1. WBS 1.05 Commissioning Detectors Specifications & 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 – Micro-TPC fast neutron detectors Summary US Belle II Independent Project Review219-20 March 2014

3. US Project Scope Construct support structure Prototype & construct PIN-diode radiation dose monitoring system Prototype & construct micro-TPC neutron monitoring system Perform acceptance tests at KEK Off Project: Lead design, simulation, DAQ integration Part of US Belle II Project US Belle II Independent Project Review319-20 March 2014

4. Latest Belle II Schedule https://docs.google.com/spreadsheet/ccc?key=0Ap1uZWWWy6I0dFpSZzlMRllsTU9D M1Y1ZjBaN1o3NUE&usp=drive_web#gid=19 https://docs.google.com/spreadsheet/ccc?key=0Ap1uZWWWy6I0dFpSZzlMRllsTU9D M1Y1ZjBaN1o3NUE&usp=drive_web#gid=19 Key dates: Phase 1 (No QCS, No Belle Detector): Jan 2015 Phase 2 (QCS, Belle, no VXD): Feb 2016 Phase 3 (QCS, Belle, VXD): October 2016 US Belle II Independent Project Review419-20 March 2014

5. Commissioning Detectors Configurations Phase 1 Main task is vacuum scrubbing of beam pipe. No collisions. Belle will not roll-in. Support structure and PIN diode system needed. 2 micro-TPC prototypes will be deployed. Phase 2 Belle rolled in. No VXD detectors. 8 Final micro-TPCs needed. US Belle II Independent Project Review519-20 March 2014

6. Support Structure 19-20 March 2014US Belle II Independent Project Review6

7. Mechanics Phase 1 (German VXD group + KEK in charge of mechanical design for phase 2) Hawaii designs + builds phase 1 mechanical mounting structure Lead: Rosen US Belle II Independent Project Review719-20 March 2014

8. 8 PIN diodes velcroed (not shown) to beam pipe Micro-TPCs and other systems attached to “Aickinstrut” (see next page) fiberglass support structure simple, (very) inexpensive can be reconfigured in minutes non-magnetic low activation micro-TPC BGO US Belle II Independent Project Review819-20 March 2014 He-3 tube PIN diodes Phase 1 BGO background & luminosity monitors two PIN diodes

9. Framing Material: Fiberglass Aickinstrut US Belle II Independent Project Review919-20 March 2014 Also used in Belle commissioning Fully non-metallic, including fasteners

10. PIN Diode System 19-20 March 2014US Belle II Independent Project Review10

11. PIN Diode System Phase 1 19-20 March 2014US Belle II Independent Project Review11 Phase 2 Proposed diode pair positions PIN Diodes

12. Lead: David Cinabro (Wayne State) Use PIN diodes, Siemens SFH 206K PIN, to measure ionizing radiation dose Inexpensive & robust Successfully used in CLEO for ~10 years and integrated a dose of < 3 Megarads Every 2 nd diode (in phi) coated with gold-paint Allows separating dose from charged particles and xrays PIN Diodes System II Synchrotron fan CLEO Measurements US Belle II Independent Project Review1219-20 March 2014

13. PIN Diode System Prototyping Commercial preamp and readout boards (from Cremat) 19-20 March 2014US Belle II Independent Project Review13

14. Prototype System US Belle II Independent Project Review1419-20 March 2014

15. Final System Worked with Cremat to design an 8-channel system Common power Common ground for power, input, and output Wayne State assembling one 8-channel system, to Hawaii for DAQ integration in April 10 boards (80 channels) To KEK for installation fall 2014 64 channels will be digitized with commercial VME-based ADC, averaged down to 1 Hz 16 channels are spares 19-20 March 2014US Belle II Independent Project Review15

16. Micro-TPC Fast Neutron Detectors 19-20 March 2014US Belle II Independent Project Review16

17. Motivation For Micro-TPCs Neutron Backgrounds – Difficult to predict & measure accurately – Problematic already at Belle and Babar – 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. Use directional neutron detectors to “image” loss spots and measure rates. 19-20 March 2014US Belle II Independent Project Review17

18. How Micro-TPCs Will Be Used Commissioning phase 2: He-3 tubes and micro- TPCs in dock space Complimentary detectors – Micro-TPCs image direction of incoming fast neutrons, but detected rate is low – He-3 tubes measure rate of thermal neutrons, which is high US Belle II Independent Project Review1819-20 March 2014

19. Recoil angle in Backward micro-TPCs Nominal beams: RBB HER dominates  measure Single beams: no RBB  measure Touchek Vacuum bumps:  measure Coulomb Correct rates, but low MC statistics Higher statistics & re-normalized Directional detection motivation 1.Isolate neutrons coming directly from beam lines (rather than re-scattered) 2.Measure neutron flux versus polar angle (beam line position)  validate/tune simulation US Belle II Independent Project Review1919-20 March 2014

20. Micro-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 efficiency Performance of these detectors studied in great detail, well understood Commissioning Detector micro-TPCs : further scale-up in size to increase detection efficiency US Belle II Independent Project Review2019-20 March 2014

21. source absent source present Demonstration of Directional Neutron Detection He-recoil measured in HeC0 2 gas at p=1atm L ~ 4 mm E ~ 400 keV/c 2 Incoming neutron Scattered neutron Nuclear recoil Cf-252 neutron source Mean direction of nuclear recoils corresponds to neutron source location Clear excess & peaks in expected direction! US Belle II Independent Project Review2119-20 March 2014

