1. Next Steps In Applied Antineutrino Physics at LLNL
Monitoring happens once per year now
Can do as well as needed approaching S.Q., don’t need to do SQ, they don’t do SQ.
Long term goal is state of the art
Show error bars on slide 16 (plot)
Required by IAEA safegaurds (plutonium inventory for reprocessing)
Muon and gamma backgrounds
Cladnestine production not allowed
Positive spin on talk
Current data with cuts
Adam Bernstein, Group Leader,
Advanced Detectors Group,
Lawrence Livermore National Laboratory Dec
neutrinos.llnl.gov
nuclear.llnl.gov

2. Outline LLNL/SNL Work to Date
Thoughts about Practical Near-Field Monitoring
Next Steps at LLNL
Range Extension: Studies of Argon Coherent Scatter Detection
Understanding Backgrounds and Operating at the Surface of the Earth
White Paper Status

3. “Standard” Applied Antineutrino Physics at LLNL/SNL
Determine on/off status
within 5 hours with 99.9% C.L.
Measure thermal power to 3% in one week
Track Pu content to ~50 kg - with known power and initial fuel content
burnup model with one free parameter
Time in hours
130
Detector is stable to ~ 1%; burnup is ~ 10%
J. App. Phys.
publication pending
Relative count rate
1.5 tons 235U consumed 250 kg Pu produced
Continuous, non-intrusive, self-calibrated, unattended, low cost and channel count, operable for months to years with rare maintenance
NIM A 572 (2007)

4. What is Needed for Near-Field Cooperative Monitoring and Safeguards ?
3x3x3 meter deployment at SONGS is already demonstrably non-intrusive for reactor operators
Acceptance depends on ability to meet diversion detection goals, cost, ease of use and operator/IAEA acceptance - not primarily on the physical footprint
there is plenty of physical space with overburden in many safeguarded reactors worldwide
New designs will be non-toxic, have negligible flammability, no cryogenics, be self-calibrated and easy to deploy
For Near-Field Monitoring at meters, Inverse Beta Detectors May Suffice
What is the Use of Coherent Scatter Detectors ?
Above-Ground Detection Would Expand Deployment Opportunities

5. Basic Principles of Coherent Scattering
Antineutrino
ν + Ar → ν + Ar
Energies 
E(MeV)
<Erecoil> (keV)
Reactor  1 8 
2.5
Solar  2 15 
9.0
Supernova  10 50 
100
Neutrino-nucleus scatter coherent for
En < 50 MeV (in Argon)
supernova, solar, reactor neutrinos
Recoil energies
among noble elements Argon (Z=18) gives the greatest number of detectable ionizations per unit mass
dP*dR < 1 (momentum transfer) (saying wavelength is better than momentum transfer)
Freedom to adjust E fields independently. Not, one is larger than the other
Atomic Number
Cross-section
Neutron Number

6. Beyond Cross-Section: Detectable Coherent Scatter Rates For Reactor Monitoring
Discovery - Ge and Ar both have potential
Exploitation – Argon enjoys scalability and (possibly) cost advantages
Element A N
Events Per Kg/Day/3GWt – 25 m standoff
Assumptions Ar 40 22 4 20
>2 primary electrons
>1 primary electron
Germanium 72 41 2 28
330 eV threshold
100 eV threshold
Charged Current for comparison -
0.6
1.5
10% efficiency (SONGS)
25% efficiency (Palo Verde)
Full CNS detection efficiency required for any significant reduction in footprint
Near-field deployment needs already well met with well engineered inverse beta detectors
There may be promise in scaling to kilometer ranges

7. 1-10 primary ionization electrons (after quenching
1-10 primary scintillation photons in liquid – very difficult to see these
1-10 primary ionization electrons (after quenching
>~25 photoelectrons per primary electron
Herein lies the signal
This signal strength has already been measured in existing ten kg noble detectors

8. Predicted Signal and Background in a 10 kg detector
Ar-39 the dominant background: what can be done about it ?
The neutrino signal including nuclear quenching
Modest (few cm) passive shields suffice to screen external backgrounds
In this simulation: external neutrons and gammas, internal Ar-39
Not yet in this simulation: PMTs ~10000 emitted gammas per day (20 mBq/tube)

