Steve Dye, John Learned , Shigenobu Matsuno, Marc Rosen,

1. Steve Dye, John Learned, Shigenobu Matsuno, Marc Rosen, Michinari Sakai, Stefanie Smith, Gary Varner, and students Univ. of Hawaii: Plus some other colleagues elsewhere The mini-Time-Cube A Portable Directional Anti-Neutrino Detector Presentation at ANT11, Philadelphia, 10 October 2011

2. John Learned at ANT11 in Philadelphia mTC Idea • Do imaging with (100 ps) fast timing, not optics (time reversal imaging). • Small portable 2.2 liter scintillating cube, • Boron doped plastic. • 4 x 6 MCP (x64 pixels each) fast pixel detectors on surrounding faces • Get neutrino directionality. • Reject noise on the fly. • ~10/day anti-neutrino interactions (inverse beta decay signature) from power reactor (San Onofre). 13 cm 2.2 liter

3. John Learned at ANT11 in Philadelphia mTC Virtues • Small size avoids positron annihilation gammas which • smear resolution (Xo ~42 cm).... gammas mostly escape, • permitting precise positron creation point location. • Fast pixel timing (<100ps) and fast pipeline processing of • waveforms rejects background in real time. • Having many pixels plus use of first-in light permits mm precision in vertex locations. • Neutrino directionality via precision positron production • and neutron absorption locations. • No need for shielding (unlike other detectors). • Feasible even in high noise environment, near reactor • vessel, at surface (eg. in a truck).

4. John Learned at ANT11 in Philadelphia Snapshot of the Fermat Surface for a Single Muon-likeTrack Track Huygens wavelets Incoherent sum coincident with Cherenkov surface: Not polarized! J. Learned arXiv:0902.4009v1

5. John Learned at ANT11 in Philadelphia Time Reversal Image Reconstruction Figure by Mich Sakai

6. John Learned at ANT11 in Philadelphia Directional Measurement Hiroko Watanabe (Workshop Towards Neutrino Technologies 2009)

7. John Learned at ANT11 in Philadelphia Reactions in the Liquid Scintillator 2.α & triton stop ~immediately (mm). 2.40 cm γ radiation length. Hiroko Watanabe (Workshop Towards Neutrino Technologies 2009)

8. John Learned at ANT11 in Philadelphia Neutrino Capture Nucleus Choices Hiroko Watanabe (Workshop Towards Neutrino Technologies 2009)

9. John Learned at ANT11 in Philadelphia KamLAND Calculations KamLAND resolution Hiroko Watanabe (Workshop Towards Neutrino Technologies 2009)

10. John Learned at ANT11 in Philadelphia Study using KamLAND LS and Resolution Hiroko Watanabe (Workshop Towards Neutrino Technologies 2009) We can, in principle, do much better with mTC. Much further gain possible if can sense first neutron elastic scattering location.

11. John Learned at ANT11 in Philadelphia Gammas Usually Leave mTC Neutrino interaction point Mini-TimeCube Gamma from neutron inelastic capture 2m Gamma from positron annihilation Conclusion: Gammas from positron annihilation leave mTC detector without interaction, thus not confusing vertex resolution.

12. John Learned at ANT11 in Philadelphia Average over reactor spectum Inverse Beta Kinematics Neutron only gets 15.75 keV mean, most to positron. Trickier than you may realize... The positron gets the kinetic energy and the neutron gets the momentum. Plots by Stefanie Smith

13. John Learned at ANT11 in Philadelphia We can select an event sample with good pointing Early neutrino captures point better Most early captures out ~ cm distance Early n captures: strong correlation between neutron and positron scattering angles. Lower energies a little better

14. John Learned at ANT11 in Philadelphia Some tentative conclusions on neutrino direction determination in mTC • Get interaction vertex to ~1 mm and positron directions using fast timing and first hit reconstruction. • Proton scatters by neutron would be most useful, but probably not enough light to reconstruct. • Neutron capture location determined best with 6 Lithium by detecting alpha and triton. • Can select golden events for best pointing. How good still TBD. • Maximally utilize full information, employing full MaxL, yet to be done. • We are exploring use of a neural network.

15. John Learned at ANT11 in Philadelphia

16. John Learned at ANT11 in Philadelphia

17. John Learned at ANT11 in Philadelphia Fitting the Positron Streak

18. John Learned at ANT11 in Philadelphia First mTC version using B loaded plastic scintillator First casting with bubble from Eljen

19. John Learned at ANT11 in Philadelphia Mini-TimeCube + PMTs and Readout Electronics (Portable) Volume ~ (2 ft)3 Weight < 30 kg ~43cm (<1’6”) Plus separate processing electronics box.

20. John Learned at ANT11 in Philadelphia Examples of PMT Read-outs Developed by IDL, Hawaii (Gary Varner) Fast waveform digitizer for the Photonis MCP is currently under development evolving from existing technology used in BELLE, BESS, ANITA. Length beyond photo-sensor will be ~125mm. One module per MCP.

