source location Source Present Nuclear recoil Incoming neutron Scattered neutron neutron source Clear excess & peaks in expected direction! 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

Angular and Energy Resolution, Nuclear Recoils Po-210 α-source inside vacuum vessel. How well can we locate it? HeC02 at 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,θ detector ~1◦ July 2013 Sven Vahsen 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

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

Sven Vahsen, Belle II Directors Review (Pre CD-2/3) Technical Status Pre-prototypes of micro-TPCs have met and exceeded all Key Performance Parameters Documented in Technical Design Report 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

Final TPC Prototype Design Sensitive volume Field cage Charge amplification (GEMs) Charge Detection (Pixel Chip) Aluminum vacuum vessel 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

Final TPC Prototype Construction Design finalized Two final prototypes are in production Testbeam in 2014. Install two at KEK fall 2014, eight in 2015. Vacuum vessel Field cage assembly Final DAQ board 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

TPC Prototype Testing: Ongoing 16-17 January 2013 Sven Vahsen, Belle II Directors Review (Pre CD-2/3)

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

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

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

BEAST Subsystem U.S. Contributions  dedicated talks 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)

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

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

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, Radiative Bhabha, Beam-gas, Synchrotron) System tests for Belle II (Beam abort system, moveable mask positions, pixel detector cooling, inner detector occupancies)