9. Are PMT Backgrounds Manageable ?
~10,000 decays per day total from PMTs - must incorporate in model
Simulated internal backgrounds
In 100 kg xenon detector (5 keV threshold)
104 suppression
Fiducial and energy cuts should suppress these: most PMT gammas will be above energy threshold or multiply scatter
Real backgrounds
10 kg xenon detector (4.5 keV threshold)
59 days livetime

10. The Ar-39 beta background
565 keV endpoint – 0.9 Bq/kg in Natural Argon
An important background for coherent scatter
Gram quantities of depleted Ar created by recovery from underground natural gas reserves (Princeton, Calaprice, Galbiati et. al.)
Kilogram quantities manufactured by Russian group
Activity limit : at least a factor of 20 lower than natural Argon
This would eliminate Ar-39 as a concern for coherent scatter in Ar
cost could be an issue
discovery can be done even with Natural Ar

11. Is The Signal Within Reach of Existing Dual-Phase Detectors ?
Lossless drift of electrons over 10 cm distances amply demonstrated in many LAr/LXe experiments – Argon purification techniques are well understood
Sensitivity to single primary electrons –
accomplished in 10 kg Xe detectors (ZEPLIN, XENON10)
Quench factor:
gas-phase quench measurement, consistent with predictions, has been measured at LLNL – this must be repeated in liquid

12. Gas Phase Studies of Very Low Energy Nuclear Recoils
Field cage mounted inside
Argon-filled chamber
12 in.
Calibration & Noise-floor estimation
Calibration 55Fe
5.9 keV X-rays
Noise wall
Single-
photoelectron
response of PMT
Energy (integral units)
By studying nuclear recoils in the gas phase, we learn about: ionization, gas phase quenching, light collection, scintillation properties
Only 1 PMT in this detector
~20 in full scale detector
1% Ni for wavelngth shifting

13. 60 keV Neutron Source: Neutrons Recoils at 8 keV and below
Borated plastic
Neutron shield
Lead
Gamma shield
LLNL LINAC Li-target
~60 keV neutron generator
Argon detector
7Li (p,n) 7Be
100 Hz rep. rate
~105 neutrons / spill
Neutron beam
Gamma
Background
478 keV from 7Li(p,p’)

14. The Predicted Recoil Spectrum
Actual detector response including PMT coll. eff.
Predicted effect of quenching
Deposited energy (before quenching)
keV
1) Incident neutrons selected by resonance
2-4) Neutron kinematics, quenching
optical collection efficiency

15. A Menagerie of Raw Events
Gate width
Single p.e.
~20 ns
X-ray or
neutron
~2 s
Extended event
~6 s
200-μsec time trace during neutron beam measurement -
←Neutron beam on→

16. Extraction of a Quench Factor –the Lowest Ever Measured in Ar ?
Energy threshold for neutron recoils
Gamma signal only above neutron recoil threshold
Derived
Quench factor:
(preliminary)
0.22
Predicted: 0.2
Residual signal attributed to neutrons
8 keV neutron recoil generates 1.8 keV electron equivalent energy deposition

17. For comparison: Liquid n-recoil Results from McKinsey Group, Yale

18. A 10 kg Liquid Argon Coherent Neutrino DetectorHV
Design by W. Stoeffl
Coherent Scatter Group:
Chris Hagmann
Celeste Winant
Kareem Kazkaz
Igor Jovanovic
Michael Foxe
Wolfgang Stoeffl
Turbo-pump
Pulse tube fridge
PMTs
Valves
Support
Bellows
Level gauge
Gain region
Super
Insulation
Drift region
Opening too many possibilities? Just list PMTs
Design on paper, issues are thought out
Borrow technology from Xenon
Central liq. Ar container surrounded by vacuum shroud.
Warm vacuum feedthroughs, stratified Ar gas into the feedthrough flange.
Phototubes radiatively cooled to ~ -30C.
Few % N2 added to Ar gas for enhanced near-UV scintillation.
DAQ built around fast digitizing readout of PMT
Liquid Nitrogen transport reservoir
Insulation Vacuum
Liquid Argon 87K

