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

10 October 2011John Learned at ANT11 in Philadelphia2 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

10 October 2011John Learned at ANT11 in Philadelphia3 mTC Virtues Small size avoids positron annihilation gammas which smear resolution (X o ~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).

10 October 2011John Learned at ANT11 in Philadelphia4 Snapshot of the Fermat Surface for a Single Muon-likeTrack Track Huygenswavelets Incoherent sum coincident with Cherenkov surface: Not polarized! J. Learned arXiv: v1

Time Reversal Image Reconstruction 10 October 2011John Learned at ANT11 in Philadelphia5 Figure by Mich Sakai

10 October 2011John Learned at ANT11 in Philadelphia6 Hiroko Watanabe (Workshop Towards Neutrino Technologies 2009) Directional Measurement

10 October 2011John Learned at ANT11 in Philadelphia cm γ radiation length. 2.α & triton stop ~immediately (mm). Hiroko Watanabe (Workshop Towards Neutrino Technologies 2009) Reactions in the Liquid Scintillator

10 October 2011John Learned at ANT11 in Philadelphia8 Hiroko Watanabe (Workshop Towards Neutrino Technologies 2009) Neutrino Capture Nucleus Choices

10 October 2011John Learned at ANT11 in Philadelphia9 Hiroko Watanabe (Workshop Towards Neutrino Technologies 2009) KamLAND resolution KamLAND Calculations

10 October 2011John Learned at ANT11 in Philadelphia10 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.

10 October 2011John Learned at ANT11 in Philadelphia11 Gammas Usually Leave mTC Gamma from neutron inelastic capture Gamma from positron annihilation 2m Neutrino interaction point Conclusion: Gammas from positron annihilation leave mTC detector without interaction, thus not confusing vertex resolution. Mini-TimeCube

Inverse Beta Kinematics 10 October 2011John Learned at ANT11 in Philadelphia12 Trickier than you may realize... The positron gets the kinetic energy and the neutron gets the momentum. Neutron only gets keV mean, most to positron. Average over reactor spectum Plots by Stefanie Smith

We can select an event sample with good pointing 10 October 2011John Learned at ANT11 in Philadelphia13 Early neutrino captures point better Early n captures: strong correlation between neutron and positron scattering angles. Most early captures out ~ cm distance Lower energies a little better

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. 10 October 2011John Learned at ANT11 in Philadelphia14

10 October 2011John Learned at ANT11 in Philadelphia15

10 October 2011John Learned at ANT11 in Philadelphia16

10 October 2011John Learned at ANT11 in Philadelphia17 Fitting the Positron Streak

10 October 2011John Learned at ANT11 in Philadelphia18 First mTC version using B loaded plastic scintillator First casting with bubble from Eljen

10 October 2011John Learned at ANT11 in Philadelphia19 Mini-TimeCube + PMTs and Readout Electronics (Portable) ~43cm (<1’6”) Volume ~ (2 ft) 3 Weight < 30 kg Plus separate processing electronics box.

10 October 2011John Learned at ANT11 in Philadelphia20 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.

10 October 2011John Learned at ANT11 in Philadelphia21 Data processing card (x3) cPCI crate cPCI CPU Data Acquisition System (DAQ) Based on cPCI Format 3Gbs fiber link x 8 x3 (= 24 PMTs) x1 MCP PMT and Digitizer Internet

10 October 2011John Learned at ANT11 in Philadelphia22 Mini Time Cube: 13cm 3 Boron Loaded Plastic Scintillator MTC with read-out electronics on one face MTC fully populated with read-out electronics 38 cm MTC within 2ft 3 anodized Al enclosure Stackable transport cases Computer and DAQ fits upper case Detector and power supplies in lower case

The mTC Being Assembled 10 October 2011John Learned at ANT11 in Philadelphia23 Gas and RF tight box UV laser illumination Rosen design

Picosecond Calibration Laser System 10 October 2011John Learned at ANT11 in Philadelphia24 Matsuno/Rosen

10 October 2011John Learned at ANT11 in Philadelphia25 Estimate Real World Unshielded Noise Rate from Italian CORMORAD Experiment Refer to CORMORAD talk given by Marco Battaglieri (Genoa) at Trieste 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”

10 October 2011John Learned at ANT11 in Philadelphia26 Mini-TimeCube Sensitivity (13cm^3 cube with 24 MCP's) Photo sensitive Area75% coverage of 1,014 cm^2 Pixel count1536 (= 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 scint decay constant120 PE/MeV in first 200ps. Vertex recon. with 1 st 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

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. 10 October 2011John Learned at ANT11 in Philadelphia27

10 October 2011John Learned at ANT11 in Philadelphia28 mTC Study and Plans Backgroundsstopping muon, decay processes, random internal/external gamma (from reactor), thermal neutron... Solid scintillatorsboron loaded plastic from Eljen for initial build, not ideal Liquid scintillatorsshort 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.

10 October 2011John Learned at ANT11 in Philadelphia29 On the Road to Short and Long Range Nuclear Reactor Monitoring and Other Physics 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 2 liters mTC 1 m^3 Truck size TC 200 m

10 October 2011John Learned at ANT11 in Philadelphia30

10 October 2011John Learned at ANT11 in Philadelphia31 Photonis 8 x 8 Multi-channel plate PMT

10 October 2011John Learned at ANT11 in Philadelphia32 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 25 μ m pore size Evaluation MCP Signal Under development Jean-Francois Genat, ANT Workshop, August 13, 2009

10 October 2011John Learned at ANT11 in Philadelphia33 The Photo-Sensor: Photonis XP85012 (64 channel MCP)

10 October 2011John Learned at ANT11 in Philadelphia34 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

10 October 2011John Learned at ANT11 in Philadelphia35 Neutron Capture Cross Section

10 October 2011John Learned at ANT11 in Philadelphia36 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.