21. John Learned at ANT11 in Philadelphia Data Acquisition System (DAQ) Based on cPCI Format MCP PMT and Digitizer Internet x1 cPCI CPU 3Gbs fiber link x 8 x3 (= 24 PMTs) Data processing card (x3) cPCI crate

22. John Learned at ANT11 in Philadelphia Mini Time Cube: 13cm3 Boron Loaded Plastic Scintillator 38 cm MTC with read-out electronics on one face MTC fully populated with read-out electronics Computer and DAQ fits upper case Detector and power supplies in lower case MTC within 2ft3 anodized Al enclosure Stackable transport cases

23. John Learned at ANT11 in Philadelphia The mTC Being Assembled Gas and RF tight box Rosen design UV laser illumination

24. John Learned at ANT11 in Philadelphia Picosecond Calibration Laser System Matsuno/Rosen

25. John Learned at ANT11 in Philadelphia Estimate Real World Unshielded Noise Rate from Italian CORMORAD Experiment • Refer to CORMORAD talk given by Marco Battaglieri (Genoa) at Trieste 2009. • Prototype segmented detector of square logs of NE110 plastic scintillator, 3 inch PMTs on ends, 40x30x30 cm^3 total volume. • No shielding => big background, outside containment building. • CORMORAD noise rate near Romanian reactor: => R = ~120 Hz (single) => 2 x R^2 x τ = ~10 Hz (for two hits in time window τ = 330μs) • mTC noise rate implications: • ≤ 1/30 vol. x 1/10 time resol. x CORM. rate = few Hz in mTC • Similar numbers from 2 expts at San Onofre • (info: LLNL/Sandia group and Juan Collar) » good enough for real-time background analysis & rejection, with no shielding Software rejection needed ~10^5 (< KamLAND) ”A proposal for a high segmented power reactor antineutrino detector”, Marco Battaglieri, July 13~17, 2009, Workshop Towards Neutrino Technologies”

26. John Learned at ANT11 in Philadelphia Mini-TimeCube Sensitivity(13cm^3 cube with 24 MCP's) • Photo sensitive Area 75% coverage of 1,014 cm^2 • Pixel count 1536 (= 64/pmt * 4 pmt/side * 6 sides) • Typical reactor anti-neutrino several PE/pixel • 100ps MCP time resolution 2 mm spatial resolution/hit • 2 ns scintdecay constant 120 PE/MeV in first 200ps. • Vertex recon. with 1st hits ~1 mm level. • Rate ~10 anti-neutrino events/day (25m from 3.3GW reactor) • Rough cost ~$300K (includes electronics, mostly MCP tubes) • much less with future LAPPDs

27. John Learned at ANT11 in Philadelphia Summary of what we can measure • Neutrino energy, via positron energy • Positron vertex and direction. • Neutron capture point & direction from vertex to capture point. • Enough information to get neutrino direction along a cone and maybe better using full constraints. • Possibly more: total neutron kinetic energy. • Probably too difficult: location of first n scatter. • Conclusion: We can do better than anyone has in the past. How much better remains to be demonstrated.

28. John Learned at ANT11 in Philadelphia mTC Study and Plans • Backgrounds stopping muon, decay processes, random internal/external • gamma (from reactor), thermal neutron... • Solid scintillators boron loaded plastic from Eljen for initial build, not ideal • Liquid scintillators short n capture time, best n absorb vertex: 6Li loading... soon • Pulse shape discrimination for neutron capture? • Can we do anything with neutron elastic scattering? First scatter important but tough. • GEANT Simulation of mini-Time Cube in progress…. Understanding tricks of simple kinematics and determining if golden sample identifiable. • Careful evaluation of angular resolution with full analysis of waveforms. • Time to activation waiting on electronics construction. • mTC operating in Lab early 2012, and take to reactor ASAP thereafter.

29. John Learned at ANT11 in Philadelphia On the Road to Short and Long Range Nuclear Reactor Monitoring and Other Physics 2 liters mTC • Start with demonstrations of detection of • reactors, first close up, then further away. • Importance of directionality understood. • Focus upon resolving positron production and • neutron absorption locations. • Start with very small demonstration…. mTC. • Build ~1 m^3 detector, range to ~200m • Possible detailed search for short range oscillations • Place a number of modules in shipping container • and monitor out to few km 1 m^3 TC Truck size 200 m

30. John Learned at ANT11 in Philadelphia

31. John Learned at ANT11 in Philadelphia Photonis 8 x 8 Multi-channel plate PMT

32. John Learned at ANT11 in Philadelphia Evaluation MCP Signal Jean-Francois Genat, ANT Workshop, August 13, 2009 408nm laser, 100 Photo-Electrons Conclusion: Gain: 40mV/100PE ~ 0.4mV/PE (25m) at 2100 V 5mV/100PE ~ 50 V/PE (10m) at 2500V 10m longer trailing edge Seems that rise time does NOT depend upon the amplitude => We choose 25μm pore size Under development

33. John Learned at ANT11 in Philadelphia The Photo-Sensor: Photonis XP85012 (64 channel MCP)

34. John Learned at ANT11 in Philadelphia Impulse Dark Noise vs HV Conclusion: At optimum efficiency (25m 2000V, 10m 2400V), dark counts rates are: 25Hz (25m)‏, 20Hz (10m)‏ per pixel

35. John Learned at ANT11 in Philadelphia Neutron Capture Cross Section

36. John Learned at ANT11 in Philadelphia Neutrino Vertex Resolution • KamLAND example: center of ionization for e+ and n capture >10 cm… not useful for present concerns. • 120 PE/MeV on Fermat surface => ~20mm/sqrt(120*E/MeV) = 1.3 mm • (2 MeV anti-neutrino). • Neutrino Vertex Resolution => Several mm -> directionality • Problem: exponential decay of scintillator. • Solution: employ first hits • In actuality do full liklihood analysis. Initial promising results from NGA collaborators employing medical imaging like algorithms.