19. Background Considerations for Antineutrino Detectors at the Surface of the Earth
Veto trigger rates increase by 5-10 relative to ‘SONGS1’ - what about deadtime ?
Correlated backgrounds gammas neutrons, pions, protons - are an additional concern, beyond the usual problem of time-correlated events from muons
We are just beginning to study this problem

20. First Consideration: Shrink Deadtime By Shrinking Detector
SONGS (3 meter)3 veto - ~30% dead at sea level (~5% at 10 m.w.e.)
(1.5 meter)3 detector/veto – ~5% dead time at sea level - but more elaborate vetoing strategies may be needed
* “Standard” veto (100 microsecond following any cosmic)
Example: (water detector now
deployed at SONGS,
below ground)
Target (1.5 m)3
Current (3 m)3

21. Second Consideration: Studying Above Ground Time Correlated Backgrounds
Characterize with Monte Carlo
Measure in meter2 detector arrays (Muon, Liquid Scint., Plastic, 3He)
Deploy existing prototypes at SONGS and measure signal and background empirically in antineutrino detectors
Explore alternative means to reject backgrounds
Water Cerenkov detectors
Segmentation (Jim’s talk)
Others..

22. Monte Carlo Generation and Detection of Sea Level Backgrounds
A) Public Code package CRY: nuclear.llnl.gov
Due to strong natl. lab interest in surface detection of plutonium and uranium, codes exist to study time correlated backgrounds at sea level – like antineutrinos, fission chains are highly time correlated
All secondaries propagated through 42 layers of atmosphere time correlated energy spectra recorded with up to 300 m horiz separation
B) GEANT and MCNP models of detectors

23. Benchmark examples from sea-level flux (CRY) code
- Muon, Pion, Neutron energy spectra match h.e. data

24. A First Comparison (For Us) Of Sea Level Showers In Meter2 Detector Arrays
Cumulative
number of
counts
Simulation
Time until
Next count
2 minutes
Cumulative
number of
counts
Data
Time until
Next count
2 seconds
Mixed Array of 3He, NaI, PSD and plastic– 100 detectors, here near 1 ton of lead

25. B) Initial Background Modeling For Water Cerenkov Detectors
Fast neutrons should not be problem since they are below the Cerenkov threshold up to high energies
But: energy scale is smeared by low light collection
250 kg detector Now deployed
below-ground
At San Onofre
above-ground test
in ’08-09

26. Conclusions
Dual Phase Detectors appear to have the sensitivity needed for coherent scatter discovery
Significant Infrastructure for background measurement and modeling at the Earth’s surface will help guide and small surface antineutrino detector designs

27. A Range of Applications
Near Field
Mid-Field
Far-Field
Use
Power, Pu content, operational status
Exclude presence of an operating reactor
Example Application: (no interest or disinterest imputed to any USG entity! )
Material Accountancy for Current IAEA Safeguards
Installation at Yong Byon in North Korea to exclude operational reactors
Installation in P.G to detect/exclude reactors in Gulf States of interest
Reactor Power
GWt
10 MWt <~1 bomb/year
10 MWt <~1 bomb/year
Standoff/Sensitive Radius
5-50 m
6 km
250 km
Detector Size
1-100 ton with shielding
600 tons (KamLAND fiducial)
1,000,000 tons
Rate
events per day (eff~ )
16 events per year (25% power measurement)

28. Summary for policy and physics community to
White Paper: A Review of the State of the Art in Antineutrino Detection as Applied to Nonproliferation of Nuclear Weapons
Summary for policy and physics community to
understand state of the art and R&D program
1 Introduction 1
2 Current Safeguards and Cooperative Monitoring Practice for Light Water Reactors 3
3 Current Nuclear Explosion Detection Technology 10
4 Production and Detection of Antineutrinos From Nuclear Reactors and Nuclear Explosions 11
5 Near-Field Detection 13
6 Mid-Field Detection 13
7 Far-Field Detection 14
8 Overview of Fundamental Physics Using Reactor Antineutrinos 17
Research and Development Needs for Basic and Applied Antineutrino
Detection 25
Inputs received for all but two chapters
editing in progress..