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

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 Review March 2014

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 Review March 2014

Latest Belle II Schedule M1Y1ZjBaN1o3NUE&usp=drive_web#gid=19 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 Review March 2014

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 Review March 2014

Support Structure March 2014US Belle II Independent Project Review6

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 Review March 2014

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 Review March 2014 He-3 tube PIN diodes Phase 1 BGO background & luminosity monitors two PIN diodes

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

PIN Diode System March 2014US Belle II Independent Project Review10

PIN Diode System Phase March 2014US Belle II Independent Project Review11 Phase 2 Proposed diode pair positions PIN Diodes

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 Review March 2014

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

Prototype System US Belle II Independent Project Review March 2014

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 channels will be digitized with commercial VME-based ADC, averaged down to 1 Hz 16 channels are spares March 2014US Belle II Independent Project Review15

Micro-TPC Fast Neutron Detectors March 2014US Belle II Independent Project Review16

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 March 2014US Belle II Independent Project Review17

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 Review March 2014

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 Review March 2014

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 Review March 2014

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 Review March 2014

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 Review March 2014

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 Review March 2014

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

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

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 Review March 2014

Micro-TPC Prototype Testing: Ongoing March 2014US Belle II Independent Project Review27

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

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 gain Gain stability, one week of operation n/a20%5%<2%Not yet measured 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

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/ March 2014US Belle II Independent Project Review30

BACKUP SLIDES US Belle II Independent Project Review March 2014

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

Angular Resolution Measurements, Final Micro-TPC Prototype 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

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 March 2014US Belle II Independent Project Review34

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) March 2014US Belle II Independent Project Review35

DAQ for PIN Diode System Digitize amplifier output with commercial ADC system Hytec MADC kHz 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 Review March 2014

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

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 March 2014US Belle II Independent Project Review38

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) March 2014US Belle II Independent Project Review39