22. Angular and Energy Resolution, Nuclear Recoils Selected events clearly point back to a single source Cut on impact parameter to eliminate spread in φ due to source-cone Results consistent with σ φ,θ detector ~1 ◦ Po-210 α-source inside vacuum vessel. How well can we locate it? σ ϕ = 1.0° σ θ = 2.2° HeC0 2 at p=1atm α US Belle II Independent Project Review2219-20 March 2014

23. Angular Resolution Versus “Track Size” 23 A 2 nd method (estimated error from track fitter) gives consistent results; σ φ ≈ 1 ◦ This also allows extrapolation to other track-lengths / recoil energies / gas pressures Analytical “prediction”: σ ϕ ~ σ POINT /(L√N) US Belle II Independent Project Review2319-20 March 2014

24. Technical Status Pre-prototypes of micro-TPCs have met and exceeded all Key Performance Parameters Documented in Technical Design Report 19-20 March 2014US Belle II Independent Project Review24

25. Final Micro-TPC Prototype Design Sensitive volume Charge amplification (GEMs) Field cage Charge Detection (Pixel Chip) Aluminum vacuum vessel US Belle II Independent Project Review2519-20 March 2014

26. Final Micro-TPC Prototype Construction Vacuum vessel Field cage assembly Final DAQ board Design finalized Building two final prototypes (one completed February 2014) Testbeam in 2014 Install two (=spares) at KEK fall 2014, for phase 1 in 2015 Eight final TPCs to KEK in fall 2015, for phase 2 operation in 2016 US Belle II Independent Project Review2619-20 March 2014

27. Micro-TPC Prototype Testing: Ongoing 19-20 March 2014US Belle II Independent Project Review27

28. Micro-TPC Prototype: First Events 19-20 March 2014US Belle II Independent Project Review28 neutron charge Final prototype meets performance objectives no noise hits!

29. Final Micro-TPC Prototype Meets Performance Objectives QuantityThresholdObjectiveSpecificationAchieved, pre- prototype Achieved, final prototype Micro-TPC track angle resolution (1 cm tracks) n/a15°5°1°4° Micro-TPC x-ray energy resolution at 5.9 keV (w/o tracking) n/a20%12%10%18% Micro-TPC gain100010000200004000020000 Gain stability, one week of operation n/a20%5%<2%Not yet measured 19-20 March 2014US Belle II Independent Project Review29 Final prototype operated stably for 1 week at time of writing Performance still improving due to gas purity, but already meets objectives

30. Conclusion WBS 1.05 technical designs are mature Detector (PIN diode and micro-TPC) performance demonstrated with (pre-) prototype systems – Satisfy all Key Performance Parameters (KPPs) Final systems – Mechanical support structure – 64 PIN diodes (16 spares) – 8 micro-TPCs (2 spares) Project Ready for CD-2/3 19-20 March 2014US Belle II Independent Project Review30

31. BACKUP SLIDES US Belle II Independent Project Review3119-20 March 2014

32. Gain Measurements, Final Micro-TPC Prototype 19-20 March 2014US Belle II Independent Project Review32 GainGain Resolution

33. Angular Resolution Measurements, Final Micro-TPC Prototype 19-20 March 2014US Belle II Independent Project Review33 σ φ =1.3° for 2-cm alpha-particle tracks that have drifted full length of field cage  scales to σ φ = 3.7° for 1 cm tracks [see page 23]. Exceeds KPP specification of 5°. 2 cm 2σφ2σφ y x Low gainMedium gain

34. Recoil Angle Distribution in Forward Micro-TPCs nominal beams: RBB LER dominates  measure Run single beams no RBB measure Touchek vacuum bump  measure Coulomb Correct rates, but low MC statistics Higher statistics & re-normalized 19-20 March 2014US Belle II Independent Project Review34

35. Commissioning Detector Subsystems U.S. Contributions – PIN diode dose monitoring system (Wayne State) – Micro-TPC directional fast neutron detectors (Hawaii) 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) 19-20 March 2014US Belle II Independent Project Review35

36. DAQ for PIN Diode System Digitize amplifier output with commercial ADC system Hytec MADC 2508 100kHz 16-bit ADC VME module ordered for DAQ integration test at Hawaii Allows easy integration w/ SuperKEKB control system (EPICS) Sample at ~1 kHz per channel, store average, min, and max current at 1 Hz Note: Not planning to resolve background from a single bunch. Cremat amplifier has a decay time of ~150 µs US Belle II Independent Project Review3619-20 March 2014

37. Commissioning Detectors DAQ & Control Stand-alone DAQ proposed – ~1Hz pseudo- events Independent of Belle II Phase 1 19-20 March 2014US Belle II Independent Project Review37

38. Introduction Commissioning detectors 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 1.05 captures U.S. contributions to this effort KEKB commissioning detectors in 1998 – effort led by U. Hawaii 19-20 March 2014US Belle II Independent Project Review38

39. Commissioning Detectors Objectives 1.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) 2.Provide real-time measurements of luminosity and backgrounds (needed by SuperKEKB during beam commissioning) 3.Validate Belle II beam background simulation (Distinguish different beam background sources (Touschek, Radiative Bhabha, Beam-gas, Synchrotron) 4.System tests for Belle II (Beam abort system, moveable mask positions, pixel detector cooling, inner detector occupancies) 19-20 March 2014US Belle II Independent Project Review39